Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Andrew F. Cheng
Harrison F. Agrusa
Brent W. Barbee
Alex J. Meyer
Tony L. Farnham
Sabina D. Raducan
Derek C. Richardson
Elisabetta Dotto
Angelo Zinzi
Vincenzo Della Corte
Thomas S. Statler
Steven Chesley
Shantanu P. Naidu
Masatoshi Hirabayashi
Jian-Yang Li
Siegfried Eggl
Olivier S. Barnouin
Nancy L. Chabot
Sidney Chocron
Gareth S. Collins
Abstract： The NASA Double Asteroid Redirection Test (DART) mission performed a kinetic impact on asteroid Dimorphos, the satellite of the binary asteroid (65803) Didymos, at 23:14 UTC on September 26, 2022 as a planetary defense test. DART was the first hypervelocity impact experiment on an asteroid at size and velocity scales relevant to planetary defense, intended to validate kinetic impact as a means of asteroid deflection. Here we report the first determination of the momentum transferred to an asteroid by kinetic impact. Based on the change in the binary orbit period, we find an instantaneous reduction in Dimorphos's along-track orbital velocity component of 2.70 +/- 0.10 mm/s, indicating enhanced momentum transfer due to recoil from ejecta streams produced by the impact. For a Dimorphos bulk density range of 1,500 to 3,300 kg/m$^3$, we find that the expected value of the momentum enhancement factor, $\beta$, ranges between 2.2 and 4.9, depending on the mass of Dimorphos. If Dimorphos and Didymos are assumed to have equal densities of 2,400 kg/m$^3$, $\beta$= 3.61 +0.19/-0.25 (1 $\sigma$). These $\beta$ values indicate that significantly more momentum was transferred to Dimorphos from the escaping impact ejecta than was incident with DART. Therefore, the DART kinetic impact was highly effective in deflecting the asteroid Dimorphos.
Peer Review Status:
Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
R. Terik Daly
Carolyn M. Ernst
Olivier S. Barnouin
Nancy L. Chabot
Andrew S. Rivkin
Andrew F. Cheng
Elena Y. Adams
Harrison F. Agrusa
Elisabeth D. Abel
Amy L. Alford
Erik I. Asphaug
Justin A. Atchison
Andrew R. Badger
Paul Baki
Ronald-L. Ballouz
Dmitriy L. Bekker
Julie Bellerose
Shyam Bhaskaran
Bonnie J. Buratti
Saverio Cambioni
Abstract： While no known asteroid poses a threat to Earth for at least the next century, the catalog of near-Earth asteroids is incomplete for objects whose impacts would produce regional devastation. Several approaches have been proposed to potentially prevent an asteroid impact with Earth by deflecting or disrupting an asteroid. A test of kinetic impact technology was identified as the highest priority space mission related to asteroid mitigation. NASA's Double Asteroid Redirection Test (DART) mission is the first full-scale test of kinetic impact technology. The mission's target asteroid was Dimorphos, the secondary member of the S-type binary near-Earth asteroid (65803) Didymos. This binary asteroid system was chosen to enable ground-based telescopes to quantify the asteroid deflection caused by DART's impact. While past missions have utilized impactors to investigate the properties of small bodies those earlier missions were not intended to deflect their targets and did not achieve measurable deflections. Here we report the DART spacecraft's autonomous kinetic impact into Dimorphos and reconstruct the impact event, including the timeline leading to impact, the location and nature of the DART impact site, and the size and shape of Dimorphos. The successful impact of the DART spacecraft with Dimorphos and the resulting change in Dimorphos's orbit demonstrates that kinetic impactor technology is a viable technique to potentially defend Earth if necessary.
Peer Review Status:Awaiting Review
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