|Alternative names||1999 RQ36|
|Minor planet category||Apollo|
|Semi-major axis||1.126 AU|
|Orbital period||436.604 d
|Longitude of ascending node||2.068°|
|Mean radius||247 ± 10 m|
|Equatorial radius||273 ± 8 m|
101955 Bennu (provisional designation 1999 RQ36) is an Apollo asteroid discovered by the LINEAR Project on September 11, 1999. It is the planned target of the OSIRIS-REx mission which is intended to return samples to Earth for further study. It is a potential Earth impactor and is listed on the Sentry Risk Table with the second highest rating on the Palermo Technical Impact Hazard Scale.
A recent dynamical study by Andrea Milani and collaborators has located a series of eight potential Earth impacts between 2169 and 2199. The cumulative probability of impact is dependent on poorly known physical properties of the object, but is not higher than 0.07% for all eight encounters. To accurately assess 101955 Bennu's probability of Earth impact will require a detailed shape model of 101955 Bennu and additional observations (either from the ground or from spacecraft visiting the object) to determine the magnitude of the Yarkovsky acceleration. On average, an asteroid with a diameter of 500 meters can be expected to impact Earth about every 130,000 years or so.
Separately, 101955 Bennu has been considered many times as the target of spacecraft missions, including OSIRIS-REx, due to the low Δv required to reach it from Earth orbit. NASA announced on May 25, 2011, that OSIRIS-REx had been selected as part of NASA's New Frontiers Program. The spacecraft is scheduled to launch in 2016, reach 101955 Bennu in 2019 and return samples to Earth in 2023.
The asteroid was named by Michael Puzio, a third-grader from North Carolina, one of more than eight thousand students from dozens of countries around the world who entered a "Name That Asteroid!" contest run by the University of Arizona, The Planetary Society, and the LINEAR Project, according to The Planetary Report, June 2013. The name refers to Bennu, an Egyptian mythological bird.
- "The Shape and Spin of 101955 (1999 RQ36) from Arecibo and Goldstone Radar Imaging".
- "Goldstone Delay-Doppler Images of 1999 RQ36". Asteroid Radar Research. Jet Propulsion Laboratory.
- Nolan, M. C.; Magri, C.; Benner, L. A. M.; Giorgini, J. D.; Hergenrother, C. W.; Howell, E. S.; Hudson, R. S.; Lauretta, D. S.; Margot, J. -L. (2012). "The Shape of OSIRIS-REx Mission Target 1999 RQ36 from Radar and Lightcurve Data". Asteroid Comet Meteors 2012 Conference 1667: 6345. Bibcode:2012LPICo1667.6345N.
- "101955 1999 RQ36: Earth Impact Risk Summary". NASA. Jet Propulsion Laboratory. August 5, 2010. Retrieved 24 November 2013.
- Emery, J. P.; Fernández, Y. R.; Kelley, M. S.; Hergenrother, C. (2010). "Thermophysical Characterization of Potential Spacecraft Target (101955) 1999 RQ36". 41st Lunar and Planetary Science Conference 1533: 2282. Bibcode:2010LPI....41.2282E.
- We have a winner! The OSIRIS-REx asteroid's name is: Bennu!
- "NASA to Launch New Science Mission to Asteroid in 2016". NASA. 25 May 2011. Retrieved 21 May 2013.
- "Sentry Risk Table". NASA/JPL Near-Earth Object Program Office. 14 Oct 2011. Archived from the original on 21 July 2011. Retrieved 2011-10-14.
- Hudson, R. S.; Ostro, S. J.; Benner, L. A. M. "Recent Delay-Doppler Radar Asteroid Modeling Results: 1999 RQ36 and Craters on Toutatis". Bulletin of the American Astronomical Society (American Astronomical Society) 32: 1001. Bibcode:2000DPS....32.0710H.
- Milani, Andrea; Chesley, Steven R.; Sansaturio, Maria Eugenia; Bernardi, Fabrizio; Valsecchi, Giovanni B.; Arratia, Oscar (2009). "Long term impact risk for (101955) 1999 RQ36". Icarus 203 (2): 460–471. arXiv:0901.3631. Bibcode:2009Icar..203..460M. doi:10.1016/j.icarus.2009.05.029.
- Robert Marcus, H. Jay Melosh, and Gareth Collins (2010). "Earth Impact Effects Program". Imperial College London / Purdue University. Retrieved 2013-02-07. (solution using 2600kg/m^3, 17km/s, 45 degrees)
- Near-Earth Asteroid Delta-V for Space Rendezvous
- Earth Impact Risk Summary: 101955 1999 RQ36 (Years: 2169–2199) – JPL near-Earth object website
- Orbit parameters – NASA website
- Temperature History and Dynamical Evolution of (101955) 1999 RQ 36: A Potential Target for Sample Return from a Primitive Asteroid (2011 ApJ 728 L42)
- Physical Properties of OSIRIS-REx Target Asteroid (101955) 1999 RQ36 derived from Herschel, ESO-VISIR and Spitzer observations (arXiv:1210.5370 : 19 Oct 2012)