:101955 Bennu

File:Bennu_rotation.gif radar images in 1999 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). The asteroid was given the provisional designation {{mp|1999 RQ|36}} and classified as a near-Earth asteroid.{{Cite web |title=All That is Known About Bennu |url=https://www.planetary.org/articles/20140917-all-that-is-known-about-bennu |access-date=2023-09-28 |website=The Planetary Society |language=en}} Bennu 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.

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. 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.

Its features will be named after birds and bird-like creatures in mythology.{{cite press release |last=Hille |first=Karl |date=2019-08-08 |df=dmy-all |title=Asteroid's features to be named after mythical birds |website=NASA.gov |publisher=National Aeronautics and Space Administration |url=http://www.nasa.gov/feature/goddard/2019/asteroid-features-to-be-named-after-mythical-birds |access-date=2019-08-10}}

File:Bennu rotation PolyCam 2018-12-02.gif in December 2018.|left]]

Bennu has a roughly spheroidal shape, resembling a spinning top. Bennu's axis of rotation is tilted 178 degrees to its orbit; the direction of rotation about its axis is retrograde with respect to its orbit. While the initial ground based radar observations indicated that Bennu had a fairly smooth shape with one prominent {{val|10|–|20|u=m}} boulder on its surface, high resolution data obtained by OSIRIS-REx revealed that the surface is much rougher with more than 200 boulders larger than {{val|10|u=m}} on the surface, the largest of which is {{val|58|u=m}} across. The boulders contain veins of high albedo carbonate minerals believed to have formed prior to the formation of the asteroid due to hot water channels on the much larger parent body.{{cite journal | author = Voosen P | title = NASA mission set to sample carbon-rich asteroid | journal = Science | volume = 370 | issue=6513 | page = 158 |date=2020 | doi = 10.1126/science.370.6513.158 | pmid = 33033199| bibcode = 2020Sci...370..158V | s2cid = 222237648 }}{{cite journal | last1= Kaplan |first1=H. H. |last2=Lauretta |first2=D. S. |last3=Simon |first3=A. A. |last4=Eno |first4=H. L. | title = Bright carbonate veins on asteroid (101955) Bennu: Implications for aqueous alteration history | journal = Science | volume = 370 | issue=6517 | page = eabc3557 |date=2020 | doi = 10.1126/science.abc3557 | pmid = 33033155| bibcode = 2020Sci...370.3557K | s2cid = 222236463 }} The veins range from 3 to 15 centimeters wide, and can be over one meter in length, much bigger than carbonate veins seen in meteorites.

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 (about once every 4.3 hours). Observation by the OSIRIS-REx spacecraft has shown that Bennu is rotating faster over time. This change in Bennu's rotation is caused by the Yarkovsky–O'Keefe–Radzievskii–Paddack effect. 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.

Observations of this minor planet by the Spitzer Space Telescope in 2007 gave an effective diameter of {{Val|484|10|u=m}}, which is in line with other studies. It has a low visible geometric albedo of {{Val|0.046|0.005}}. The thermal inertia was measured and found to vary by approximately 19% during each rotational period. It was based on this observation that scientists (incorrectly) estimated a moderate regolith grain size, ranging from several millimeters up to a centimeter, 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.

Astrometric observations between 1999 and 2013 have demonstrated that 101955 Bennu is influenced by the Yarkovsky effect, causing the semimajor axis of its orbit to drift on average by {{Val|284|1.5}} meters/year. Analysis of the gravitational and thermal effects has given a bulk density of ρ = {{Val|1190|13}} kg/m³, which is only slightly denser than water. Therefore, the predicted macroporosity is {{Val|40|10}}%, suggesting the interior has a rubble pile structure or even hollows.{{cite journal |last1=Scheeres |first1=D.J. |title=Heterogeneous mass distribution of the rubble-pile asteroid (101955) Bennu |journal=Science Advances |date=8 October 2020 |volume=6 |issue=41 |pages=eabc3350 |doi=10.1126/sciadv.abc3350 |pmid=33033036 |pmc=7544499 |bibcode=2020SciA....6.3350S |doi-access=free }} The estimated mass is {{Val|7.329|0.009|e=10|u=kg}}. The sample of Bennu revealed that some of the makings of living things are present on Bennu.{{cite press release |last=Taveau |first=Jessica |date=29 January 2025 |title=NASA’s Asteroid Bennu Sample Reveals Mix of Life’s Ingredients |url=https://www.nasa.gov/news-release/nasas-asteroid-bennu-sample-reveals-mix-of-lifes-ingredients/ |publisher=NASA |access-date=30 January 2025}}

Photometric observations of Bennu in 2005 yielded a synodic rotation period of {{Val|4.2905|0.0065|u=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. 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.

Before OSIRIS-REx, spectroscopy indicated a correspondence with the CI and/or CM carbonaceous chondrite meteorites,{{cite journal |last1=King |first1=A.|last2=Solomon |first2=J. |last3=Schofield |first3=P. |last4=Russell |first4=S. |title=Characterising the CI and CI-like carbonaceous chondrites using thermogravimetric analysis and infrared spectroscopy |journal=Earth, Planets and Space |date=Dec 2015 |volume=67 |page=1989|bibcode=2015EP&S...67..198K |doi=10.1186/s40623-015-0370-4 |doi-access=free |hdl=10141/622224 |hdl-access=free }}{{cite conference |last1=Takir |first1=D. |last2=Emery |first2=J. |last3=Hibbits |first3=C.|title=3-μm Spectroscopy of Water-Rich Meteorites and Asteroids: New Results and Implications |journal=Hayabusa Symposium 2017 |date=2017}}{{cite conference |last1=Bates |first1=H. |last2=Hanna |first2=K. |last3=King |first3=A. |last4=Bowles |first4=N. |title=Thermal Infrared Spectra of Heated CM and C2 Chondrites and Implications for Asteroid Sample Return Missions |journal=Hayabusa Symposium 2018 |date=2018|url=https://curation.isas.jaxa.jp/symposium/abstract/2018/1206_1545_Helena_Bates.pdf}} including carbonaceous-chondrite mineral magnetite.{{cite book |last=Mason |first=B. |title=Meteorites |date=1962 |publisher=John Wiley and Sons, Inc. |location=New York and London |page=60 |quote=an important constituent in many of the carbonaceous chondrites|oclc=468300914 }}{{cite journal |last1=Takir |first1=D. |last2=Emery |first2=J. |last3=McSween |first3=H. |last4=Hibbits |first4=C.|last5=Clark |first5=R. |last6=Pearson |first6=N. |last7=Wang |first7=A.|journal=Meteoritics & Planetary Science |date=2013 |title=Nature and degree of aqueous alteration in CM and CI carbonaceous chondrites |volume=48 |issue=9 |page=1618 |doi=10.1111/maps.12171 |bibcode=2013M&PS...48.1618T |s2cid=129003587 |doi-access=free }} Magnetite, a spectrally prominent{{cite journal |last1=King |first1=A.|last2=Schofield |first2=P. |last3=Russell |first3=S. |title=Type 1 aqueous alteration in CM carbonaceous chondrites: Implications for the evolution of water-rich asteroids |date=2017 |journal=Meteoritics & Planetary Science |volume=52 |issue=6 |page=1197 |doi=10.1111/maps.12872 |bibcode=2017M&PS...52.1197K |quote=small amounts of opaque phases (e.g., magnetite, Fe-sulfides) known to ...have a large effect on the overall spectral shape |doi-access=free |hdl=10141/622203 |hdl-access=free }} water product{{cite journal |last1=Kerridge |first1=J. |last2=Mackay |first2=A.|last3=Boynton |first3=W. |s2cid=9916605 |journal=Science |date=27 Jul 1979 |title=Magnetite in CI Carbonaceous Meteorites: Origin by Aqueous Activity on a Planetesimal Surface |url=https://archive.org/details/sim_science_1979-07-27_205_4404/page/395 |volume=205 |issue=4404 |pages=395–397 |doi=10.1126/science.205.4404.395 |pmid=17790849 |bibcode=1979Sci...205..395K }}{{cite book |last1=Brearley |first1=A.|title=Meteorites and the Early Solar System II |publisher=University of Arizona Press |location=Tucson |isbn=978-0-8165-2562-1 |page=587 |chapter=The Action of Water |year=2006 }}{{cite journal |last1=Rubin |first1=A.|last2=Li |first2=Y. |journal=Geochemistry |date=Dec 2019 |title=Formation and destruction of magnetite in CO3 chondrites and other chondrite groups |volume=79 |issue=4 |page=article 125528 |doi=10.1016/j.chemer.2019.07.009 |bibcode=2019ChEG...79l5528R |s2cid=201224827 |doi-access= }} but destroyed by heat, is an important proxy of astronomers{{cite journal |last1=Yang |first1=B.|last2=Jewitt |first2=D. |s2cid=724871 |title=Identification of Magnetite in B-type asteroids |date=2010 |journal=Astronomical Journal |volume=140 |issue=3 |page=692 |doi=10.1088/0004-6256/140/3/692 |arxiv=1006.5110 |bibcode=2010AJ....140..692Y |quote="evidence of water ice" "an important product of parent-body aqueous alteration" }}{{cite journal |journal=Annual Meeting of the Meteoritical Society 2017 (LPI Contrib. No. 1987)|last1=Kita |first1=J. |last2=Defouilloy |first2=C.|last3=Goodrich |first3=C.|last4=Zolensky |first4=M. |title=O. isotope ratios of magnetite in CI-like clasts from a polymict ureilite |date=2017|url=https://www.hou.usra.edu/meetings/metsoc2017/pdf/6153.pdf |quote="ratios of magnetite are of special interest because..." }}{{cite journal |last1=Cloutis |first1=E. |last2=Hiroi |first2=T. |last3=Gaffey |first3=M. |last4=Alexander |first4=C.|last5=Mann |first5=P. |journal=Icarus |date=2011 |title=Spectral Reflectance Properties of carbonaceous chondrites: 1. CI chondrites |volume=212 |issue=1 |page=180 |doi=10.1016/j.icarus.2010.12.009 |bibcode=2011Icar..212..180C }} including OSIRIS-REx staff.{{cite journal |last1=Clark |first1=B.|last2=Binzel |first2=R. |last3=Howell |first3=E|author3-link=Ellen Howell |last4=Cloutis |first4=E. |last5=Ockert-Bell |first5=M. |last6=Christensen |first6=P. |last7=Barucci |first7=M. |last8=DeMeo |first8=F. |last9=Lauretta |first9=D. |last10=Connolly |first10=H. |last11=Soderberg |first11=A.|author11-link= Alicia M. Soderberg |last12=Hergenrother |first12=C.|last13=Lim |first13=L. |last14=Emery |first14=J. |last15=Mueller |first15=M. |journal=Icarus |date=2011 |title=Asteroid (101955) 1999 RQ36: Spectroscopy from 0.4 to 2.4 μm and meteorite analogs |volume=216 |issue=2 |page=462 |doi=10.1016/j.icarus.2011.08.021 |bibcode=2011Icar..216..462C }}

