Year: 2021
Type: article
Abstract: We estimate the total population of near-Earth objects (NEOs) in the solar system using an extensive, “solar-system-to-pixels” fake-asteroid simulation to debias detections of real NEOs by the ATLAS survey. Down to absolute magnitudes H = 25 and 27.6 (diameters of ∼34 and 10 m, respectively, for 15% albedo), we find total populations of (3.72 ± 0.49) × 105 and (1.59 ± 0.45) × 107 NEOs, respectively. Most of the plausible sources of error tend toward underestimation, so the true populations are likely larger. We find the distribution of H magnitudes steepens for NEOs fainter than H ∼ 22.5, making small asteroids more common than extrapolation from brighter H mags would predict. Our simulation indicates a strong bias against detecting small but dangerous asteroids that encounter Earth with high relative velocities—i.e., asteroids in highly inclined and/or eccentric orbits. Worldwide NEO discovery statistics indicate this bias affects global NEO detection capability to the point that an observational census of small asteroids in such orbits is probably not currently feasible. Prompt and aggressive followup of NEO candidates, combined with closer collaborations between segments of the global NEO community, can increase detection rates for these dangerous objects.
Source: The Planetary Science Journal
DOI: 10.3847/psj/abd325
Language: English
Topic: Astro and Planetary Science
Subfield: Space and Planetary Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,800
Funders: National Science Foundation, Smithsonian Institution, National Aeronautics and Space Administration, Gordon and Betty Moore Foundation, Johns Hopkins University, Space Telescope Science Institute, University of Edinburgh, Queen's University Belfast, Durham University, Queen's University, Nuclear Safety and Security Commission, Max-Planck-Gesellschaft, National Central University, Eötvös Loránd Tudományegyetem, Max-Planck-Institut für Astronomie, Smithsonian Astrophysical Observatory, Science Mission Directorate, Science and Technology Facilities Council, Planetary Science Division, Los Alamos National Laboratory
Awards: EARTH IS OCCASIONALLY STRUCK BY AN ASTEROID OR COMET LARGE ENOUGH TO CAUSE A SIGNIFICANT EXPLOSION AND LOSS OF LIFE. THE MOST LIKELY IMPACT IS BY A RELATIVELY SMALL OBJECT AND THE BEST MITIGATION STRATEGY MAY SIMPLY BE TO MOVE PEOPLE OUT OF THE WAY. WITH ENOUGH WARNING A SMALL ASTEROID IMPACT WOULD NOT CAUSE LOSS OF LIFE AND PORTABLE PROPERTY MIGHT EVEN BE PRESERVED. WE HAVE BUILT AN "EARLY WARNING" SYSTEM THAT PROVIDES A THREE WEEK NOTICE OF MOST 140M ASTEROIDS OR COMETS ON TRACK TO HIT THE EARTH AND A WEEK'S NOTICE FOR MOST 50M ASTEROIDS. THE SYSTEM HAS BEEN DESIGNED BUILT AND BROUGHT INTO OPERATION IN LESS THAN THREE YEARS AND IS EASILY REPLICABLE. THE "ASTEROID TERRESTRIAL-IMPACT LAST ALERT SYSTEM" (ATLAS) CURRENTLY COMPRISES TWO OBSERVATORIES SEPARATED BY ABOUT 100KM THAT CAN SCAN THE ENTIRE VISIBLE SKY MORE THAN TWICE A NIGHT TO MAGNITUDE 20. SOFTWARE AUTOMATICALLY REGISTERS COMPARISONS WITH THE UNCHANGING SKY AND IDENTIFIES EVERYTHING THAT HAS MOVED OR CHANGED. COMMUNICATION BETWEEN THE OBSERVATORIES AND THE IAU MINOR PLANET CENTER LOCKS DOWN THE ORBIT OF ANYTHING