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D E Trilling - One of the best experts on this subject based on the ideXlab platform.
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spitzer albedos of Near Earth Objects
The Astronomical Journal, 2019Co-Authors: Annika Gustafsson, D E Trilling, Michael Mommert, A Mcneill, J L Hora, Howard A Smith, S Hellmich, S Mottola, Alan W HarrisAbstract:Thermal infrared observations are the most effective way to measure asteroid diameter and albedo for a large number of Near-Earth Objects. Major surveys like NEOWISE, NEOSurvey, ExploreNEOs, and NEOLegacy find a small fraction of high albedo Objects that do not have clear analogs in the current meteorite population. About 8% of Spitzer-observed Near-Earth Objects have nominal albedo solutions greater than 0.5. This may be a result of lightcurve variability leading to an incorrect estimate of diameter or inaccurate absolute visual magnitudes. For a sample of 23 high albedo NEOs we do not find that their shapes are significantly different from the McNeill et al. (2019) Near-Earth object shape distribution. We performed a Monte Carlo analysis on 1505 Near-Earth Objects observed by Spitzer, sampling the visible and thermal fluxes of all targets to determine the likelihood of obtaining a high albedo erroneously. Implementing the McNeill shape distribution for Near-Earth Objects, we provide an upper-limit on the geometric albedo of 0.5+/-0.1 for the Near-Earth population.
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constraining the shape distribution of Near Earth Objects from partial lightcurves
arXiv: Earth and Planetary Astrophysics, 2019Co-Authors: A Mcneill, Annika Gustafsson, D E Trilling, J L Hora, Michael MommertAbstract:In the absence of dense photometry for a large population of Near Earth Objects (NEOs), the best method of obtaining a shape distribution comes from sparse photometry and partial lightcurves. We have used 867 partial lightcurves obtained by Spitzer to determine a shape distribution for sub-kilometre NEOs. From this data we find a best fit average elongation $\frac{b}{a}=0.72 \pm 0.08$. We compare this result with a shape distribution obtained from 1869 NEOs in the same size range observed by Pan-STARRS 1 and find the Spitzer-obtained elongation to be in excellent agreement with this PS1 value of $\frac{b}{a}=0.70 \pm 0.10$. These values are also in agreement with literature values for $1
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infrared light curves of Near Earth Objects
Astrophysical Journal Supplement Series, 2018Co-Authors: J L Hora, Annika Gustafsson, D E Trilling, Michael Mommert, A Mcneill, Howard A Smith, Amir Siraj, G G Fazio, Steven R ChesleyAbstract:We present light curves and derive periods and amplitudes for a subset of 38 Near-Earth Objects (NEOs) observed at 4.5 μm with the IRAC camera on the the Spitzer Space Telescope, many of them having no previously reported rotation periods. This subset was chosen from about 1800 IRAC NEO observations as having obvious periodicity and significant amplitude. For Objects where the period observed did not sample the full rotational period, we derived lower limits to these parameters based on sinusoidal fits. Light curve durations ranged from 42 to 544 minutes, with derived periods from 16 to 270 minutes. We discuss the effects of light curve variations on the thermal modeling used to derive diameters and albedos from Spitzer photometry. We find that both diameters and albedos derived from the light curve maxima and minima agree with our previously published results, even for extreme Objects, showing the conservative nature of the thermal model uncertainties. We also evaluate the NEO rotation rates, sizes, and their cohesive strengths.
