OSIRIS-REx spacecraft.png
Artist's rendering of the OSIRIS-REx spacecraft
NamesOrigins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer
Mission typeAsteroid sample return[1]
Mission durationPlanned: 7 years
               505 days at asteroid
Elapsed: 3 years, 6 days
               286 days at asteroid
Spacecraft properties
ManufacturerLockheed Martin
Launch mass2,110 kg (4,650 lb)[2]
Dry mass880 kg (1,940 lb)[2]
Dimensions2.44 × 2.44 × 3.15 m (8 × 8 × 10.33 ft)[2]
Power1,226 to 3,000 W[2]
Start of mission
Launch date8 September 2016, 23:05 (2016-09-08UTC23:05) UTC[3]
RocketAtlas V 411, AV-067[3]
Launch siteCape Canaveral SLC-41
ContractorUnited Launch Alliance
End of mission
Landing datePlanned: 24 September 2023, 15:00 (2023-09-24UTC16) UTC[4]
Landing siteUtah Test and Training Range[4]
Flyby of Earth
Closest approach22 September 2017[2]
Bennu orbiter
Orbital insertion31 December 2018[5]
(Rendezvous: 3 December 2018)
Orbital departure3 March 2021 (planned)[2]
Sample mass0.1–2.0 kg (0.13–4.4 lb)[4]
OSIRIS-REx mission logo (circa 2015).png
← Juno

The OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) is a NASA asteroid study and sample-return mission.[6] The mission's main goal is to obtain a sample of at least 60 grams (2.1 oz) from 101955 Bennu, a carbonaceous near-Earth asteroid, and return the sample to Earth for a detailed analysis. The material returned is expected to enable scientists to learn more about the formation and evolution of the Solar System, its initial stages of planet formation, and the source of organic compounds that led to the formation of life on Earth.[7] If successful, OSIRIS-REx will be the first U.S. spacecraft to return samples from an asteroid. The Lidar instrument used aboard the OSIRIS-REx was built by Lockheed Martin, in conjunction with the Canadian Space Agency.[8][9]

OSIRIS-REx was launched on 8 September 2016, flew past Earth on 22 September 2017, and reached the proximity of Bennu on 3 December 2018,[10] where it began analyzing its surface for a target sample area over the next several months. It is expected to return with its sample to Earth on 24 September 2023.[11]

The cost of the mission is approximately US$800 million[12] not including the Atlas V launch vehicle, which is about US$183.5 million.[13] It is the third planetary science mission selected in the New Frontiers program, after Juno and New Horizons. The principal investigator is Dante Lauretta from the University of Arizona.


Asteroid Bennu, imaged by the OSIRIS-REx probe
(3 December 2018)

Overall management, engineering and navigation for the mission is provided by NASA's Goddard Space Flight Center, while the University of Arizona's Lunar and Planetary Laboratory provides principal science operations and Lockheed Martin Space Systems built the spacecraft and provides mission operations.[2] The science team includes members from the United States, Canada, France, Germany, United Kingdom, and Italy.[14]

After traveling for approximately two years, the spacecraft rendezvoused with asteroid 101955 Bennu in December 2018[15] and began 505 days of surface mapping at a distance of approximately 5 km (3.1 mi).[1] Results of that mapping will be used by the mission team to select the site from which to take a sample of the asteroid's surface.[16] Then a close approach (without landing) will be attempted to allow extension of a robotic arm to gather the sample.[17]

An asteroid was chosen as the target of study because an asteroid is a 'time capsule' from the birth of our Solar System.[18] In particular, 101955 Bennu was selected because of the availability of pristine carbonaceous material, a key element in organic molecules necessary for life as well as representative of matter from before the formation of Earth. Organic molecules, such as amino acids, have previously been found in meteorite and comet samples, indicating that some ingredients necessary for life can be naturally synthesized in outer space.[1]

OSIRIS-REx mission overview video

Following collection of material (from 60 grams to two kilograms), the sample will be returned to Earth in a 46-kilogram (101 lb) capsule similar to that which returned the samples of comet 81P/Wild on the Stardust spacecraft. The return trip to Earth will be shorter and the capsule will land with a parachute at the Utah Test and Training Range in September 2023 before being transported to the Johnson Space Center for processing in a dedicated research facility.[1]


OSIRIS-REx launch video
Animation of OSIRIS-REx's trajectory from 9 September 2016 to 3 December 2018
  OSIRIS-REx ·   101955 Bennu ·   Earth
Animation of OSIRIS-REx's trajectory around 101955 Bennu from 26 December 2018 to 20 March 2021
  OSIRIS-REx ·   101955 Bennu

The launch was on 8 September 2016 at 23:05 UTC on a United Launch Alliance Atlas V 411 from Cape Canaveral Space Launch Complex 41.[3] The 411 rocket configuration consists of a RD-180 powered first stage with a single AJ-60A solid fuel booster, and a Centaur upper stage.[19] OSIRIS-REx separated from the launch vehicle 55 minutes after ignition.[2] The launch was declared "exactly perfect" by the mission's Principal Investigator, with no anomalies worked before or during launch.[20]


