101955 Bennu

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101955 Bennu
Mosaic image of 101955 Bennu consisting of 12 PolyCam images collected on 2 December 2018 by OSIRIS-REx from a range of 24 km (15 mi).
Discovered by LINEAR
Discovery site Lincoln Lab's ETS
Discovery date 11 September 1999
MPC designation (101955) Bennu
Pronunciation /bɛˈn/
Named after
1999 RQ36
Apollo · NEO · PHA
Orbital characteristics[2]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc 13.36 yr (4880 days)
Aphelion 1.3559 au (202.84 Gm)
Perihelion 0.89689 au (134.173 Gm)
1.1264 au (168.51 Gm)
Eccentricity 0.20375
1.20 yr (436.65 d)
Average orbital speed
28,000 metres per second (63,000 mph)
0° 49m 28.056s / day
Inclination 6.0349°
Earth MOID 0.0032228 au (482,120 km)
Venus MOID 0.194 au (29,000,000 km)[1]
Mars MOID 0.168 au (25,100,000 km)[1]
Jupiter MOID 3.877 au (580.0 Gm)
TJupiter 5.525
Proper orbital elements[3]
Proper eccentricity
Proper inclination
Proper mean motion
301.1345 deg / yr
1.19548 yr
(436.649 d)
Physical characteristics
Mean radius
245.03±0.08 m[4]
Equatorial radius
(282.37±0.06) × (268.05±0.06) m[4]
Polar radius
249.25±0.06 m[4]
0.782±0.004 km2[4]
Volume 0.0615±0.0001 km3[4]
Mass 7.329±0.009×1010 kg[4]
Mean density
1.190±0.013 g/cm3[4]
Equatorial surface gravity
6 micro-g[5]
4.296057 h (0.1790024 d)[4]
North pole right ascension
North pole declination
Surface temp. min mean max
Kelvin[6] 236 259 279
Fahrenheit -34.6 6.8 42.8
Celsius -37 -14 6

101955 Bennu (provisional designation 1999 RQ36)[8] 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 with the second-highest cumulative rating on the Palermo Technical Impact Hazard Scale.[9] It has a cumulative 1-in-2,700 chance of impacting Earth between 2175 and 2199.[10][11] It is named after the Bennu, the ancient Egyptian mythological bird associated with the Sun, creation, and rebirth.

101955 Bennu has a mean diameter of approximately 492 m (1,614 ft; 0.306 mi) and has been observed extensively with the Arecibo Observatory planetary radar and the Goldstone Deep Space Network.[12][13][14]

Bennu is the target of the OSIRIS-REx mission which is intended to return samples to Earth in 2023 for further study.[15][16][17] On 3 December 2018, the OSIRIS-REx spacecraft arrived at Bennu after a two-year journey.[18] Before attempting to obtain a sample from the asteroid, it will map out Bennu's surface in detail and orbit the asteroid to calculate its mass.[19] On 18 June 2019, NASA announced that OSIRIS-REx managed to get even closer and capture an image at a distance of 0.4 miles (0.64 km) from Bennu's surface.[20]

Discovery and observation

Series of Goldstone radar images showing Bennu's rotation.

Bennu was discovered on 11 September 1999 during a Near-Earth asteroid survey by the Lincoln Near-Earth Asteroid Research (LINEAR).[1] The asteroid was designated 1999 RQ36 and classified a near-Earth asteroid. Bennu approached close to Earth and it was observed extensively by the Arecibo Observatory and the Goldstone Deep Space Network using radar imaging as Bennu closely approached Earth on 23 September 1999.[12][13]


The name Bennu was selected from more than eight thousand student entries 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 in 2012.[2][8] Third-grade student Michael Puzio from North Carolina proposed the name in reference to the Egyptian mythological bird Bennu. To Puzio, the OSIRIS-REx spacecraft with its extended TAGSAM arm resembled the Egyptian deity, which is typically depicted as a heron.[2]

Its features will be named after birds and bird-like creatures in mythology.[21]

Physical characteristics

Image sequence showing the rotation of Bennu, imaged by OSIRIS-REx at a distance of around 80 km (50 mi).
Wide angle shot of the Northern Hemisphere of Bennu, imaged by OSIRIS-REx at an altitude of approximately 1.1 mi (1.8 km).

