Bolides

@article{denning1881bolides,
    author = "Denning, W. F.",
    title = "[Bolides]",
    year = "1881",
    journal = "Science",
    url = "https://doi.org/10.1126/science.os-2.29.22-b",
    doi = "10.1126/science.os-2.29.22-b",
    number = "29",
    pages = "22-22",
    volume = "os-2"
}

@article{audax1894aerolites,
    author = "Audax, Celer Et",
    title = "Aerolites: Bolides",
    year = "1894",
    journal = "Notes and Queries",
    url = "https://doi.org/10.1093/nq/s8-v.126.412c",
    doi = "10.1093/nq/s8-v.126.412c",
    number = "126",
    pages = "412-412",
    volume = "s8-V"
}

Asteroids that can intersect the orbit of the earth are discussed, which include Aten asteroids (semimajor axis (a) less than 1 AU, aphelion greater than 0.983 AU), Apollo asteroids (a greater than 1 AU, perihelion less than 1.017 AU), and Amor asteroids (perihelion distance between 1.017 and 1.3 AU). The principal sources of earth-crossing asteroids appear to be extinct comet nuclei and collision fragments from regions in the main asteroid belt. The total population of earth-crossers is estimated at 13,000, of which approximately 8% are Atens, 50% are Apollos, and 40% are Amors,and the present collision rate of such asteroids with the earth is estimated at about 3.5 objects, to absolute magnitude 18, per million years.

@article{openalexw1615946943,
    author = "Shoemaker, E. M. and Williams, J. G. and Helin, E. F. and Wolfe, R. F.",
    title = "Earth-crossing asteroids - Orbital classes, collision rates with earth, and origin",
    year = "1979",
    journal = "NASA Technical Reports Server (NASA)",
    abstract = "Asteroids that can intersect the orbit of the earth are discussed, which include Aten asteroids (semimajor axis (a) less than 1 AU, aphelion greater than 0.983 AU), Apollo asteroids (a greater than 1 AU, perihelion less than 1.017 AU), and Amor asteroids (perihelion distance between 1.017 and 1.3 AU). The principal sources of earth-crossing asteroids appear to be extinct comet nuclei and collision fragments from regions in the main asteroid belt. The total population of earth-crossers is estimated at 13,000, of which approximately 8\% are Atens, 50\% are Apollos, and 40\% are Amors,and the present collision rate of such asteroids with the earth is estimated at about 3.5 objects, to absolute magnitude 18, per million years.",
    openalex = "W1615946943"
}

Platinum metals are depleted in the earth's crust relative to their cosmic abundance; concentrations of these elements in deep-sea sediments may thus indicate influxes of extraterrestrial material. Deep-sea limestones exposed in Italy, Denmark, and New Zealand show iridium increases of about 30, 160, and 20 times, respectively, above the background level at precisely the time of the Cretaceous-Tertiary extinctions, 65 million years ago. Reasons are given to indicate that this iridium is of extraterrestrial origin, but did not come from a nearby supernova. A hypothesis is suggested which accounts for the extinctions and the iridium observations. Impact of a large earth-crossing asteroid would inject about 60 times the object's mass into the atmosphere as pulverized rock; a fraction of this dust would stay in the stratosphere for several years and be distributed worldwide. The resulting darkness would suppress photosynthesis, and the expected biological consequences match quite closely the extinctions observed in the paleontological record. One prediction of this hypothesis has been verified: the chemical composition of the boundary clay, which is thought to come from the stratospheric dust, is markedly different from that of clay mixed with the Cretaceous and Tertiary limestones, which are chemically similar to each other. Four different independent estimates of the diameter of the asteroid give values that lie in the range 10 +/- 4 kilometers.

@article{doi101126science20844481095,
    author = "Alvarez, Luis W. and Álvarez, Walter and Asaro, Frank and Michel, Helen V.",
    title = "Extraterrestrial Cause for the Cretaceous-Tertiary Extinction",
    year = "1980",
    journal = "Science",
    abstract = "Platinum metals are depleted in the earth's crust relative to their cosmic abundance; concentrations of these elements in deep-sea sediments may thus indicate influxes of extraterrestrial material. Deep-sea limestones exposed in Italy, Denmark, and New Zealand show iridium increases of about 30, 160, and 20 times, respectively, above the background level at precisely the time of the Cretaceous-Tertiary extinctions, 65 million years ago. Reasons are given to indicate that this iridium is of extraterrestrial origin, but did not come from a nearby supernova. A hypothesis is suggested which accounts for the extinctions and the iridium observations. Impact of a large earth-crossing asteroid would inject about 60 times the object's mass into the atmosphere as pulverized rock; a fraction of this dust would stay in the stratosphere for several years and be distributed worldwide. The resulting darkness would suppress photosynthesis, and the expected biological consequences match quite closely the extinctions observed in the paleontological record. One prediction of this hypothesis has been verified: the chemical composition of the boundary clay, which is thought to come from the stratospheric dust, is markedly different from that of clay mixed with the Cretaceous and Tertiary limestones, which are chemically similar to each other. Four different independent estimates of the diameter of the asteroid give values that lie in the range 10 +/- 4 kilometers.",
    url = "https://doi.org/10.1126/science.208.4448.1095",
    doi = "10.1126/science.208.4448.1095",
    openalex = "W2110619496",
    references = "doi101007bf00212446, doi1010160016703773900665, doi1010160031018268900473, doi101038242032a0, doi101038267403a0, doi1010970001069419540800000019, doi101126science18441411079, doi10113000167606197788374ucmsag20co2, doi10113000167606197788383ucmsag20co2, doi101146annurevea07050179001115"
}

@misc{crossref1982geological,
    title = "Geological Implications of Impacts of Large Asteroids and Comets on the Earth",
    year = "1982",
    url = "https://doi.org/10.1130/spe190",
    doi = "10.1130/spe190",
    openalex = "W1568935506"
}

@misc{silver1982geological3,
    author = "Silver, L. T. and Schultz, P. H",
    title = "Geological implications of impacts of large asteroids and comets on the earth",
    year = "1982",
    howpublished = "Boulder, Colorado, Geological Society of America, 528 p.; Geological Society of America Special Paper, No. 190",
    note = "talkorigins\_source = {true}; raw\_reference = {Silver, L. T., and Schultz, P. H., 1982, Geological implications of impacts of large asteroids and comets on the earth: Boulder, Colorado, Geological Society of America, 528 p.; Geological Society of America Special Paper, No. 190.}"
}

Two classes of solid bodies large enough to be detected by telescopes occur in orbits that overlap that of the Earth. These bodies are the Earth-crossing asteroids and comet nuclei. Although their orbits only rarely intersect the Earth's, the probabilities of their collision with the Earth are nevertheless finite and calculable. Systematic telescopic surveys carried out over the past two decades show that the flux of asteroids and comet nuclei in the Earth's neighborhood is sufficiently high that the effects of occasional collisions should be recognizable in the geological record. During these same two decades, an intensive international search for ancient impact structures has gone forward. The actual rate of bombardment of the Earth during the last half-billion years has been found to be roughly consistent with the present rate predicted from astronomical observations. Within a factor of about two, the average rate of bombardment of the Earth during the last half­ billion years also appears to be consistent with the average rate of bombardment of the Moon over the last 3.3 billion years. Spectacular new lines of study have developed in recent years leading to the recognition of rare large impact events that produce geochemical anomalies on a global scale. The possible effects of these large impacts on the Earth's biota have become the subject of vigorous debate. In this paper, I first review the astronomical and geologic evidence concerning the history of bombardment and then discuss the physical effects of large impacts, as they may apply to both the inorganic and organic worlds.

@article{doi101146annurevea11050183002333,
    author = "Shoemaker, Eugene M.",
    title = "ASTEROID AND COMET BOMBARDMENT OF THE EARTH",
    year = "1983",
    journal = "Annual Review of Earth and Planetary Sciences",
    abstract = "Two classes of solid bodies large enough to be detected by telescopes occur in orbits that overlap that of the Earth. These bodies are the Earth-crossing asteroids and comet nuclei. Although their orbits only rarely intersect the Earth's, the probabilities of their collision with the Earth are nevertheless finite and calculable. Systematic telescopic surveys carried out over the past two decades show that the flux of asteroids and comet nuclei in the Earth's neighborhood is sufficiently high that the effects of occasional collisions should be recognizable in the geological record. During these same two decades, an intensive international search for ancient impact structures has gone forward. The actual rate of bombardment of the Earth during the last half-billion years has been found to be roughly consistent with the present rate predicted from astronomical observations. Within a factor of about two, the average rate of bombardment of the Earth during the last half­ billion years also appears to be consistent with the average rate of bombardment of the Moon over the last 3.3 billion years. Spectacular new lines of study have developed in recent years leading to the recognition of rare large impact events that produce geochemical anomalies on a global scale. The possible effects of these large impacts on the Earth's biota have become the subject of vigorous debate. In this paper, I first review the astronomical and geologic evidence concerning the history of bombardment and then discuss the physical effects of large impacts, as they may apply to both the inorganic and organic worlds.",
    url = "https://doi.org/10.1146/annurev.ea.11.050183.002333",
    doi = "10.1146/annurev.ea.11.050183.002333",
    openalex = "W2137685264",
    references = "openalexw1615946943"
}

@article{mclaren1983bolides,
    author = "McLAREN, DIGBY J.",
    title = "Bolides and biostratigraphy",
    year = "1983",
    journal = "Geological Society of America Bulletin",
    url = "https://doi.org/10.1130/0016-7606(1983)94<313:bab>2.0.co;2",
    doi = "10.1130/0016-7606(1983)94<313:bab>2.0.co;2",
    number = "3",
    pages = "313",
    volume = "94"
}

@misc{davis1984extinction1,
    author = "Davis, M. and Hut, P. and Muller, R. A",
    title = "Extinction by periodic comet showers",
    year = "1984",
    howpublished = "Nature, v. 308, p. 715-717",
    note = "talkorigins\_source = {true}; raw\_reference = {Davis, M., Hut, P., and Muller, R. A., 1984, Extinction by periodic comet showers: Nature, v. 308, p. 715-717.}"
}

The Earth-approaching asteroids 1986 DA and 1986 EB are found to belong to the M class of asteroids. These are the first of this class to be identified among the Aten, Apollo, and Amor populations. The inferred composition of the M class asteroids is primary metallic iron. If this is indeed the case, then current models for meteorite production based on strength-related collisional processes on asteroidal surfaces predict that these two objects alone should produce about 1% of all meteorite falls. The relative abundances of classes C, S, M, and "other" among the near-Earth asteroid population are remarkably similar to those found in the inner asteroid belt between the 3:1 and 5:2 resonances, i.e., between 2.50 and 2.82 AU. This dominating presence of the three major asteroid taxonomic classes among the Earth-approaching population argues strongly in favor of an asteroidal source for most such objects. This conclusion leads to the suggestion that "extinct" comet nuclei, if of a composition other than that found in the asteroid belt, are rare, if they exist at all.

@article{doi101086114356,
    author = "Tedesco, E. F. and Gradie, J.",
    title = "Discovery of M class objects among the near-earth asteroid population",
    year = "1987",
    journal = "The Astronomical Journal",
    abstract = {The Earth-approaching asteroids 1986 DA and 1986 EB are found to belong to the M class of asteroids. These are the first of this class to be identified among the Aten, Apollo, and Amor populations. The inferred composition of the M class asteroids is primary metallic iron. If this is indeed the case, then current models for meteorite production based on strength-related collisional processes on asteroidal surfaces predict that these two objects alone should produce about 1\% of all meteorite falls. The relative abundances of classes C, S, M, and "other" among the near-Earth asteroid population are remarkably similar to those found in the inner asteroid belt between the 3:1 and 5:2 resonances, i.e., between 2.50 and 2.82 AU. This dominating presence of the three major asteroid taxonomic classes among the Earth-approaching population argues strongly in favor of an asteroidal source for most such objects. This conclusion leads to the suggestion that "extinct" comet nuclei, if of a composition other than that found in the asteroid belt, are rare, if they exist at all.},
    url = "https://doi.org/10.1086/114356",
    doi = "10.1086/114356",
    openalex = "W2018726674"
}

We report 10 micrometers infrared photometry for 22 Aten, Apollo, and Amor asteroids. Thermal models are used to derive the corresponding radiometric albedos and diameters. Several of these asteroids appear to have surfaces of relatively high thermal inertia due to the exposure of bare rock or a coarse regolith. The Apollo asteroid 3103, 1982 BB, is recognized as class E. The Jupiter-crossing Amor asteroid 3552, 1983 SA, is confirmed as class D, but low albedos remain rare for near-Earth asteroids.