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the mission accessible Near Earth Objects survey four years of photometry
Astrophysical Journal Supplement Series, 2018Co-Authors: Audrey Thirouin, D E Trilling, Richard P Binzel, Cristina A Thomas, Nicholas Moskovitz, E Christensen, Francesca E Demeo, D Polishook, Mark WillmanAbstract:Over 4.5 years, the Mission Accessible Near-Earth Object Survey assembled 228 Near-Earth object (NEO) light curves. We report rotational light curves for 82 NEOs, constraints on amplitudes and periods for 21 NEOs, light curves with no detected variability within the image signal-to-noise and length of our observing block for 30 NEOs, and 10 tumblers. We uncovered two ultra-rapid rotators with periods below 20 s,—2016 MA with a potential rotational periodicity of 18.4 s, and 2017 QG18 rotating in 11.9 s—and estimated the fraction of fast/ultra-rapid rotators undetected in our project plus the percentage of NEOs with a moderate/long periodicity undetectable during our typical observing blocks. We summarize the findings of a simple model of synthetic NEOs to infer the object's morphology distribution using the measured distribution of light curve amplitudes. This model suggests that a uniform distribution of axis ratio can reproduce the observed sample. This suggests that the quantity of spherical NEOs (e.g., Bennu) is almost equivalent to the quantity of highly elongated Objects (e.g., Itokawa), a result that can be directly tested thanks to shape models from Doppler delay radar imaging analysis. Finally, we fully characterized two NEOs—2013 YS2 and 2014 FA7—as appropriate targets for a potential robotic/human mission due to their moderate spin periods and low Δv.
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the mission accessible Near Earth Objects survey four years of photometry
arXiv: Earth and Planetary Astrophysics, 2018Co-Authors: Audrey Thirouin, D E Trilling, Richard P Binzel, Cristina A Thomas, Nicholas Moskovitz, E Christensen, Francesca E Demeo, D Polishook, Mark WillmanAbstract:Over 4.5 years, the Mission Accessible Near-Earth Object Survey (MANOS) assembled 228 Near-Earth Object (NEO) lightcurves. We report rotational lightcurves for 82 NEOs, constraints on amplitudes and periods for 21 NEOs, lightcurves with no detected variability within the image signal to noise and length of our observing block for 30 NEOs, and 10 tumblers. We uncovered 2 ultra-rapid rotators with periods below 20s; 2016MA with a potential rotational periodicity of 18.4s, and 2017QG$_{18}$ rotating in 11.9s, and estimate the fraction of fast/ultra-rapid rotators undetected in our project plus the percentage of NEOs with a moderate/long periodicity undetectable during our typical observing blocks. We summarize the findings of a simple model of synthetic NEOs to infer the object morphologies distribution using the measured distribution of lightcurve amplitudes. This model suggests a uniform distribution of axis ratio can reproduce the observed sample. This suggests that the quantity of spherical NEOs (e.g., Bennu) is almost equivalent to the quantity of highly elongated Objects (e.g., Itokawa), a result that can be directly tested thanks to shape models from Doppler delay radar imaging analysis. Finally, we fully characterized 2 NEOs as appropriate targets for a potential robotic/human mission: 2013YS$_{2}$ and 2014FA$_{7}$ due to their moderate spin periods and low $\Delta v$.
Cristina A Thomas - One of the best experts on this subject based on the ideXlab platform.
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the mission accessible Near Earth Objects survey four years of photometry
arXiv: Earth and Planetary Astrophysics, 2018Co-Authors: Audrey Thirouin, D E Trilling, Richard P Binzel, Cristina A Thomas, Nicholas Moskovitz, E Christensen, Francesca E Demeo, D Polishook, Mark WillmanAbstract:Over 4.5 years, the Mission Accessible Near-Earth Object Survey (MANOS) assembled 228 Near-Earth Object (NEO) lightcurves. We report rotational lightcurves for 82 NEOs, constraints on amplitudes and periods for 21 NEOs, lightcurves with no detected variability within the image signal to noise and length of our observing block for 30 NEOs, and 10 tumblers. We uncovered 2 ultra-rapid rotators with periods below 20s; 2016MA with a potential rotational periodicity of 18.4s, and 2017QG$_{18}$ rotating in 11.9s, and estimate the fraction of fast/ultra-rapid rotators undetected in our project plus the percentage of NEOs with a moderate/long periodicity undetectable during our typical observing blocks. We summarize the findings of a simple model of synthetic NEOs to infer the object morphologies distribution using the measured distribution of lightcurve amplitudes. This model suggests a uniform distribution of axis ratio can reproduce the observed sample. This suggests that the quantity of spherical NEOs (e.g., Bennu) is almost equivalent to the quantity of highly elongated Objects (e.g., Itokawa), a result that can be directly tested thanks to shape models from Doppler delay radar imaging analysis. Finally, we fully characterized 2 NEOs as appropriate targets for a potential robotic/human mission: 2013YS$_{2}$ and 2014FA$_{7}$ due to their moderate spin periods and low $\Delta v$.