Bennu has a roughly spheroidal shape, resembling a spinning top. Bennu's axis of rotation is tilted 176 degrees to its orbit; the direction of rotation about its axis is retrograde with respect to its orbit.[22] Bennu has a fairly smooth shape with one prominent 10–20 m boulder on its surface, in the southern hemisphere.[11]

There is a well-defined ridge along the equator of Bennu. The presence of this ridge suggests that fine-grained regolith particles have accumulated in this area, possibly because of its low gravity and fast rotation.[11] Observations by the OSIRIS-Rex spacecraft has shown that Bennu is rotating faster over time.[23] This change in Bennu's rotation is caused by the Yarkovsky-O'Keefe-Radzievskii-Paddack effect, or the YORP effect.[23] Due to the uneven emission of thermal radiation from its surface as Bennu rotates in sunlight, the rotation period of Bennu decreases by about one second every 100 years.[23]

Observations of this minor planet by the Spitzer Space Telescope in 2007 gave an effective diameter of 484±10 m, which is in line with other studies. It has a low visible geometric albedo of 0.046±0.005. The thermal inertia was measured and found to vary by approximately 19% during each rotational period. The data suggest that the regolith grain size is moderate, ranging from several millimeters up to a centimeter, and evenly distributed. No emission from a potential dust coma has been detected around Bennu, which puts a limit of 106 g of dust within a radius of 4750 km.[24]

Astrometric observations between 1999 and 2013 have demonstrated that 101955 Bennu is influenced by the Yarkovsky effect, causing the semimajor axis to drift on average by 284±1.5 meters/year. Analysis of the gravitational and thermal effects has given a bulk density of ρ = 1260±70 kg/m3, which is only slightly denser than water. Therefore, the predicted macroporosity is 40±10%, suggesting the interior has a rubble pile structure. The estimated mass is (7.8±0.9)×1010 kg.[25]

Photometry and spectroscopy

Image of Bennu ejecting particles from its surface, taken by OSIRIS-REx on 19 March 2019.[23][26]

Photometric observations of Bennu in 2005 yielded a synodic rotation period of 4.2905±0.0065 h. It has a B-type classification, which is a sub-category of carbonaceous asteroids. Polarimetric observations show that Bennu belongs to the rare F subclass of carbonaceous asteroids, which is usually associated with cometary features.[7] Measurements over a range of phase angles showed a phase function slope of 0.040 magnitudes per degree, which is similar to other near-Earth asteroids with low albedo.[27]

Before OSIRIS-REx, spectroscopy indicated a correspondence with the CI and/or CM carbonaceous chondrite meteorites.[28][29][30] Preliminary spectroscopic surveys of the asteroid's surface by OSIRIS-REx then confirmed this meteorite-asteroid linkage,[31][32][33] dominated by phyllosilicates.[34][35][36] These phyllosilicates are hydrated minerals that hold water chemically bound,[37][38][39] so that Bennu could potentially be mined for water.[40] (See: Asteroidal water.)

Surface features

As of August 2019, there are only 4 named features, being the 4 candidate landing sites.[41] All four sites and all future geological features are named after various species of birds and bird-like figures in mythology. [42] No feature has received an official designation by the IAU.

Name Notes
Kingfisher A relatively new crater with the highest water signature of all four sites.
Osprey Located on a low albedo patch with a large variety of rocks.
Nightingale Abundant fine-grained material with a large variation in color.
Sandpiper Located between two young craters, located in rough terrain. Minerals vary in brightness with hints of hydrated minerals.

Origin and evolution

The carbonaceous material that composes Bennu originally came from the breakup of a much larger parent body—a planetoid or a proto-planet. But like nearly all other matter in the Solar System, the origins of its minerals and atoms are to be found in dying stars such as red giants and supernovae.[43] According to the accretion theory, this material came together 4.5 billion years ago during the formation of the Solar System.