@article{doi101086115064,
    author = "Veeder, G. J. and Hanner, M. S. and Matson, D. L. and Tedesco, E. F. and Lebofsky, L. A. and Tokunaga, A. T.",
    title = "Radiometry of near-earth asteroids",
    year = "1989",
    journal = "The Astronomical Journal",
    abstract = "We report 10 micrometers infrared photometry for 22 Aten, Apollo, and Amor asteroids. Thermal models are used to derive the corresponding radiometric albedos and diameters. Several of these asteroids appear to have surfaces of relatively high thermal inertia due to the exposure of bare rock or a coarse regolith. The Apollo asteroid 3103, 1982 BB, is recognized as class E. The Jupiter-crossing Amor asteroid 3552, 1983 SA, is confirmed as class D, but low albedos remain rare for near-Earth asteroids.",
    url = "https://doi.org/10.1086/115064",
    doi = "10.1086/115064",
    openalex = "W2052361063"
}

The discovery circumstances of the near-earth asteroids (NEAs) were modeled in order to investigate the observational selection effects associated with NEAs. It is suggested that these selection effects are responsible for the apparent overabundance of S types among the NEAs and that this overabundance is in part a result of the larger phase darkening of the C types over the S types. The large phase angles and preferential phase darkening of the C type NEAs force some of them below the threshold of detectability (in a magnitude-limited survey), thus exaggerating the number of S type NEAs.

@article{doi101086115267,
    author = "Luu, Jane and Jewitt, David",
    title = "On the relative numbers of C types and S types among near-earth asteroids",
    year = "1989",
    journal = "The Astronomical Journal",
    abstract = "The discovery circumstances of the near-earth asteroids (NEAs) were modeled in order to investigate the observational selection effects associated with NEAs. It is suggested that these selection effects are responsible for the apparent overabundance of S types among the NEAs and that this overabundance is in part a result of the larger phase darkening of the C types over the S types. The large phase angles and preferential phase darkening of the C type NEAs force some of them below the threshold of detectability (in a magnitude-limited survey), thus exaggerating the number of S type NEAs.",
    url = "https://doi.org/10.1086/115267",
    doi = "10.1086/115267",
    openalex = "W1963918109"
}

It has long been speculated that Earth accreted prebiotic organic molecules important for the origins of life from impacts of carbonaceous asteroids and comets during the period of heavy bombardment 4.5 x 10(9) to 3.8 x 10(9) years ago. A comprehensive treatment of comet-asteroid interaction with the atmosphere, surface impact, and resulting organic pyrolysis demonstrates that organics will not survive impacts at velocities greater than about 10 kilometers per second and that even comets and asteroids as small as 100 meters in radius cannot be aerobraked to below this velocity in 1-bar atmospheres. However, for plausible dense (10-bar carbon dioxide) early atmospheres, we find that 4.5 x 10(9) years ago Earth was accreting intact cometary organics at a rate of at least approximately 10(6) to 10(7) kilograms per year, a flux that thereafter declined with a half-life of approximately 10(8) years. These results may be put in context by comparison with terrestrial oceanic and total biomasses, approximately 3 x 10(12) kilograms and approximately 6 x 10(14) kilograms, respectively.

@article{doi101126science11538074,
    author = "Chyba, Christopher F. and Thomas, Paul J. and Brookshaw, Leigh and Sagan, Carl",
    title = "Cometary Delivery of Organic Molecules to the Early Earth",
    year = "1990",
    journal = "Science",
    abstract = "It has long been speculated that Earth accreted prebiotic organic molecules important for the origins of life from impacts of carbonaceous asteroids and comets during the period of heavy bombardment 4.5 x 10(9) to 3.8 x 10(9) years ago. A comprehensive treatment of comet-asteroid interaction with the atmosphere, surface impact, and resulting organic pyrolysis demonstrates that organics will not survive impacts at velocities greater than about 10 kilometers per second and that even comets and asteroids as small as 100 meters in radius cannot be aerobraked to below this velocity in 1-bar atmospheres. However, for plausible dense (10-bar carbon dioxide) early atmospheres, we find that 4.5 x 10(9) years ago Earth was accreting intact cometary organics at a rate of at least approximately 10(6) to 10(7) kilograms per year, a flux that thereafter declined with a half-life of approximately 10(8) years. These results may be put in context by comparison with terrestrial oceanic and total biomasses, approximately 3 x 10(12) kilograms and approximately 6 x 10(14) kilograms, respectively.",
    url = "https://doi.org/10.1126/science.11538074",
    doi = "10.1126/science.11538074",
    openalex = "W2076605024",
    references = "doi1010079789400972223, doi101016001670378990286x, doi1010160019103589901292, doi101016002199918790074x, doi101029jb091ib02p01921, doi101038190389a0, doi101038332691a0, doi101038333313a0, doi101038342139a0, doi101038342255a0, doi101038343129a0"
}

Approximately 90 Earth-crossing asteroids had been discovered through September 1989. Discovery is thought to be complete at absolute V magnitude (H) = 13.2 (the magnitude of the brightest known object, diameter ∼8.1 km), and about 6 percent complete at H = 17.7 (typical diameter about 1 km). The calculated mean probability of collision of Earth-crossing asteroids with Earth is (4.2 ± 1.7) × 10 −9yr −1. When multiplied by the estimated population of 1030 ± 470 at H = 17.7, this probability yields a collision rate of (4.3 ± 2.6) × 10 −6yr −1for asteroids larger than about 1 km in diameter. At H = 15.8, roughly equivalent to asteroid diameters more than 2 km, the estimated collision rate is ≈7 × 10 −7yr −1, and at 8-km diameter, the rate is ≈3 × 10 −9yr −1. Comet nuclei with diameters more than 2.5 km are estimated to strike the Earth at the rate of ≈ 10 −7yr −1; comets larger than 10 km in diameter probably strike at a rate ≈10 −8yr −1. Impact of asteroids probably dominates the production of craters smaller than 30 km in diameter, whereas comet impact probably forms most craters larger than 50 km. The production rate for craters larger than 20 km in diameter, estimated from the astronomical evidence, is (4.9 ± 2.9) × 10 −15km −2yr −1; this rate is consistent with the cratering rate estimated by Grieve from the geologic record for the last 120 m.y.

@incollection{doi101130spe247p155,
    author = "Shoemaker, Eugene M. and Wolfe, R. F. and Shoemaker, C. S.",
    title = "Asteroid and comet flux in the neighborhood of Earth",
    year = "1990",
    booktitle = "Geological Society of America eBooks",
    abstract = "Approximately 90 Earth-crossing asteroids had been discovered through September 1989. Discovery is thought to be complete at absolute V magnitude (H) = 13.2 (the magnitude of the brightest known object, diameter ∼8.1 km), and about 6 percent complete at H = 17.7 (typical diameter about 1 km). The calculated mean probability of collision of Earth-crossing asteroids with Earth is (4.2 ± 1.7) × 10 −9yr −1. When multiplied by the estimated population of 1030 ± 470 at H = 17.7, this probability yields a collision rate of (4.3 ± 2.6) × 10 −6yr −1for asteroids larger than about 1 km in diameter. At H = 15.8, roughly equivalent to asteroid diameters more than 2 km, the estimated collision rate is ≈7 × 10 −7yr −1, and at 8-km diameter, the rate is ≈3 × 10 −9yr −1. Comet nuclei with diameters more than 2.5 km are estimated to strike the Earth at the rate of ≈ 10 −7yr −1; comets larger than 10 km in diameter probably strike at a rate ≈10 −8yr −1. Impact of asteroids probably dominates the production of craters smaller than 30 km in diameter, whereas comet impact probably forms most craters larger than 50 km. The production rate for craters larger than 20 km in diameter, estimated from the astronomical evidence, is (4.9 ± 2.9) × 10 −15km −2yr −1; this rate is consistent with the cratering rate estimated by Grieve from the geologic record for the last 120 m.y.",
    url = "https://doi.org/10.1130/spe247-p155",
    doi = "10.1130/spe247-p155",
    openalex = "W2149644358"
}

Computer software, called the Moving Object Detection Program (MODP), is described which detects earth-approaching asteroids in near real time. The software runs on a workstation linked to the output of the drift-scanning CCD camera of the Spacewatch Telescope. MOPD recognizes trailed images, detects motion, and accurately determines angular positions and rates of motion for moving objects in the scan images. The results are obtained a few seconds after the image signals are shifted out of the CCD. During 2 months of trial observations with this system, 304 asteroids were detected down to a limiting apparent magnitude for untrailed images of V = 20.5.

@article{doi101086115785,
    author = "Rabinowitz, D.",
    title = "Detection of earth-approaching asteroids in near real time",
    year = "1991",
    journal = "The Astronomical Journal",
    abstract = "Computer software, called the Moving Object Detection Program (MODP), is described which detects earth-approaching asteroids in near real time. The software runs on a workstation linked to the output of the drift-scanning CCD camera of the Spacewatch Telescope. MOPD recognizes trailed images, detects motion, and accurately determines angular positions and rates of motion for moving objects in the scan images. The results are obtained a few seconds after the image signals are shifted out of the CCD. During 2 months of trial observations with this system, 304 asteroids were detected down to a limiting apparent magnitude for untrailed images of V = 20.5.",
    url = "https://doi.org/10.1086/115785",
    doi = "10.1086/115785",
    openalex = "W2008721775"
}

Impacts by Earth-approaching asteroids and comets pose a significant hazard to life and property. Although the annual probability of the Earth being struck by a large asteroid or comet is extremely small, the consequences of such a collision are so catastrophic that it is prudent to assess the nature of the threat and to prepare to deal with it. The first step in any program for the prevention or mitigation of impact catastrophes must involve a comprehensive search for Earth-crossing asteroids and comets and a detailed analysis of their orbits. At the request of the U.S. Congress, NASA has carried out a preliminary study to define a program for dramatically increasing the detection rate of Earth-crossing objects, as documented in this workshop report.

@article{openalexw1648623345,
    author = "Morrison, David",
    title = "The Spaceguard Survey: Report of the NASA International Near-Earth-Object Detection Workshop",
    year = "1992",
    journal = "NASA STI Repository (National Aeronautics and Space Administration)",
    abstract = "Impacts by Earth-approaching asteroids and comets pose a significant hazard to life and property. Although the annual probability of the Earth being struck by a large asteroid or comet is extremely small, the consequences of such a collision are so catastrophic that it is prudent to assess the nature of the threat and to prepare to deal with it. The first step in any program for the prevention or mitigation of impact catastrophes must involve a comprehensive search for Earth-crossing asteroids and comets and a detailed analysis of their orbits. At the request of the U.S. Congress, NASA has carried out a preliminary study to define a program for dramatically increasing the detection rate of Earth-crossing objects, as documented in this workshop report.",
    openalex = "W1648623345"
}

The effect of the atmosphere on impacting asteroids and comets is investigated. It is found that the atmosphere is inefficient in preventing impact damage to the ground when the radius of a stony asteroid exceeds 100 m and that of a comet exceeds 500 m. For iron meteorites that impact at greater than 20 km/s, the critical radius is about 20-30 m. For low-velocity iron meteorites that hit at 11.2-15 km/s, the critical radius is only 2 m. While the dissipation of energy in the atmosphere protects the ground from impact damage, it can enhance the damage done by the airburst. The area of destruction produced by the airburst during the impact of small asteroids can be up to twice as large as would have been the case had the same energy been released at sea level. The plumes of stony meteorites with radii over about 60 km break out of the atmosphere and float around the earth, carrying entrapped dust whose deposition may provide a counter for large meteorite impacts.

@article{doi101086116499,
    author = "Hills, J. G. and Goda, M. P.",
    title = "The fragmentation of small asteroids in the atmosphere",
    year = "1993",
    journal = "The Astronomical Journal",
    abstract = "The effect of the atmosphere on impacting asteroids and comets is investigated. It is found that the atmosphere is inefficient in preventing impact damage to the ground when the radius of a stony asteroid exceeds 100 m and that of a comet exceeds 500 m. For iron meteorites that impact at greater than 20 km/s, the critical radius is about 20-30 m. For low-velocity iron meteorites that hit at 11.2-15 km/s, the critical radius is only 2 m. While the dissipation of energy in the atmosphere protects the ground from impact damage, it can enhance the damage done by the airburst. The area of destruction produced by the airburst during the impact of small asteroids can be up to twice as large as would have been the case had the same energy been released at sea level. The plumes of stony meteorites with radii over about 60 km break out of the atmosphere and float around the earth, carrying entrapped dust whose deposition may provide a counter for large meteorite impacts.",
    url = "https://doi.org/10.1086/116499",
    doi = "10.1086/116499",
    openalex = "W2047757483"
}

@article{doi101038367033a0,
    author = "Chapman, C. R. and Morrison, David",
    title = "Impacts on the Earth by asteroids and comets: assessing the hazard",
    year = "1994",
    journal = "Nature",
    url = "https://doi.org/10.1038/367033a0",
    doi = "10.1038/367033a0",
    openalex = "W2057273337",
    references = "doi101038331612a0, doi101038361040a0, doi101126science2575072954, doi105860choice293880"
}

@article{openalexw3005477057,
    author = "Bowell, E. and Muinonen, K.",
    title = "Earth-crossing Asteroids and Comets: Groundbased Search Strategies",
    year = "1994",
    openalex = "W3005477057"
}

@incollection{schmeidler1994meteors,
    author = "Schmeidler, F.",
    title = "Meteors and Bolides",
    year = "1994",
    booktitle = "Compendium of Practical Astronomy",
    url = "https://doi.org/10.1007/978-3-642-45704-3\_9",
    doi = "10.1007/978-3-642-45704-3\_9",
    pages = "283-293"
}

In 1993, the U.S. Department of Defense declassified information dealing with frequent explosions in the upper atmosphere caused by meteoric impact. It is estimated that impacts have occurred of a magnitude equivalent to the atomic bomb detonated at Hiroshima. Not all such space voyagers meet their end in the atmosphere, however; huge craters attest to the bombardment of earth over millions of years, and a major impact may have resulted in the extinction of dinosaurs. An impact in Siberia near the beginning of this century proves that such events are not confined to geologic time. Hazards Due to Comets and Asteroids marks a significant step in the attempt to come to grips with the threats posed by such phenomena. It brings together more than one hundred scientists from around the world, who draw on observational and theoretical research to focus on the technical problems related to all aspects of dealing with these hazards: searching for and identifying hazardous comets and asteroids; describing their statistics and characteristics; intercepting and altering the orbits of dangerous objects; and applying existent technologies rocket boosters, rendezvous and soft-landing techniques, instrumentation to such missions. The book considers defensive options for diverting or disrupting an approaching body, including solar sails, kinetic-energy impacts, nuclear explosives, robotic mass drivers, and various propulsion systems. A cataclysmic impact posing a threat to life on Earth is a possibility that tomorrow's technology is capable of averting. This book examines in depth the reality of the threat and proposes practical measures that can be initiated now should we ever need to deal with it.

