Discovery[1] | |||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Discovered by | LINEAR | ||||||||||||||||
Discovery site | Lincoln Lab's ETS | ||||||||||||||||
Discovery date | 11 September 1999 | ||||||||||||||||
Designations | |||||||||||||||||
(101955) Bennu | |||||||||||||||||
Pronunciation | /ˈbɛnuː/[2] | ||||||||||||||||
Named after | Bennu | ||||||||||||||||
1999 RQ36 | |||||||||||||||||
Apollo · NEO · PHA · risk listed | |||||||||||||||||
Orbital characteristics[1] | |||||||||||||||||
Epoch 1 January 2011 (JD 2455562.5) | |||||||||||||||||
Uncertainty parameter 0 | |||||||||||||||||
Observation arc | 21.06 yr (7693 days) | ||||||||||||||||
Aphelion | 1.3559 au (202.84 Gm) | ||||||||||||||||
Perihelion | 0.8969 au (134.17 Gm) | ||||||||||||||||
1.1264 au (168.51 Gm) | |||||||||||||||||
Eccentricity | 0.2038 | ||||||||||||||||
1.1955 yr (436.65 d) | |||||||||||||||||
Average orbital speed | 28.0 km/s (63,000 mph) | ||||||||||||||||
101.7039° | |||||||||||||||||
0° 49m 28.056s / day | |||||||||||||||||
Inclination | 6.0349° | ||||||||||||||||
2.0609° | |||||||||||||||||
66.2231° | |||||||||||||||||
Earth MOID | 0.0032228 au (482,120 km) | ||||||||||||||||
Venus MOID | 0.194 au (29,000,000 km)[3] | ||||||||||||||||
Mars MOID | 0.168 au (25,100,000 km)[3] | ||||||||||||||||
Jupiter MOID | 3.877 au (580.0 Gm) | ||||||||||||||||
TJupiter | 5.525 | ||||||||||||||||
Proper orbital elements[4] | |||||||||||||||||
Proper eccentricity | 0.21145 | ||||||||||||||||
Proper inclination | 5.0415° | ||||||||||||||||
Proper mean motion | 301.1345 deg / yr | ||||||||||||||||
Proper orbital period | 1.19548 yr (436.649 d) | ||||||||||||||||
Physical characteristics[5] | |||||||||||||||||
Dimensions | 565 m × 535 m × 508 m (1854 ft × 1755 ft × 1667 ft)[1] | ||||||||||||||||
245.03±0.08 m (804±0.262 ft) | |||||||||||||||||
Equatorial radius | 282.37±0.06 m (926.4±0.197 ft) | ||||||||||||||||
Polar radius | 249.25±0.06 m (817.74±0.197 ft) | ||||||||||||||||
0.782±0.004 km2 (0.302±0.002 sq mi) | |||||||||||||||||
Volume | 0.0615±0.0001 km3 | ||||||||||||||||
Mass | (7.329±0.009)×1010 kg | ||||||||||||||||
Mean density | 1.190±0.013 g/cm3 | ||||||||||||||||
Equatorial surface gravity | 6.27 micro-g[6] (61.5 μm/s2) | ||||||||||||||||
Equatorial escape velocity | 20 cm/s | ||||||||||||||||
4.296057±0.000002 h | |||||||||||||||||
177.6±0.11° | |||||||||||||||||
North pole right ascension | +85.65±0.12° | ||||||||||||||||
North pole declination | −60.17±0.09° | ||||||||||||||||
0.044±0.002 | |||||||||||||||||
| |||||||||||||||||
B[1][5] F[8] | |||||||||||||||||
20.9 | |||||||||||||||||
101955 Bennu (provisional designation 1999 RQ36) is a carbonaceous asteroid in the Apollo group discovered by the LINEAR Project on 11 September 1999. It is a potentially hazardous object that is listed on the Sentry Risk Table and has the highest cumulative rating on the Palermo Technical Impact Hazard Scale.[9] It has a cumulative 1-in-1,750 chance of impacting Earth between 2178 and 2290 with the greatest risk being on 24 September 2182.[10][11] It is named after Bennu, the ancient Egyptian mythological bird associated with the Sun, creation, and rebirth.
101955 Bennu has a mean diameter of 490 m (1,610 ft; 0.30 mi) and has been observed extensively by the Arecibo Observatory planetary radar and the Goldstone Deep Space Network.[5][12][13]
Bennu was the target of the OSIRIS-REx mission that returned samples of the asteroid to Earth.[14][15][16] The spacecraft, launched in September 2016, arrived at the asteroid two years later and mapped its surface in detail, seeking potential sample collection sites.[17] Analysis of the orbits allowed calculation of Bennu's mass and its distribution.[18] In October 2020, OSIRIS-REx briefly touched down and collected a sample of the asteroid's surface.[19][20][21] A capsule containing the sample was returned and landed on Earth in September 2023, with distribution and analysis of the sample ongoing.[22][23][24] On 15 May 2024, an overview of preliminary analytical studies on the returned samples was reported.[25]
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