The operational environment and rotational acceleration of asteroid (101955) Bennu from OSIRIS-REx observations

C. Hergenrother (1) , C. Maleszewski (1) , M. Nolan (1) , J.-Y. Li (2) , C. Drouet D’aubigny (1) , F. Shelly (1) , E. Howell (1) , T. Kareta (1) , M. Izawa (3) , M. Barucci (4) , E. Bierhaus (5) , H. Campins (6) , S. Chesley (7) , B. Clark (8) , E. Christensen (1) , D. Dellagiustina (1) , S. Fornasier (4) , D. Golish (1) , C. Hartzell (9) , B. Rizk (1) , D. Scheeres (10) , P. Smith (1) , X.-D. Zou (2) , D. Lauretta (1) , Marc Bernacki (11) , Daniel Pino Muñoz (11)

1 LPL - Lunar and Planetary Laboratory [Tucson]
2 PSI - Planetary Science Institute [Tucson]
3 Okayama University, Misasa
4 LESIA (UMR_8109) - Laboratoire d'études spatiales et d'instrumentation en astrophysique
5 Lockheed Martin Space Sciences Laboratory
6 Dept. of Physics
7 JPL - Jet Propulsion Laboratory
8 Ithaca College
9 University of Maryland [College Park]
10 University of Colorado [Boulder]
11 CEMEF - Centre de Mise en Forme des Matériaux

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, and rotation state. Discovery of a dusty environment, a natural satellite, or unexpected asteroid characteristics would have had consequences for the mission’s safety and observation strategy. Here we show that spacecraft observations during this period were highly sensitive to satellites (sub-meter scale) but reveal none, although later navigational images indicate that further investigation is needed. We constrain average dust production in September 2018 from Bennu’s surface to an upper limit of 150 g s–1 averaged over 34 min. Bennu’s disk-integrated photometric phase function validates measurements from the pre-encounter astronomical campaign. We demonstrate that Bennu’s rotation rate is accelerating continuously at 3.63 ± 0.52 × 10–6 degrees day–2, likely due to the Yarkovsky–O’Keefe–Radzievskii–Paddack (YORP) effect, with evolutionary implications.

Mots clés: Asteroids; Comets and Kuiper belt; Rings and moons

Domaines: Sciences de l'ingénieur [physics]; Matériaux; Physique [physics]; Astrophysique [astro-ph]

C. Hergenrother, C. Maleszewski, M. Nolan, J.-Y. Li, C. Drouet D’aubigny, et al.. The operational environment and rotational acceleration of asteroid (101955) Bennu from OSIRIS-REx observations. Nature Communications, 2019, 10 (1), ⟨10.1038/s41467-019-09213-x⟩. ⟨hal-02417614⟩