Bennu's basic mineralogy and chemical nature would have been established during the first 10 million years of the Solar System's formation, where the carbonaceous material underwent some geologic heating and chemical transformation inside a much larger planetoid or a proto-planet capable of producing the requisite pressure, heat and hydration (if need be)—into more complex minerals.[11] Bennu probably began in the inner asteroid belt as a fragment from a larger body with a diameter of 100 km. Simulations suggest a 70% chance it came from the Polana family and a 30% chance it derived from the Eulalia family.[44]

Subsequently, the orbit drifted as a result of the Yarkovsky effect and mean motion resonances with the giant planets, such as Jupiter and Saturn. Various interactions with the planets in combination with the Yarkovsky effect modified the asteroid, possibly changing its spin, shape, and surface features.[45]

Cellino et al. have suggested a possible cometary origin for Bennu, based on similarities of its spectroscopic properties with known comets. The estimated fraction of comets in the population of near Earth objects is 8%±5%.[7] This includes rock comet 3200 Phaethon, originally discovered as, and still numbered as an asteroid.[46][47]


Diagram of the orbits of Bennu and the inner planets around the Sun.

Possible Earth impact

On average, an asteroid with a diameter of 500 m (1,600 ft; 0.31 mi) can be expected to impact Earth about every 130,000 years or so.[48] A 2010 dynamical study by Andrea Milani and collaborators predicted a series of eight potential Earth impacts by Bennu between 2169 and 2199. The cumulative probability of impact is dependent on physical properties of Bennu that were poorly known at the time, but was found to not exceed 0.071% for all eight encounters.[49] The authors recognized that an accurate assessment of 101955 Bennu's probability of Earth impact would require a detailed shape model and additional observations (either from the ground or from spacecraft visiting the object) to determine the magnitude and direction of the Yarkovsky effect.

The publication of the shape model and of astrometry based on radar observations obtained in 1999, 2005, and 2011,[12] made possible an improved estimate of the Yarkovsky acceleration and a revised assessment of the impact probability. The current (as of 2014) best estimate of the impact probability is a cumulative probability of 0.037% in the interval 2175 to 2196.[25] This corresponds to a cumulative score on the Palermo scale of −1.71. If an impact were to occur, the expected kinetic energy associated with the collision would be 1,200 megatons in TNT equivalent (for comparison, TNT equivalent of Little Boy was approx 15 kiloton).[10]

2060 close approach

Animation of 101955 Bennu's orbit around Earth 2128-2138. 2135 close approach is shown.
   Earth ·   101955 Bennu

Bennu will pass 0.005 au (750,000 km; 460,000 mi) from Earth on 23 September 2060,[2] and will be too dim to be seen with common binoculars.[50] The close approach of 2060 causes divergence in the close approach of 2135. On 25 September 2135, the nominal approach distance is 0.002 au (300,000 km; 190,000 mi) from Earth, but Bennu could pass as close as 0.0007 au (100,000 km; 65,000 mi).[2] There is no chance of an Earth impact in 2135.[51][10] The 2135 approach will create many lines of variations and Bennu may pass through a gravitational keyhole during the 2135 passage which could create an impact scenario at a future encounter. The keyholes are all less than 55 km wide.[25]

On 25 September 2175, there is a 1 in 24,000 chance of an Earth impact,[10] but the nominal 2175 approach is in February 2175 at a distance of roughly 0.1 au (15,000,000 km; 9,300,000 mi).[2] The most threatening virtual impactor is on 24 September 2196 when there is a 1 in 11,000 chance of an Earth impact.[10] There is a cumulative 1 in 2,700 chance of an Earth impact between 2175–2199.[10]

Long term

Lauretta et al. reported in 2015 their results of a computer simulation, concluding that it is more likely that 101955 Bennu will be destroyed by some other cause:

The orbit of Bennu is intrinsically dynamically unstable, as are those of all NEOs. In order to glean probabilistic insights into the future evolution and likely fate of Bennu beyond a few hundred years, we tracked 1,000 virtual "Bennus" for an interval of 300 Myr with the gravitational perturbations of the planets Mercury–Neptune included. Our results ... indicate that Bennu has a 48% chance of falling into the Sun. There is a 10% probability that Bennu will be ejected out of the inner Solar System, most likely after a close encounter with Jupiter. The highest impact probability for a planet is with Venus (26%), followed by the Earth (10%) and Mercury (3%). The odds of Bennu striking Mars are only 0.8% and there is a 0.2% chance that Bennu will eventually collide with Jupiter.[45]