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the mission accessible Near Earth Objects survey four years of photometry
Astrophysical Journal Supplement Series, 2018Co-Authors: Audrey Thirouin, D E Trilling, Richard P Binzel, Cristina A Thomas, Nicholas Moskovitz, E Christensen, Francesca E Demeo, D Polishook, Mark WillmanAbstract:Over 4.5 years, the Mission Accessible Near-Earth Object Survey assembled 228 Near-Earth object (NEO) light curves. We report rotational light curves for 82 NEOs, constraints on amplitudes and periods for 21 NEOs, light curves with no detected variability within the image signal-to-noise and length of our observing block for 30 NEOs, and 10 tumblers. We uncovered two ultra-rapid rotators with periods below 20 s,—2016 MA with a potential rotational periodicity of 18.4 s, and 2017 QG18 rotating in 11.9 s—and estimated the fraction of fast/ultra-rapid rotators undetected in our project plus the percentage of NEOs with a moderate/long periodicity undetectable during our typical observing blocks. We summarize the findings of a simple model of synthetic NEOs to infer the object's morphology distribution using the measured distribution of light curve amplitudes. This model suggests that a uniform distribution of axis ratio can reproduce the observed sample. This suggests that the quantity of spherical NEOs (e.g., Bennu) is almost equivalent to the quantity of highly elongated Objects (e.g., Itokawa), a result that can be directly tested thanks to shape models from Doppler delay radar imaging analysis. Finally, we fully characterized two NEOs—2013 YS2 and 2014 FA7—as appropriate targets for a potential robotic/human mission due to their moderate spin periods and low Δv.
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the mission accessible Near Earth Objects survey manos first photometric results
The Astronomical Journal, 2016Co-Authors: Audrey Thirouin, D E Trilling, Richard P Binzel, Cristina A Thomas, Nicholas Moskovitz, E Christensen, Francesca E Demeo, D Polishook, Mark WillmanAbstract:Discovery Communications; National Science Foundation [AST-1005313]; NASA NEOO [NNX14AN82G]; Lowell Observatory; Ministry of Science, Technology and Space of the Israeli government; AXA Research Fund
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the mission accessible Near Earth Objects survey manos first photometric results
arXiv: Earth and Planetary Astrophysics, 2016Co-Authors: Audrey Thirouin, D E Trilling, Richard P Binzel, Cristina A Thomas, Nicholas Moskovitz, E Christensen, Francesca E Demeo, D Polishook, Mark WillmanAbstract:The Mission Accessible Near-Earth Objects Survey (MANOS) aims to physically characterize sub-km Near-Earth Objects (NEOs). We report first photometric results from the survey which began in August, 2013. Photometric observations were performed using 1 m to 4 m class telescopes around the world. We present rotational periods and lightcurve amplitudes for 86 sub-km NEOs, though in some cases, only lower limits are provided. Our main goal is to obtain lightcurves for small NEOs (typically, sub-km Objects) and estimate their rotational periods, lightcurve amplitudes, and shapes. These properties are used for statistical study to constrain overall properties of the NEO population. A weak correlation seems to indicate that smaller Objects are more spherical than the larger ones. We also report 7 NEOs that are fully characterized (lightcurve and visible spectra) as the most suitable candidates for a future human or robotic mission. Viable mission targets are Objects fully characterized, with a Delta_v(NHATS) 1h. Assuming a similar rate of object characterization as reported in this paper, approximately 1,230 NEOs need to be characterized in order to find 100 viable mission targets.
