Year: 2025
Type: article
Abstract: The relationship of an asteroid's reduced magnitude to its phase has a long history of study. Included in this history have been efforts to study the correlation between these parameters and spectral type. However, these efforts often suffer from the inclusion of only a few asteroids, missing phase curve data, uncorrected rotational or apparitional aberrations, and other issues. In this paper, we build upon previous approaches and address these issues. Broadly, this paper is split into two parts. The first is primarily concerned with carefully deriving phase curve parameters using a combined data set from several different sources, including observations from Gaia, the Transiting Exoplanet Survey Satellite, Palomar Transient Factory, Asteroid Terrestrial-impact Last Alert System, and Asteroid Lightcurve Data Exchange Format database using an ellipsoidal model that can correct for rotational and apparitional effects. The second concerns itself with making predictions on that data set and quantifying what can and cannot be inferred from phase parameters, both as a function of the phase curve parameterization chosen and as a function of the chosen model. We find that, while individual spectral classes remain hard to infer from the phase curves, broader statements on the presence of absorption features can dependably be made.
Source: The Planetary Science Journal
DOI: 10.3847/psj/ada0ad
Author: Zachary Murray
Institution: Center for Astrophysics Harvard & Smithsonian
Language: English
Topic: Astro and Planetary Science
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,800
Awards: G1028008162, 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., INTRODUCTION A PRIMARY REASON FOR THE STUDY OF THE NEAR-EARTH OBJECT (NEO) POPULATION IS TO DETERMINE THE POTENTIAL IMPACT HAZARD FOR INDIVIDUAL OBJECTS AS WELL AS THE POPULATION AS A WHOLE. SUCH ANALYSIS REQUIRES UNDERSTANDING PHYSICAL CHARACTERISTICS BEYOND SIZE AND RAW POPULATION NUMBERS. CHIEF AMONG THESE ARE ROTATION RATE AND SPIN AXIS ALIGNMENT THOUGH OTHERS CAN BE EASILY OBTAINED WITH EVEN MODEST TELESCOPES. RECENT EFFORTS CONCENTRATING ON THE DISCOVERY AND ORBITAL DETERMINATION OF VERY SMALL NEOS DIRECTLY ADDRESS STATED NEOO OBJECTIVES WHICH ALSO INCLUDE THE CHARACTERIZATION (ROTATION RATE TAXONOMY ETC.) OF A REPRESENTATIVE SAMPLE OF NEOS. WE TAKE THIS TO MEAN NOT JUST THE SMALLEST MEMBERS OF THE NEO POPULATION OR THOSE THAT MAKE VERY CLOSE EARTH-ENCOUNTERS WITHIN A FEW DECADES. THE BEST UNDERSTANDING OF NEOS REQUIRES GIVING CONTEXT TO INDIVIDUAL RESULTS BY DEVELOPING A LARGER POPULATION SAMPLE THAT INCLUDES LARGER NEOS THAT MAY OR MAY NOT BE SUITABLE FOR