@article{doi105860choice330281,
    title = "Hazards due to comets and asteroids",
    year = "1995",
    journal = "Choice Reviews Online",
    abstract = "In 1993, the U.S. Department of Defense declassified information dealing with frequent explosions in the upper atmosphere caused by meteoric impact. It is estimated that impacts have occurred of a magnitude equivalent to the atomic bomb detonated at Hiroshima. Not all such space voyagers meet their end in the atmosphere, however; huge craters attest to the bombardment of earth over millions of years, and a major impact may have resulted in the extinction of dinosaurs. An impact in Siberia near the beginning of this century proves that such events are not confined to geologic time. Hazards Due to Comets and Asteroids marks a significant step in the attempt to come to grips with the threats posed by such phenomena. It brings together more than one hundred scientists from around the world, who draw on observational and theoretical research to focus on the technical problems related to all aspects of dealing with these hazards: searching for and identifying hazardous comets and asteroids; describing their statistics and characteristics; intercepting and altering the orbits of dangerous objects; and applying existent technologies rocket boosters, rendezvous and soft-landing techniques, instrumentation to such missions. The book considers defensive options for diverting or disrupting an approaching body, including solar sails, kinetic-energy impacts, nuclear explosives, robotic mass drivers, and various propulsion systems. A cataclysmic impact posing a threat to life on Earth is a possibility that tomorrow's technology is capable of averting. This book examines in depth the reality of the threat and proposes practical measures that can be initiated now should we ever need to deal with it.",
    url = "https://doi.org/10.5860/choice.33-0281",
    doi = "10.5860/choice.33-0281",
    openalex = "W1612135897"
}

@misc{schnug1995boundary,
    author = "Schnug, Ewald and Heym, Jürgen and Murphy, Donal P.",
    title = "Boundary Line Determination Technique (BOLIDES)",
    year = "1995",
    booktitle = "ASA, CSSA, and SSSA Books",
    url = "https://doi.org/10.2134/1995.site-specificmanagement.c66",
    doi = "10.2134/1995.site-specificmanagement.c66",
    pages = "899-908"
}

@inproceedings{donnell1996earthcrossing,
    author = "Donnell, Tyler",
    title = "Earth-Crossing Asteroids and Comets",
    year = "1996",
    booktitle = "Engineering, Construction, and Operations in Space V",
    url = "https://doi.org/10.1061/40177(207)175",
    doi = "10.1061/40177(207)175",
    openalex = "W2335444540",
    pages = "1278-1280"
}

We review the major impact‐associated mechanisms proposed to cause extinctions at the Cretaceous‐Tertiary geological boundary. We then discuss how the proposed extinction mechanisms may relate to the environmental consequences of asteroid and comet impacts in general. Our chief goal is to provide relatively simple prescriptions for evaluating the importance of impacting objects over a range of energies and compositions, but we also stress that there are many uncertainties. We conclude that impacts with energies less than about 10 Mt are a negligible hazard. For impacts with energies above 10 Mt and below about 10 4 Mt (i.e., impact frequencies less than one in 6 × 10 4 years, corresponding to comets and asteroids with diameters smaller than about 400 m and 650 m, respectively), blast damage, earthquakes, and fires should be important on a scale of 10 4 or 10 5 km², which corresponds to the area damaged in many natural disasters of recent history. However, tsunami excited by marine impacts could be more damaging, flooding a kilometer of coastal plain over entire ocean basins. In the energy range of 10 4 –10 5 Mt (intervals up to 3 × 10 5 years, corresponding to comets and asteroids with diameters up to 850 m and 1.4 km, respectively) water vapor injections and ozone loss become significant on the global scale. In our nominal model, such an impact does not inject enough submicrometer dust into the stratosphere to produce major adverse effects, but if a higher fraction of pulverized rock than we think likely reaches the stratosphere, stratospheric dust (causing global cooling) would also be important in this energy range. Thus 10 5 Mt is a lower limit where damage might occur beyond the experience of human history. The energy range from 10 5 to 10 6 Mt (intervals up to 2 × 10 6 years, corresponding to comets and asteroids up to 1.8 and 3 km diameter) is transitional between regional and global effects. Stratospheric dust, sulfates released from within impacting asteroids, and soot from extensive wild‐fires sparked by thermal radiation from the impact can produce climatologically significant global optical depths of the order of 10. Moreover, the ejecta plumes of these impacts may produce enough NO from shock‐heated air to destroy the ozone shield. Between 10 6 and 10 7 Mt (intervals up to 1.5 × 10 7 years, corresponding to comets and asteroids up to 4 and 6.5 km diameter), dust and sulfate levels would be high enough to reduce light levels below those necessary for photosynthesis. Ballistic ejecta reentering the atmosphere as shooting stars would set fires over regions exceeding 10 7 km², and the resulting smoke would reduce light levels even further. At energies above 10 7 Mt, blast and earthquake damage reach the regional scale (10 6 km²). Tsunami cresting to 100 m and flooding 20 km inland could sweep the coastal zones of one of the world's ocean basins. Fires would be set globally. Light levels may drop so low from the smoke, dust, and sulfate as to make vision impossible. At energies approaching 10 9 Mt (>10 8 years) the ocean surface waters may be acidified globally by sulfur from the interiors of comets and asteroids. The Cretaceous‐Tertiary impact in particular struck evaporate substrates that very likely generated a dense, widespread sulfate aerosol layer with consequent climatic effects. The combination of all of these physical effects would surely represent a devastating stress on the global biosphere.

@article{doi10102996rg03038,
    author = "Toon, O. B. and Zahnle, Kevin and Morrison, David and Turco, R. P. and Covey, Curt",
    title = "Environmental perturbations caused by the impacts of asteroids and comets",
    year = "1997",
    journal = "Reviews of Geophysics",
    abstract = "We review the major impact‐associated mechanisms proposed to cause extinctions at the Cretaceous‐Tertiary geological boundary. We then discuss how the proposed extinction mechanisms may relate to the environmental consequences of asteroid and comet impacts in general. Our chief goal is to provide relatively simple prescriptions for evaluating the importance of impacting objects over a range of energies and compositions, but we also stress that there are many uncertainties. We conclude that impacts with energies less than about 10 Mt are a negligible hazard. For impacts with energies above 10 Mt and below about 10 4 Mt (i.e., impact frequencies less than one in 6 × 10 4 years, corresponding to comets and asteroids with diameters smaller than about 400 m and 650 m, respectively), blast damage, earthquakes, and fires should be important on a scale of 10 4 or 10 5 km², which corresponds to the area damaged in many natural disasters of recent history. However, tsunami excited by marine impacts could be more damaging, flooding a kilometer of coastal plain over entire ocean basins. In the energy range of 10 4 –10 5 Mt (intervals up to 3 × 10 5 years, corresponding to comets and asteroids with diameters up to 850 m and 1.4 km, respectively) water vapor injections and ozone loss become significant on the global scale. In our nominal model, such an impact does not inject enough submicrometer dust into the stratosphere to produce major adverse effects, but if a higher fraction of pulverized rock than we think likely reaches the stratosphere, stratospheric dust (causing global cooling) would also be important in this energy range. Thus 10 5 Mt is a lower limit where damage might occur beyond the experience of human history. The energy range from 10 5 to 10 6 Mt (intervals up to 2 × 10 6 years, corresponding to comets and asteroids up to 1.8 and 3 km diameter) is transitional between regional and global effects. Stratospheric dust, sulfates released from within impacting asteroids, and soot from extensive wild‐fires sparked by thermal radiation from the impact can produce climatologically significant global optical depths of the order of 10. Moreover, the ejecta plumes of these impacts may produce enough NO from shock‐heated air to destroy the ozone shield. Between 10 6 and 10 7 Mt (intervals up to 1.5 × 10 7 years, corresponding to comets and asteroids up to 4 and 6.5 km diameter), dust and sulfate levels would be high enough to reduce light levels below those necessary for photosynthesis. Ballistic ejecta reentering the atmosphere as shooting stars would set fires over regions exceeding 10 7 km², and the resulting smoke would reduce light levels even further. At energies above 10 7 Mt, blast and earthquake damage reach the regional scale (10 6 km²). Tsunami cresting to 100 m and flooding 20 km inland could sweep the coastal zones of one of the world's ocean basins. Fires would be set globally. Light levels may drop so low from the smoke, dust, and sulfate as to make vision impossible. At energies approaching 10 9 Mt (>10 8 years) the ocean surface waters may be acidified globally by sulfur from the interiors of comets and asteroids. The Cretaceous‐Tertiary impact in particular struck evaporate substrates that very likely generated a dense, widespread sulfate aerosol layer with consequent climatic effects. The combination of all of these physical effects would surely represent a devastating stress on the global biosphere.",
    url = "https://doi.org/10.1029/96rg03038",
    doi = "10.1029/96rg03038",
    openalex = "W1997782776",
    references = "alvarez1980extraterrestrial, doi1010079781489921246, doi1010160016703789901506, doi101016001670378990286x, doi101038361040a0, doi101126science22246301283, doi101126science25049881669, doi1011300091761319910190867ccapct23co2, doi101130spe247p155, doi1011751520046919640210361teotaw20co2, doi1011751520046919670240241teotaw20co2, doi105860choice330281"
}

Abstract Why do mass extinctions occur? The demise of the dinosaurs has been discussed exhaustively, but has never been out into the context of other extinction events. This is the first systematic review of the mass extinctions of all organisms, plant and animal, terrestrial and marine, that have occurred in the history of life. This includes the major crisis 250 million years ago which nearly wiped out all life on Earth. By examining current paleontological, geological, and sedimentological evidence of environmental changes, the cases for explanations based on climate change, marine regressions, asteroid or comet impact, anoxia, and volcanic eruptions are all critically evaluated.

@book{doi101093oso97801985491780010001,
    author = "Hallam, A. and Wignall, Paul B.",
    title = "Mass Extinctions and Their Aftermath",
    year = "1997",
    abstract = "Abstract Why do mass extinctions occur? The demise of the dinosaurs has been discussed exhaustively, but has never been out into the context of other extinction events. This is the first systematic review of the mass extinctions of all organisms, plant and animal, terrestrial and marine, that have occurred in the history of life. This includes the major crisis 250 million years ago which nearly wiped out all life on Earth. By examining current paleontological, geological, and sedimentological evidence of environmental changes, the cases for explanations based on climate change, marine regressions, asteroid or comet impact, anoxia, and volcanic eruptions are all critically evaluated.",
    url = "https://doi.org/10.1093/oso/9780198549178.001.0001",
    doi = "10.1093/oso/9780198549178.001.0001",
    openalex = "W4388328712"
}

@inproceedings{friedman1997defense,
    author = "Friedman, G.",
    title = "Defense of Earth against large comets and asteroids",
    year = "1997",
    booktitle = "1997 IEEE Aerospace Conference",
    url = "https://doi.org/10.1109/aero.1997.577494",
    doi = "10.1109/aero.1997.577494",
    openalex = "W2212012580",
    pages = "5-29 vol.4",
    references = "doi101111j153969241981tb01363x, openalexw3113098276"
}

We present results of numerical simulations that show that Earth's tidal forces can both distort and disrupt Earth-crossing asteroids that have weak “rubble-pile” structures. Building on previous studies, we consider more realistic asteroid shapes and trajectories, test a variety of spin rates and axis orientations, and employ a dissipation algorithm to treat more accurately collisions between the particles that make up the model asteroid. We explore a large parameter space, including the asteroid's periapseq, encounter velocity with the Earthv∞, spin periodP, initial spin axis orientation, and body orientation at periapse. We parameterize the simulation outcomes by the amount of mass stripped from the asteroid during a flyby. Our most severe disruptions result in fragment trains similar in character to the “string of pearls” created when Comet D/Shoemaker–Levy 9 was disrupted near Jupiter in 1992. Less catastrophic disruptions cause material to be stripped off in more isotropic fashion, leaving a central remnant with a characteristic distorted shape. Some ejecta can enter into stable orbits around the remnant, creating a binary or multiple system. Even when no mass is lost tidal forces and torques can modify the asteroid's shape and spin. Our results show that mass loss is enhanced for small values ofq,v∞, andP, and depends to a certain extent on the body's initial spin orientation (for example, retrograde rotation reduces mass loss). An elongated asteroid was found to be far easier to disrupt than a spherical one, though the orientation of the ellipsoid at periapse can noticeably change the outcome. The size and orbital distribution of the ejecta are discussed, along with the applications of this technique towards an understanding of doublet craters, crater chains, and asteroids with peculiar shapes and spins.