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observing Near Earth Objects with the james webb space telescope
Publications of the Astronomical Society of the Pacific, 2016Co-Authors: Cristina A Thomas, V Reddy, Nicholas Moskovitz, Paul A Abell, Julie Castillorogez, Michael Muller, A S Rivkin, E L Ryan, J A StansberryAbstract:The James Webb Space Telescope (JWST) has the potential to enhance our understanding of Near-Earth Objects (NEOs). We present results of investigations into the observability of NEOs given the nominal observing requirements of JWST on elongation (85°–135°) and non-sidereal rates (<30 mas s−1). We find that approximately 75% of NEOs can be observed in a given year. However, observers will need to wait for appropriate observing windows. We find that JWST can easily execute photometric observations of meter-sized NEOs that will enhance our understanding of the small NEO population.
P Michel - One of the best experts on this subject based on the ideXlab platform.
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Debiased albedo distribution for Near Earth Objects
Icarus, 2020Co-Authors: A Morbidelli, W F Bottke, P Michel, Mikael Granvik, B Bolin, M Delbo, R Jedicke, David VokrouhlickýAbstract:We extend the most recent orbital-absolute magnitude Near Earth Object (NEO) model (Granvik et al., 2018) to provide a statistical description of NEO geometric albedos. Our model is calibrated on NEOWISE albedo data for the NEO population and reproduces these data very well once a simple model for the NEOWISE observational biases is applied. The results are consistent with previous estimates. There are ~1,000 NEOs with diameter D>1km and the mean albedo to convert absolute magnitude into diameter is 0.147. We don't find any statistically significant evidence that the albedo distribution of NEOs depends on NEO size. Instead, we find evidence that the disruption of NEOs at small perihelion distances found in Granvik et al. (2016) occurs preferentially for dark NEOs. The interval between km-sized bodies striking the Earth should occur on average once every 750,000 years. Low and high albedo NEOs are well mixed in orbital space, but a trend remains with higher albedo Objects being at smaller semimajor axes and lower albedo Objects more likely found at larger semimajor axes.
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debiased orbit and absolute magnitude distributions for Near Earth Objects
Icarus, 2018Co-Authors: Mikael Granvik, Alessandro Morbidelli, W F Bottke, Robert Jedicke, B Bolin, E C Beshore, David Vokrouhlický, David Nesvorný, P MichelAbstract: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 17 962 − 56 + 52 ( 802 − 42 + 48 × 10 3 ) NEOs with H
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physical properties of Near Earth Objects that inform mitigation
Acta Astronautica, 2013Co-Authors: P MichelAbstract:Abstract Various methods have been proposed to avoid the collision of a Near-Earth Object (NEO) with the Earth. Each of these methods relies on a mitigation concept (deflection or fragmentation), an energy source (e.g. kinetic, gravitational, solar, thermal, etc.) and a mode of approach (e.g. remote station and interaction). The efficiency of each method depends on the physical properties of the considered NEO that influence the way the body will respond to the considered energy source. While the knowledge of properties such as the mass, spin rate and obliquity as well as the shape is generally required for all mitigation methods, there are other properties that are important to know for some methods and that have no great influence for other ones. This paper summarizes the current knowledge of main physical properties of NEOs and their importance for the most usual mitigation strategies that have been proposed, i.e. the kinetic impactor, the gravity tractor, strategies based on anchoring or depositing material on the surface, and strategies aimed at modifying the thermal properties of the NEO in order to either modify or cancel the Yarkovsky effect, or cause surface vaporization.
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origin and dynamics of Near Earth Objects
Comptes Rendus Physique, 2005Co-Authors: P Michel, Alessandro Morbidelli, W F BottkeAbstract:Abstract The population of Near-Earth Objects (NEOs) evolves on orbits which can cross the orbit of the Earth. Most NEOs come from the asteroid belt via unstable zones associated with powerful or diffusive resonances. Their evolutionary paths and the statistical properties of their dynamics have been determined by massive numerical integrations. A steady-state model of their orbital and magnitude distributions has been elaborated which indicates that 1000 NEOs are kilometre-size with an impact frequency with the Earth around 0.5 Myr. A non-gravitational mechanism, the Yarkovsky thermal drag, plays the dominant role in delivering material in the NEO source regions, explaining how this population is maintained in a steady-state and why its size distribution is shallower than expected if NEOs were created through the direct injection of fresh fragments from collisional break ups into resonances. To cite this article: P. Michel et al., C. R. Physique 6 (2005).