A MISSION. GOALS AND OBJECTIVES ASTEROID PHOTOMETRY OUR FIRST GOAL IS TO OBTAIN A LARGE NUMBER OF NEO LIGHTCURVES AND WHEN POSSIBLE H-G PARAMETERS COLOR INDICES AND SHAPE/SPIN AXIS MODELS TO HELP PAINT A BROADER PICTURE. FIRST PRIORITY WILL BE GIVEN TO OBJECTS OF HIGHEST INTEREST: POTENTIAL MISSION TARGETS OR IMPACTORS. WHILE WE ARE MINDFUL OF THEORETICAL INTERPRETATIONS OF OUR OBSERVATIONS OUR MAIN THRUST WILL BE OPEN AND IMMEDIATE ACCESS TO OUR RESULTS TO ALLOW OTHERS TO ENGAGE IN INTERPRETING THEM AS WELL. WE WILL PROVIDE THE RAW DATA AND INITIAL ANALYSIS E.G. ROTATION PERIODS AND ANALYSIS OF ROTATION RATE STATISTICS WHICH ARE REQUIRED FOR THOSE WORKING ON A FULL CHARACTERIZATION OF THE NEA POPULATION. WE WILL NOT WORK IN ISOLATION BUT WILL COORDINATE OUR EFFORTS WITH OTHER OBSERVERS IN PARTICULAR WITH THE RADAR TEAMS WORKING OUT OF ARECIBO AND GOLDSTONE. HAND-IN-HAND WITH THESE EFFORTS WILL BE CONTINUED MAINTENANCE OF THE ASTEROID LIGHTCURVE DATABASE (LCDB; WARNER ET AL.; 2009). THE LCDB IS ONE OF THE MORE WIDELY-USED DATABASES IN ASTEROID RESEARCH. AT ALMOST ANY ASTEROID-RELATED MEETING SEVERAL POSTERS OR PRESENTATIONS HAVE PLOTS BASED ON LCDB DATA OR USED THE DATA FOR ONGOING RESEARCH. WE WILL CONTINUE TO MAINTAIN DEVELOP AND ENHANCE THE ASTEROID LIGHTCURVE DATA EXCHANGE FORMAT (ALCDEF) DATABASE WHICH NOW HOLDS MORE THAN 2.8 MILLION RAW ASTEROID PHOTOMETRIC MEASUREMENTS. THESE DATA HAVE BEEN AND WILL CONTINUE TO BE ESSENTIAL TO THOSE WORKING ON ASTEROID SHAPE/SPIN AXIS MODELING. BOTH OF THESE DATABASES WILL BE MIGRATED TO THE NASA PDS ON A REGULAR BASIS. NEO POPULATION ANALYSIS CO-I ALAN HARRIS WILL CONTINUE HIS WORK ON THE NEA POPULATION IN TERMS OF SIZE DISTRIBUTION AND THE EFFECTIVENESS OF CURRENT AND SOONTO- BE LARGE SURVEY EFFORTS TO MEET THE NASA DISCOVERY REQUIREMENTS. RECENT WORK BY OTHERS INDICATES PREVIOUS ANALYSES MAY HAVE BEEN TAINTED BY INCORRECT SIZE ESTIMATES. CO-I HARRIS WILL EXPLORE THE EXTENT AND EFFECT OF THE CHANGES IN SIZE ESTIMATES AND PROVIDE ONE OR MORE UPDATES TO HIS PREVIOUS WORK ON THE NEA POPULATION SIZE DISTRIBUTION. METHODOLOGY FOR ASTEROID PHOTOMETRY WORK WE WILL EMPLOY A CADRE OF UP TO TEN TELESCOPES (0.3-0.7 M) AT OUR OBSERVATORY COMPLEX IN LANDERS CA WHICH AVERAGES 275-300 USABLE NIGHTS A YEAR. THE ROBOTIC OPERATIONS CAN BE CONDUCTED FROM ANYWHERE THERE IS INTERNET ACCESS. DATA MEASUREMENT AND ANALYSIS WILL BE DONE WITH READILY AVAILABLE COMMERCIAL SOFTWARE. WE WILL PUBLISH OUR ANALYSIS AND DATA QUARTERLY IF NOT MORE FREQUENTLY. THIS PIPELINE PRODUCED MORE THAN 500 NEA LIGHTCURVES OVER FOUR YEARS STARTING IN MID-2013. WE EXPECT TO MAINTAIN THAT PACE. PROGRAM RELEVANCE THE PROPOSED PHOTOMETRY AND