@article{doi101006icar19985954,
    author = "Richardson, D. C. and Bottke, W. F. and Love, Stanley G.",
    title = "Tidal Distortion and Disruption of Earth-Crossing Asteroids",
    year = "1998",
    journal = "Icarus",
    abstract = "We present results of numerical simulations that show that Earth's tidal forces can both distort and disrupt Earth-crossing asteroids that have weak “rubble-pile” structures. Building on previous studies, we consider more realistic asteroid shapes and trajectories, test a variety of spin rates and axis orientations, and employ a dissipation algorithm to treat more accurately collisions between the particles that make up the model asteroid. We explore a large parameter space, including the asteroid's periapseq, encounter velocity with the Earthv∞, spin periodP, initial spin axis orientation, and body orientation at periapse. We parameterize the simulation outcomes by the amount of mass stripped from the asteroid during a flyby. Our most severe disruptions result in fragment trains similar in character to the “string of pearls” created when Comet D/Shoemaker–Levy 9 was disrupted near Jupiter in 1992. Less catastrophic disruptions cause material to be stripped off in more isotropic fashion, leaving a central remnant with a characteristic distorted shape. Some ejecta can enter into stable orbits around the remnant, creating a binary or multiple system. Even when no mass is lost tidal forces and torques can modify the asteroid's shape and spin. Our results show that mass loss is enhanced for small values ofq,v∞, andP, and depends to a certain extent on the body's initial spin orientation (for example, retrograde rotation reduces mass loss). An elongated asteroid was found to be far easier to disrupt than a spherical one, though the orientation of the ellipsoid at periapse can noticeably change the outcome. The size and orbital distribution of the ejecta are discussed, along with the applications of this technique towards an understanding of doublet craters, crater chains, and asteroids with peculiar shapes and spins.",
    url = "https://doi.org/10.1006/icar.1998.5954",
    doi = "10.1006/icar.1998.5954",
    openalex = "W2139359797",
    references = "doi102307jctv1v3gr3r6, openalexw3113098276"
}

@article{doi101016s0167278999000913,
    author = "Hills, J. G. and Goda, M. P.",
    title = "Damage from comet-asteroid impacts with earth",
    year = "1999",
    journal = "Physica D Nonlinear Phenomena",
    url = "https://doi.org/10.1016/s0167-2789(99)00091-3",
    doi = "10.1016/s0167-2789(99)00091-3",
    openalex = "W1972120928",
    references = "openalexw3113098276"
}

We have deduced the orbital and size distributions of the near-Earth asteroids (NEAs) by (i) numerically integrating NEAs from their source regions to their observed orbits, (ii) estimating the observational biases and size distribution associated with asteroids on those orbits, and (iii) creating a model population that can be fit to the known NEAs. We predict that there are approximately 900 NEAs with absolute magnitude less than 18 (that is, kilometer-sized), of which 29, 65, and 6% reside on Amor, Apollo, and Aten orbits, respectively. These results suggest that roughly 40% of the kilometer-sized NEAs have been found. The remainder, on highly eccentric and inclined orbits, are more difficult to detect.

@article{doi101126science28854742190,
    author = "Bottke, W. F. and Jedicke, Robert and Morbidelli, Alessandro and Petit, Jean-Marc and Gladman, Brett",
    title = "Understanding the Distribution of Near-Earth Asteroids",
    year = "2000",
    journal = "Science",
    abstract = "We have deduced the orbital and size distributions of the near-Earth asteroids (NEAs) by (i) numerically integrating NEAs from their source regions to their observed orbits, (ii) estimating the observational biases and size distribution associated with asteroids on those orbits, and (iii) creating a model population that can be fit to the known NEAs. We predict that there are approximately 900 NEAs with absolute magnitude less than 18 (that is, kilometer-sized), of which 29, 65, and 6\% reside on Amor, Apollo, and Aten orbits, respectively. These results suggest that roughly 40\% of the kilometer-sized NEAs have been found. The remainder, on highly eccentric and inclined orbits, are more difficult to detect.",
    url = "https://doi.org/10.1126/science.288.5474.2190",
    doi = "10.1126/science.288.5474.2190",
    openalex = "W2022978242",
    references = "doi101006icar19941039, doi101006icar19975872, doi101006icar19985954, doi1010160019103583901276, doi10102992je01246, doi101029jb074i010p02531, doi101038367033a0, doi101086115978, doi101086300632, doi101126science2775323197"
}

@article{upchurch2000from,
    author = "Upchurch, Garland R.",
    title = "From boreal forests to bolides",
    year = "2000",
    journal = "Journal of Biogeography",
    url = "https://doi.org/10.1046/j.1365-2699.2000.00413-2.x",
    doi = "10.1046/j.1365-2699.2000.00413-2.x",
    number = "2",
    pages = "502-502",
    volume = "27"
}

Asteroids and comets on orbits with perihelion distance q 0.983 AU are usually called near-Earth objects (NEOs). It has long been debated whether the NEOs are mostly of asteroidal or cometary origin. With improved knowledge of resonant dynamics, it is now clear that the asteroid belt is capable of supplying most of the observed NEOs. Particular zones in the main belt provide NEOs via powerful and diffusive resonances. Through the numerical integration of a large number of test asteroids in these zones, the possible evolutionary paths of NEOs have been identified and the statistical properties of NEOs dynamics have been quantified. This work has allowed the construction of a steady-state model of the orbital and magnitude distribution of the NEO population, dependent on parameters that are quantified by calibration with the available observations. The model accounts for the existence of ~1000 NEOs with absolute magnitude H < 18 (roughly 1 km in size). These bodies carry a probability of one collision with the Earth every 0.5 m.y. Only 6% of the NEO population should be of Kuiper Belt origin. Finally, it has been generally believed that collisional activity in the main belt, which continuously breaks up large asteroids, injects a large quantity of fresh material into the NEO source regions. In this manner, the NEO population is kept in steady state. The steep size distribution associated with fresh collisonal debris, however, is not observed among the NEO population. This paradox might suggest that Yarkovsky thermal drag, rather than collisional injection, plays the dominant role in delivering material to the NEO source resonances.

@incollection{doi102307jctv1v7zdn433,
    author = "Morbidelli, Alessandro and Bottke, W. F. and Froeschlé, Ch. and Michel, Patrick",
    title = "Origin and Evolution of Near-Earth Objects",
    year = "2002",
    booktitle = "University of Arizona Press eBooks",
    abstract = "Asteroids and comets on orbits with perihelion distance q 0.983 AU are usually called near-Earth objects (NEOs). It has long been debated whether the NEOs are mostly of asteroidal or cometary origin. With improved knowledge of resonant dynamics, it is now clear that the asteroid belt is capable of supplying most of the observed NEOs. Particular zones in the main belt provide NEOs via powerful and diffusive resonances. Through the numerical integration of a large number of test asteroids in these zones, the possible evolutionary paths of NEOs have been identified and the statistical properties of NEOs dynamics have been quantified. This work has allowed the construction of a steady-state model of the orbital and magnitude distribution of the NEO population, dependent on parameters that are quantified by calibration with the available observations. The model accounts for the existence of \textasciitilde 1000 NEOs with absolute magnitude H < 18 (roughly 1 km in size). These bodies carry a probability of one collision with the Earth every 0.5 m.y. Only 6\% of the NEO population should be of Kuiper Belt origin. Finally, it has been generally believed that collisional activity in the main belt, which continuously breaks up large asteroids, injects a large quantity of fresh material into the NEO source regions. In this manner, the NEO population is kept in steady state. The steep size distribution associated with fresh collisonal debris, however, is not observed among the NEO population. This paradox might suggest that Yarkovsky thermal drag, rather than collisional injection, plays the dominant role in delivering material to the NEO source resonances.",
    url = "https://doi.org/10.2307/j.ctv1v7zdn4.33",
    doi = "10.2307/j.ctv1v7zdn4.33",
    openalex = "W1585054956"
}

@article{doi101007s110380059016z,
    author = "Hildebrand, A. R. and Carroll, K. A. and Tedesco, E. F. and Faber, Daniel and Cardinal, R. D. and Matthews, J. M. and Kuschnig, R. and Walker, G. A. H. and Gladman, Brett and Pazder, John and Brown, Peter and Larson, S. M. and Worden, S. P. and Wallace, B. and Chodas, P. W. and Muinonen, K. and Cheng, A. F.",
    title = "ADVANTAGES OF SEARCHING FOR ASTEROIDS FROM LOW EARTH ORBIT: THE NEOSSat MISSION",
    year = "2004",
    journal = "Earth Moon and Planets",
    url = "https://doi.org/10.1007/s11038-005-9016-z",
    doi = "10.1007/s11038-005-9016-z",
    openalex = "W2031180782",
    references = "doi101016s0019103503000824"
}

We have performed a Near Earth Asteroid search and follow-up test beyond 22nd magnitude with the 2.2-m MPG/ESO and the New Technology Telescope (NTT) facilities at La Silla. The experiment comprised a total number of 4 nights at the 2.2-m telescope and 3 nights at the NTT on two separate runs. In addition to the discovery of two NEAs and the recovery of many more, this pilot program has shown the advantages as well as the problems of a dedicated program using much larger facilities than the ones currently used worldwide. We confirm the results of Jedicke et al. ([CITE]), that by observing at fainter magnitudes and finding objects at larger distances, such a system will discover km-sized NEAs with higher orbital e and i as well as a larger proportion of the smaller NEAs; moreover, it will shorten the time needed to reach 90% completeness for km-sized objects. The pilot program also evidenced the need for follow-up facilities compatible with the discovery telescopes.

@article{doi1010510004636120034428,
    author = "Boattini, A. and D’Abramo, Germano and Schöll, H. and Hainaut, O. and Boehnhardt, H. and West, R. M. and Carpino, M. and Hahn, Gerhard and Michelsen, R. and Forti, G. and Pravec, Petr and Valsecchi, G. B. and Asher, D. J.",
    title = "Near Earth Asteroid search and follow-up beyond 22nd magnitude",
    year = "2004",
    journal = "Astronomy and Astrophysics",
    abstract = "We have performed a Near Earth Asteroid search and follow-up test beyond 22nd magnitude with the 2.2-m MPG/ESO and the New Technology Telescope (NTT) facilities at La Silla. The experiment comprised a total number of 4 nights at the 2.2-m telescope and 3 nights at the NTT on two separate runs. In addition to the discovery of two NEAs and the recovery of many more, this pilot program has shown the advantages as well as the problems of a dedicated program using much larger facilities than the ones currently used worldwide. We confirm the results of Jedicke et al. ([CITE]), that by observing at fainter magnitudes and finding objects at larger distances, such a system will discover km-sized NEAs with higher orbital e and i as well as a larger proportion of the smaller NEAs; moreover, it will shorten the time needed to reach 90\% completeness for km-sized objects. The pilot program also evidenced the need for follow-up facilities compatible with the discovery telescopes.",
    url = "https://doi.org/10.1051/0004-6361:20034428",
    doi = "10.1051/0004-6361:20034428",
    openalex = "W2100075029",
    references = "doi101016s0019103503000824"
}

The absolute magnitude and perihelion distributions of long-period comets are derived, using data from the Lincoln Near-Earth Asteroid Research (LINEAR) survey. The results are surprising in three ways. Firstly, the flux of comets through the inner solar system is much lower than some previous estimates. Secondly, the expected rise in comet numbers to larger perihelia is not seen. Thirdly, the number of comets per unit absolute magnitude does not significantly rise to fainter magnitudes. These results imply that the Oort cloud contains many fewer comets than some previous estimates, that small long-period comets collide with the Earth too infrequently to be a plausible source of Tunguska-style impacts, and that some physical process must have prevented small icy planetesmals from reaching the Oort cloud, or have rendered them unobservable. A tight limit is placed on the space density of interstellar comets, but the predicted space density is lower still. The number of long-period comets that will be discovered by telescopes such as SkyMapper, Pan-Starrs and LSST is predicted, and the optimum observing strategy discussed.