Meteor shower

The small Earth-MOID may result in a weak meteor shower around September 25 radiating from the southern constellation of Sculptor.[52] The meteors are expected to be near the naked eye limit and only produce a Zenith hourly rate of less than 1.[52]


OSIRIS-REx's first images of Bennu.
Animation of OSIRIS-REx's trajectory from 9 September 2016 to 3 December 2018.
OSIRIS-REx; 101955 Bennu; Earth; Sun;
Animation of OSIRIS-REx's trajectory around 101955 Bennu from 26 December 2018 to 20 March 2021
   OSIRIS-REx ·   101955 Bennu

The OSIRIS-REx mission of NASA's New Frontiers program was launched towards 101955 Bennu on September 8, 2016. On December 3, 2018, the spacecraft arrived at the asteroid Bennu after a two-year journey.[18] One week later, at the American Geophysical Union Fall Meeting, investigators announced that OSIRIS-REx had discovered spectroscopic evidence for hydrated minerals on the surface of the asteroid, implying that liquid water was present in Bennu's parent body before it split off.[53][4] OSIRIS-REx is expected to return samples to Earth in 2023.[54]


Bennu was selected from over 500000 known asteroids by the OSIRIS-REx selection committee. The primary constraint for selection was close proximity to Earth, since proximity implies low impulse (Δv) required to reach an object from Earth orbit.[55] The criteria stipulated an asteroid in an orbit with low eccentricity, low inclination, and an orbital radius of 0.8–1.6 au.[56] Furthermore, the candidate asteroid for a sample-return mission must have loose regolith on its surface, which implies a diameter greater than 200 meters. Asteroids smaller than this typically spin too fast to retain dust or small particles. Finally, a desire to find an asteroid with pristine carbon material from the early Solar System, possibly including volatile molecules and organic compounds, reduced the list further.

With the above criteria applied, five asteroids remained as candidates for the OSIRIS-REx mission, and Bennu was chosen, in part for its potentially hazardous orbit.[56]