CHARACTERIZATION OF NEO MEMBERS AS WELL AS ANALYSIS OF THE NEO POPULATION SIZE DISTRIBUTION ADDRESS SPECIFIC ELEMENTS OF THE NEOO PROGRAM. THIS MAKES OUR PROPOSAL BOTH COMPLIANT AND RELEVANT TO THE C.6 SSO/NEOO PROGRAM AND OBJECTIVES., Queen's University Belfast Astronomy Observation and Theory Consolidated Grant 2020-2023, THE ASTEROID TERRESTRIAL-IMPACT LAST ALERT SYSTEM (ATLAS) WAS AWARDED A 5 YEAR GRANT BY NASA NEOO IN 2013 TO CONSTRUCT AND OPERATE WIDE FIELD TELESCOPES THAT ARE CAPABLE OF SCANNING THE ENTIRE SKY EACH NIGHT TO MAGNITUDE 20. THE PARTICULAR STRENGTH OF ATLAS IS TO BE COMPLEMENTARY TO LARGER TELESCOPES SUCH AS PAN-STARRS AND CATALINA - ATLAS COVERS MUCH MORE AREA EACH NIGHT TO A SHALLOWER DEPTH. ATLAS IS DESIGNED TO BE AN "EARLY WARNING" SYSTEM THAT WILL PROVIDE THREE WEEKS' NOTICE OF MOST 140M ASTEROIDS OR COMETS ON TRACK TO HIT THE EARTH AND A WEEK'S NOTICE FOR MOST 50M ASTEROIDS. WE HAVE COMPLETED TWO ATLAS UNITS AND INSTALLED THEM ON HALEAKALA AND MAUNA LOA IN HAWAII. THE TELESCOPES OPERATE COMPLETELY ROBOTICALLY EACH NIGHT AND THROUGHOUT THE NIGHT THE DATA ARE REDUCED IN REAL-TIME ON EACH SUMMIT AND ANALYZED FOR CANDIDATE NEAR-EARTH ASTEROIDS. IN THE MORNING A HUMAN REVIEWER VERIFIES THE NEW ASTEROIDS IN THE NIGHTLY PROCESSING AND SUBMITS ASTROMETRY TO THE IAU MINOR PLANET CENTER. WE OBSERVE ABOUT HALF THE VISIBLE SKY EACH NIGHT FIVE TIMES WITH THE TWO-TELESCOPE SYSTEM BUT AT REDUCED SENSITIVITY DUE TO IMPROPERLY FIGURED SCHMIDT CORRECTORS ON THE TELESCOPES. REPLACEMENT LENSES FROM A DIFFERENT VENDOR ARE EXPECTED TO BE INSTALLED IN APRIL 2017 IMPROVING THE SENSITIVITY OF THE SYSTEM FROM M~19 TO THE DESIGNED CAPABILITY OF M~20 AND INCREASING THE DISCOVERY RATE BY MORE THAN 5X. TO DATE IN EARLY 2017 ATLAS HAS DISCOVERED 34 NEAS AND 5 PHAS SINCE START OF OPERATIONS. EXCEPT FOR DELAYS DUE TO THE SCHMIDT CORRECTORS ALL OTHER ASPECTS OF THE BUILD CONSTRUCTION AND COMMISSIONING OF BOTH THE HARDWARE AND SOFTWARE PROJECTS HAVE BEEN ON-TIME AND ON-BUDGET. WE ARE PROPOSING TO BUILD TWO MORE IDENTICAL "ATLAS UNITS" AND DEPLOY THEM AT THE BEST SITES POSSIBLE. WE EXPECT THAT THESE SITES WILL BE SAAO IN SOUTH AFRICA AND CHILE BUT WE WILL PERFORM A COMPETITIVE SEARCH FOR ALTERNATE SITES ONCE THE PROPOSAL IS FUNDED. BECAUSE OF THE DIVERSITY IN LATITUDE LONGITUDE AND WEATHER THESE TWO ADDITIONAL UNITS SHOULD DOUBLE THE ATLAS DISCOVERY RATE OF THE MOST PERNICIOUS PHAS - THE 20-50M ASTEROIDS THAT PASS VERY CLOSE TO THE EARTH AND ARE ONLY VISIBLE TO ANY TELESCOPE FOR A SHORT TIME., G3733088626, UK Involvement in LSST: Phase B (QUB component), G4797677415, G6120759733, G6131798161, G6549972864, G6900289228, G7258890752
OpenAlex ID: W4407196615