@article{doi101086497684,
    author = "Francis, Paul",
    title = "The Demographics of Long‐Period Comets",
    year = "2005",
    journal = "The Astrophysical Journal",
    abstract = "The absolute magnitude and perihelion distributions of long-period comets are derived, using data from the Lincoln Near-Earth Asteroid Research (LINEAR) survey. The results are surprising in three ways. Firstly, the flux of comets through the inner solar system is much lower than some previous estimates. Secondly, the expected rise in comet numbers to larger perihelia is not seen. Thirdly, the number of comets per unit absolute magnitude does not significantly rise to fainter magnitudes. These results imply that the Oort cloud contains many fewer comets than some previous estimates, that small long-period comets collide with the Earth too infrequently to be a plausible source of Tunguska-style impacts, and that some physical process must have prevented small icy planetesmals from reaching the Oort cloud, or have rendered them unobservable. A tight limit is placed on the space density of interstellar comets, but the predicted space density is lower still. The number of long-period comets that will be discovered by telescopes such as SkyMapper, Pan-Starrs and LSST is predicted, and the optimum observing strategy discussed.",
    url = "https://doi.org/10.1086/497684",
    doi = "10.1086/497684",
    openalex = "W2167131971",
    references = "doi101016s001910350200026x, doi101086113494"
}

Abstract— We have developed a Web-based program for quickly estimating the regional environmental consequences of a comet or asteroid impact on Earth (http:www.lpl.arizona.eduimpacteffects). This paper details the observations, assumptions and equations upon which the program is based. It describes our approach to quantifying the principal impact processes that might affect the people, buildings, and landscape in the vicinity of an impact event and discusses the uncertainty in our predictions. The program requires six inputs: impactor diameter, impactor density, impact velocity before atmospheric entry, impact angle, the distance from the impact at which the environmental effects are to be calculated, and the target type (sedimentary rock, crystalline rock, or a water layer above rock). The program includes novel algorithms for estimating the fate of the impactor during atmospheric traverse, the thermal radiation emitted by the impact-generated vapor plume (fireball), and the intensity of seismic shaking. The program also approximates various dimensions of the impact crater and ejecta deposit, as well as estimating the severity of the air blast in both crater-forming and airburst impacts. We illustrate the utility of our program by examining the predicted environmental consequences across the United States of hypothetical impact scenarios occurring in Los Angeles. We find that the most wide-reaching environmental consequence is seismic shaking: both ejecta deposit thickness and air-blast pressure decay much more rapidly with distance than with seismic ground motion. Close to the impact site the most devastating effect is from thermal radiation; however, the curvature of the Earth implies that distant localities are shielded from direct thermal radiation because the fireball is below the horizon.

@article{doi101111j194551002005tb00157x,
    author = "Collins, G. S. and Melosh, H. J. and Marcus, Robert",
    title = "Earth Impact Effects Program: A Web-based computer program for calculating the regional environmental consequences of a meteoroid impact on Earth",
    year = "2005",
    journal = "Meteoritics and Planetary Science",
    abstract = "Abstract— We have developed a Web-based program for quickly estimating the regional environmental consequences of a comet or asteroid impact on Earth (http:www.lpl.arizona.eduimpacteffects). This paper details the observations, assumptions and equations upon which the program is based. It describes our approach to quantifying the principal impact processes that might affect the people, buildings, and landscape in the vicinity of an impact event and discusses the uncertainty in our predictions. The program requires six inputs: impactor diameter, impactor density, impact velocity before atmospheric entry, impact angle, the distance from the impact at which the environmental effects are to be calculated, and the target type (sedimentary rock, crystalline rock, or a water layer above rock). The program includes novel algorithms for estimating the fate of the impactor during atmospheric traverse, the thermal radiation emitted by the impact-generated vapor plume (fireball), and the intensity of seismic shaking. The program also approximates various dimensions of the impact crater and ejecta deposit, as well as estimating the severity of the air blast in both crater-forming and airburst impacts. We illustrate the utility of our program by examining the predicted environmental consequences across the United States of hypothetical impact scenarios occurring in Los Angeles. We find that the most wide-reaching environmental consequence is seismic shaking: both ejecta deposit thickness and air-blast pressure decay much more rapidly with distance than with seismic ground motion. Close to the impact site the most devastating effect is from thermal radiation; however, the curvature of the Earth implies that distant localities are shielded from direct thermal radiation because the fireball is below the horizon.",
    url = "https://doi.org/10.1111/j.1945-5100.2005.tb00157.x",
    doi = "10.1111/j.1945-5100.2005.tb00157.x",
    openalex = "W2143040029",
    references = "alvarez1980extraterrestrial, doi101006icar20026856, doi1010160016703789901506, doi1010160022286070900190, doi1010160031920184900736, doi101016b9780123956729x50012, doi10102996rg03038, doi10102997je01743, doi101038361040a0, doi101126science20844481095, doi101130spe247p155, doi101146annurevea21050193002001, doi105408002213687121, doi105860choice330281, openalexw2139291338"
}

@inproceedings{brotot2008bolides,
    author = "Brotot, Anne",
    title = "Bolides",
    year = "2008",
    booktitle = "ACM SIGGRAPH 2008 computer animation festival",
    url = "https://doi.org/10.1145/1400468.1400481",
    doi = "10.1145/1400468.1400481",
    pages = "25-25"
}

The Cretaceous-Paleogene boundary approximately 65.5 million years ago marks one of the three largest mass extinctions in the past 500 million years. The extinction event coincided with a large asteroid impact at Chicxulub, Mexico, and occurred within the time of Deccan flood basalt volcanism in India. Here, we synthesize records of the global stratigraphy across this boundary to assess the proposed causes of the mass extinction. Notably, a single ejecta-rich deposit compositionally linked to the Chicxulub impact is globally distributed at the Cretaceous-Paleogene boundary. The temporal match between the ejecta layer and the onset of the extinctions and the agreement of ecological patterns in the fossil record with modeled environmental perturbations (for example, darkness and cooling) lead us to conclude that the Chicxulub impact triggered the mass extinction.

@article{doi101126science1177265,
    author = "Schulte, Peter and Alegret, Laia and Arenillas, Ignacio and Arz, José Antonio and Barton, P. J. and Bown, Paul R. and Bralower, Timothy J. and Christeson, Gail and Claeys, Philippe and Cockell, Charles S. and Collins, G. S. and Deutsch, A. and Goldin, Tamara and Goto, Kazuhisa and Grajales-Nishimura, José Manuel and Grieve, R. A. F. and Gulick, S. P. S. and Johnson, Kirk R. and Kiessling, Wolfgang and Koeberl, Christian and Kring, D. A. and MacLeod, Kenneth G. and Matsui, Takafumi and Melosh, J. and Montanari, Alessandro and Morgan, Joanna and Neal, C. R. and Nichols, Douglas J. and Norris, Richard D. and Pierazzo, E. and Ravizza, Greg and Rebolledo‐Vieyra, M. and Reimold, W. U. and Robin, Éric and Salge, T. and Speijer, Robert P. and Sweet, A R and Urrutia‐Fucugauchi, J. and Vajda, Vivi and Whalen, Michael T. and Willumsen, Pi Suhr",
    title = "The Chicxulub Asteroid Impact and Mass Extinction at the Cretaceous-Paleogene Boundary",
    year = "2010",
    journal = "Science",
    abstract = "The Cretaceous-Paleogene boundary approximately 65.5 million years ago marks one of the three largest mass extinctions in the past 500 million years. The extinction event coincided with a large asteroid impact at Chicxulub, Mexico, and occurred within the time of Deccan flood basalt volcanism in India. Here, we synthesize records of the global stratigraphy across this boundary to assess the proposed causes of the mass extinction. Notably, a single ejecta-rich deposit compositionally linked to the Chicxulub impact is globally distributed at the Cretaceous-Paleogene boundary. The temporal match between the ejecta layer and the onset of the extinctions and the agreement of ecological patterns in the fossil record with modeled environmental perturbations (for example, darkness and cooling) lead us to conclude that the Chicxulub impact triggered the mass extinction.",
    url = "https://doi.org/10.1126/science.1177265",
    doi = "10.1126/science.1177265",
    openalex = "W2160490562",
    references = "alvarez1980extraterrestrial, doi101016jepsl200605041, doi101016jepsl200607020, doi101016jepsl200902019, doi101016jpalaeo200702037, doi101016jpalaeo200709016, doi101017cbo9780511535536, doi1010292008jb005644, doi10102996rg03038, doi10102997je01743, doi101038285198a0, doi101073pnas0802597105, doi101126science1064706, doi101126science20844481095, doi1011300091761319910190867ccapct23co2, doi101130081372356655, doi1011302007242401, doi101146annurevearth27175, doi101146annurevecolsys35021103105715"
}

Ocean acidification may have severe consequences for marine ecosystems; however, assessing its future impact is difficult because laboratory experiments and field observations are limited by their reduced ecologic complexity and sample period, respectively. In contrast, the geological record contains long-term evidence for a variety of global environmental perturbations, including ocean acidification plus their associated biotic responses. We review events exhibiting evidence for elevated atmospheric CO(2), global warming, and ocean acidification over the past ~300 million years of Earth's history, some with contemporaneous extinction or evolutionary turnover among marine calcifiers. Although similarities exist, no past event perfectly parallels future projections in terms of disrupting the balance of ocean carbonate chemistry-a consequence of the unprecedented rapidity of CO(2) release currently taking place.

@article{doi101126science1208277,
    author = "Hönisch, Bärbel and Ridgwell, Andy and Schmidt, Daniela N. and Thomas, Ellen and Gibbs, Samantha J. and Sluijs, Appy and Zeebe, Richard E. and Kump, Lee R. and Martindale, Rowan C. and Greene, Sarah E. and Kiessling, Wolfgang and Ries, Justin B. and Zachos, James C. and Royer, Dana L. and Barker, S. and Marchitto, Thomas M. and Moyer, Ryan P. and Pelejero, Carles and Ziveri, Patrizia and Foster, Gavin L. and Williams, B.",
    title = "The Geological Record of Ocean Acidification",
    year = "2012",
    journal = "Science",
    abstract = "Ocean acidification may have severe consequences for marine ecosystems; however, assessing its future impact is difficult because laboratory experiments and field observations are limited by their reduced ecologic complexity and sample period, respectively. In contrast, the geological record contains long-term evidence for a variety of global environmental perturbations, including ocean acidification plus their associated biotic responses. We review events exhibiting evidence for elevated atmospheric CO(2), global warming, and ocean acidification over the past \textasciitilde 300 million years of Earth's history, some with contemporaneous extinction or evolutionary turnover among marine calcifiers. Although similarities exist, no past event perfectly parallels future projections in terms of disrupting the balance of ocean carbonate chemistry-a consequence of the unprecedented rapidity of CO(2) release currently taking place.",
    url = "https://doi.org/10.1126/science.1208277",
    doi = "10.1126/science.1208277",
    openalex = "W2147331520",
    references = "doi101007978366206278418, doi1010160031018294902518, doi101016jpalaeo200508011, doi101016s0012825200000374, doi101016s0031018298000170, doi1010292001pa000623, doi1010292004gb002247, doi1010292009gc002788, doi101038353225a0, doi101126science1133822, doi101126science1177265, doi101126science1213454, doi101126science29255252310, doi101130g322301, doi101130spe369, doi101146annurevecolsys35021103105715, doi102475ajs2914377"
}

Abstract Near–Earth asteroids and comets, collectively the near-Earth objects (NEOs), represent a large population of minor planetary bodies whose orbits lie mostly within the zone between Venus and Mars. Many of these objects cross Earth’s orbit, providing relatively easy access from Earth for manned or robotic sampling and exploration missions with fewer propulsion requirements than trips to the Moon or to Mars. This chapter provides a review of NEOs in the context of supporting, through in-situ resource utilization, an active and expanding space exploration and resource development program capable of becoming self-funding and supporting a solar systemwide expansion program. The NEO compositions range from highly metallic asteroids composed predominantly of iron, nickel, and cobalt to cometlike objects composed of frozen water and gases of various compositions. The NEOs are the most easily accessible objects in near–Earth space, and they are numerous. As of January 2011, a total of 7872 NEOs had been identified. The number of NEOs with diameters greater than 1 km (&gt;0.6 mi) reached 1269 by June 2012. Moreover, 1176 have been identified as potentially hazardous Earth impactors by the National Aeronautics and Space Administration’s Near–Earth Object Program, approaching Earth to within 0.05 astronomical units or approximately 7,480,000 km (4,647,860 mi). The value of NEOs for space exploration may far exceed the immediate scientific information that they provide on the origin of the solar system: NEOs have the potential to provide fuel for rockets; oxygen and life support materials for explorers; valuable materials and metals for construction in space; and critical, strategic, and highly valuable materials for Earth. Water ice derived from extinct NEO comets or water–rich asteroids can be refined to provide liquid oxygen and liquid hydrogen for rocket fuel and the oxygen necessary for life support. Carbonaceous chondrites contain kerogenlike compounds that can support the immense carbon chemistry developed for our petroleum industry, and metallic asteroids contain platinum–group and rare–earth elements that have been conservatively valued in the hundreds of billions to trillions of dollars if they were made available in Earth markets. These resources are accessible using existing rockets and boosters, but these existing systems and technologies are nearly 50 years out–of–date. Active space exploration and development programs require highly efficient nuclear rockets and space–based nuclear power systems to reduce launch costs to economically tolerable numbers and to provide the heavy–lift capacity and highly efficient rocket engines for crew health and safety and minimum duration missions. Once flight launches are outside Earth’s atmosphere, the NEOs can provide nearly unlimited resources for further exploration.