APPROACHING THE EARTH. THIS PROPOSAL SEEKS FUNDING TO CONTINUE OPERATIONS OF THE TWO ATLAS UNITS ALREADY BUILT AND TO CONSTRUCT TWO MORE UNITS FOR THE SOUTHERN HEMISPHERE. ATLAS IS COMPLEMENTARY TO MANY EXISTING SURVEYS FOR NEAR-EARTH OBJECTS (NEOS) BY VIRTUE OF BEING ALL-SKY: IT CAN DETECT MOST 140M NEOS THAT PASS WITHIN 0.1AU OF THE EARTH. ATLAS MAY FIND MORE THAN 500 NEOS PER YEAR EVEN THOUGH ITS FORTE IS DISCOVERY OF THE SUBSET OF NEOS THAT PASS VERY CLOSE TO THE EARTH. ITS STEADY SKY COVERAGE IS ALSO VALUABLE FOR DISCOVERY OF LOW DELTA-V ASTEROIDS CANDIDATE TARGETS FOR A MANNED MISSION. FURTHERMORE ATLAS WILL CHARACTERIZE THE NEO POPULATION AND ALL THE OTHER OBJECTS IT DETECTS BY OBTAINING HUNDREDS OF LIGHT CURVE POINTS PER YEAR THAT WILL ENABLE THE DETERMINATION OF THEIR SHAPE AND SPIN AND ALSO BY OBTAINING SIMULTANEOUS COLOR MEASUREMENTS. OBJECTIVES: ATLAS WILL 1) PROVIDE WARNING THAT IS USEFUL ON A CIVIL DEFENSE TIMESCALE FOR THE MAJORITY OF EARTH-IMPACTING ASTEROIDS OF 50M SIZE OR LARGER 2) REDISCOVER 50% OF ALL 1000M NEOS AND POTENTIALLY HAZARDOUS OBJECTS (PHO) WITHIN 1 YEAR 70% IN 3 YEARS AND 90% IN 10 YEARS DISCOVER MORE THAN 400 NEOS AND 100 PHOS PER YEAR OF 140M SIZE OR LARGER 3) DETECT ABOUT ONE SMALL ASTEROID PER YEAR THAT HITS THE EARTH 4) DISCOVER LOW DELTA-V ASTEROIDS 5) ENABLE SHAPE AND SPIN CALCULATIONS FROM HUNDREDS OF OBSERVATIONS PER YEAR OF THOUSANDS OF ASTEROIDS AND 6) DETECT ALL PLUTO-SIZED OBJECTS WITHIN A DISTANCE OF 120 AU. METHODS: WE HAVE BUILT A PAIR OF SMALL OBSERVATORIES EACH WITH AN 0.5M TELESCOPE THAT COVERS 30 SQUARE DEG WITH EACH EXPOSURE AND WE HAVE WRITTEN ALL THE SOFTWARE REQUIRED FOR THEM TO OPERATE WITHOUT HUMAN INTERVENTION. WE ARE CURRENTLY REPORTING ASTEROID AND COMET DETECTIONS TO THE MPC AND AS THE SYSTEM COMES FULLY ONLINE OUR RATE OF DISCOVERY WILL INCREASE BY A FACTOR OF 10. BY BUILDING ANOTHER TWO UNITS IN THE SOUTH AND AT DIFFERENT LONGITUDE WE WILL DOUBLE OUR DETECTION PROBABILITY FOR THE NEXT CHELYABINSKSIZED IMPACTOR. SIGNIFICANCE: THIS PROJECT WORKS TOWARDS ACCOMPLISHING THE CONGRESSIONAL MANDATE TO MITIGATE THE HAZARD FROM EARTH-IMPACTING ASTEROIDS BY FOCUSING ON DETECTION OF NEARLY ALL HAZARDOUS ASTEROIDS IN THE DAYS OR WEEKS BEFORE IMPACT. ALTHOUGH DETECTION IN TIME TO DIVERT DANGEROUS ASTEROIDS IS LAUDABLE IT IS ALSO CURRENTLY UNAFFORDABLE AND ATLAS ADDRESSES THE INTENT OF THE MANDATE BY PROTECTING LIVES. ATLAS WILL AFFORD A YEARLY OPPORTUNITY TO STUDY A METEORITE BEFORE IT STRIKES THE EARTH'S ATMOSPHERE AND WILL PROVIDE MUCH BETTER STATISTICS ON THE POPULATION THAT DOES PASS CLOSE TO THE EARTH. ATLAS WILL DISCOVER LOW DELTA-V ASTEROIDS SUITABLE FOR A MANNED MISSION AND CHARACTERIZATION OF THE SPIN AND SHAPE OF MANY ASTEROIDS MAY PROVE VALUABLE FOR FUTURE MISSIONS., Queen's University Belfast Consolidated Grant in Solar Physics and Solar System Studies 2020 - 2023, G3095507666, Queen's University Belfast Consolidated Grant in Solar Physics and Solar System Studies 2017 - 2020, G4474636675, G4800998230, A NEO SEARCH PROGRAM USING THE PAN-STARRS PS1 TELESCOPETHE GOAL OF THE PROPOSED RESEARCH IS TO USE T, G7187964967, Pan-STARRS1: Operations; Public Data Release; Education and Outreach, G833430883
OpenAlex ID: W3127059548