According to Dante Lauretta,{{cite news |last=Miller |first=Katrina |title=Life After Asteroid Bennu – Dante Lauretta, the planetary scientist who led the OSIRIS-REx mission to retrieve a handful of space dust, discusses his next final frontier. |url=https://www.nytimes.com/2024/03/22/science/astronomy-asteroid-bennu-osiris-lauretta.html |date=22 March 2024 |work=The New York Times |url-status=live |archiveurl=https://archive.today/20240322110628/https://www.nytimes.com/2024/03/22/science/astronomy-asteroid-bennu-osiris-lauretta.html |archivedate=22 March 2024 |accessdate=22 March 2024 }} OSIRIS-REx Principal Investigator, "Bennu appears to be a very water-rich target, and water is the most interesting and perhaps the most lucrative commodity that you would mine from an asteroid".{{cite web |url=https://www.theverge.com/2018/12/10/18134714/bennu-water-evidence-nasa-osiris-rex |title=NASA's latest asteroid target had a wet and wild history|date=10 December 2018 |access-date=19 September 2023}}{{cite web |url=http://svs.gsfc.nasa.gov/12658 |title=OSIRIS-REx Arrives at Bennu – 2018 AGU Press Conference |date=10 December 2018 |access-date=31 December 2020 }}

Predicted beforehand,{{cite web |last1=Stolte |first1=D. |title=7 Questions for Dante Lauretta, Leader of UA's Biggest Space Mission |url=https://news.arizona.edu/story/7-questions-for-dante-lauretta-leader-of-ua-s-biggest-space-mission |access-date=31 December 2020 |date=9 January 2014 |quote="We think Bennu is a water-rich asteroid" }} Dante Lauretta (University of Arizona) reiterates that Bennu is water-rich- already detectable while OSIRIS-REx was still technically in approach.{{cite web |last1=Lauretta |first1=D. |title=OSIRIS-REx Explores Asteroid Bennu

|url=https://mediastream.ndc.nasa.gov/Public3/webvid/SCI/2019/GSFC-2019-SCI-0925/default.html |access-date=31 December 2020 |date=25 September 2019 |quote="water-rich asteroid"}}

Preliminary spectroscopic surveys of the asteroid's surface by OSIRIS-REx confirmed magnetite and the meteorite-asteroid linkage,[https://eos.org/articles/all-about-bennu-a-rubble-pile-with-a-lot-of-surprises 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 {{as written|minerology}}, Bennu's rocks 'look a lot like the rarest, most fragile meteorites in our collection,' Lauretta said, referring to the CM carbonaceous chondrites"{{cite journal | last1 = Hamilton | first1 = V.E. | last2 = Simon | first2 = A.A. | year = 2019| title = Evidence for widespread hydrated minerals on asteroid (101955) Bennu | journal = Nature Astronomy | volume = 3 | issue = 4| pages = 332–340 | doi = 10.1038/s41550-019-0722-2 | pmid = 31360777 | pmc = 6662227 | bibcode = 2019NatAs...3..332H | hdl = 1721.1/124501 }}{{cite journal |last1=Lauretta |first1=D. |title=The unexpected surface of asteroid (101955) Bennu |journal=Nature |date=4 Apr 2019 |volume=568 |issue=7750 |pages=55–60 |doi=10.1038/s41586-019-1033-6|pmid=30890786 |pmc=6557581 |bibcode=2019Natur.568...55L }} "This finding is in agreement with pre-encounter measurements and consistent with CI and CM chondrites." dominated by phyllosilicates.{{cite web |title=NASA's Newly Arrived OSIRIS-REx Spacecraft Already Discovers Water on Asteroid |date=11 December 2018 |publisher=NASA |url=https://www.nasa.gov/press-release/nasa-s-newly-arrived-osiris-rex-spacecraft-already-discovers-water-on-asteroid}}{{cite web | url = https://www.sciencedaily.com/releases/2018/12/181210150554.htm |title = Water found on asteroid, confirming Bennu as excellent mission target | date = 10 December 2018 | access-date = 10 December 2018 | work = Science Daily }}{{cite web |last1=Lauretta |first1=D. |title=Welcome to Bennu Press Conference – First Mission Science Results |website=YouTube |date=12 December 2018 |url=https://www.youtube.com/watch?v=qaPHXXZTkAU |archive-url=https://ghostarchive.org/varchive/youtube/20211215/qaPHXXZTkAU |archive-date=2021-12-15 |url-status=live|access-date=24 Jul 2019}}{{cbignore}} "Report Card" at 25:15 Phyllosilicates, among others, hold water.{{cite journal |last1=Feierberg |first1=M. |last2=Lebofsky |first2=L. |last3=Tholen |first3=D. |title=The nature of C-class asteroids from 3u spectrophotometry |journal=Icarus |date=1985 |volume=63 |issue=2 |page=191|doi=10.1016/0019-1035(85)90002-8 |bibcode=1985Icar...63..183F }}{{cite book |last1=Sears |first1=D. |title=The Origin of Chondrules and Chondrites |date=2004 |publisher=Cambridge University Press |isbn=978-1-107-40285-0}}{{page needed|date=August 2021}}{{cite journal |last1=Russell |first1=Sara S. |last2=Ballentine |first2=Chris J. |last3=Grady |first3=Monica M. |title=The origin, history and role of water in the evolution of the inner Solar System |journal=Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences |date=17 April 2017 |volume=375 |issue=2094 |page=20170108 |doi=10.1098/rsta.2017.0108 |pmid=28416731 |pmc=5394259 |quote=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|bibcode=2017RSPTA.37570108R }}

Bennu's water spectra were detectable on approach,{{cite journal |last1=Kaplan |first1=H. |last2=Hamilton |first2=V. |last3=Howell |first3=E. |author3-link=Ellen Howell|last4=Anderson |first4=S. |last5=Barrucci |first5=M. |last6=Brucato |first6=J. |last7=Burbine |first7=T. |last8=Clark |first8=B.|last9=Cloutis |first9=E. |last10=Connolly |first10=H. |last11=Dotto |first11=E. |last12=Emery |first12=J. |last13=Fornasier |first13=S. |last14=Lantz |first14=C.|last15=Lim |first15=L. |last16=Merlin |first16=F. |last17=Praet |first17=A. |last18=Reuter |first18=D. |last19=Sandford |first19=S. |last20=Simon |first20=A. |last21=Takir |first21=D. |last22=Lauretta |first22=D. |journal=Meteoritics & Planetary Science |date=2020 |title=Visible-near infrared spectral indices for mapping mineralogy and chemistry with OSIRIS-REx |volume=55 |issue=4 |pages=744–765 |doi=10.1111/maps.13461 |bibcode=2020M&PS...55..744K |s2cid=216247217 }} reviewed by outside scientists,{{cite journal |last1=Potin |first1=S. |last2=Beck |first2=P. |last3=Usui |first3=F. |last4=Bonal |first4=L. |last5=Vernazza |first5=P. |last6=Schmidtt |first6=B.|journal=Icarus |date=Sep 2020 |title=Style and intensity of hydration among C-complex asteroids: A comparison to desiccated carbonaceous chondrites |volume=348 |page=article 113826 |doi=10.1016/j.icarus.2020.113826 |arxiv=2004.09872 |bibcode=2020Icar..34813826P |s2cid=216036128 }}{{cite journal |last1=Bates |first1=H. |last2=King |first2=A. |last3=Donaldson-Hanna |first3=K. |last4=Bowles |first4=N. |last5=Russell |first5=S. |journal=Meteoritics & Planetary Science |date=19 Nov 2019 |title=Linking mineralogy and spectroscopy of highly aqueously altered CM and CI carbonaceous chondrites in preparation for primitive asteroid sample return |volume=55 |issue=1 |pages=77–101 |doi=10.1111/maps.13411 |quote="observations of primitive, water‐rich asteroids" |doi-access=free |hdl=10141/622636 |hdl-access=free }} then confirmed from orbit.{{cite conference |last1=Hamilton |first1=V. |last2=Simon |first2=A. |last3=Kaplan |first3=H. |last4=Christensen |first4=P. |last5=Reuter |first5=D. |last6=DellaGiustina |first6=D. |last7=Haberle |first7=C.|last8=Hanna |first8=R. |last9=Brucato |first9=J. |last10=Praet |first10=A. |last11=Glotch |first11=T. |last12=Rogers |first12=A. |last13=Connolly |first13=H. |last14=McCoy |first14=T. |last15=Emery |first15=J. |last16=Howell |first16=E|author16-link=Ellen Howell |last17=Barucci |first17=M. |last18=Clark |first18=B.|last19=Lauretta |first19=D. |conference=51st LPSC |date=Mar 2020 |title=VNIR and TIR spectral characteristics of (101955) Bennu from OSIRIS-REx Detailed Survey and Reconnaissance Observations |issue=1049 |section=OVIRS Results|url=https://www.hou.usra.edu/meetings/lpsc2020/pdf/1049.pdf }}{{cite conference |last1=Praet |first1=A. |last2=Barucci |first2=M. |last3=Kaplan |first3=H. |last4=Merlin |first4=F. |last5=Clark |first5=B.|last6=Simon |first6=A.|last7=Hamilton |first7=V. |last8=Emery |first8=J. |last9=Howell |first9=E. |author9-link=Ellen Howell|last10=Lim |first10=L. |conference=51st LPSC |date=Mar 2020 |title=Estimated hydration of Bennu's surface from OVIRS observations by the OSIRIS-REx mission|url=https://ui.adsabs.harvard.edu/abs/2020LPI....51.1058P/abstract |issue=1058 |bibcode=2020LPI....51.1058P }}{{cite journal |last1=Simon |first1=A.A. |last2=Kaplan |first2=H.H. |last3=Hamilton |first3=V.E. |last4=Lauretta |first4=D.S. |last5=Campins |first5=H. |last6=Emery |first6=J.P. |last7=Barucci |first7=M.A. |last8=DellaGiustina |first8=D. N |last9=Reuter D.C. |last10=Sandford S.A. |last11=Golish D.R. |last12=Lim L.F. |last13=Ryan A. |last14=Rozitis B. |last15=Bennett C.A. |journal=Science |date=8 Oct 2020 |title=Widespread carbon-bearing materials on near-Earth asteroid (101955) Bennu |volume=370 |issue=6517 |pages=eabc3522 |doi=10.1126/science.abc3522 |pmid=33033153 |bibcode=2020Sci...370.3522S |s2cid=222236203 |url=http://oro.open.ac.uk/73157/1/Simon_et_al_2020_accepted.pdf |quote="water-rich, similar to the CM class of chondrites" }}