@incollection{doi10130613361574m1013543,
    author = "Cutright, Bruce L.",
    title = "The Near–Earth Asteroids on the Pathway to Earth’s Future in Space",
    year = "2013",
    booktitle = "American Association of Petroleum Geologists eBooks",
    abstract = "Abstract Near–Earth asteroids and comets, collectively the near-Earth objects (NEOs), represent a large population of minor planetary bodies whose orbits lie mostly within the zone between Venus and Mars. Many of these objects cross Earth’s orbit, providing relatively easy access from Earth for manned or robotic sampling and exploration missions with fewer propulsion requirements than trips to the Moon or to Mars. This chapter provides a review of NEOs in the context of supporting, through in-situ resource utilization, an active and expanding space exploration and resource development program capable of becoming self-funding and supporting a solar systemwide expansion program. The NEO compositions range from highly metallic asteroids composed predominantly of iron, nickel, and cobalt to cometlike objects composed of frozen water and gases of various compositions. The NEOs are the most easily accessible objects in near–Earth space, and they are numerous. As of January 2011, a total of 7872 NEOs had been identified. The number of NEOs with diameters greater than 1 km (\>0.6 mi) reached 1269 by June 2012. Moreover, 1176 have been identified as potentially hazardous Earth impactors by the National Aeronautics and Space Administration’s Near–Earth Object Program, approaching Earth to within 0.05 astronomical units or approximately 7,480,000 km (4,647,860 mi). The value of NEOs for space exploration may far exceed the immediate scientific information that they provide on the origin of the solar system: NEOs have the potential to provide fuel for rockets; oxygen and life support materials for explorers; valuable materials and metals for construction in space; and critical, strategic, and highly valuable materials for Earth. Water ice derived from extinct NEO comets or water–rich asteroids can be refined to provide liquid oxygen and liquid hydrogen for rocket fuel and the oxygen necessary for life support. Carbonaceous chondrites contain kerogenlike compounds that can support the immense carbon chemistry developed for our petroleum industry, and metallic asteroids contain platinum–group and rare–earth elements that have been conservatively valued in the hundreds of billions to trillions of dollars if they were made available in Earth markets. These resources are accessible using existing rockets and boosters, but these existing systems and technologies are nearly 50 years out–of–date. Active space exploration and development programs require highly efficient nuclear rockets and space–based nuclear power systems to reduce launch costs to economically tolerable numbers and to provide the heavy–lift capacity and highly efficient rocket engines for crew health and safety and minimum duration missions. Once flight launches are outside Earth’s atmosphere, the NEOs can provide nearly unlimited resources for further exploration.",
    url = "https://doi.org/10.1306/13361574m1013543",
    doi = "10.1306/13361574m1013543",
    openalex = "W2197711792",
    references = "doi102514620096489"
}

The end-Permian mass extinction was the most severe loss of marine and terrestrial biota in the last 542 My. Understanding its cause and the controls on extinction/recovery dynamics depends on an accurate and precise age model. U-Pb zircon dates for five volcanic ash beds from the Global Stratotype Section and Point for the Permian-Triassic boundary at Meishan, China, define an age model for the extinction and allow exploration of the links between global environmental perturbation, carbon cycle disruption, mass extinction, and recovery at millennial timescales. The extinction occurred between 251.941 ± 0.037 and 251.880 ± 0.031 Mya, an interval of 60 ± 48 ka. Onset of a major reorganization of the carbon cycle immediately precedes the initiation of extinction and is punctuated by a sharp (3‰), short-lived negative spike in the isotopic composition of carbonate carbon. Carbon cycle volatility persists for ∼500 ka before a return to near preextinction values. Decamillenial to millennial level resolution of the mass extinction and its aftermath will permit a refined evaluation of the relative roles of rate-dependent processes contributing to the extinction, allowing insight into postextinction ecosystem expansion, and establish an accurate time point for evaluating the plausibility of trigger and kill mechanisms.

@article{doi101073pnas1317692111,
    author = "Burgess, Seth D. and Bowring, Samuel A. and Shen, Shu‐zhong",
    title = "High-precision timeline for Earth’s most severe extinction",
    year = "2014",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "The end-Permian mass extinction was the most severe loss of marine and terrestrial biota in the last 542 My. Understanding its cause and the controls on extinction/recovery dynamics depends on an accurate and precise age model. U-Pb zircon dates for five volcanic ash beds from the Global Stratotype Section and Point for the Permian-Triassic boundary at Meishan, China, define an age model for the extinction and allow exploration of the links between global environmental perturbation, carbon cycle disruption, mass extinction, and recovery at millennial timescales. The extinction occurred between 251.941 ± 0.037 and 251.880 ± 0.031 Mya, an interval of 60 ± 48 ka. Onset of a major reorganization of the carbon cycle immediately precedes the initiation of extinction and is punctuated by a sharp (3‰), short-lived negative spike in the isotopic composition of carbonate carbon. Carbon cycle volatility persists for ∼500 ka before a return to near preextinction values. Decamillenial to millennial level resolution of the mass extinction and its aftermath will permit a refined evaluation of the relative roles of rate-dependent processes contributing to the extinction, allowing insight into postextinction ecosystem expansion, and establish an accurate time point for evaluating the plausibility of trigger and kill mechanisms.",
    url = "https://doi.org/10.1073/pnas.1317692111",
    doi = "10.1073/pnas.1317692111",
    openalex = "W2109960660",
    references = "doi101016jchemgeo200503011, doi101038nature06588, doi101038ngeo1475, doi101038ngeo1649, doi101126science1097023, doi101126science1101012, doi101126science1177265, doi101126science1213454, doi101126science1234204, doi101126science27252651155, doi101130g327071, doi101146annurevearth042711105329, doi101146annurevecolsys35021103105715, doi105860choice435903"
}

Non-avian dinosaurs went extinct 66 million years ago, geologically coincident with the impact of a large bolide (comet or asteroid) during an interval of massive volcanic eruptions and changes in temperature and sea level. There has long been fervent debate about how these events affected dinosaurs. We review a wealth of new data accumulated over the past two decades, provide updated and novel analyses of long-term dinosaur diversity trends during the latest Cretaceous, and discuss an emerging consensus on the extinction's tempo and causes. Little support exists for a global, long-term decline across non-avian dinosaur diversity prior to their extinction at the end of the Cretaceous. However, restructuring of latest Cretaceous dinosaur faunas in North America led to reduced diversity of large-bodied herbivores, perhaps making communities more susceptible to cascading extinctions. The abruptness of the dinosaur extinction suggests a key role for the bolide impact, although the coarseness of the fossil record makes testing the effects of Deccan volcanism difficult.

@article{doi101111brv12128,
    author = "Brusatte, Stephen L. and Butler, Richard J. and Barrett, Paul M. and Carrano, Matthew T. and Evans, David C. and Lloyd, Graeme T. and Mannion, Philip D. and Norell, Mark A. and Peppe, Daniel J. and Upchurch, Paul and Williamson, Thomas E.",
    title = "The extinction of the dinosaurs",
    year = "2014",
    journal = "Biological reviews/Biological reviews of the Cambridge Philosophical Society",
    abstract = "Non-avian dinosaurs went extinct 66 million years ago, geologically coincident with the impact of a large bolide (comet or asteroid) during an interval of massive volcanic eruptions and changes in temperature and sea level. There has long been fervent debate about how these events affected dinosaurs. We review a wealth of new data accumulated over the past two decades, provide updated and novel analyses of long-term dinosaur diversity trends during the latest Cretaceous, and discuss an emerging consensus on the extinction's tempo and causes. Little support exists for a global, long-term decline across non-avian dinosaur diversity prior to their extinction at the end of the Cretaceous. However, restructuring of latest Cretaceous dinosaur faunas in North America led to reduced diversity of large-bodied herbivores, perhaps making communities more susceptible to cascading extinctions. The abruptness of the dinosaur extinction suggests a key role for the bolide impact, although the coarseness of the fossil record makes testing the effects of Deccan volcanism difficult.",
    url = "https://doi.org/10.1111/brv.12128",
    doi = "10.1111/brv.12128",
    openalex = "W1515034626",
    references = "alvarez1980extraterrestrial, doi101007s0011400804990, doi101007s1091400569434, doi101016jpalaeo200702037, doi101016jpalaeo200909018, doi101016jpalaeo201206024, doi101016jpalaeo201206027, doi101016s0012825200000374, doi101016s1631071303000063, doi101038ncomms1815, doi101073pnas1211526110, doi101080027246342010483632, doi101126science1116412, doi101126science1156963, doi101126science1177265, doi101126science28454232137, doi1011300091761319910190867ccapct23co2, doi1011300091761320020300123dsproe20co2, doi101139cjes20120185, doi101371journalpone0016574, doi101371journalpone0025186, doi101371journalpone0072579, doi1015259780520941434, doi10166612041, doi102475ajss32313381, horner2011dinosaur, lofgren1990reworking, openalexw2183707334, sloan1986gradual"
}

Procedures introduced here make it possible, first, to show that background (piecemeal) extinction is recorded throughout geologic stages and substages (not all extinction has occurred suddenly at the ends of such intervals); second, to separate out background extinction from mass extinction for a major crisis in earth history; and third, to correct for clustering of extinctions when using the rarefaction method to estimate the percentage of species lost in a mass extinction. Also presented here is a method for estimating the magnitude of the Signor-Lipps effect, which is the incorrect assignment of extinctions that occurred during a crisis to an interval preceding the crisis because of the incompleteness of the fossil record. Estimates for the magnitudes of mass extinctions presented here are in most cases lower than those previously published. They indicate that only ∼81% of marine species died out in the great terminal Permian crisis, whereas levels of 90-96% have frequently been quoted in the literature. Calculations of the latter numbers were incorrectly based on combined data for the Middle and Late Permian mass extinctions. About 90 orders and more than 220 families of marine animals survived the terminal Permian crisis, and they embodied an enormous amount of morphological, physiological, and ecological diversity. Life did not nearly disappear at the end of the Permian, as has often been claimed.

@article{doi101073pnas1613094113,
    author = "Stanley, Steven M.",
    title = "Estimates of the magnitudes of major marine mass extinctions in earth history",
    year = "2016",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "Procedures introduced here make it possible, first, to show that background (piecemeal) extinction is recorded throughout geologic stages and substages (not all extinction has occurred suddenly at the ends of such intervals); second, to separate out background extinction from mass extinction for a major crisis in earth history; and third, to correct for clustering of extinctions when using the rarefaction method to estimate the percentage of species lost in a mass extinction. Also presented here is a method for estimating the magnitude of the Signor-Lipps effect, which is the incorrect assignment of extinctions that occurred during a crisis to an interval preceding the crisis because of the incompleteness of the fossil record. Estimates for the magnitudes of mass extinctions presented here are in most cases lower than those previously published. They indicate that only ∼81\% of marine species died out in the great terminal Permian crisis, whereas levels of 90-96\% have frequently been quoted in the literature. Calculations of the latter numbers were incorrectly based on combined data for the Middle and Late Permian mass extinctions. About 90 orders and more than 220 families of marine animals survived the terminal Permian crisis, and they embodied an enormous amount of morphological, physiological, and ecological diversity. Life did not nearly disappear at the end of the Permian, as has often been claimed.",
    url = "https://doi.org/10.1073/pnas.1613094113",
    doi = "10.1073/pnas.1613094113",
    openalex = "W2529501031",
    references = "doi101002gj1090, doi101007978364270831215, doi101016s001282520000026x, doi101016s0012825203000825, doi101017s0094837300013178, doi101130g211551, doi101146annurevearth33092203122654, doi1016660094837320050310006poaeit20co2, doi105860choice435903"
}

As part of the EURONEAR project, almost 70,000 mosaic Suprime‐Cam images taken between 1999 and 2013 were data‐mined for about 9,800 near‐Earth asteroids (NEAs) known by 2013 May. Using our PRECOVERY server and the new Find Subaru CCD tool, we scrutinized 4,186 candidate CCD images possibly holding 518 NEAs. We found 113 NEAs as faint as V <25 magnitude, their positions being measured in 589 images using Astrometrica, and then reported to the Minor Planet Center. Among them, 18 objects represent encounters of previously single opposition NEAs, their orbital arcs being extended by up to 10 years. In the second part of this work, we searched for unknown NEAs in 78 sequences (780 CCD fields) of 4–5 mosaic images selected from the same Suprime‐Cam archive and totaling 16.6 deg 2, with the aim to assess the faint NEA distribution observable with an 8‐m class survey. A total of 2,018 moving objects were measured, from which we identified 18 better NEA candidates. Using the R c filter in good weather conditions, mostly dark time and sky directions slightly biased towards the ecliptic, at least one NEA could be discovered in every 1 deg 2 surveyed.

