8419.- OSIRIS-REX

OSIRIS-REx

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OSIRIS-REx
Mission type	Asteroid sample return[1][2]
Operator	NASA
Website	asteroidmission.org
Mission duration	7 years 505 days at asteroid
Spacecraft properties
Manufacturer	Lockheed Martin
Launch mass	1,529 kg (3,371 lb)[3]
Dimensions	2 m (6.6 ft) cube
Power	Solar arrays
Start of mission
Launch date	September 2016 (planned)[4]
Rocket	Atlas V 411[5]
Launch site	Cape Canaveral SLC-41
Contractor	United Launch Alliance
End of mission
Landing date	2023[6]
Landing site	Utah Test and Training Range
Orbital parameters
Reference system	Heliocentric
(101955) Bennu orbiter
(101955) Bennu lander
Sample mass	up to 2 kg (4.4 lb)

OSIRIS-REx is a planned asteroid study and sample return mission. It is a planetary science mission, the third selected in the New Frontiers Program, after Juno and New Horizons. The mission is planned for a 2016 launch and will study and return a sample of asteroid 101955 Bennu (formerly designated 1999 RQ36), a carbonaceous asteroid, to Earth for detailed analyses in 2023. Material returned is expected to enable scientists to learn more about the time before the formation and evolution of the Solar System, initial stages of planet formation, and the source of organic compounds which led to the formation of life.^[7]

The cost of the mission will be approximately USD $800 million^[8] not including the launch vehicle, which is about $183.5 million.^[4]

OSIRIS-REx stands for Origins Spectral Interpretation Resource Identification Security Regolith Explorer

The mission, developed by the University of Arizona's Lunar and Planetary Laboratory, NASA Goddard Space Flight Center and Lockheed Martin Space Systems, is planned for launch in September 2016.^[2] After traveling for approximately two years, the spacecraft will rendezvous with asteroid 101955 Bennu (1999 RQ36), and begin 505 days of surface mapping at a distance of approximately 5 km (3.1 mi).^[1] Results of that study will be used by the mission team to select the sample site and the gradual process of approaching, but not landing, and ultimately extending a robotic arm to gather the sample.^[9]

An asteroid was chosen as the target of study because asteroids are a 'time capsule' from the birth of our Solar System. 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 have previously been found in meteorite and comet samples, indicating that some ingredients necessary for life can be created in space.^[1]

Following collection (from 60 grams to 2 kilograms, or 2.1 oz to 4.4 lb), the sample will be returned to Earth in a capsule similar to that which returned the samples of comet 81P/Wild on the Stardust spacecraft. The return trip to Earth will be shorter, allowing the sample to return and land at the Utah Test and Training Range in 2023. The capsule will then be transported to the Johnson Space Center for processing in a dedicated research facility.

Launch

Launch is planned for September of 2016. On August 5, 2013, NASA announced OSIRIS-REx would launch on an Atlas V 411. Interested persons are welcome to have their names inscribed on a microchip to be carried in the spacecraft. 

Science objectives

Samples will be returned to planet Earth

Telescopic observations have helped define the orbit of 101955 Bennu, a near-Earth object with a mean diameter in the range of 480 to 511 meters (1575 to 1678 ft).^[11] It completes an orbit of the Sun every 436.604 days (1.2 years). This orbit takes it close to the Earth every six years. Although the orbit is reasonably well known, scientists continue to refine it. It is critical to know the orbit of Bennu because recent calculations produced a cumulative probability of 1 in 1410 (or 0.071%) of impact with Earth in the period 2169 to 2199.^[12] Part of the OSIRIS-REx mission is to refine understanding of non-gravitational effects (such as the Yarkovsky effect) on this orbit, and the implications of those effects for Bennu's collision probability.

Telescopic observations have revealed some basic properties of 101955 Bennu. They indicate that 101955 Bennu is very dark and is classified as a B-type asteroid, a sub-type of the carbonaceous C-group asteroids. Such asteroids are considered "primitive", having undergone little geological change from their time of formation.

The science objectives of the mission are:^[13]

1.     Return and analyze a sample of pristine carbonaceous asteroid regolith in an amount sufficient to study the nature, history, and distribution of its constituent minerals and organic material.

2.     Map the global properties, chemistry, and mineralogy of a primitive carbonaceous asteroid to characterize its geologic and dynamic history and provide context for the returned samples.

3.     Document the texture, morphology, geochemistry, and spectral properties of the regolith at the sampling site in situ at scales down to millimeters.

4.     Measure the Yarkovsky effect (a thermal force on the object) on a potentially hazardous asteroid and constrain the asteroid properties that contribute to this effect.

5.     Characterize the integrated global properties of a primitive carbonaceous asteroid to allow for direct comparison with ground-based telescopic data of the entire asteroid population.