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The OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) mission is designed to return a sample of material from near-Earth carbonaceous asteroid Bennu. The primary scientific objectives are to: (1) return and analyze a sample (at least 60 g, with a capability of up to 2 kg) of pristine asteroid regolith; (2) map the global properties, chemistry, and mineralogy; (3) document the texture, morphology, volatile chemistry, and spectral properties of the sample site; (4) measure the orbit deviation caused by non-gravitational forces (the Yarkovsky effect); and, (5) characterize the integrated global properties of the asteroid for comparison with ground-based observations. OSIRIS-REx launched on 08 September 2016 at 23:05 UT (7:05 p.m. EDT) and reached Bennu in December 2018. It mapped the asteroid and a sampling site, "Nightingale", in a crater in the northern hemisphere, has been selected. It will sample the site in October 2020, depart the asteroid in 2021, and return the sample to Earth in September 2023.

Spacecraft and Subsystems

The spacecraft is a roughly cubic shape, 2.72 meters high and 3.1 meters wide with two solar panel wings extending from opposite sides with an active collecting area of 8.5 square meters. Launch mass including propellant is 1529 kg. Power from the solar arrays is stored in lithium-ion batteries. Propulsion uses 200 N hydrazine thrusters mounted at the base of the spacecraft. Primary communication is via a 2 meter high gain directional dish antenna.

The sample collection will be achieved using the Touch and Go Sample Acquisition Mechanism (TAGSAM). TAGSAM consists of an articulated arm with a sampler head. The sampler head uses a jet of nitrogen gas to fluidize the regolith and force it into a collection area, while a set of surface contact pads collects material directly from the top surface layer. In addition to the sampling mechanism, the scientific payload comprises five investigations: the OSIRIS-REx Camera Suite (OCAMS); OSIRIS-REx Laser Altimetry (OLA); OSIRIS-REx Visible and IR SPectrometer (OVIRS); OSIRIS-REx Thermal Emission Spectrometer (OTES); and Spacecraft Telecom for mass and gravity.

Mission Profile

OSIRIS-REx launched on 08 September 2016 at 23:05 UT on an Atlas 5 in the 411 configuration with a 4-meter fairing from Cape Canaveral Air Force Station in Florida. It made an Earth flyby on 22 September 2017 at 16:52 UT (12:52 p.m. EDT) within 17,237 km. After a two year cruise, OSIRIS-REx made a series of five approach maneuvers to Bennu starting on 1 October 2018. It reached the asteroid on 3 December and began its preliminary survey. This involves a series of flybys within about 7 km of the surface every 48 hours to refine gravity measurements. The preliminary phase was followed by the first insertion, on 31 December 2018, into a 1.75 km orbit. This was followed by global mapping of the surface, a second orbit, site reconnaissance, evaluation, and site selection. The selected site, designated "Nightingale", is in a crater in the northern hemisphere.

A "checkpoint rehearsal", a test run at sampling, was held on 14 April 2020, in which the spacecraft drifted down to within 65 meters of the surface and then moved back up to its nominal 1 km circular orbit. The "matchpoint rehearsal" on August 11 will involve a close approach of 40 m. The "touch and go" sample collection is scheduled for 20 October 2020. The spacecraft will approach the surface at about 10 cm/sec. The sampling arm will allow the sampler head to contact the surface for about 5 seconds, during which time a jet of nitrogen gas will fluidize the surface and drive particles into the collection chamber. Contact pads will pick up material from the immediate surface. A successful collection will be confirmed by change in the spacecraft inertia and imaging the sample pads. The sampler head with samples will then be stored in a return capsule (based on the Stardust sample return capsule). The return cruise will begin in March 2021, with the sample return capsule separating from the main spacecraft on 24 September 2023 and re-entering Earth's atmosphere four hours later. It will be slowed by a heat shield and then a parachute and land at the Utah Test and Training Range.

The target of the OSIRIS-REx mission, near-Earth asteroid 101955 Bennu (originally 1999 RQ36), is a primitive B-type carbonaceous asteroid. It is roughly 492 m in diameter and has an orbital period of 436.6 days. Every six years its orbit brings it relatively close to Earth.

Alternate Names

  • Origins Spectral Interpretation Resource Identification Security - Regolith Explorer (OSIRIS-REx)
  • 41757

Facts in Brief

Launch Date: 2016-09-08
Launch Vehicle: Atlas V
Launch Site: Cape Canaveral, United States
Mass: 1528 kg

Funding Agency

  • National Aeronautics and Space Administration (United States)


  • Planetary Science

Additional Information

Questions and comments about this spacecraft can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail
Dr. Dante LaurettaMission Principal InvestigatorUniversity of
Dr. Ed BeshoreDeputy Mission Principal InvestigatorUniversity of
Dr. Jason DworkinProject ScientistNASA Goddard Space Flight
Dr. Joseph A. Nuth, IIIDeputy Project ScientistNASA Goddard Space Flight
Dr. Robert JenkinsProject ManagerNASA Goddard Space Flight

Selected References

  • Beshore, Edward, et al., The OSIRIS-REx Asteroid Sample Return Mission, 2015 IEEE Aerospace Conference, 7-14 March 2015
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