OSIRIS-REx observations have resulted in a (self-styled) conservative estimate of about 7 x 10⁸ kg water in one form alone, neglecting additional forms. This is a water content of ~1 wt.%, and potentially much more. In turn this suggests transient pockets of water beneath Bennu's regolith. The surficial water may be lost from the collected samples. However, if the sample return capsule maintains low temperatures, the largest (centimeter-scale) fragments may contain measurable quantities of adsorbed water, and some fraction of Bennu's ammonium compounds.{{cite journal |last1=Nuth, III |first1=J. |last2=Abreu |first2=N. |last3=Ferguson |first3=F. |last4=Glavin |first4=D. |last5=Hergenrother |first5=C.|last6=Hill |first6=H. |last7=Johnson |first7=N. |last8=Pajola |first8=M. |last9=Walsh |first9=K. |journal=Planetary Science Journal |date=Dec 2020 |title=Volatile-rich Asteroids in the Inner Solar System |volume=1 |issue=3 |page=82 |doi=10.3847/PSJ/abc26a |bibcode=2020PSJ.....1...82N |doi-access=free }} A separate estimate, including other forms of water storage, is 6.2 wt%.{{cite news |last1=Osinski |first1=G. |title=Feasibility Of Mining Bennu |url=https://ir.lib.uwo.ca/cgi/viewcontent.cgi?article=1581&context=usri |access-date=22 August 2023}}

NASA and university sample facilities are preparing to secure, study, and curate the sample, predicted to be rich in water and organic compounds.{{cite journal |last1=Kurokawa |first1=H. |last2=Shibuya |first2=T. |last3=Sekine |first3=Y. |last4=Ehlmann |first4=B.L. |last5=Usui |first5=F. |last6=Kikuchi |first6=S. |last7=Yoda |first7=M. |date=Jan 2022 |title=Distant Formation and Differentiation of Outer Main Belt Asteroids and Carbonaceous Chondrite Parent Bodies |journal=AGU Advances |volume=3 |issue=1 |doi=10.1029/2021AV000568 |arxiv=2112.10284 |bibcode=2022AGUA....300568K |s2cid=245302669 }}{{cite conference |last1=Montoya |first1=M. |last2=Plummer |first2=J. |last3=Martinez |first3=S. III |last4=Snead |first4=C.J. |last5=Lunning |first5=N. |last6=Righter |first6=K. |last7=Allums |first7=K. |last8=Rodriguez |first8=M. |last9=Funk |first9=R.C. |last10=Connelly |first10=W. |last11=Gonzalez |first11=C. |last12=Calva |first12=C. |last13=Ferrodous |first13=J. |last14=Lugo |first14=G. |last15=Hernandez Gomez |first15=N. |last16=Connolly |first16=H.C. Jr. |date=2023 |title=Materials-Compliant Containers in Preparation for OSIRIS-REx Sample Return |conference=86th Meteoritical Society Meeting |page=6050 }}{{cite conference |last1=Prince |first1=B.S. |last2=Zega |first2=T.J. |last3=Connolly |first3=H.C. Jr. |last4=Lauretta |first4=D.S. |date=2023 |title=Developing Fluid Inclusion Analysis Techniques in Anticipation of OSIRIS-REx Sample Return |conference=86th MetSoc |page=6155 }}

The German SAL (Sample Analysis Laboratory) is preparing to receive cosmochemical water from Ryugu, Bennu, and other airless bodies.{{cite conference |last1=Bonato |first1=E. |last2=Helbert |first2=J. |last3=Schwinger |first3=S. |last4=Maturilli |first4=A. |last5=Greshake |first5=A. |last6=Hecht |first6=L. |date=2023 |title=The Sample Analysis Laboratory At DLR And Its Extension To Curation Facility for MMX |conference=86th MetSoc |page=6035 }}

{{further|Asteroidal water|162173 Ryugu#Water}}

Bennu is an active asteroid,{{cite conference |last1=Connolly |first1=H. |last2=Jawin |first2=E. |last3=Ballouz |first3=R. |last4=Walsh |first4=K. |last5=McCoy |first5=T. |last6=Dellagiustina |first6=D. |title=OSIRIS-REx sample science and the geology of active asteroid Bennu |conference=82nd Meteoritical Society Meeting |date=2019 |page=2157|bibcode=2019LPICo2157.6209C |url=https://ui.adsabs.harvard.edu/abs/2019LPICo2157.6209C/abstract}}{{cite conference |last1=Lim |first1=L. |title=OSIRIS-REx update |conference=21st NASA Small Bodies Assessment Group |date=2019 }} "Bennu is an Active Asteroid!"{{cite conference |last1=Barrucci |first1=M. |last2=Michel |first2=P. |title=Asteroid-Comet continuum: no doubt but many questions |conference=2019 EPSC-DPS conference |date=Sep 2019 |pages=202–1}}{{cite conference |last1=Hergenrother |first1=C.|last2=Adam |first2=C.|last3=Antreasian |first3=P. |last4=Al Asad |first4=M. |last5=Balram-Knutson |first5=S. |title=(101955) Bennu is an active asteroid |conference=2019 EPSC-DPS conference |date=Sep 2019 |pages=852–1 }} sporadically emitting plumes of particles{{cite web |url=https://www.asteroidmission.org/?mission_update=feb-11-2019 |title=Feb 11, 2019 |access-date=15 Nov 2019 }}{{cite journal |last1=Hergenrother |first1=C.|last2=Maleszweski |first2=C.|last3=Nolan |first3=C.|last4=Li |first4=J. |last5=Drouet D'aubigny |first5=C.|title=The Operational Environment and Rotational Acceleration of Asteroid (101955) Bennu from OSIRIS-REx Observations |journal=Nature Communications |volume=10 |issue=1 |page=1291 |date=19 Mar 2019 |doi=10.1038/s41467-019-09213-x |pmid=30890725 |pmc=6425024 |bibcode=2019NatCo..10.1291H }} and rocks as large as {{cvt|10|cm}},[https://www.wired.com/story/no-one-knows-why-rocks-are-exploding-from-asteroid-bennu/ No One Knows Why Rocks Are Exploding From Asteroid Bennu.] Daniel Oberhaus, Wired. 5 December 2019.{{cite journal|title = Episodes of particle ejection from the surface of the active asteroid (101955) Bennu|first1 = D.S. | last1 = Lauretta| first2 = C.W. |last2 = Hergenrother | first3 = S.R. | last3 = Chesley | first4 = J.M. | last4 = Leonard | first5 = J.Y. | last5 = Pelgrift | first6 = C.D. | last6 = Adam | first7 = M. | last7 = Al Asad|s2cid = 208764910 |display-authors=5| journal = Science | date = 6 Dec 2019| volume = 366 | issue = 6470 |pages = eaay3544 | doi = 10.1126/science.aay3544 |pmid = 31806784 |bibcode = 2019Sci...366.3544L |url = http://oro.open.ac.uk/68479/1/Lauretta_et_al_2019_accepted.pdf | doi-access = free }}. (not dust, defined as tens of micrometers).{{cite web |title=Definitions of terms in meteor astronomy |url=http://www.iau.org/static/science/scientific_bodies/commissions/f1/meteordefinitions_approved.pdf |access-date=31 Jul 2020}}{{cite journal |last1=Grun |first1=E. |last2=Krüger |first2=H. |last3=Srama |first3=R. |s2cid=208527737 |date=2019 |title=The Dawn of Dust Astronomy |journal=Space Science Reviews |volume=215 |issue=7 |page=46 |doi=10.1007/s11214-019-0610-1 |doi-access=free |arxiv=1912.00707 |bibcode=2019SSRv..215...46G}} 3. Multifaceted Scientific Dust Observations Scientists hypothesize the releases may be caused by thermal fracturing, volatile release through dehydration of phyllosilicates, pockets of subsurface water, and/or meteoroid impacts.

