(101955) Bennu

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Asteroid
(101955) Bennu
Asteroid-Bennu-OSIRIS-RExArrival-GifAnimation-20181203.gif
Animation composed of images taken by OSIRIS-REx on November 25, 2018 from a distance of around 80 km.
Properties of the orbit ( animation )
Epoch:  January 1st, 2011 ( JD 2,455,562.5)
Orbit type Near-Earth asteroid, Apollo-type
Major semi-axis 1.126  AU
eccentricity 0.204
Perihelion - aphelion 0.897 AU - 1.356 AU
Inclination of the orbit plane 6.0 °
Length of the ascending node 2.1 °
Argument of the periapsis 66.2 °
Sidereal period of rotation 1 a 71 d
Mean orbital velocity 0.00 km / s
Physical Properties
Dimensions 566 m × 542 m × 499 m
Dimensions 6.0 - 7.76  x  10 10Template: Infobox asteroid / maintenance / mass kg
Medium density 0.97 g / cm³
Rotation period 4.297 h
Absolute brightness 20.2 mag
Spectral class
(according to SMASSII ) 		B.
history
Explorer LINEAR
Date of discovery September 11, 1999
Another name 1999 RQ 36
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . The affiliation to an asteroid family is automatically determined from the AstDyS-2 database . Please also note the note on asteroid items.

(101955) Bennu is an asteroid of the Apollo-type , the September 11, 1999 under the LINEAR was discovered -project and initially the designation 1999 RQ 36 received. The asteroid was observed by the Arecibo Observatory and continues to be extensively observed by the Goldstone Deep Space Communications Complex .

Physical Properties

The diameter is about 492 meters.

The asteroid was observed from 1999 to 2011 in order to be able to provide precise information, to get a more precise idea of ​​the nature and structure and to better estimate the effects of the Jarkowski effect on the orbit. A density of 0.97 t / m³ with a mass of 62 million tons could be determined by the measured deviation from the path of 160 km.

Orbit

Bennu orbits the sun within 436 days at a distance of 0.9  AU to 1.35 AU, so it crosses the orbit of the earth and approaches the orbit of Mars. The smallest distance between the asteroid and the earth (Earth MOID) is 469,737.31 km.

construction

  • Close-up of the asteroid Bennu

  • View of Bennu's equator and the northern hemisphere from a distance of 3.6 km, March 28, 2019.

  • Detail in the southern hemisphere from March 7, 2019. The rock in the lower center of the picture is about 7.4 meters in size.

  • On the left is an area of ​​180 meters in the Northern Hemisphere. In the detailed images (right) a 15 meter large rock can be seen at the top and a regolith "pond" at the bottom (images from February 25, 2019).

Possible collision with the earth

In 2009 Andrea Milani calculated a series of possible collisions with the earth in the period from 2169 to 2199 as part of a study. The probability of an impact depends on the physical properties of the asteroid, which are insufficiently known, but is less than 0.07%.

In 2016, it was predicted that Bennu would come closer to Earth than Earth's moon in his flyby in 2135. This flyby could alter Bennus further trajectory so that he collides with the earth later in the same century . The surveillance system for near-earth objects Sentry lists 78 possible impacts by Bennu between the years 2175 and 2199 on its collision risk list, with an overall probability of 0.037% being given.

exploration

Exploration from Earth

After the discovery of the asteroid in 1999 there were three good opportunities to measure the asteroid, since the brightness with V = 14.4 mag (1999 to 2000), 16.1 mag (2005 to 2006) and 19.9 mag (2011 to 2012) was particularly high.

Mission OSIRIS-REx

After name suggestions were received from more than 8,000 students in a NASA competition, the official proper name Bennu for the asteroid was announced on May 1, 2013 . Bennu is the English name for the ancient Egyptian god of the dead Benu .

Particles leave the surface of Bennu, January 19, 2019

On May 25, 2011 NASA announced that it would fly to (101955) Bennu as part of the OSIRIS-REx mission . The start date was September 8, 2016, the return to earth with collected soil samples is planned for 2023.

Particle emission

As a surprising interim result of the mission, it was announced in early 2019 that Bennu was losing mass. In several bursts, particles up to 10 cm in size, sometimes several hundred at the same time, flowed away from the asteroid; lighter ones fell back on him. The speed and origin of the eruptions could be precisely measured. With this data (December 2019) various theories for the causes are tested, e.g. B. internal tensions, rotational forces, meteorite impacts, effects of ice formation or melting or effects of temperature differences due to different solar radiation on the rotating body. In January and February 2019, Bennu lost about one kilogram of his matter.

Taking the soil samples

Soil samples were taken while the robot arm was touched down for a few seconds on October 20, 2020. On May 10, 2021, the return journey to earth began. The technology and structure of the capsule, which is scheduled to land in the USA with around 100 grams of material in 2023, correspond to those of the Stardust space probe , which brought particle samples to Earth in January 2006 from the coma of comet 81P / Wild 2 .

See also

Web links

Commons : 101955 Bennu  - Collection of images, videos and audio files

Individual evidence

  1. ↑ Asteroid Bennu P_constants (PcK) SPICE kernel file. Retrieved November 11, 2020 .
  2. ↑ a b asteroid on the light scales. In: Science ticker Astro. May 25, 2012, Retrieved August 4, 2012 .
  3. ↑ 101955 Bennu. In: neo.ssa.ESA.int. European Space Agency , September 24, 2019, accessed September 24, 2019 .
  4. ↑ Andrea Milani, Steven R. Chesley, Maria Eugenia Sansaturio, Fabrizio Bernardi, Giovanni B. Valsecchi, Oscar Arratia: Long-term impact risk for (101955) 1999 RQ 36 . In: Icarus . 203, No. 2, October 2009, pp. 460-471. arxiv : 0901.3631 . doi : 10.1016 / j.icarus.2009.05.029 .
  5. ↑ Samuel Osorne: NASA to launch probe to investigate 'Armageddon' asteroid. In: The Independent. July 31, 2016 (English).
  6. ↑ Sentry: Earth Impact Monitoring. Retrieved March 23, 2021 .
  7. ↑ DS Lauretta, AE Bartels, MA Barucci, EB Bierhaus, RP Binzel: The OSIRIS-REx target asteroid (101955) Bennu: Constraints on its physical, geological, and dynamical nature from astronomical observations . In: Meteoritics & Planetary Science . tape 50 , no. 4 , November 10, 2014, p. 834–849 , doi : 10.1111 / maps.12353 .
  8. ↑ That Asteroid has a Name! In: The OSIRIS-REx Mission - An Asteroid Sample Return Mission. May 1, 2013, accessed May 7, 2013 .
  9. ↑ OSIRIS-REX, Asteroid 1999 RQ36 becomes Bennu. In: Astronews.com. May 6, 2013, accessed May 7, 2013 .
  10. ↑ NASA News: NASA to Launch New Science Mission to Asteroid in 2016 May 25, 2011
  11. ^ Mission "Osiris Rex": NASA wants to land on asteroid with probe Spiegel Online, April 12, 2014, accessed on September 14, 2015.
  12. ↑ Teilchenausstoß an asteroid signed by "sian", Frankfurter Allgemeine Zeitung no. 288, p. N1 (print edition, supplement nature and science), December 11, 2019.
  13. ↑ NASA documentation on the mission
  14. ↑ NASA To Launch New Science Mission To Asteroid In 2016. In: OSIRIS-REX. May 25, 2011, accessed September 25, 2019 .