See also


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  2. ^ a b c d e f g "JPL Small-Body Database Browser: 101955 Bennu (1999 RQ36)" (2017-09-01 last observation. Solution includes non-gravitational parameters). Jet Propulsion Laboratory. Archived from the original on 19 March 2018. Retrieved 20 August 2016.
  3. ^ "(101955) Bennu". NEODyS. University of Pisa. Retrieved 1 December 2015.
  4. ^ a b c d e f g h i j k l m n Lauretta, D. S. (March 19, 2019). "The unexpected surface of asteroid (101955) Bennu". Nature. 568: 55–60. doi:10.1038/s41586-019-1033-6. Retrieved June 22, 2019.
  5. ^ Barnouin, O. S. (March 19, 2019). "Shape of (101955) Bennu indicative of a rubble pile with internal stiffness". Nature Geoscience. 12: 247–252. doi:10.1038/s41561-019-0330-x. Retrieved June 22, 2019.
  6. ^ "Planetary Habitability Calculators". Planetary Habitability Laboratory. University of Puerto Rico at Arecibo. Retrieved 6 December 2015.
  7. ^ a b c Hergenrother, Carl W; Maria Antonietta Barucci; Barnouin, Olivier; Bierhaus, Beau; Binzel, Richard P; Bottke, William F; Chesley, Steve; Clark, Ben C; Clark, Beth E; Cloutis, Ed; Christian Drouet d'Aubigny; Delbo, Marco; Emery, Josh; Gaskell, Bob; Howell, Ellen; Keller, Lindsay; Kelley, Michael; Marshall, John; Michel, Patrick; Nolan, Michael; Rizk, Bashar; Scheeres, Dan; Takir, Driss; Vokrouhlický, David D; Beshore, Ed; Lauretta, Dante S (2018). "Unusual polarimetric properties of (101955) Bennu: similarities with F-class asteroids and cometary bodies". Monthly Notices of the Royal Astronomical Society: Letters. 481: L49–L53. arXiv:1808.07812. doi:10.1093/mnrasl/sly156.
  8. ^ a b Murphy, Diane (1 May 2013). "Nine-Year-Old Names Asteroid Target of NASA Mission in Competition Run By The Planetary Society". The Planetary Society. Retrieved 20 August 2016.
  9. ^ "Sentry Risk Table". NASA/JPL Near-Earth Object Program Office. Archived from the original on 2016-09-11. Retrieved 2018-03-20. (Use Unconstrained Settings)
  10. ^ a b c d e f "101955 1999 RQ36: Earth Impact Risk Summary". NASA. Jet Propulsion Laboratory. 25 March 2016. Retrieved 20 March 2018.
  11. ^ a b c d Lauretta, D. S.; Bartels, A. E.; et al. (April 2015). "The OSIRIS-REx target asteroid (101955) Bennu: Constraints on its physical, geological, and dynamical nature from astronomical observations". Meteoritics & Planetary Science. 50 (4): 834–849. Bibcode:2015M&PS...50..834L. CiteSeerX doi:10.1111/maps.12353.
  12. ^ a b c Nolan, M. C.; Magri, C.; Howell, E. S.; Benner, L. A. M.; Giorgini, J. D.; Hergenrother, C. W.; Hudson, R. S.; Lauretta, D. S.; Margot, J. L.; Ostro, S. J.; Scheeres, D. J. (2013). "Shape model and surface properties of the OSIRIS-REx target Asteroid (101955) Bennu from radar and lightcurve observations". Icarus. 226 (1): 629–640. Bibcode:2013Icar..226..629N. doi:10.1016/j.icarus.2013.05.028. ISSN 0019-1035.
  13. ^ a b "Goldstone Delay-Doppler Images of 1999 RQ36". Asteroid Radar Research. Jet Propulsion Laboratory.
  14. ^ Hudson, R. S.; Ostro, S. J.; Benner, L. A. M. (2000). "Recent Delay-Doppler Radar Asteroid Modeling Results: 1999 RQ36 and Craters on Toutatis". Bulletin of the American Astronomical Society. 32: 1001. Bibcode:2000DPS....32.0710H.
  15. ^ Corum, Jonathan (8 September 2016). "NASA Launches the Osiris-Rex Spacecraft to Asteroid Bennu". The New York Times. Retrieved 9 September 2016.
  16. ^ Chang, Kenneth (8 September 2016). "The Osiris-Rex Spacecraft Begins Chasing an Asteroid". The New York Times. Retrieved 9 September 2016.
  17. ^ Brown, Dwayne; Neal-Jones, Nancy (31 March 2015). "RELEASE 15-056 – NASA's OSIRIS-REx Mission Passes Critical Milestone". NASA. Retrieved 4 April 2015.
  18. ^ a b Chang, Kenneth (December 3, 2018). "NASA's Osiris-Rex Arrives at Asteroid Bennu After a Two-Year Journey — The spacecraft now begins a close study of the primitive space rock, seeking clues to the early solar system". The New York Times. Retrieved December 3, 2018.
  19. ^ Plait, Phil (2018-12-04). "Welcome to Bennu!". SYFY WIRE. Retrieved 2018-12-05.
  20. ^ "NASA captures closest-ever photo of massive asteroid Bennu flying near Earth". Sky News. 18 June 2019.
  21. ^ Hille, Karl (2019-08-08). "Asteroid's Features To Be Named After Mythical Birds". NASA. Retrieved 2019-08-10.
  22. ^ Hergenrother, CW; Barucci, MA; Barnouin, O (16 Sep 2014). "The Design Reference Asteroid for the OSIRIS-REx Mission Target (101955) Bennu". arXiv:1409.4704 [astro-ph.EP].
  23. ^ a b c d "NASA Mission Reveals Asteroid Has Big Surprises". www.asteroidmission.org. 19 March 2019. Retrieved 19 March 2019.
  24. ^ Emery, J.; et al. (July 2014), Muinonen, K. (ed.), "Thermal infrared observations and thermophysical characterization of the OSIRIS-REx target asteroid (101955) Bennu", Conference Proceedings Asteroids, Comets, Meteors 2014: 148, Bibcode:2014acm..conf..148E.
  25. ^ a b c Chesley, Steven R.; Farnocchia, Davide; Nolan, Michael C.; Vokrouhlický, David; Chodas, Paul W.; Milani, Andrea; Spoto, Federica; Rozitis, Benjamin; Benner, Lance A.M.; Bottke, William F.; Busch, Michael W.; Emery, Joshua P.; Howell, Ellen S.; Lauretta, Dante S.; Margot, Jean-Luc; Taylor, Patrick A. (2014). "Orbit and bulk density of the OSIRIS-REx target Asteroid (101955) Bennu". Icarus. 235: 5–22. arXiv:1402.5573. Bibcode:2014Icar..235....5C. doi:10.1016/j.icarus.2014.02.020. ISSN 0019-1035.