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debiased orbital and absolute magnitude distribution of the Near Earth Objects
Icarus, 2002Co-Authors: W F Bottke, Alessandro Morbidelli, P Michel, Robert Jedicke, Jeanmarc Petit, Harold F Levison, T S MetcalfeAbstract:The orbital and absolute magnitude distribution of the Near-Earth Objects (NEOs) is difficult to compute, partly because only a modest fraction of the entire NEO population has been discovered so far, but also because the known NEOs are biased by complicated observational selection effects. To circumvent these problems, we created a model NEO population which was fit to known NEOs discovered or accidentally rediscovered by Spacewatch. Our method was to numerically integrate thousands of test particles from five source regions that we believe provide most NEOs to the inner Solar System. Four of these source regions are in or adjacent to the main asteroid belt, while the fifth one is associated with the transneptunian disk. The Nearly isotropic comets, which include the Halley-type comets and the long-period comets, were not included in our model. Test bodies from our source regions that passed into the NEO region (perihelia q<1.3 AU and aphelia Q≥0.983 AU) were tracked until they were eliminated by striking the Sun or a planet or were ejected out of the inner Solar System. These integrations were used to create five residence time probability distributions in semimajor axis, eccentricity, and inclination space (one for each source). These distributions show where NEOs from a given source are statistically most likely to be located. Combining these five residence time probability distributions with an NEO absolute magnitude distribution computed from previous work and a probability function representing the observational biases associated with the Spacewatch NEO survey, we produced an NEO model population that could be fit to 138 NEOs discovered or accidentally rediscovered by Spacewatch. By testing a range of possible source combinations, a best-fit NEO model was computed which (i) provided the debiased orbital and absolute magnitude distributions for the NEO population and (ii) indicated the relative importance of each NEO source region. Our best-fit model is consistent with 960±120 NEOs having H 2.8 AU), and ∼6% comes from the Jupiter-family comet region (2
Mark Willman - One of the best experts on this subject based on the ideXlab platform.
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the mission accessible Near Earth Objects survey four years of photometry
Astrophysical Journal Supplement Series, 2018Co-Authors: Audrey Thirouin, D E Trilling, Richard P Binzel, Cristina A Thomas, Nicholas Moskovitz, E Christensen, Francesca E Demeo, D Polishook, Mark WillmanAbstract:Over 4.5 years, the Mission Accessible Near-Earth Object Survey assembled 228 Near-Earth object (NEO) light curves. We report rotational light curves for 82 NEOs, constraints on amplitudes and periods for 21 NEOs, light curves with no detected variability within the image signal-to-noise and length of our observing block for 30 NEOs, and 10 tumblers. We uncovered two ultra-rapid rotators with periods below 20 s,—2016 MA with a potential rotational periodicity of 18.4 s, and 2017 QG18 rotating in 11.9 s—and estimated the fraction of fast/ultra-rapid rotators undetected in our project plus the percentage of NEOs with a moderate/long periodicity undetectable during our typical observing blocks. We summarize the findings of a simple model of synthetic NEOs to infer the object's morphology distribution using the measured distribution of light curve amplitudes. This model suggests that a uniform distribution of axis ratio can reproduce the observed sample. This suggests that the quantity of spherical NEOs (e.g., Bennu) is almost equivalent to the quantity of highly elongated Objects (e.g., Itokawa), a result that can be directly tested thanks to shape models from Doppler delay radar imaging analysis. Finally, we fully characterized two NEOs—2013 YS2 and 2014 FA7—as appropriate targets for a potential robotic/human mission due to their moderate spin periods and low Δv.