@article{doi101002asna201713296,
    author = "Văduvescu, O. and Conovici, Matei and Popescu, Marcel and Şonka, A. and Paraschiv, Alin Rǎzvan and Lacatus, D. A. and Tudorica, A. and Hudin, L. and Curelaru, Lucian and Inceu, V. and Zavoianu, D. and Cornea, R. and Toma, R. and Asher, D. J. and Hadnett, J. and Cheallaigh, L. Ó",
    title = "Data mining of near‐Earth asteroids in the Subaru Suprime‐Cam archive",
    year = "2017",
    journal = "Astronomische Nachrichten",
    abstract = "As part of the EURONEAR project, almost 70,000 mosaic Suprime‐Cam images taken between 1999 and 2013 were data‐mined for about 9,800 near‐Earth asteroids (NEAs) known by 2013 May. Using our PRECOVERY server and the new Find Subaru CCD tool, we scrutinized 4,186 candidate CCD images possibly holding 518 NEAs. We found 113 NEAs as faint as V <25 magnitude, their positions being measured in 589 images using Astrometrica, and then reported to the Minor Planet Center. Among them, 18 objects represent encounters of previously single opposition NEAs, their orbital arcs being extended by up to 10 years. In the second part of this work, we searched for unknown NEAs in 78 sequences (780 CCD fields) of 4–5 mosaic images selected from the same Suprime‐Cam archive and totaling 16.6 deg 2, with the aim to assess the faint NEA distribution observable with an 8‐m class survey. A total of 2,018 moving objects were measured, from which we identified 18 better NEA candidates. Using the R c filter in good weather conditions, mostly dark time and sky directions slightly biased towards the ecliptic, at least one NEA could be discovered in every 1 deg 2 surveyed.",
    url = "https://doi.org/10.1002/asna.201713296",
    doi = "10.1002/asna.201713296",
    openalex = "W2606450461",
    references = "doi101016jpss201306026"
}

Context. One-opposition near-Earth asteroids (NEAs) are growing in number, and they must be recovered to prevent loss and mismatch risk, and to improve their orbits, as they are likely to be too faint for detection in shallow surveys at future apparitions. Aims. We aimed to recover more than half of the one-opposition NEAs recommended for observations by the Minor Planet Center (MPC) using the Isaac Newton Telescope (INT) in soft-override mode and some fractions of available D-nights. During about 130 h in total between 2013 and 2016, we targeted 368 NEAs, among which 56 potentially hazardous asteroids (PHAs), observing 437 INT Wide Field Camera (WFC) fields and recovering 280 NEAs (76% of all targets). Methods. Engaging a core team of about ten students and amateurs, we used the THELI, Astrometrica, and the Find_Orb software to identify all moving objects using the blink and track-and-stack method for the faintest targets and plotting the positional uncertainty ellipse from NEODyS. Results. Most targets and recovered objects had apparent magnitudes centered around V ~ 22.8 mag, with some becoming as faint as V ~ 24 mag. One hundred and three objects (representing 28% of all targets) were recovered by EURONEAR alone by Aug. 2017. Orbital arcs were prolonged typically from a few weeks to a few years; our oldest recoveries reach 16 years. The O−C residuals for our 1854 NEA astrometric positions show that most measurements cluster closely around the origin. In addition to the recovered NEAs, 22 000 positions of about 3500 known minor planets and another 10 000 observations of about 1500 unknown objects (mostly main-belt objects) were promptly reported to the MPC by our team. Four new NEAs were discovered serendipitously in the analyzed fields and were promptly secured with the INT and other telescopes, while two more NEAs were lost due to extremely fast motion and lack of rapid follow-up time. They increase the counting to nine NEAs discovered by the EURONEAR in 2014 and 2015. Conclusions. Targeted projects to recover one-opposition NEAs are efficient in override access, especially using at least two-meter class and preferably larger field telescopes located in good sites, which appear even more efficient than the existing surveys.

@article{doi10105100046361201731844,
    author = "Văduvescu, O. and Hudin, L. and Močnik, Teo and Char, F. and Şonka, A. and Tudor, Vlad and Ordóñez‐Etxeberria, I. and Alfaro, M. Díaz and Ashley, R. P. and Errmann, R. and Short, P. and Moloceniuc, A. and Cornea, R. and Inceu, V. and Zavoianu, D. and Popescu, Marcel and Curelaru, Lucian and Mihalea, S. and Stoian, A.-M. and Boldea, Afrodita Liliana and Toma, R. and Fields, L. and Grigore, V. and Stoev, H. and López-Martínez, F. and Humphries, N. and Sowicka, Paulina and Ramanjooloo, Y. and Manilla-Robles, A. and Riddick, F. C. and Jiménez‐Luján, F. and Méndez, Javier and Aceituno, F. J. and Sota, A. and Jones, David and Hidalgo, S. L. and Murabito, S. and Oteo, I. and Bongiovanni, Á. and Zamora, O. and Pyrzas, S. and Génova-Santos, R. T. and Font, Joan and Bereciartua, A. and Pérez-Fournon, I. and Martínez-Vázquez, C. E. and Monelli, M. and Cicuéndez, L. and Monteagudo, L. and Agulli, I. and Bouy, H. and Huélamo, N. and Monguió, M. and Gänsicke, B. T. and Steeghs, D. and Gentile-Fusillo, N. P. and Hollands, Mark and Toloza, Odette and Manser, Christopher J. and Dhillon, V. S. and Sahman, D. I. and Fitzsimmons, A. and McNeill, A. and Thompson, A. and Tabor, M. and Murphy, D. N. A. and Davies, John K. and Snodgrass, C. and Triaud, A. H. M. J. and Groot, P. and Macfarlane, S. and Peletier, R. F. and Sen, S. and İKİZ, Tuba and Hoekstra, Henk and Herbonnet, Ricardo and Köhlinger, F. and Greimel, R. and Paulino-Afonso, Ana and Parker, Q. A. and Kong, A. K. H. and Bassa, C. and Pleunis, Ziggy",
    title = "280 one-opposition near-Earth asteroids recovered by the EURONEAR with the Isaac Newton Telescope",
    year = "2017",
    journal = "Astronomy and Astrophysics",
    abstract = "Context. One-opposition near-Earth asteroids (NEAs) are growing in number, and they must be recovered to prevent loss and mismatch risk, and to improve their orbits, as they are likely to be too faint for detection in shallow surveys at future apparitions. Aims. We aimed to recover more than half of the one-opposition NEAs recommended for observations by the Minor Planet Center (MPC) using the Isaac Newton Telescope (INT) in soft-override mode and some fractions of available D-nights. During about 130 h in total between 2013 and 2016, we targeted 368 NEAs, among which 56 potentially hazardous asteroids (PHAs), observing 437 INT Wide Field Camera (WFC) fields and recovering 280 NEAs (76\% of all targets). Methods. Engaging a core team of about ten students and amateurs, we used the THELI, Astrometrica, and the Find\_Orb software to identify all moving objects using the blink and track-and-stack method for the faintest targets and plotting the positional uncertainty ellipse from NEODyS. Results. Most targets and recovered objects had apparent magnitudes centered around V \textasciitilde\ 22.8 mag, with some becoming as faint as V \textasciitilde\ 24 mag. One hundred and three objects (representing 28\% of all targets) were recovered by EURONEAR alone by Aug. 2017. Orbital arcs were prolonged typically from a few weeks to a few years; our oldest recoveries reach 16 years. The O−C residuals for our 1854 NEA astrometric positions show that most measurements cluster closely around the origin. In addition to the recovered NEAs, 22 000 positions of about 3500 known minor planets and another 10 000 observations of about 1500 unknown objects (mostly main-belt objects) were promptly reported to the MPC by our team. Four new NEAs were discovered serendipitously in the analyzed fields and were promptly secured with the INT and other telescopes, while two more NEAs were lost due to extremely fast motion and lack of rapid follow-up time. They increase the counting to nine NEAs discovered by the EURONEAR in 2014 and 2015. Conclusions. Targeted projects to recover one-opposition NEAs are efficient in override access, especially using at least two-meter class and preferably larger field telescopes located in good sites, which appear even more efficient than the existing surveys.",
    url = "https://doi.org/10.1051/0004-6361/201731844",
    doi = "10.1051/0004-6361/201731844",
    openalex = "W2765224421",
    references = "doi101016jpss201306026"
}

@incollection{crossref2018comets,
    title = "Comets and Asteroids on Earth",
    year = "2018",
    booktitle = "CATCHING STARDUST",
    url = "https://doi.org/10.5040/9781472944023.0007",
    doi = "10.5040/9781472944023.0007",
    openalex = "W4241151238"
}

The debiased absolute-magnitude and orbit distributions as well as source regions for near-Earth objects (NEOs) provide a fundamental frame of reference for studies of individual NEOs and more complex population-level questions. We present a new four-dimensional model of the NEO population that describes debiased steady-state distributions of semimajor axis, eccentricity, inclination, and absolute magnitude H in the range 17 < H < 25. The modeling approach improves upon the methodology originally developed by Bottke et al. (2000, Science 288, 2190–2194) in that it is, for example, based on more realistic orbit distributions and uses source-specific absolute-magnitude distributions that allow for a power-law slope that varies with H. We divide the main asteroid belt into six different entrance routes or regions (ER) to the NEO region: the ν6, 3:1J, 5:2J and 2:1J resonance complexes as well as Hungarias and Phocaeas. In addition we include the Jupiter-family comets as the primary cometary source of NEOs. We calibrate the model against NEO detections by Catalina Sky Surveys’ stations 703 and G96 during 2005–2012, and utilize the complementary nature of these two systems to quantify the systematic uncertainties associated to the resulting model. We find that the (fitted) H distributions have significant differences, although most of them show a minimum power-law slope at H ∼ 20. As a consequence of the differences between the ER-specific H distributions we find significant variations in, for example, the NEO orbit distribution, average lifetime, and the relative contribution of different ERs as a function of H. The most important ERs are the ν6 and 3:1J resonance complexes with JFCs contributing a few percent of NEOs on average. A significant contribution from the Hungaria group leads to notable changes compared to the predictions by Bottke et al. in, for example, the orbit distribution and average lifetime of NEOs. We predict that there are 962−56+52 (802−42+48×103) NEOs with H < 17.75 (H < 25) and these numbers are in agreement with the most recent estimates found in the literature (the uncertainty estimates only account for the random component). Based on our model we find that relative shares between different NEO groups (Amor, Apollo, Aten, Atira, Vatira) are (39.4,54.4,3.5,1.2,0.3)%, respectively, for the considered H range and that these ratios have a negligible dependence on H. Finally, we find an agreement between our estimate for the rate of Earth impacts by NEOs and recent estimates in the literature, but there remains a potentially significant discrepancy in the frequency of Tunguska-sized and Chelyabinsk-sized impacts.