Before the arrival of OSIRIS-REx, Bennu had displayed polarization consistent with Comet Hale-Bopp and 3200 Phaethon, a rock comet. Bennu, Phaethon, and inactive Manx comets{{cite conference |last1=Boe |first1=B.|last2=Jedicke |first2=R. |last3=Wiegert |first3=P. |last4=Meech |first4=K. |last5=Morbidelli |first5=A. |title=Distinguishing Between Solar System Formation Models with Manxes (or not) |date=Sep 2019 |conference=2019 EPSC-DPS conference |pages=626–2}}{{page needed|date=August 2021}} are examples of active asteroids.{{cite conference |last1=Gounelle |first1=M. |title=The Asteroid-Comet Continuum: Evidence from Extraterrestrial Samples |date=2012 |conference=2012 European Planetary Science Congress |page=220 }}{{cite book |last1=Rickman |first1=H. |title=Origin and Evolution of Comets: Ten Years after the Nice Model, One Year after Rosetta |date=2018 |publisher=World Scientific |location=Singapore |pages=162–168}} Sec. 4.3 Dormancy and Rejuvenation B-type asteroids displaying a blue color in particular, may be dormant comets,{{cite conference |last1=Nuth |first1=J. |last2=Johnson |first2=N. |last3=Abreu |first3=N. |title=Are B-type Asteroids Dormant Comets? |url=https://www.hou.usra.edu/meetings/lpsc2019/pdf/3059.pdf |date=Mar 2019 |conference=50th LPSC |page=2132 }}{{cite conference |last1=Schroder |first1=S. |last2=Poch |first2=I. |last3=Ferrari |first3=M. |last4=De Angelis |first4=S. |last5=Sultana |first5=R. |title=Experimental evidence for the nature of Ceres blue material |url=https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-78-2.pdf |journal=Epsc-DPS Joint Meeting 2019 |volume=2019 |pages=EPSC–DPS2019–78 |date=Sep 2019 |conference=2019 EPSC-DPS conference |bibcode=2019EPSC...13...78S }}{{cite conference |last1=Marsset |first1=M. |last2=DeMeo |first2=F. |last3=Polishook |first3=D. |last4=Binzel |first4=R. |title=Near-infrared spectral variability on the newly active asteroid (6478) Gault |journal=Epsc-DPS Joint Meeting 2019 |date=Sep 2019 |volume=2019 |pages=EPSC-DPS2019-280 |conference=2019 EPSC-DPS conference |bibcode=2019EPSC...13..280M }}{{cite journal |last1=Fukai |first1=R. |last2=Arakawa |first2=S. |journal=The Astrophysical Journal |date=2021 |title=Assessment of Cr isotopic heterogeneities of volatile-rich asteroids based on multiple planet formation models |volume=908 |issue=1 |page=64 |doi=10.3847/1538-4357/abd2b9 |arxiv=2012.05467 |bibcode=2021ApJ...908...64F |s2cid=228084040 |doi-access=free }} similar to Ryugu but at an earlier stage.{{cite journal |last1=Miura |first1=H. |last2=Nakamura |first2=E. |last3=Kunihiro |first3=T. |title=The Asteroid 162173 Ryugu: a Cometary Origin |journal= The Astrophysical Journal Letters|date=2022 |volume=925 |issue=2 |page=15|doi=10.3847/2041-8213/ac4bd5 |bibcode=2022ApJ...925L..15M |doi-access=free }} If the IAU declares Bennu to be a dual-status object, its comet designation would be P/{{mp|1999 RQ|36}} (LINEAR).{{cite conference |last1=Bauer |first1=G. |title=Active Asteroids |url=https://www.lpi.usra.edu/sbag/meetings/jun2019/presentations/Bauer-2.pdf |conference=21st NASA Small Bodies Assessment Group |date=2019 }}

{{multipleimage

| header = Asteroid Bennu ejecting particles

| direction = horizontal

| caption_align = center

| align = center

| width =

| image1 = PIA23554-AsteroidBennu-EjectingParticles-20190106.jpg

| caption1 = 6 January 2019

| width1 = 227

| image2 = PIA24101-AsteroidBennu-ParticleEjectionEvents.webm

| caption2 = Particle trajectories from four 2019 ejection events (video; 0:43)

| width2 = 300

| image3 = Bennu-Particle-Ejection-Event-20190119.jpg

| caption3 = 19 January 2019

| width3 = 232

| footer = OSIRIS-REx mission{{cite web |last=Morton |first=Erin |title=NASA Mission Reveals Asteroid Has Big Surprises |url=https://www.asteroidmission.org/?latest-news=nasa-mission-reveals-asteroid-big-surprises |work=AsteroidMission.org |date=19 March 2019 |access-date=19 March 2019}}{{cite news |last1=Chang |first1=Kenneth |last2=Stirone |first2=Shannon |title=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) |url=https://www.nytimes.com/2019/03/19/science/bennu-ryugu-asteroids.html |date=19 March 2019 |work=The New York Times |access-date=21 March 2019}}

}}

{{multiple image

| header = Asteroid Bennu regolith surface

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| image1 = 2019-02-25 regolith image compilation.png

| caption1 = Wide angle shot of the Northern Hemisphere of Bennu, imaged by OSIRIS-REx at an altitude of approximately {{convert|1.1|mi|km|abbr=on|order=flip}}

| width1 = 300

| image2 = Bennu’s boulder-covered surface 20190411 bennu bird rock 0.png

| caption2 = Bennu's regolith-covered surface as imaged by OSIRIS-REx

| width2 = 200|footer

| total_width =

| alt1 =

| image3 = OSIRIS-REx landing.jpg

| caption3 = The Nightingale sample site imaged by OSIRIS-REx at touchdown. The circular TAGSAM head in the center of the frame is {{cvt|1|ft|m|order=flip}} in diameter.

}}

All geological features on Bennu are named after various species of birds and bird-like figures in mythology.{{Cite web | url=https://www.nasa.gov/feature/goddard/2019/asteroid-features-to-be-named-after-mythical-birds |title = Asteroid's Features to be Named After Mythical Birds|date = 8 August 2019}} The first features to be named were the final four candidate OSIRIS-REx sample sites, which were given unofficial names by the team in August 2019.{{Cite web | url=https://www.planetary.org/articles/osiris-rex-4-sample-sites |title = OSIRIS-REx Team Picks 4 Candidate Sample Sites on Asteroid Bennu | publisher=The Planetary Society | first=Jason | last=Davis | date=15 August 2019 | access-date=24 May 2021 }} On 6 March 2020 the IAU announced the first official names for 12 Bennu surface features, including regiones (broad geographic regions), craters, dorsa (ridges), fossae (grooves or trenches) and saxa (rocks and boulders).{{cite web|title = First Official Names Given to Features on Asteroid Bennu | date = 6 March 2020 | website = AsteroidMission.org | publisher = NASA | url = https://www.asteroidmission.org/?latest-news=first-official-names-given-to-features-on-asteroid-bennu | access-date = 6 May 2020}}

Analysis showed that the particles making up Bennu's exterior are loosely packed and lightly bound to each other; "The spacecraft would have sunk into Bennu had it not fired its thrusters to back away immediately after it grabbed dust and rock from the asteroid's surface."{{cite web |last1=Shekhtman |first1=Svetlana |title=NASA Reveals Surface of Asteroid Bennu is Like Plastic Ball Pit |url=https://www.nasa.gov/feature/goddard/2022/surprise-again-asteroid-bennu-reveals-its-surface-is-like-a-plastic-ball-pit |website=NASA |access-date=4 November 2022 |date=6 July 2022}} {{PD-notice}} Analysis also revealed that the Sun's heat fractures rocks on Bennu in just 10,000 to 100,000 years instead of millions of years as was thought before.{{cite web |last1=Steigerwald |first1=Bill |title=Some Asteroids 'Aged Early' by Sun, NASA Finds |url=https://www.nasa.gov/feature/goddard/2022/some-asteroids-aged-early-by-sun-nasa-finds |website=NASA |access-date=4 November 2022 |date=30 June 2022}} {{PD-notice}}

After a thorough analysis of Bennu’s surface by the OSIRIS-REx mission team, using data from both MapCam and OVIRS, four candidate sites were selected for sample collection: Nightingale, Kingfisher, Osprey, and Sandpiper. Among these, Nightingale was ultimately chosen, as it exhibited a stronger spectral reddening compared to the rest of the surface (indicating fresher or less exposed terrain).{{Cite journal |last=Rizos |first=J. L. |last2=de León |first2=J. |last3=Licandro |first3=J. |last4=Golish |first4=D. R. |last5=Campins |first5=H. |last6=Tatsumi |first6=E. |last7=Popescu |first7=M. |last8=DellaGiustina |first8=D. N. |last9=Pajola |first9=M. |last10=Li |first10=J. -Y. |last11=Becker |first11=K. J. |last12=Lauretta |first12=D. S. |date=2021-08-01 |title=Bennu's global surface and two candidate sample sites characterized by spectral clustering of OSIRIS-REx multispectral images |url=https://linkinghub.elsevier.com/retrieve/pii/S0019103521001482 |journal=Icarus |volume=364 |pages=114467 |doi=10.1016/j.icarus.2021.114467 |issn=0019-1035|arxiv=2104.02435 }} Additionally, it successfully passed the safety assessment tests for the spacecraft’s descent.