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the mission accessible Near Earth Objects survey four years of photometry
arXiv: Earth and Planetary Astrophysics, 2018Co-Authors: Audrey Thirouin, D E Trilling, Richard P Binzel, Cristina A Thomas, Nicholas Moskovitz, E Christensen, Francesca E Demeo, D Polishook, Mark WillmanAbstract:Over 4.5 years, the Mission Accessible Near-Earth Object Survey (MANOS) assembled 228 Near-Earth Object (NEO) lightcurves. We report rotational lightcurves for 82 NEOs, constraints on amplitudes and periods for 21 NEOs, lightcurves with no detected variability within the image signal to noise and length of our observing block for 30 NEOs, and 10 tumblers. We uncovered 2 ultra-rapid rotators with periods below 20s; 2016MA with a potential rotational periodicity of 18.4s, and 2017QG$_{18}$ rotating in 11.9s, and estimate the fraction of fast/ultra-rapid rotators undetected in our project plus the percentage of NEOs with a moderate/long periodicity undetectable during our typical observing blocks. We summarize the findings of a simple model of synthetic NEOs to infer the object morphologies distribution using the measured distribution of lightcurve amplitudes. This model suggests a uniform distribution of axis ratio can reproduce the observed sample. This suggests that the quantity of spherical NEOs (e.g., Bennu) is almost equivalent to the quantity of highly elongated Objects (e.g., Itokawa), a result that can be directly tested thanks to shape models from Doppler delay radar imaging analysis. Finally, we fully characterized 2 NEOs as appropriate targets for a potential robotic/human mission: 2013YS$_{2}$ and 2014FA$_{7}$ due to their moderate spin periods and low $\Delta v$.
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the mission accessible Near Earth Objects survey manos first photometric results
The Astronomical Journal, 2016Co-Authors: Audrey Thirouin, D E Trilling, Richard P Binzel, Cristina A Thomas, Nicholas Moskovitz, E Christensen, Francesca E Demeo, D Polishook, Mark WillmanAbstract:Discovery Communications; National Science Foundation [AST-1005313]; NASA NEOO [NNX14AN82G]; Lowell Observatory; Ministry of Science, Technology and Space of the Israeli government; AXA Research Fund
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the mission accessible Near Earth Objects survey manos first photometric results
arXiv: Earth and Planetary Astrophysics, 2016Co-Authors: Audrey Thirouin, D E Trilling, Richard P Binzel, Cristina A Thomas, Nicholas Moskovitz, E Christensen, Francesca E Demeo, D Polishook, Mark WillmanAbstract:The Mission Accessible Near-Earth Objects Survey (MANOS) aims to physically characterize sub-km Near-Earth Objects (NEOs). We report first photometric results from the survey which began in August, 2013. Photometric observations were performed using 1 m to 4 m class telescopes around the world. We present rotational periods and lightcurve amplitudes for 86 sub-km NEOs, though in some cases, only lower limits are provided. Our main goal is to obtain lightcurves for small NEOs (typically, sub-km Objects) and estimate their rotational periods, lightcurve amplitudes, and shapes. These properties are used for statistical study to constrain overall properties of the NEO population. A weak correlation seems to indicate that smaller Objects are more spherical than the larger ones. We also report 7 NEOs that are fully characterized (lightcurve and visible spectra) as the most suitable candidates for a future human or robotic mission. Viable mission targets are Objects fully characterized, with a Delta_v(NHATS) 1h. Assuming a similar rate of object characterization as reported in this paper, approximately 1,230 NEOs need to be characterized in order to find 100 viable mission targets.