OSIRIS-REx entered the cruise phase shortly after separation from the launch vehicle, following successful solar panel deployment, propulsion system initiation, and establishment of a communication link with Earth.[20] Its hyperbolic escape speed from Earth was about 5.41 km/s (3.36 mi/s).[21] On 28 December 2016, the spacecraft successfully performed its first deep space maneuver to change its velocity by 431 m/s (1,550 km/h; 960 mph) using 354 kg (780 lb) of fuel.[22][23] An additional, smaller firing of its thrusters on 18 January further refined its course for an Earth gravity assist on 22 September 2017.[22] The cruise phase lasted until its encounter with Bennu in December 2018,[15] after which it entered its science and sample collection phase.[22]

During its cruise phase, OSIRIS-REx was used to search for a class of near-Earth objects known as Earth-Trojan asteroids as it passed through Sun–Earth L4 Lagrange point. Between 9 and 20 February 2017, the OSIRIS-REx team used the spacecraft's MapCam camera to search for the objects, taking about 135 survey images each day for processing by scientists at the University of Arizona. The search was beneficial even though no new trojans were found,[24] as it closely resembled the operation required as the spacecraft approached Bennu, searching for natural satellites and other potential hazards.[23][25]

On 12 February 2017, while 673 million km (418 million mi) from Jupiter, the PolyCam instrument aboard OSIRIS-REx successfully imaged the giant planet and three of its moons, Callisto, Io, and Ganymede.[26]

OSIRIS-REx flew by Earth on 22 September 2017.

Arrival and survey

On 3 December 2018, NASA affirmed that OSIRIS-REx had matched the speed and orbit of Bennu at a distance of about 19 kilometers (12 mi), effectively reaching the asteroid. OSIRIS-REx performed closer passes of the Bennu surface, initially at about 6.5 km (4.0 mi) through December to further refine the shape and orbit of Bennu. Preliminary spectroscopic surveys of the asteroid's surface by OSIRIS-REx spacecraft, detected the presence of hydrated minerals in the form of clay. While researchers suspect that Bennu was too small to host water, the hydroxyl groups may have come from water presence in its parent body before Bennu split off.[27][28]

OSIRIS-REx entered orbit around Bennu on 31 December 2018 at about 1.75 km (1.09 mi) to start its extensive remote mapping and sensing campaign for the selection of a sample site. This is the closest distance that any spacecraft has orbited a celestial object, surpassing the Rosetta's orbit of comet 67P/Churyumov–Gerasimenko at 7 km (4.3 mi).[10][29] At this altitude, it takes the spacecraft 62 hours per orbit.[30] At the end of this detailed survey, the spacecraft will enter a closer orbit with a radius of 1 km (0.62 mi).[31]

Sample acquisition

Artist's concept of TAGSAM instrument in operation

Rehearsals will be performed before the sampling event, during which the solar arrays will be raised into a Y-shaped configuration to minimize the chance of dust accumulation during contact and provide more ground clearance in case the spacecraft tips over (up to 45°) during contact.[14] The descent will be very slow to minimize thruster firings prior to contact in order to reduce the likelihood of asteroid surface contamination by unreacted hydrazine propellant. Contact with the surface of Bennu will be detected using accelerometers, and the impact force will be dissipated by a spring in the TAGSAM arm.

Upon surface contact by the TAGSAM instrument, a burst of nitrogen gas will be released, which will blow regolith particles smaller than 2 cm (0.8 in) into the sampler head at the end of the robotic arm. A five-second timer will limit collection time to mitigate the chance of a collision. After the timer expires, the back-away maneuver will initiate a safe departure from the asteroid.[14]

OSIRIS-REx will then halt the drift away from the asteroid in case it is necessary to return for another sampling attempt. The spacecraft will use images and spinning maneuvers to verify the sample has been acquired as well as determine its mass and verify it is in excess of the required 60 grams (2.1 oz).[14] In the event of a failed sampling attempt, the spacecraft will return for another try. There is enough nitrogen gas for three attempts.[2]

In addition to the bulk sampling mechanism, contact pads on the end of the sampling head will passively collect dust grains smaller than 1 mm, upon contact with the asteroid. These pads are made from tiny loops of stainless steel.[32]

After the sampling attempt, the Sample-Return Capsule (SRC) lid will be opened to allow the sampler head to be stowed. The arm will then be retracted into its launch configuration, and the SRC lid will be closed and latched preparing to return to Earth.[33]


On 24 September 2023 the OSIRIS-REx return capsule will re-enter Earth's atmosphere and land under a parachute at the Air Force's Utah Test and Training Range.[34] The sample will be curated at NASA's Astromaterials Research and Exploration Science Directorate (ARES) and at Japan's Extraterrestrial Sample Curation Center.[34][35] The sample material from the asteroid will be distributed to requesting organisations worldwide by ARES.[36]

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