On 12 December 2019, after a year of mapping Bennu's surface, a target site was announced. Named Nightingale, the area is near Bennu's north pole and lies inside a small crater within a larger crater. Osprey was selected as the backup sample site.File:OSIRIS-REx candidate sample sites on Bennu.png

File:Bennu named surface features.png

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.

{{cite journal

| last1=Bensby |first1=T.

| last2=Feltzing |first2=S.|s2cid=7771039

|author2-link= Sofia Feltzing

| year=2006

| title=The origin and chemical evolution of carbon in the Galactic thin and thick discs

| journal=Monthly Notices of the Royal Astronomical Society

| volume=367 |issue=3

|pages=1181–1193

| bibcode=2006MNRAS.367.1181B

| doi=10.1111/j.1365-2966.2006.10037.x

|doi-access=free

| url=https://deepblue.lib.umich.edu/bitstream/2027.42/74854/1/j.1365-2966.2006.10037.x.pdf

|arxiv=astro-ph/0601130

}} 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. Bennu probably began in the inner asteroid belt as a fragment from a larger body with a diameter of 100 km.{{Cite journal|last1=Michel|first1=P.|last2=Ballouz|first2=R.-L.|last3=Barnouin|first3=O.S.|last4=Jutzi|first4=M.|last5=Walsh|first5=K.J.|last6=May|first6=B.H.|last7=Manzoni|first7=C.|last8=Richardson|first8=D.C.|last9=Schwartz|first9=S.R.|last10=Sugita|first10=S.|last11=Watanabe|first11=S.|date=2020-05-27|title=Collisional formation of top-shaped asteroids and implications for the origins of Ryugu and Bennu|journal=Nature Communications|language=en|volume=11|issue=1|page=2655|doi=10.1038/s41467-020-16433-z|pmid=32461569 |pmc=7253434 |bibcode=2020NatCo..11.2655M |issn=2041-1723}} Simulations suggest a 70% chance it came from the Polana family and a 30% chance it derived from the Eulalia family. Impactors on boulders of Bennu indicate that Bennu has been in near Earth orbit (separated from the main asteroid belt) for 1–2.5 million years.{{cite journal | last1=Ballouz |first1=R. |last2=Walsh |first2=K. J. |last3=Barnouin |first3=O. S. |last4=Lauretta |first4=D. S. | title=Bennu's near-Earth lifetime of 1.75 million years inferred from craters on its boulders | journal=Nature | volume=5 | issue=587 | pages=205–209 | year=2020 | doi = 10.1038/s41586-020-2846-z | pmid=33106686| bibcode=2020Natur.587..205B | s2cid=225082141 | url=https://hal.archives-ouvertes.fr/hal-03080437/file/BallouzEtAl2020_AuthorVersion.pdf }}

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.

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 {{val|8|5|u=%}}. This includes rock comet 3200 Phaethon, discovered and still numbered as an asteroid.{{cite web |last1=Hergenrother |first1=C.|title=The Strange Life of Asteroid Phaethon – Source of the Geminid Meteors |url=https://dslauretta.com/2013/12/12/the-strange-life-of-asteroid-phaethon-source-of-the-geminid-meteors/ |website=Dslauretta: Life on the Asteroid Frontier |access-date=25 Jul 2019 |date=12 December 2013 |archive-date=24 March 2019 |archive-url=https://web.archive.org/web/20190324205753/https://dslauretta.com/2013/12/12/the-strange-life-of-asteroid-phaethon-source-of-the-geminid-meteors/ }}{{cite journal |last1=Maltagliati |first1=L. |s2cid=189930305 |title=Cometary Bennu? |journal=Nature Astronomy |date=24 Sep 2018 |volume=2 |issue=10 |page=761 |doi=10.1038/s41550-018-0599-5|bibcode=2018NatAs...2..761M |doi-access=free }}

File:Bennu Orbit.png

Bennu orbits the Sun with a period of {{convert|1.19|years|days|abbr=off|sigfig=3}} {{as of|2022|lc=y}}. Earth gets as close as about 480,000 km (0.0032 au) from its orbit around 23 to 25 September. On 22 September 1999 Bennu passed 0.0147 au from Earth, and six years later on 20 September 2005 it passed 0.033 au from Earth. The next close approaches of less than 0.04 au will be 30 September 2054 and then 23 September 2060, which will perturb the orbit slightly. Between the close approach of 1999 and that of 2060, Earth completes 61 orbits and Bennu 51. An even closer approach will occur on 25 September 2135 around 0.0014 au (see table). In the 75 years between the 2060 and 2135 approaches, Bennu completes 64 orbits, meaning its period will have changed to {{convert|427|days|years|abbr=off|sigfig=3|order=flip}}. The Earth approach of 2135 will increase the orbital period to about {{convert|452|days|years|abbr=off|sigfig=3|order=flip}}. Before the 2135 Earth approach, Bennu will be at its maximum distance from Earth on 27 November 2045 at a distance of {{Convert|2.34|AU|e6km|abbr=unit}}.

On average, an asteroid with a diameter of {{convert|500|m|ft mi|sigfig=2|abbr=on}} can be expected to impact Earth about every 130,000 years. 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. The authors recognized that an accurate assessment of {{mp|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 made possible an improved estimate of the Yarkovsky acceleration and a revised assessment of the impact probability. In 2014, the best estimate of the impact probability was a cumulative probability of 0.037% in the interval 2175 to 2196. This corresponds to a cumulative rating 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 Tsar Bomba, the most powerful nuclear weapon ever tested, was approximately 54 megatons, and that of the Tunguska event, the most energetic impact event in recorded history, has been estimated at 3–5 megatons,{{cite news|url=https://share.sandia.gov/news/resources/releases/2007/asteroid.html|title=Sandia supercomputers offer new explanation of Tunguska disaster|date=17 December 2007|publisher=Sandia National Laboratories|access-date=22 December 2007|archive-date=19 February 2013|archive-url=https://web.archive.org/web/20130219203913/https://share.sandia.gov/news/resources/releases/2007/asteroid.html}} though another estimate is 20–30 megatons{{cite journal|title=Probabilistic assessment of Tunguska-scale asteroid impacts|journal=Icarus|volume=327|pages=83–96|doi=10.1016/j.icarus.2018.12.017|year=2019|last1=Wheeler|first1=Lorien F.|last2=Mathias|first2=Donovan L.|bibcode=2019Icar..327...83W|doi-access=free}}).

The 2021 orbit solution extended the virtual impactors from the year 2200 to the year 2300 and slightly increased the cumulative Palermo impact hazard scale rating to −1.42. The solution included the estimated gravitational effect of 343 other asteroids, representing about 90% of the total mass of the main asteroid belt.

File:Animation of 101955 Bennu orbit around Earth 2128-2138.gif

Bennu will pass {{convert|0.005|au|km mi|abbr=on}} from Earth on 23 September 2060, while for comparison the Moon's average orbital distance (lunar distance) is {{convert|384,402|km|mi|abbr=on}} and will only change to 384,404 km in 50 years time.{{cn|date=January 2025}} Bennu will be too dim to be seen with common binoculars. The close approach of 2060 causes divergence in the close approach of 2135. On 25 September 2135, the Earth approach distance is {{convert|0.00136|au|km mi|abbr=on}} ±20 thousand km. There is no chance of an Earth impact in 2135. 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 ~20 km wide with some keyholes being only 5 meters wide.

The most threatening virtual impactor is on Tuesday, 24 September 2182 when there is a 1 in 2,700 chance of an Earth impact, but the asteroid could be as far as the Sun is from Earth. To impact Earth on 24 September 2182 Bennu must pass through a keyhole roughly 5 km wide on 25 September 2135.[https://www.sciencedirect.com/science/article/pii/S0019103521002591#tbl3 Table 3. Impact dates, keyhole centers and widths in the 2135 B-plane] (Farnocchia2021) The table reports the zeta coordinate on the B-plane, which is not the same thing as the miss distance during the 2135 encounter. The next two biggest risks occur in 2187 (1:14,000) and 2192 (1:26,000). There is a cumulative 1 in 1,800 chance of an Earth impact between 2178 and 2290.

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.

As an active asteroid with a small minimum orbit intersection distance from Earth, Bennu may be the parent body of a weak meteor shower. Bennu particles would radiate around 25 September from the southern constellation of Sculptor. The meteors are expected to be near the naked eye visibility limit and only produce a Zenith hourly rate of less than 1.

{{main|OSIRIS-REx}}

File:OSIRIS-REX SamCam TAGSAM Event 2020-10-20 small.gif

The OSIRIS-REx mission of NASA's New Frontiers program was launched towards {{mp|101955 Bennu}} on 8 September 2016. On 3 December 2018, the spacecraft arrived at the asteroid Bennu after a two-year journey.{{cite news|last=Chang|first=Kenneth|date=3 December 2018|title=NASA's Osiris-Rex Arrives at Asteroid Bennu After a Two-Year Journey|work=The New York Times|url=https://www.nytimes.com/2018/12/03/science/osiris-rex-bennu-asteroid-arrival.html|access-date=12 February 2021}} 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.{{cite news | url = https://www.space.com/42690-asteroid-bennu-had-water-nasa-osiris-rex-discovery.html | title= Asteroid Bennu Had Water! NASA Probe Makes Tantalizing Find | first= Mike | last = Wall | date = 10 December 2018 | access-date = 6 January 2019 | website = Space.com }}

On 20 October 2020, OSIRIS-REx descended to the asteroid and "pogo-sticked off" it while successfully collecting a sample.[https://www.pbs.org/wgbh/nova/video/touching-the-asteroid/ "Touching the Asteroid" (video, 54:03 min.)], Nova on PBS, 21 October 2020. Retrieved 20-10-22. On 7 April 2021, OSIRIS-REx completed its final flyover of the asteroid and began slowly drifting away from it.{{cite news|url=https://www.nasa.gov/feature/goddard/2021/nasa-osiris-rex-completes-final-tour-of-asteroid-bennu|title=NASA's OSIRIS-REx Completes Final Tour of Asteroid Bennu|publisher=NASA|date=7 April 2021|access-date=10 May 2021}} On 10 May 2021, the departure was completed with OSIRIS-REx still managing to contain the asteroid sample. OSIRIS-REx returned samples to Earth in 2023 via a capsule-drop by parachute, ultimately, from the spacecraft to the Earth's surface in Utah on 24 September 2023.