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the mission accessible Near Earth Objects survey manos
Amreican Astronomical Society Division for Planetary Sciences Meeting, 2013Co-Authors: Paul A Abell, D E Trilling, Cristina A Thomas, Nicholas Moskovitz, Francesca E Demeo, Mark Willman, Thomas Endicott, Michael W Busch, H G Roe, W M GrundyAbstract:Near‐Earth Objects (NEOs) are essential to understanding the origin of the Solar System. Their relatively small sizes and complex dynamical histories make them excellent laboratories for studying ongoing Solar System processes. The proximity of NEOs to Earth makes them favorable targets for space missions. In addition, knowledge of their physical properties is crucial for impact hazard assessment. However, in spite of their importance to science, exploration, and planetary defense, a representative sample of physical characteristics for sub‐km NEOs does not exist. Here we present the Mission Accessible Near‐Earth Objects Survey (MANOS), a multi‐year survey of subkm NEOs that will provide a large, uniform catalog of physical properties (light curves + colors + spectra + astrometry), representing a 100‐fold increase over the current level of NEO knowledge within this size range. This survey will ultimately characterize more than 300 mission‐accessible NEOs across the visible and Near‐infrared ranges using telescopes in both the northern and southern hemispheres. MANOS has been awarded 24 nights per semester for the next three years on NOAO facilities including Gemini North and South, the Kitt Peak Mayall 4m, and the SOAR 4m. Additional telescopic assets available to our team include facilities at Lowell Observatory, the University of Hawaii 2.2m, NASA's IRTF, and the Magellan 6.5m telescopes. Our focus on sub‐km sizes and mission accessibility (dv < 7 km/s) is a novel approach to physical characterization studies and is possible through a regular cadence of observations designed to access newly discovered NEOs within days or weeks of first detection before they fade beyond observational limits. The resulting comprehensive catalog will inform global properties of the NEO population, advance scientific understanding of NEOs, produce essential data for robotic and spacecraft exploration, and develop a critical knowledge base to address the risk of NEO impacts. We intend to conduct this survey with complete transparency, publicly sharing our target lists and survey progress. We invite collaborative uses for these data as a way to broaden the scientific impact of this survey.
W F Bottke - One of the best experts on this subject based on the ideXlab platform.
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Debiased albedo distribution for Near Earth Objects
Icarus, 2020Co-Authors: A Morbidelli, W F Bottke, P Michel, Mikael Granvik, B Bolin, M Delbo, R Jedicke, David VokrouhlickýAbstract:We extend the most recent orbital-absolute magnitude Near Earth Object (NEO) model (Granvik et al., 2018) to provide a statistical description of NEO geometric albedos. Our model is calibrated on NEOWISE albedo data for the NEO population and reproduces these data very well once a simple model for the NEOWISE observational biases is applied. The results are consistent with previous estimates. There are ~1,000 NEOs with diameter D>1km and the mean albedo to convert absolute magnitude into diameter is 0.147. We don't find any statistically significant evidence that the albedo distribution of NEOs depends on NEO size. Instead, we find evidence that the disruption of NEOs at small perihelion distances found in Granvik et al. (2016) occurs preferentially for dark NEOs. The interval between km-sized bodies striking the Earth should occur on average once every 750,000 years. Low and high albedo NEOs are well mixed in orbital space, but a trend remains with higher albedo Objects being at smaller semimajor axes and lower albedo Objects more likely found at larger semimajor axes.
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debiased orbit and absolute magnitude distributions for Near Earth Objects
Icarus, 2018Co-Authors: Mikael Granvik, Alessandro Morbidelli, W F Bottke, Robert Jedicke, B Bolin, E C Beshore, David Vokrouhlický, David Nesvorný, P MichelAbstract: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 17 962 − 56 + 52 ( 802 − 42 + 48 × 10 3 ) NEOs with H
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neokepler discovering Near Earth Objects using the kepler spacecraft
arXiv: Earth and Planetary Astrophysics, 2013Co-Authors: Kevin B Stevenson, R Jedicke, Daniel C Fabrycky, W F BottkeAbstract:The Kepler Mission has been an irrefutable success. In the last 4.5 years, it has monitored 150 confirmed exoplanets in over 75 stellar systems and detected an additional �3,300 planet candidates. Using these data, we have learned the size distribution of planets in our galaxy, the likelihood that a star hosts an Earth-sized planet, and the percentage of stars that contain multiplanet systems. The recent failure of a second reaction wheel has ended Kepler’s primary mission; however, its plight is a unique opportunity to make significant advances in another important field, without the time and costs associated with designing, building, and launching another spacecraft. We propose a new Kepler mission, called NEOKepler, that would survey Near Earth’s orbit to identify potentially hazardous Objects (PHOs). To understand its surveying power, Kepler’s large field of view produces an etendue (A) that is 4.5 times larger than the best survey telescope currently in operation. In this paper, we investigate the feasibility of NEOKepler using a double “fence post” survey pattern that efficiently detects PHOs. Ina simulated 12-month survey, we estimate that NEOKepler would detect �150 new NEOs with absolute magnitudes of less than 21.5, �50 of which would be new PHOs. This would increase the annual PHO discovery rate by at least 50% and improve upon our goal of discovering 90% of PHOs by the end of 2020. Due to its heliocentric orbit, Kepler would also be sensitive to Objects inside Earth’s orbit, discovering more Objects in its first year than are currently known to exist. Understanding this undersampled sub-population of NEOs will reveal new insights into the actual PHO distribution by further constraining current NEO models. As an alternative science goal, NEOKepler could employ a different observing strategy to discover suitable targets for NASA’s Asteroid Redirect Mission.