  26. ^ Chang, Kenneth; Stirone, Shannon (19 March 2019). "The Asteroid Was Shooting Rocks Into Space. 'Were We Safe in Orbit?' - NASA's Osiris-Rex and Japan's Hayabusa2 spacecraft reached the space rocks they are surveying last year, and scientists from both teams announced early findings on Tuesday (03/19/2019)". The New York Times. Retrieved 21 March 2019.
  27. ^ Hergenrother, Carl W.; et al. (September 2013), "Lightcurve, Color and Phase Function Photometry of the OSIRIS-REx Target Asteroid (101955) Bennu", Icarus, 226 (1): 663–670, Bibcode:2013Icar..226..663H, doi:10.1016/j.icarus.2013.05.044.
  28. ^ King, A; Solomon, J; Schofield, P; Russell, S (Dec 2015). "Characterising the CI and CI-like carbonaceous chondrites using thermogravimetric analysis and infrared spectroscopy". Earth, Planets and Space. 67: 1989.
  29. ^ Takir, D; Emery, J; Hibbits, C (2017). 3-μm Spectroscopy Of Water-Rich Meteorites And Asteroids: New Results And Implications. Hayabusa Symposium 2017.
  30. ^ Bates, H; Hanna, K; King, A; Bowles, N (2018). Thermal Infrared Spectra of Heated CM and C2 Chondrites and Implications for Asteroid Sample Return Missions. Hayabusa Symposium 2018.
  31. ^ All About Bennu: A Rubble Pile with a Lot of Surprises. Kimberly M. S. Cartier, EOS Planetary Sciences. 21 March 2019. "In terms of spectra and minerology, Bennu’s rocks “look a lot like the rarest, most fragile meteorites in our collection,” Lauretta said, referring to the CM carbonaceous chondrites"
  32. ^ Evidence for widespread hydrated minerals on asteroid (101955) Bennu. V. E. Hamilton, A. A. Simon, etal. Nature Astronomy, volume 3, pages3 32–340. 19 March 2019. doi:10.1038/s41550-019-0722-2
  33. ^ Lauretta, D (4 Apr 2019). "The unexpected surface of asteroid (101955) Bennu". Nature. 568: 55. doi:10.1038/s41586-019-1033-6. "This finding is in agreement with pre-encounter measurements and consistent with CI and CM chondrites."
  34. ^ "NASA's Newly Arrived OSIRIS-REx Spacecraft Already Discovers Water on Asteroid". NASA. December 11, 2018.
  35. ^ "Water found on asteroid, confirming Bennu as excellent mission target". Science Daily. 10 December 2018. Retrieved 10 December 2018.
  36. ^ Lauretta, D. "Welcome to Bennu Press Conference - First Mission Science Results". Retrieved 24 Jul 2019. "Report Card" at 25:15
  37. ^ Feierberg, M; Lebofsky, L; Tholen, D (1985). "The nature of C-class asteroids from 3u spectrophotometry". Icarus. 63: 191.
  38. ^ Sears, D (2004). The Origin of Chondrules and Chondrites. Cambridge University Press. ISBN 978-1107402850.
  39. ^ Russell, Sara S.; Ballentine, Chris J.; Grady, Monica M. (17 April 2017). "The origin, history and role of water in the evolution of the inner Solar System". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 375 (2094): 20170108. doi:10.1098/rsta.2017.0108. Water in chondrites is contained within clay minerals, with H2O accounting for up to 10% weight percent...water is also stored in chondrites in direct liquid form as inclusions
  40. ^ Q&A: Water Found on Asteroid. Interview with Professor Beth Ellen Clark, OSIRIS-REx mission scientist. Ithaca College. 13 December 2018. Quote:"Third, the asteroid mining community has set a commercial price point for mining water on asteroids, and if Bennu's water is held in clays and other water-rich minerals on the surface, that would make asteroids like Bennu attractive for mining water."
  41. ^ http://www.planetary.org/blogs/jason-davis/osiris-rex-4-sample-sites.html
  42. ^ https://www.nasa.gov/feature/goddard/2019/asteroid-features-to-be-named-after-mythical-birds
  43. ^ Bensby, T.; Feltzing, S. (2006). "The origin and chemical evolution of carbon in the Galactic thin and thick discs" (PDF). Monthly Notices of the Royal Astronomical Society. 367 (3): 1181–1193. doi:10.1111/j.1365-2966.2006.10037.x.
  44. ^ Bottke, William F.; et al. (February 2015), "In search of the source of asteroid (101955) Bennu: Applications of the stochastic YORP model", Icarus, 247: 191–217, Bibcode:2015Icar..247..191B, doi:10.1016/j.icarus.2014.09.046.
  45. ^ a b Lauretta, D. S.; et al. (April 2015), "The OSIRIS-REx target asteroid (101955) Bennu: Constraints on its physical, geological, and dynamical nature from astronomical observations", Meteoritics & Planetary Science, 50 (4): 834–849, Bibcode:2015M&PS...50..834L, CiteSeerX, doi:10.1111/maps.12353.
  46. ^ Hergenrother, C. "The Strange Life of Asteroid Phaethon – Source of the Geminid Meteors". Dslauretta: Life on the Asteroid Frontier. Retrieved 25 Jul 2019.
  47. ^ Maltagliati, L (24 Sep 2018). "Cometary Bennu?". Nature Astronomy. 2: 761. doi:10.1038/s41550-018-0599-5.
  48. ^ Robert Marcus; H. Jay Melosh & Gareth Collins (2010). "Earth Impact Effects Program". Imperial College London / Purdue University. Retrieved 2013-02-07. (solution using density of 2,600 kg/m^3, sped of 17km/s, and impact angle of 45 degrees)
  49. ^ 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.
  50. ^ "(101955) Bennu Ephemerides for September 2060". NEODyS (Near Earth Objects – Dynamic Site). Retrieved 2019-05-15.
  51. ^ Paul Chodas (24 March 2018). "Recent Bennu Press Stories Need Correction". Center for NEO Studies (CNEOS).
  52. ^ a b Ye, Quanzhi (2019). "Prediction of Meteor Activities from (101955) Bennu". American Astronomical Society. 3 (3). doi:10.3847/2515-5172/ab12e7.
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  55. ^ Near-Earth Asteroid Delta-V for Space Rendezvous
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External links