Shortly after the sample container was retrieved and transferred to an airtight chamber at the Johnson Space Center in Houston, Texas, the lid on the container was opened. Scientists commented that they "found black dust and debris on the avionics deck of the OSIRIS-REx science canister" on the initial opening. Further study is planned. On 11 October 2023, the recovered capsule was opened to reveal a "first look" at the asteroid sample contents.{{cite news |last=Chang |first=Kenneth |title=NASA Unveils First Glimpse of 'Scientific Treasure' Collected From Asteroid – Scientists said they got more material than expected from the Osiris-Rex mission during its seven-year journey to the asteroid Bennu. |url=https://www.nytimes.com/2023/10/11/science/nasa-asteroid-osiris-rex-bennu.html |date=11 October 2023 |work=The New York Times |url-status=live |archive-url=https://archive.today/20231011174611/https://www.nytimes.com/2023/10/11/science/nasa-asteroid-osiris-rex-bennu.html |archive-date=11 October 2023 |access-date=12 October 2023 }} On 13 December 2023, further studies of the returned sample were reported and revealed organic molecules as well as unknown materials which require more study to have a better idea of their composition and makeup.{{cite news |last=Kuthunur |first=Sharmila |title='What is that material?': Potentially hazardous asteroid Bennu stumps scientists with its odd makeup – Scientists found signs of organic molecules in the first samples of potentially hazardous asteroid Bennu, as well as a 'head scratching' material that has yet to be identified. |url=https://www.livescience.com/space/space-exploration/what-is-that-material-potentially-hazardous-asteroid-bennu-stumps-scientists-with-its-odd-makeup |date=13 December 2023 |work=LiveScience |url-status=live |archive-url=https://archive.today/20231214014121/https://www.livescience.com/space/space-exploration/what-is-that-material-potentially-hazardous-asteroid-bennu-stumps-scientists-with-its-odd-makeup |archive-date=14 December 2023 |access-date=13 December 2023 }}{{cite news |last=Rabie |first=Passant |title=It's Been 2 Months. Why Can't NASA Open the Asteroid Sample Container? – The space agency is having to develop new tools to crack open the canister containing bits from asteroid Bennu |url=https://gizmodo.com/nasa-osiris-rex-asteroid-samples-bennu-stuck-container-1851102598 |date=15 December 2023 |work=Gizmodo |url-status=live |archive-url=https://archive.today/20231215230642/https://gizmodo.com/nasa-osiris-rex-asteroid-samples-bennu-stuck-container-1851102598 |archive-date=15 December 2023 |access-date=16 December 2023 }} On 11 January 2024, NASA reported finally fully opening, after three months of trying, the recovered container with samples from the Bennu asteroid.{{cite web

| url = https://blogs.nasa.gov/osiris-rex/2024/01/11/nasas-osiris-rex-team-clears-hurdle-to-access-remaining-bennu-sample/

| title = NASA's OSIRIS-REx Team Clears Hurdle to Access Remaining Bennu Sample

| last = Barry

| first = Rachel Ann

| date = 2024-01-11

| website = OSIRIS-REx Mission

| publisher = NASA

}}{{cite news |last=MacDonald |first=Cheyenne |title=NASA finally got the stuck lid off its asteroid Bennu sample container – Thanks to some stubborn fasteners, the agency spent three months locked out of the sample OSIRIS-REx dropped off. |url=https://www.engadget.com/nasa-finally-got-the-stuck-lid-off-its-asteroid-bennu-sample-container-185814782.html |date=13 January 2024 |work=Engadget |url-status=live |archive-url=https://archive.today/20240114015754/https://www.engadget.com/nasa-finally-got-the-stuck-lid-off-its-asteroid-bennu-sample-container-185814782.html |archive-date=14 January 2024 |access-date=13 January 2024 }}{{cite news |last=Rabie |first=Passant |title=NASA Finally Opened the Asteroid Container and Holy Crap That's a Lot of Asteroid – After months of struggling to get to the bulk of the OSIRIS-REx asteroid sample, the space agency has unveiled a treasure trove of ancient rocks and dust. |url=https://gizmodo.com/nasa-osiris-rex-canister-reveal-asteroid-sample-trove-1851184737 |date=22 January 2024 |work=Gizmodo |url-status=live |archive-url=https://archive.today/20240123011843/https://gizmodo.com/nasa-osiris-rex-canister-reveal-asteroid-sample-trove-1851184737 |archive-date=23 January 2024 |access-date=22 January 2024 }} The total weight of the recovered material weighed {{convert|121.6|g|oz|abbr=on}}, over twice the mission's goal.{{cite news |last=Rabie |first=Passant |title=We Finally Know How Much of That Asteroid OSIRIS-REx Grabbed in Space – Engineers struggled to open the sample canister for months, but it was all worth it for twice the amount of asteroid they thought they were getting. |url=https://gizmodo.com/how-much-nasa-osiris-rex-collected-asteroid-space-1851261317 |date=15 February 2024 |work=Gizmodo |url-status=live |archiveurl=https://archive.today/20240216145102/https://gizmodo.com/how-much-nasa-osiris-rex-collected-asteroid-space-1851261317 |archivedate=16 February 2024 |accessdate=16 February 2024 }} On 15 May 2024, an overview of preliminary analytical studies on the returned samples was reported.{{cite news |last=Nicitopoulos |first=Theo |title=NASA's asteroid Bennu samples have rocks unlike any meteorite ever found – Early results from NASA's OSIRIS-REx mission to Bennu have uncovered exotic versions of chondrules – rocks commonly found in meteorites. |url=https://www.astronomy.com/science/nasas-asteroid-bennu-samples-have-rocks-unlike-any-meteorite-ever-found/ |date=15 May 2024 |work=Astronomy |url-status=live |archiveurl=https://archive.today/20240516190933/https://www.astronomy.com/science/nasas-asteroid-bennu-samples-have-rocks-unlike-any-meteorite-ever-found/ |archivedate=16 May 2024 }}

The asteroid Bennu was selected from over half a million 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. The criteria stipulated an asteroid in an orbit with low eccentricity, low inclination, and an orbital radius of {{val|0.8|-|1.6|ul=au}}. 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.

File:Animation of OSIRIS-REx trajectory.gif|Trajectory in the Solar System from 9 August 2016 to 24 September 2023

File:Animation of OSIRIS-Rex trajectory around 101955 Bennu.gif|Trajectory around 101955 Bennu from 25 December 2018

File:Animation of OSIRIS-REx around Bennu - touch down on Bennu.gif|Touchdown on Bennu

File:Maps14227-fig-0005-m.jpg

File:Maps14227-fig-0017-m.jpg

The OSIRIS-REx mission successfully returned approximately 120 grams of material from Bennu to Earth in September 2023. The returned material is predominantly very dark, with reflectance values consistent with observations of Bennu's surface, though it contains some brighter inclusions and particles. Particle sizes in the sample span a wide range, from submicron dust to rocks measuring about 3.5 cm in length. Mineralogical analysis shows that the sample is rich in hydrated minerals, particularly Mg-rich phyllosilicates, confirming predictions from remote sensing data. Other major components include magnetite, sulfides, carbonates, and organic compounds. An unexpected discovery was the presence of phosphate minerals in some samples, including Mg, Na-rich phosphates found as veins and crusts in some particles.{{cite journal |last1=Lauretta |first1=Dante S. |last2=Connolly |first2=Harold C. |last3=Aebersold |first3=Joseph E. |title=Asteroid (101955) Bennu in the laboratory: Properties of the sample collected by OSIRIS-REx |journal=Meteoritics & Planetary Science |date=26 June 2024 |volume=59 |issue=9 |pages=2453–2486 |doi=10.1111/maps.14227 |display-authors=1|doi-access=free }}

The elemental composition of the Bennu samples closely resembles that of CI chondrite meteorites. However, the Bennu material shows some distinct isotopic ratios. The average oxygen isotopic composition places Bennu in the same region of oxygen three-isotope space as CI and CY chondrites, as well as samples from asteroid Ryugu. The carbon content of the samples (4.5–4.7 wt%) is higher than that found in known meteorites and Ryugu samples. The presence of presolar grains in the samples indicates that some of the material has remained largely unprocessed since the formation of the solar system. Presolar silicon carbide and graphite were identified, with abundances of {{val|52|12|10|u=ppm}} and {{val|12|7|5|u=ppm}} respectively, similar to unheated chondrite samples.

Evidence suggests that the samples come from at least two different lithologies on Bennu's surface. Three predominant types of particles were identified: hummocky, angular, and mottled. These show distinct densities, with hummocky particles having the lowest average density ({{val|1.55|0.07|u=g/cm³}}) and mottled particles the highest ({{val|1.77|0.04|u=g/cm³}}). Spectral analysis of the samples shows a redder slope from 0.4 to 2.5 μm compared to Bennu's global spectrum, potentially indicating differences in particle size, surface texture, or space weathering between the sampled material and the asteroid's surface.