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exploreneos a search for Near Earth Objects of cometary origin
44th Meeting of the American Astronomical Society’s Division for Planetary Sciences (DPS) 14 -19 October 2012 Reno Nevada, 2012Co-Authors: M Mommert, W F Bottke, J L Hora, M Delbo, Michael Mueller, G G Fazio, A W Harris, David E Trilling, J P Emery, Alex HagenAbstract:The short dynamical lifetime of Near-Earth Objects (NEOs) compared to the age of the Solar System implies the existence of sources of replenishment in order to maintain the observed population of NEOs. Main belt asteroids and Jupiter family comets (JFCs), which can end up in typical NEO orbits via planetary perturbations and non-gravitational forces, are the most important sources of replenishment of NEOs. JFCs that become NEOs suffer accelerated loss of their Near-surface volatiles, evolving into inactive "dormant" or "extinct" comets that are observationally indistinguishable from low albedo asteroids. Dynamically, however, they retain "comet-like" orbital characteristics. Knowledge of the fraction of extinct comets in the NEO population is important for assessing the amount of cometary material that has been transported to Earth. Furthermore, identifying inactive comet candidates facilitates detailed investigations of the final phase of comet evolution. We present an independent analysis of the fraction of former cometary Objects in the NEO population. Due to the large number of NEOs we use a statistical approach to identify dormant or extinct comets based on dynamical and physical properties. We utilize (1) the Tisserand parameter with respect to Jupiter, (2) the minimum orbit intersection distance with respect to Jupiter and (3) albedo measurements. Our albedos are determined from thermal-IR observations made by the Warm Spitzer Space Telescope Exploration Science project "ExploreNEOs", using thermal modeling. The main goal of this work is to estimate the fraction of dormant or extinct comets in the NEO population. We will further provide a list of former comet candidate Objects and assess their accessibility with spacecraft via the delta-V parameter. We enhance our investigation by adding data from the literature to our sample and compare our results to earlier published works based on independent analyses. MM acknowledges support by the DFG SPP 1385.
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origin and dynamics of Near Earth Objects
Comptes Rendus Physique, 2005Co-Authors: P Michel, Alessandro Morbidelli, W F BottkeAbstract:Abstract The population of Near-Earth Objects (NEOs) evolves on orbits which can cross the orbit of the Earth. Most NEOs come from the asteroid belt via unstable zones associated with powerful or diffusive resonances. Their evolutionary paths and the statistical properties of their dynamics have been determined by massive numerical integrations. A steady-state model of their orbital and magnitude distributions has been elaborated which indicates that 1000 NEOs are kilometre-size with an impact frequency with the Earth around 0.5 Myr. A non-gravitational mechanism, the Yarkovsky thermal drag, plays the dominant role in delivering material in the NEO source regions, explaining how this population is maintained in a steady-state and why its size distribution is shallower than expected if NEOs were created through the direct injection of fresh fragments from collisional break ups into resonances. To cite this article: P. Michel et al., C. R. Physique 6 (2005).