  • Video (01:32) – OSIRIS REx's approach to asteroid Bennu (NASA; 7 January 2019)
  • Earth Impact Risk Summary: 101955 1999 RQ36 (Years: 2175–2199) – Jet Propulsion Laboratory near-Earth object site
  • NEODyS-2 Ephemerides for 2135 (step size: 10 days)
  • Delbo, Marco; Michel, Patrick (2011). "Temperature History and Dynamical Evolution of (101955) 1999 Rq 36: A Potential Target for Sample Return from a Primitive Asteroid". The Astrophysical Journal. 728 (2): L42. doi:10.1088/2041-8205/728/2/L42.
  • Hergenrother, Carl W.; et al. (2012). "Physical Properties of OSIRIS-REx Target Asteroid (101955) 1999 RQ36 derived from Herschel, ESO-VISIR and Spitzer observations". Astronomy & Astrophysics. 548: A36. arXiv:1210.5370. doi:10.1051/0004-6361/201220066.
  • Hergenrother, Carl W.; et al. (2014). "The Design Reference Asteroid for the OSIRIS-REx Mission Target (101955) Bennu". arXiv:1409.4704 [astro-ph.EP].
  • 101955 Bennu orbit and observations at International Astronomical Union Minor Planet Center
  • 101955 Bennu at the JPL Small-Body Database
    • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters
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