Since 3 November 2023, a part of the sample is exhibited at the Hall of Meteorites of the National Museum of Natural History (Washington, DC).{{cite web |last1=Pearlman |first1=Robert Z. |title=Smithsonian debuts 1st display of asteroid Bennu sample brought back by OSIRIS-REx |url=https://www.space.com/smithsonian-osiris-rex-bennu-asteroid-unveiling |website=space.com |access-date=6 November 2023 |date=3 November 2023}}

Another portion of the sample was exhibited by NASA at the International Astronautical Congress in Milan, Italy, from 14 to 18 October 2024.{{cite tweet |user=NASAExhibit |number=1845910951054205193 |title=NASA exhibit at IAC 2024 opens with Bennu sample |date=15 October 2024 |url=https://x.com/NASAExhibit/status/1845910951054205193 |access-date=24 October 2024}}{{cite tweet |user=NASAExhibit |number=1847158178120675712 |title=NASA invites the general public to view a Bennu sample at their booth for the IAC 2024 public day |date=18 October 2024 |url=https://x.com/NASAExhibit/status/1847158178120675712 |access-date=24 October 2024}}

In January 2025, it was reported that a wide range of carbon- and nitrogen-rich organic compounds have been identified in samples returned from Bennu, including 14 of the 20 amino acids that make up proteins in terrestrial organisms, as well as all five nucleobases (adenine, thymine, cytosine, guanine, and uracil) that are the essential building blocks of DNA and RNA.{{Cite web |title=NASA’s Asteroid Bennu Sample Reveals Mix of Life’s Ingredients - NASA |url=https://www.nasa.gov/news-release/nasas-asteroid-bennu-sample-reveals-mix-of-lifes-ingredients/ |access-date=2025-01-31 |language=en-US}}{{Cite web |date=2025-01-29 |title=Bennu asteroid contains building blocks of life, say scientists |url=https://www.bbc.co.uk/news/articles/c7vd1zjlr5lo |access-date=2025-01-31 |website=BBC News |language=en-GB}}{{Cite journal |last=Petrić Howe |first=Nick |last2=Thompson |first2=Benjamin |date=2025-01-29 |title=Asteroid Bennu contains building blocks of life |url=https://www.nature.com/articles/d41586-025-00267-0 |journal=Nature |language=en |doi=10.1038/d41586-025-00267-0 |issn=0028-0836}}{{Cite journal |last=McCoy |first=T. J. |last2=Russell |first2=S. S. |last3=Zega |first3=T. J. |last4=Thomas-Keprta |first4=K. L. |last5=Singerling |first5=S. A. |last6=Brenker |first6=F. E. |last7=Timms |first7=N. E. |last8=Rickard |first8=W. D. A. |last9=Barnes |first9=J. J. |last10=Libourel |first10=G. |last11=Ray |first11=S. |last12=Corrigan |first12=C. M. |last13=Haenecour |first13=P. |last14=Gainsforth |first14=Z. |last15=Dominguez |first15=G. |date=2025-01-30 |title=An evaporite sequence from ancient brine recorded in Bennu samples |url=https://www.nature.com/articles/s41586-024-08495-6 |journal=Nature |language=en |volume=637 |issue=8048 |pages=1072–1077 |doi=10.1038/s41586-024-08495-6 |issn=0028-0836}}{{cite journal |last1=Glavin |first1=D.P. |last2=Dworkin |first2=J.P. |last3=Alexander |first3=C.M.O'D. |last4=Aponte |first4=J.C. |last5=Bacynski |first5=A.A. |last6=Barnes |first6=J.J. |last7=Bechtel |first7=H.A. |last8=Berger |first8=E.L. |last9=Burton |first9=A.S. |last10=Caselli |first10=P. |last11=Chung |first11=A.H. |last12=Clemett |first12=S.J. |last13=Cody |first13=G.D. |last14=Dominguez |first14=G. |last15=Elsila |first15=J.E. |last16=Farnsworth |first16=K.K. |last17=Foustoukos |first17=D.I. |last18=Freeman |first18=K.H. |last19=Furukawa |first19=Y. |last20=Gainsforth |first20=Z. |last21=Graham |first21=H.V. |last22=Grassi |first22=T. |last23=Guiliano |first23=B.M. |last24=Hamilton |first24=V.E. |last25=Haenecour |first25=P. |last26=Heck |first26=P.R. |last27=Hofmann |first27=A.E. |last28=House |first28=C.H. |last29=Huang |first29=Y. |last30=Kaplan |first30=H.H. |last31=Keller |first31=L.P. |last32=Kim |first32=B. |last33=Koga |first33=T. |last34=Liss |first34=M. |last35=McLain |first35=H.L. |last36=Marcus |first36=M.A. |last37=Matney |first37=M. |last38=McCoy |first38=T.J. |last39=McIntosh |first39=O.M. |last40=Mojarro |first40=A. |last41=Naraoka |first41=H. |last42=Nguyen |first42=A.N. |last43=Nuevo |first43=M. |last44=Nuth III |first44=J.A. |last45=Oba |first45=Y. |last46=Parker |first46=E.T. |last47=Peretyazhko |first47=T.S. |last48=Sandford |first48=S.A. |last49=Santos |first49=E. |last50=Schmitt-Kopplin |first50=P. |last51=Seguin |first51=F. |last52=Simkus |first52=D.N. |last53=Shahid |first53=A. |last54=Takano |first54=Y. |last55=Thomas-Keprta |first55=K.L. |last56=Tripathi |first56=H. |last57=Weiss |first57=G. |last58=Zheng |first58=Y. |last59=Lunning |first59=N.G. |last60=Righter |first60=K. |last61=Connolly Jr |first61=H.C. |last62=Lauretta |first62=D.S. |title=Abundant ammonia and nitrogen-rich soluble organic matter in samples from asteroid (101955) Bennu |journal=Nature Astronomy |date=2025 |volume=9 |pages=199-210 |doi=10.1038/s41550-024-02472-9 |url=https://www.nature.com/articles/s41550-024-02472-9 |access-date=6 March 2025|pmc=11842271 }}

• List of minor planets and comets visited by spacecraft
• 162173 Ryugu, an asteroid being studied by JAXA concurrent with the NASA mission to 101955 Bennu

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| url = https://cneos.jpl.nasa.gov/news/news201.html

| date = 24 March 2018}}

{{cite journal |author=Hudson, R.S. |author2=Ostro, S.J. |author3=Benner, L.A.M. |bibcode=2000DPS....32.0710H |title=Recent Delay-Doppler Radar Asteroid Modeling Results: 1999 RQ36 and Craters on Toutatis |journal=Bulletin of the American Astronomical Society |volume=32 |page=1001

| year=2000}}

{{Cite journal |last1=Milani |first1=Andrea |last2=Chesley |first2=Steven R. |last3=Sansaturio |first3=Maria Eugenia |last4=Bernardi |first4=Fabrizio |last5=Valsecchi |first5=Giovanni B. |last6=Arratia |first6=Oscar |s2cid=54594575 |date=2009 |title=Long term impact risk for (101955) 1999 RQ₃₆ |journal=Icarus |volume=203 |issue=2 |pages=460–471 |doi=10.1016/j.icarus.2009.05.029 |bibcode=2009Icar..203..460M|arxiv = 0901.3631

}}

[https://web.archive.org/web/20010603042837/http://echo.jpl.nasa.gov/~lance/delta_v/delta_v.rendezvous.html Near-Earth Asteroid Delta-V for Space Rendezvous]

{{cite web

| date=2010

| title=Earth Impact Effects Program

| publisher=Imperial College London / Purdue University

| author=Robert Marcus

| author2=H. Jay Melosh

| author3=Gareth Collins

| name-list-style=amp| url=http://impact.ese.ic.ac.uk/ImpactEffects/

| access-date=2013-02-07

}} (solution using density of 2,600 kg/m^3, sped of 17km/s, and impact angle of 45 degrees)

{{cite journal|last1=Nolan|first1=M.C.|last2=Magri|first2=C.|last3=Howell|first3=E.S.|author3-link=Ellen Howell|last4=Benner|first4=L.A.M.|last5=Giorgini|first5=J.D.|last6=Hergenrother|first6=C.W.|last7=Hudson|first7=R.S.|last8=Lauretta|first8=D.S.|last9=Margot|first9=J.L.|last10=Ostro|first10=S.J.|last11=Scheeres|first11=D.J.|title=Shape model and surface properties of the OSIRIS-REx target Asteroid (101955) Bennu from radar and lightcurve observations|journal=Icarus|volume=226|issue=1|year=2013|pages=629–640|issn=0019-1035|doi=10.1016/j.icarus.2013.05.028|bibcode=2013Icar..226..629N

| url=http://www.escholarship.org/uc/item/6mh8b2t5}}

{{cite journal|last1=Chesley|first1=Steven R.|last2=Farnocchia|first2=Davide|last3=Nolan|first3=Michael C.|last4=Vokrouhlický|first4=David|last5=Chodas|first5=Paul W.|last6=Milani|first6=Andrea|last7=Spoto|first7=Federica|last8=Rozitis|first8=Benjamin|last9=Benner|first9=Lance A.M.|last10=Bottke|first10=William F.|last11=Busch|first11=Michael W.|last12=Emery|first12=Joshua P.|last13=Howell|first13=Ellen S.|author13-link=Ellen Howell|last14=Lauretta|first14=Dante S.|last15=Margot|first15=Jean-Luc|last16=Taylor|first16=Patrick A.|s2cid=30979660|title=Orbit and bulk density of the OSIRIS-REx target Asteroid (101955) Bennu|journal=Icarus|volume=235|date=2014|pages=5–22|issn=0019-1035|doi=10.1016/j.icarus.2014.02.020

| bibcode=2014Icar..235....5C|arxiv=1402.5573

}}

{{citation

| title=Thermal infrared observations and thermophysical characterization of the OSIRIS-REx target asteroid (101955) Bennu

| display-authors=1 | last1=Emery | first1=J.