@article{doi101016jicarus201804018,
    author = "Granvik, Mikael and Morbidelli, Alessandro and Jedicke, Robert and Bolin, Bryce and Bottke, W. F. and Beshore, E. C. and Vokrouhlický, David and Nesvorný, David and Michel, Patrick",
    title = "Debiased orbit and absolute-magnitude distributions for near-Earth objects",
    year = "2018",
    journal = "Icarus",
    abstract = "The debiased absolute-magnitude and orbit distributions as well as source regions for near-Earth objects (NEOs) provide a fundamental frame of reference for studies of individual NEOs and more complex population-level questions. We present a new four-dimensional model of the NEO population that describes debiased steady-state distributions of semimajor axis, eccentricity, inclination, and absolute magnitude H in the range 17 < H < 25. The modeling approach improves upon the methodology originally developed by Bottke et al. (2000, Science 288, 2190–2194) in that it is, for example, based on more realistic orbit distributions and uses source-specific absolute-magnitude distributions that allow for a power-law slope that varies with H. We divide the main asteroid belt into six different entrance routes or regions (ER) to the NEO region: the ν6, 3:1J, 5:2J and 2:1J resonance complexes as well as Hungarias and Phocaeas. In addition we include the Jupiter-family comets as the primary cometary source of NEOs. We calibrate the model against NEO detections by Catalina Sky Surveys’ stations 703 and G96 during 2005–2012, and utilize the complementary nature of these two systems to quantify the systematic uncertainties associated to the resulting model. We find that the (fitted) H distributions have significant differences, although most of them show a minimum power-law slope at H ∼ 20. As a consequence of the differences between the ER-specific H distributions we find significant variations in, for example, the NEO orbit distribution, average lifetime, and the relative contribution of different ERs as a function of H. The most important ERs are the ν6 and 3:1J resonance complexes with JFCs contributing a few percent of NEOs on average. A significant contribution from the Hungaria group leads to notable changes compared to the predictions by Bottke et al. in, for example, the orbit distribution and average lifetime of NEOs. We predict that there are 962−56+52 (802−42+48×103) NEOs with H < 17.75 (H < 25) and these numbers are in agreement with the most recent estimates found in the literature (the uncertainty estimates only account for the random component). Based on our model we find that relative shares between different NEO groups (Amor, Apollo, Aten, Atira, Vatira) are (39.4,54.4,3.5,1.2,0.3)\%, respectively, for the considered H range and that these ratios have a negligible dependence on H. Finally, we find an agreement between our estimate for the rate of Earth impacts by NEOs and recent estimates in the literature, but there remains a potentially significant discrepancy in the frequency of Tunguska-sized and Chelyabinsk-sized impacts.",
    url = "https://doi.org/10.1016/j.icarus.2018.04.018",
    doi = "10.1016/j.icarus.2018.04.018",
    openalex = "W2798470423",
    references = "doi101038nature12741, doi101126science28854742190"
}

Avian diversification has been influenced by global climate change, plate tectonic movements, and mass extinction events. However, the impact of these factors on the diversification of the hyperdiverse perching birds (passerines) is unclear because family level relationships are unresolved and the timing of splitting events among lineages is uncertain. We analyzed DNA data from 4,060 nuclear loci and 137 passerine families using concatenation and coalescent approaches to infer a comprehensive phylogenetic hypothesis that clarifies relationships among all passerine families. Then, we calibrated this phylogeny using 13 fossils to examine the effects of different events in Earth history on the timing and rate of passerine diversification. Our analyses reconcile passerine diversification with the fossil and geological records; suggest that passerines originated on the Australian landmass ∼47 Ma; and show that subsequent dispersal and diversification of passerines was affected by a number of climatological and geological events, such as Oligocene glaciation and inundation of the New Zealand landmass. Although passerine diversification rates fluctuated throughout the Cenozoic, we find no link between the rate of passerine diversification and Cenozoic global temperature, and our analyses show that the increases in passerine diversification rate we observe are disconnected from the colonization of new continents. Taken together, these results suggest more complex mechanisms than temperature change or ecological opportunity have controlled macroscale patterns of passerine speciation.

@article{doi101073pnas1813206116,
    author = "Oliveros, Carl H. and Field, Daniel J. and Ksepka, Daniel T. and Barker, F. Keith and Aleixo, Alexandre Luis Padovan and Andersen, Michael J. and Alström, Per and Benz, Brett W. and Braun, Edward L. and Braun, Michael J. and Bravo, Gustavo A. and Brumfield, Robb T. and Chesser, R. Terry and Claramunt, Santiago and Cracraft, Joël and Cuervo, Andrés M. and Derryberry, Elizabeth P. and Glenn, Travis C. and Harvey, Michael and Hosner, Peter A. and Joseph, Leo and Kimball, Rebecca T. and Mack, Andrew L. and Miskelly, Colin M. and Peterson, A. Townsend and Robbins, Mark B. and Sheldon, Frederick H. and Silveira, Luís Fábio and Smith, Brian Tilston and White, Noor D. and Moyle, Robert G. and Faircloth, Brant C.",
    title = "Earth history and the passerine superradiation",
    year = "2019",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "Avian diversification has been influenced by global climate change, plate tectonic movements, and mass extinction events. However, the impact of these factors on the diversification of the hyperdiverse perching birds (passerines) is unclear because family level relationships are unresolved and the timing of splitting events among lineages is uncertain. We analyzed DNA data from 4,060 nuclear loci and 137 passerine families using concatenation and coalescent approaches to infer a comprehensive phylogenetic hypothesis that clarifies relationships among all passerine families. Then, we calibrated this phylogeny using 13 fossils to examine the effects of different events in Earth history on the timing and rate of passerine diversification. Our analyses reconcile passerine diversification with the fossil and geological records; suggest that passerines originated on the Australian landmass ∼47 Ma; and show that subsequent dispersal and diversification of passerines was affected by a number of climatological and geological events, such as Oligocene glaciation and inundation of the New Zealand landmass. Although passerine diversification rates fluctuated throughout the Cenozoic, we find no link between the rate of passerine diversification and Cenozoic global temperature, and our analyses show that the increases in passerine diversification rate we observe are disconnected from the colonization of new continents. Taken together, these results suggest more complex mechanisms than temperature change or ecological opportunity have controlled macroscale patterns of passerine speciation.",
    url = "https://doi.org/10.1073/pnas.1813206116",
    doi = "10.1073/pnas.1813206116",
    openalex = "W2931899952",
    references = "doi101016jcub201804062, doi101017s0016756807004268, doi101038nature03150, doi101038nature11631, doi101038nature15697, doi101038nbt1883, doi10108001621459199510476572, doi10108010635150701883881, doi101093bioinformaticsbtu033, doi101093molbevmss075, doi101093sysbiosyu056, doi101126science1059412, doi101126science1157704, doi101126science1194585, doi101126science1253451"
}

The Cretaceous/Paleogene mass extinction, 66 Ma, included the demise of non-avian dinosaurs. Intense debate has focused on the relative roles of Deccan volcanism and the Chicxulub asteroid impact as kill mechanisms for this event. Here, we combine fossil-occurrence data with paleoclimate and habitat suitability models to evaluate dinosaur habitability in the wake of various asteroid impact and Deccan volcanism scenarios. Asteroid impact models generate a prolonged cold winter that suppresses potential global dinosaur habitats. Conversely, long-term forcing from Deccan volcanism (carbon dioxide [CO 2]-induced warming) leads to increased habitat suitability. Short-term (aerosol cooling) volcanism still allows equatorial habitability. These results support the asteroid impact as the main driver of the non-avian dinosaur extinction. By contrast, induced warming from volcanism mitigated the most extreme effects of asteroid impact, potentially reducing the extinction severity.

@article{doi101073pnas2006087117,
    author = "Chiarenza, Alfio Alessandro and Farnsworth, Alexander and Mannion, Philip D. and Lunt, Daniel J. and Valdes, Paul J. and Morgan, Joanna and Allison, Peter A.",
    title = "Asteroid impact, not volcanism, caused the end-Cretaceous dinosaur extinction",
    year = "2020",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "The Cretaceous/Paleogene mass extinction, 66 Ma, included the demise of non-avian dinosaurs. Intense debate has focused on the relative roles of Deccan volcanism and the Chicxulub asteroid impact as kill mechanisms for this event. Here, we combine fossil-occurrence data with paleoclimate and habitat suitability models to evaluate dinosaur habitability in the wake of various asteroid impact and Deccan volcanism scenarios. Asteroid impact models generate a prolonged cold winter that suppresses potential global dinosaur habitats. Conversely, long-term forcing from Deccan volcanism (carbon dioxide [CO 2]-induced warming) leads to increased habitat suitability. Short-term (aerosol cooling) volcanism still allows equatorial habitability. These results support the asteroid impact as the main driver of the non-avian dinosaur extinction. By contrast, induced warming from volcanism mitigated the most extreme effects of asteroid impact, potentially reducing the extinction severity.",
    url = "https://doi.org/10.1073/pnas.2006087117",
    doi = "10.1073/pnas.2006087117",
    openalex = "W3038551147",
    references = "alvarez1980extraterrestrial, doi101007s1091400569434, doi101016jcub201804062, doi101016s0012825200000374, doi10102993jd02553, doi101038s41467019089972, doi101073pnas1211526110, doi101073pnas1319253111, doi101111brv12128, doi101111ecog03049, doi101111j14724642201000725x, doi101111j16000587200805742x, doi101126sciadvaat4858, doi101126science1177265, doi101126science1229237, doi101126science20844481095, doi101126science21545391501, doi101126scienceaau2422, doi101126scienceaay2268, doi1011302014250315, doi1011302014250502, doi101130spe247, doi101144sp35813"
}

@incollection{bowell2021earthcrossing,
    author = "BOWELL, EDWARD and MUINONEN, KARRI",
    title = "EARTH-CROSSING ASTEROIDS AND COMETS:",
    year = "2021",
    booktitle = "Hazards Due to Comets and Asteroids",
    url = "https://doi.org/10.2307/j.ctv23khmpv.10",
    doi = "10.2307/j.ctv23khmpv.10",
    openalex = "W4205695748",
    pages = "149-198"
}

Abstract In this article, the methodology of using a telescope and charge-coupled device camera for organizing astrometric observations of asteroids and comets, as well as photometric observations of asteroids, is presented. Since astronomy is not studied as a separate subject in schools in Romania and the Republic of Moldova (as well as in many other countries), this methodology can be used within extracurricular activities for students. The observations described in the article took place at the astronomical observatory within the ‘Răsvan Angheluță’ Natural Sciences Museum Complex in Galați, Romania.

@article{doi10108813616552ad0d0a,
    author = "Tercu, Jan Ovidiu and Chistol, V.",
    title = "Methodology of organizing astronomical observations of asteroids and comets within the extracurricular activities of students",
    year = "2023",
    journal = "Physics Education",
    abstract = "Abstract In this article, the methodology of using a telescope and charge-coupled device camera for organizing astrometric observations of asteroids and comets, as well as photometric observations of asteroids, is presented. Since astronomy is not studied as a separate subject in schools in Romania and the Republic of Moldova (as well as in many other countries), this methodology can be used within extracurricular activities for students. The observations described in the article took place at the astronomical observatory within the ‘Răsvan Angheluță’ Natural Sciences Museum Complex in Galați, Romania.",
    url = "https://doi.org/10.1088/1361-6552/ad0d0a",
    doi = "10.1088/1361-6552/ad0d0a",
    openalex = "W4389173729",
    references = "doi101016jpss201306026"
}

Context. Further activities in detecting near-Earth asteroids (NEAs) using the blink method are hampered by the required size of the telescopes. Synthetic tracking (ST) is an effective solution, but the computational demands make operation difficult at survey data rates for fast moving objects. Aims. We aim to show that, through efficient use of hardware, judicious pipeline design and choice of algorithms, ST at survey levels of data rates is possible even for objects with very fast apparent motion, such as NEAs. Methods. We developed a GPU-accelerated ST pipeline, called synthetic tracking on Umbrella (STU), which targets real-time detection of fast NEAs through algorithms designed to make efficient use of data-parallel hardware. STU was developed as part of the Umbrella software suite, which we have expanded to provide an end-to-end data reduction pipeline. Results. We demonstrate the capabilities of the STU pipeline to scan for moving objects faster than the acquisition rate at search radii of 10 arcseconds per minute, with good detection rates on several archival datasets without specific tuning. Conclusions. Our investigation shows that ST is viable for large-scale surveys and that STU may perform such a role.

@article{doi10105100046361202553973,
    author = "Stǎnescu, M. and Popescu, Marcel and Curelaru, Lucian and Văduvescu, O. and Bertesteanu, Daniel and Predatu, M.",
    title = "Data-parallel methods for fast and deep detection of asteroids on the Umbrella platform: Near-real-time synthetic tracking algorithm for near-Earth objects",
    year = "2025",
    journal = "Astronomy and Astrophysics",
    abstract = "Context. Further activities in detecting near-Earth asteroids (NEAs) using the blink method are hampered by the required size of the telescopes. Synthetic tracking (ST) is an effective solution, but the computational demands make operation difficult at survey data rates for fast moving objects. Aims. We aim to show that, through efficient use of hardware, judicious pipeline design and choice of algorithms, ST at survey levels of data rates is possible even for objects with very fast apparent motion, such as NEAs. Methods. We developed a GPU-accelerated ST pipeline, called synthetic tracking on Umbrella (STU), which targets real-time detection of fast NEAs through algorithms designed to make efficient use of data-parallel hardware. STU was developed as part of the Umbrella software suite, which we have expanded to provide an end-to-end data reduction pipeline. Results. We demonstrate the capabilities of the STU pipeline to scan for moving objects faster than the acquisition rate at search radii of 10 arcseconds per minute, with good detection rates on several archival datasets without specific tuning. Conclusions. Our investigation shows that ST is viable for large-scale surveys and that STU may perform such a role.",
    url = "https://doi.org/10.1051/0004-6361/202553973",
    doi = "10.1051/0004-6361/202553973",
    openalex = "W4415009010",
    references = "doi101016jpss201306026"
}

@misc{crossrefNonefireballs,
    title = "Fireballs and Bolides",
    year = "None",
    booktitle = "Wolfram Research Data Repository",
    url = "https://doi.org/10.24097/wolfram.56418.data",
    doi = "10.24097/wolfram.56418.data"
}