Steven R. Chesley
A5021819630- Astro and Planetary Science
- Planetary Science and Exploration
- Stellar, planetary, and galactic studies
- Space Satellite Systems and Control
- Isotope Analysis in Ecology
- Gamma-ray bursts and supernovae
- Spacecraft and Cryogenic Technologies
- Space Exploration and Technology
- Astronomy and Astrophysical Research
- High-pressure geophysics and materials
- Astronomical Observations and Instrumentation
- Nuclear Physics and Applications
- Spacecraft Design and Technology
- Geology and Paleoclimatology Research
- Geological and Geochemical Analysis
- Space Science and Extraterrestrial Life
- Geomagnetism and Paleomagnetism Studies
- Spacecraft Dynamics and Control
- earthquake and tectonic studies
- Astrophysics and Star Formation Studies
- Nuclear physics research studies
- Solar and Space Plasma Dynamics
- Astronomical and nuclear sciences
- Space exploration and regulation
- Experimental and Theoretical Physics Studies
Jet Propulsion Laboratory
2016-2025
California Institute of Technology
2004-2024
Auburn University
2022
Space Telescope Science Institute
2017
Purdue University West Lafayette
2016
Charles University
2000-2015
Institute of Astronomy
2015
University of Colorado Boulder
2015
Southwest Research Institute
2015
Ohio University
2015
(Abridged) We describe here the most ambitious survey currently planned in optical, Large Synoptic Survey Telescope (LSST). A vast array of science will be enabled by a single wide-deep-fast sky survey, and LSST have unique capability faint time domain. The design is driven four main themes: probing dark energy matter, taking an inventory Solar System, exploring transient optical sky, mapping Milky Way. wide-field ground-based system sited at Cerro Pach\'{o}n northern Chile. telescope 8.4 m...
A survey that can cover the sky in optical bands over wide fields to faint magnitudes with a fast cadence will enable many of exciting science opportunities next decade. The Large Synoptic Survey Telescope (LSST) have an effective aperture 6.7 meters and imaging camera field view 9.6 deg^2, be devoted ten-year 20,000 deg^2 south +15 deg. Each pointing imaged 2000 times fifteen second exposures six broad from 0.35 1.1 microns, total point-source depth r~27.5. LSST Science Book describes basic...
Abstract During its approach to asteroid (101955) Bennu, NASA’s Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) spacecraft surveyed Bennu’s immediate environment, photometric properties, rotation state. Discovery of a dusty natural satellite, or unexpected characteristics would have had consequences for the mission’s safety observation strategy. Here we show that observations during this period were highly sensitive satellites (sub-meter...
Abstract We review the results of an extensive campaign to determine physical, geological, and dynamical properties asteroid (101955) Bennu. This investigation provides information on orbit, shape, mass, rotation state, radar response, photometric, spectroscopic, thermal, regolith, environmental combine these data with cosmochemical models develop a hypothetical timeline for Bennu's formation evolution. infer that Bennu is ancient object has witnessed over 4.5 Gyr solar system history. Its...
Abstract The Double Asteroid Redirection Test (DART) is a Planetary Defense mission, designed to demonstrate the kinetic impactor technique on (65803) Didymos I Dimorphos, secondary of system. DART has four level 1 requirements meet in order declare mission success: (1) impact Dimorphos between 2022 September 25 and October 2, (2) cause at least 73 s change its binary orbit period via impact, (3) measure an uncertainty 7.3 or less, (4) momentum transfer efficiency ( β ) characterize...
Active asteroids are those that show evidence of ongoing mass loss. We report repeated instances particle ejection from the surface (101955) Bennu, demonstrating it is an active asteroid. The events were imaged by OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) spacecraft. For three largest observed events, we estimated ejected velocities sizes, event times, source regions, energies. also determined trajectories photometric properties...
Abstract Although no known asteroid poses a threat to Earth for at least the next century, catalogue of near-Earth asteroids is incomplete objects whose impacts would produce regional devastation 1,2 . Several approaches have been proposed potentially prevent an impact with by deflecting or disrupting 1–3 A test kinetic technology was identified as highest-priority space mission related mitigation 1 NASA’s Double Asteroid Redirection Test (DART) full-scale technology. The mission’s target...