| last2=Fernandez | first2=Y. | last3=Kelley | first3=M.

| last4=Warden | first4=K. | last5=Hergenrother | first5=C.

| last6=Lauretta | first6=D. | last7=Drake | first7=M.

| last8=Campins | first8=H. | last9=Ziffer | first9=J.

| journal=Conference Proceedings Asteroids, Comets, Meteors 2014

| page=148 | editor1-first=K. | editor1-last=Muinonen | date=July 2014

| bibcode=2014acm..conf..148E | postscript=.}}

{{citation

| title=Lightcurve, Color and Phase Function Photometry of the OSIRIS-REx Target Asteroid (101955) Bennu

| display-authors=1

| last1=Hergenrother | first1=Carl W. | last2=Nolan | first2=Michael C.

| last3=Binzel | first3=Richard P. | last4=Cloutis | first4=Edward A.

| last5=Barucci | first5=Maria Antonietta | last6=Michel | first6=Patrick

| last7=Scheeres | first7=Daniel J. | last8=d'Aubigny | first8=Christian Drouet

| last9=Lazzaro | first9=Daniela | last10=Pinilla-Alonso | first10=Noemi

| last11=Campins | first11=Humberto | last12=Licandro | first12=Javier

| last13=Clark | first13=Beth E. | last14=Rizk | first14=Bashar

| last15=Beshore | first15=Edward C. | last16=Lauretta | first16=Dante S.

| journal=Icarus | volume=226 | issue=1 | pages=663–670 | date=September 2013

| doi=10.1016/j.icarus.2013.05.044 | bibcode=2013Icar..226..663H

| postscript=.}}

{{citation

| title=The OSIRIS-REx target asteroid (101955) Bennu: Constraints on its physical, geological, and dynamical nature from astronomical observations

| display-authors=1 | last1=Lauretta | first1=D. S.

| last2=Bartels | first2=A.E. | last3=Barucci | first3=M.A.

| last4=Bierhaus | first4=E.B. | last5=Binzel | first5=R.P.

| last6=Bottke | first6=W.F. | last7=Campins | first7=H.

| last8=Chesley | first8=S.R. | last9=Clark | first9=B.C.

| last10=Clark | first10=B.E. | last11=Cloutis | first11=E.A.

| last12=Connolly | first12=HC. | last13=Crombie | first13=M. K.

| last14=Delbó | first14=M. | last15=Dworkin | first15=J. P.

| last16=Emery | first16=J. P. | last17=Glavin | first17=D. P.

| last18=Hamilton | first18=V. E. | last19=Hergenrother | first19=C. W.

| last20=Johnson | first20=C. L. | last21=Keller | first21=L.P.

| last22=Michel | first22=P. | last23=Nolan | first23=M.C.

| last24=Sandford | first24=S.A. | last25=Scheeres | first25=D.J.

| last26=Simon | first26=A.A. | last27=Sutter | first27=B.M.

| last28=Vokrouhlický | first28=D. | last29=Walsh | first29=K.J.

| journal=Meteoritics & Planetary Science

| volume=50 | issue=4 | pages=834–849 | date=April 2015

| doi=10.1111/maps.12353 | bibcode=2015M&PS...50..834L

| postscript=. | citeseerx=10.1.1.723.9955| s2cid=32777236 }}

{{cite journal|last1=Lauretta|first1=D.S.|last2=Bartels|first2=A.E.|last3=Barucci|first3=M.A.|last4=Bierhaus|first4=E.B.|last5=Binzel|first5=R.P.|last6=Bottke|first6=W.F.|last7=Campins|first7=H.|last8=Chesley|first8=S.R.|last9=Clark|first9=B.C.|last10=Clark|first10=B.E.|last11=Cloutis|first11=E.A.|last12=Connolly|first12=H.C.|last13=Crombie|first13=M.K.|last14=Delbó|first14=M.|last15=Dworkin|first15=J.P.|last16=Emery|first16=J.P.|last17=Glavin|first17=D.P.|last18=Hamilton|first18=V.E.|last19=Hergenrother|first19=C.W.|last20=Johnson|first20=C.L.|last21=Keller|first21=L.P.|last22=Michel|first22=P.|last23=Nolan|first23=M.C.|last24=Sandford|first24=S.A.|last25=Scheeres|first25=D. J.|last26=Simon|first26=A.A.|last27=Sutter|first27=B.M.|last28=Vokrouhlický|first28=D.|last29=Walsh|first29=K.J.|title=The OSIRIS-REx target asteroid (101955) Bennu: Constraints on its physical, geological, and dynamical nature from astronomical observations|journal=Meteoritics & Planetary Science|date=April 2015|volume=50|issue=4|pages=834–849|doi=10.1111/maps.12353|display-authors=2|bibcode=2015M&PS...50..834L|citeseerx=10.1.1.723.9955|s2cid=32777236 }}

{{cite web|title=Why Bennu?|url=http://www.asteroidmission.org/why-bennu/|website=OSIRIS-REx Mission|publisher=Arizona Board of Regents|access-date=10 September 2016}}

{{citation

| title=In search of the source of asteroid (101955) Bennu: Applications of the stochastic YORP model

| display-authors=1

| last1=Bottke | first1=William F. | last2=Vokrouhlický | first2=David

| last3=Walsh | first3=Kevin J. | last4=Delbo | first4=Marco

| last5=Michel | first5=Patrick | last6=Lauretta | first6=Dante S.

| last7=Campins | first7=Humberto | last8=Connolly | first8=Harold C.

| last9=Scheeres | first9=Daniel J. | last10=Chelsey | first10=Steven R.

| journal=Icarus | volume=247 | pages=191–217 | date=February 2015

| doi=10.1016/j.icarus.2014.09.046 | bibcode=2015Icar..247..191B

| postscript=.}}

{{cite journal

|last1=Ye |first1=Quanzhi

|title=Prediction of Meteor Activities from (101955) Bennu

|journal=American Astronomical Society

|volume=3 |issue=3 |page=56

|year=2019

|doi=10.3847/2515-5172/ab12e7 |bibcode=2019RNAAS...3...56Y

|s2cid=187247696

|url=https://authors.library.caltech.edu/94305/1/Ye_2019p56.pdf

|doi-access=free

}}

https://www.nasa.gov/press-release/nasa-spacecraft-provides-insight-into-asteroid-bennu-s-future-orbit

}}

{{Commons category}}

• [https://www.youtube.com/watch?v=5dA15GCrAXk Video (2:53)] – Asteroid Bennu Mission Overview (NASA; 11 May 2021).
• [https://www.cnn.com/2019/12/05/world/osirix-rex-asteroid-bennu-activity-scn/index.html Video (01:12) – Asteroid Bennu ejecting material into space] (CNN; 5 December 2019)
• [https://www.youtube.com/watch?v=S29O8dUhFgY Video (01:32) – OSIRIS REx's approach to asteroid Bennu] (NASA; 7 January 2019)
• [https://cneos.jpl.nasa.gov/sentry/details.html#?des=101955 Earth Impact Risk Summary: 101955 1999 RQ36] (Years: 2175–2199) – Jet Propulsion Laboratory near-Earth object site
• [https://newton.spacedys.com/neodys/index.php?pc=1.1.3.1&n=101955&oc=500&y0=2135&m0=1&d0=1&h0=0&mi0=0&y1=2135&m1=12&d1=31&h1=0&mi1=0&ti=10.0&tiu=days NEODyS-2 Ephemerides for 2135] (step size: 10 days)
• {{cite journal |doi=10.1088/2041-8205/728/2/L42|title=Temperature History and Dynamical Evolution of (101955) 1999 Rq 36: A Potential Target for Sample Return from a Primitive Asteroid|journal=The Astrophysical Journal|volume=728|issue=2|pages=L42|year=2011|last1=Delbo|first1=Marco|last2=Michel|first2=Patrick|bibcode=2011ApJ...728L..42D|doi-access=free}}
• {{Cite journal |arxiv=1210.5370|last1=Hergenrother|first1=Carl W. |s2cid=55689658|display-authors=etal|title=Physical Properties of OSIRIS-REx Target Asteroid (101955) 1999 RQ36 derived from Herschel, ESO-VISIR and Spitzer observations|journal=Astronomy & Astrophysics|volume=548|pages=A36|year=2012|doi=10.1051/0004-6361/201220066|bibcode=2012A&A...548A..36M}}
• {{Cite arXiv |eprint=1409.4704|last1=Hergenrother|first1=Carl W. |display-authors=etal|title=The Design Reference Asteroid for the OSIRIS-REx Mission Target (101955) Bennu|class=astro-ph.EP|year=2014}}
• [https://svs.gsfc.nasa.gov/4921 Nominal and impacting solution for 2182]
• {{NeoDys|101955}}
• {{JPL small body}}

{{Minor planets navigator |(101869) 1999 MM |number=101955 |102211 Angelofaggiano}}

{{Planetary defense}}

{{Small Solar System bodies}}

{{2018 in space}}

{{2020 in space}}

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Category:Apollo asteroids

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Category:Active asteroids

Category:Discoveries by LINEAR

Bennu

Category:Potential impact events caused by near-Earth objects

Category:Minor planets visited by spacecraft

Bennu

Category:Articles containing video clips

19990911

Category:B-type asteroids (SMASS)