Abstract The NASA Double Asteroid Redirection Test (DART) mission performed a kinetic impact on asteroid Dimorphos, the satellite of binary (65803) Didymos, at 23:14 UTC 26 September 2022 as planetary defence test 1 . DART was first hypervelocity experiment an size and velocity scales relevant to defence, intended validate means deflection. Here we report determination momentum transferred by impact. On basis change in orbit period 2 , find instantaneous reduction Dimorphos’s along-track...
Abstract The Double Asteroid Redirection Test (DART) spacecraft successfully performed the first test of a kinetic impactor for asteroid deflection by impacting Dimorphos, secondary near-Earth binary (65803) Didymos, and changing orbital period Dimorphos. A change in approximately 7 min was expected if incident momentum from DART directly transferred to target perfectly inelastic collision 1 , but studies probable impact conditions properties indicated that considerable enhancement ( β )...
Some active asteroids have been proposed to be formed as a result of impact events1. Because are generally discovered by chance only after their tails fully formed, the process how ejecta evolve into tail has, our knowledge, not directly observed. The Double Asteroid Redirection Test (DART) mission NASA2, in addition having successfully changed orbital period Dimorphos3, demonstrated activation an asteroid resulting from under precisely known conditions. Here we report observations DART with...
Abstract NASA's Double Asteroid Redirection Test (DART) mission was the first to demonstrate asteroid deflection, and mission's Level 1 requirements guided its planetary defense investigations. Here, we summarize DART's achievement of those requirements. On 2022 September 26, DART spacecraft impacted Dimorphos, secondary member Didymos near-Earth binary system, demonstrating an autonomously navigated kinetic impact into with limited prior knowledge for defense. Months subsequent Earth-based...
Abstract The Double Asteroid Redirection Test (DART) mission impacted Dimorphos, the satellite of binary near-Earth asteroid (65803) Didymos, on 2022 September 26 UTC. We estimate changes in orbital and physical properties system due to impact using ground-based photometric radar observations, as well DART camera observations. Under assumption that Didymos is an oblate spheroid, we its equatorial polar radii are 394 ± 11 m 290 16 m, respectively. instantaneously changed along-track velocity...
We determined the mass of asteroid 433 Eros, its lower order gravitational harmonics, and rotation state, using ground-based Doppler range tracking Near Earth Asteroid Rendezvous (NEAR)–Shoemaker spacecraft images asteroid's surface landmarks. The Eros is (6.687 ± 0.003) × 10 18 grams, which, coupled with our volume estimate, implies a bulk density 2.67 0.03 grams per cubic centimeter. appears to have uniform distribution. right ascension declination pole are 11.37 0.05 17.22 degrees,...
Radar ranging from Arecibo, Puerto Rico, to the 0.5-kilometer near-Earth asteroid 6489 Golevka unambiguously reveals a small nongravitational acceleration caused by anisotropic thermal emission of absorbed sunlight. The magnitude this perturbation, known as Yarkovsky effect, is function asteroid's mass and surface characteristics. Direct detection effect on asteroids will help constrain their physical properties, such bulk density, refine orbital paths. Based strength detected we estimate...
We describe the Pan-STARRS Moving Object Processing System (MOPS), a modern software package that produces automatic asteroid discoveries and identifications from catalogs of transient detections next-generation astronomical survey telescopes. MOPS achieves > 99.5% efficiency in producing orbits synthetic but realistic population asteroids whose measurements were simulated for Pan-STARRS4-class telescope. Additionally, using non-physical grid population, we demonstrate can detect populations...
Abstract 1I/‘Oumuamua is the first confirmed interstellar body in our solar system. Here we report on observations of ‘Oumuamua made with Spitzer Space Telescope 2017 November 21–22 (UT). We integrated for 30.2 hr at 4.5 μ m (IRAC channel 2). did not detect object and place an upper limit flux 0.3 Jy (3 σ ). This implies effective spherical diameter less than [98, 140, 440] albedo greater [0.2, 0.1, 0.01] under assumption low, middle, or high thermal beaming parameter η , respectively. With...
Abstract Near-Earth Objects (NEOs) are a transient population of small bodies with orbits near or in the terrestrial planet region. They represent mid-stage dynamical cycle asteroids and comets, which starts their removal from respective source regions—the main belt trans-Neptunian scattered disk—and ends as impact planets, disintegrate Sun, ejected solar system. Here we develop new orbital model NEOs by numerically integrating asteroid main-belt sources calibrating results on observations...