OSIRIS-REx

OSIRIS-REx

Illustration of OSIRIS-REx collecting a sample from asteroid Bennu.
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 ≈3 m (9.8 ft) cube[4]
Power Solar arrays
Start of mission
Launch date 8 September 2016 (planned)[5]
Rocket Atlas V 411[6]
Launch site Cape Canaveral SLC-41
Contractor United Launch Alliance
End of mission
Landing date September 2023[7]
Landing site Utah Test and Training Range
Orbital parameters
Reference system Heliocentric
(101955) Bennu lander
Landing date September 2019
Return launch March 2021
Sample mass up to 2 kg (4.4 lb)

New Frontiers program
← Juno New Frontiers 4 →

The Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) is a planned NASA asteroid study and sample return mission.[8] The launch is planned for 8 September 2016, and it will study and return a sample of asteroid 101955 Bennu (formerly designated 1999 RQ36), a carbonaceous asteroid, to Earth in 2023 for detailed analyses. 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.[9]

The cost of the mission will be approximately USD $800 million[10] not including the launch vehicle, which is about $183.5 million.[5] Lockheed Martin has completed assembly and testing of the spacecraft. 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.

Mission

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] The science team includes members from the United States, Canada, France, Germany, Great Britain, and Italy.[11]

After traveling for approximately two years, the spacecraft will rendezvous with asteroid 101955 Bennu (1999 RQ36) in 2018, 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.[12]

An asteroid was chosen as the target of study because an asteroid is 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, 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]

Following collection (from 60 grams to 2 kilograms, or 2.1 oz to 4.4 lb) in September 2019, 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 September 2023. The capsule will then be transported to the Johnson Space Center for processing in a dedicated research facility.[1]

Osiris, the Egyptian underworld lord of the dead

The acronym OSIRIS was chosen in reference to the ancient Egyptian mythological god Osiris, the underworld lord of the dead. He was classically depicted as a green-skinned man with a pharaoh's beard, partially mummy-wrapped at the legs and wearing a distinctive crown with two large ostrich feathers at either side. Rex means 'king' in Latin.[13] His name was chosen for this mission as asteroid Bennu is a threatening Earth impactor capable of causing vast destruction and death.[14][13]

Launch

Launch is planned for 8 September 2016 on a United Launch Alliance Atlas V 411.[6] Interested persons were able to have their names[15] or artwork on the mission's spirit of exploration saved on a microchip to be carried in the spacecraft.[16] Submitted works of art will be saved on a chip on the spacecraft.

Sample acquisition

Solar arrays raised into a "Y-wing" configuration prior to arm contact

After an extensive remote sensing campaign, a sample site will be chosen and rehearsals will be performed leading up to the final sampling event. The solar arrays will be raised into a "Y-wing" configuration to minimize the chance of dust accumulation during contact, as well as provide more ground clearance in the case the spacecraft tips over (up to 45°) during contact.[11] The descent will be very slow in order to mitigate unnecessary thruster firings prior to contact, thus reducing the likelihood of surface contamination from unreacted hydrazine propellant. The spacecraft will descend to about 5 m (16 ft) from the surface and upon contact by its arm, a timer begins to allow for up to 5 seconds of collection before the back-away maneuver initiates to safely depart the asteroid.[11] The spacecraft will then halt the drift away from the asteroid in case it is necessary to go back for a second sample attempt. The spacecraft will use several images and maneuvers to verify the sample has been acquired as well as determine its mass within ±90 grams.[11]

Finally, the Sample Return Capsule (SRC) lid is opened to allow the sampler head to move into position. The arm is then retracted into the launch configuration and the SRC lid is closed and latched for Earth return.

Science objectives

Based on current knowledge of its trajectory, Bennu has an estimated chance of about 0.07% of striking Earth in the late 2100s. Measurement of Bennu's mass and Yarkovsky acceleration would help clarify this.[17]

The science objectives of the mission are:[18]

  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.

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).[19] 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.[20] 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. Knowing Bennu's physical properties will be critical for future scientists to know when developing an asteroid impact avoidance mission.[21]

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

Specifications

Payload

In addition to its telecommunication equipment, the spacecraft will carry a suite of instruments which will study the asteroid in many wavelengths,[23] as well as image the asteroid, and retrieve a physical sample to return to Earth.

OCAMS

The OSIRIS-REx Camera Suite (OCAMS) consists of the PolyCam, the MapCam, and the SamCam.[24] Together they acquire information on asteroid Bennu by providing global mapping, sample site reconnaissance and characterization, high-resolution imaging, and records of the sample acquisition.[25]

  • PolyCam, an 8-inch telescope, acquires images with increasingly higher resolution as the spacecraft approaches the asteroid.
  • MapCam searches for satellites and outgassing plumes. It maps the asteroid in 4 different colors, informs our model of asteroid shape and provides high resolution imaging of the sample-site.
  • SamCam continuously documents the sample acquisitions.

OLA

The OSIRIS-REx Laser Altimeter (OLA) is a scanning and LIDAR instrument that will provide high resolution topographical information throughout the entire mission.[26] The information received by OLA will create global topographic maps of Bennu, local maps of candidate sample sites, ranging in support of other instruments, and support navigation and gravity analyses.

OLA will scan the surface of Bennu at specific intervals in the mission to rapidly map out the entire surface of the asteroid to achieve its primary objective of producing local and global topographic maps. What OLA brings back about Bennu will also be used to develop a control network relative to the center of mass of the asteroid and enhance and refine gravitational studies of Bennu.

OLA has a single common receiver and two complementary transmitter assemblies which enhance the resolution of the information brought back. OLA’s high-energy laser transmitter is used for ranging and mapping from 1 to 7.5 km. The low-energy transmitter is used for ranging and imaging at smaller distances (500 m to 1 km). The repetition rate of these transmitters sets the data acquisition rate of OLA. Laser pulses from both the low and high energy transmitters are directed onto a movable scanning mirror, which is co-aligned with the field of view of the receiver telescope limiting the effects of background solar radiation. Each pulse provides target range, azimuth, elevation, received intensity and a time-tag.

OLA is funded by the Canadian Space Agency (CSA) and is being built by MacDonald, Dettwiler and Associates at Brampton, Ontario, Canada.[27] OLA was delivered for integration with the spacecraft on November 17, 2015.[28][29]

OVIRS

The OSIRIS-REx Visible and IR Spectrometer (OVIRS) is a spectrometer, which measures light to provide mineral and organic spectral maps and local spectral information of candidate sample sites.[30] It also provides full-disc asteroid spectral data, global spectral maps (20 m resolution), and spectra of the sample site (0.08–2 m resolution). These data will be used in concert with OTES spectra to guide sample-site selection. These spectral ranges and resolving powers are sufficient to provide surface maps of mineralogical and molecular components including carbonates, silicates, sulfates, oxides, adsorbed water and a wide range of organic compounds. It provides at least two spectral samples per resolution element taking full advantage of the spectral resolution.

OTES

The OSIRIS-REx Thermal Emission Spectrometer (OTES) provides mineral and thermal emission spectral maps and local spectral information of candidate sample sites by collecting thermal infrared data from 4 - 50 µm.[31]

OTES provides full-disc Bennu spectral data, global spectral maps, and local sample site spectral information used to characterize the global, region, and local mineralogic composition and thermal emission from the asteroid surface. The wavelength range, spectral resolution, and radiometric performance are sufficient to resolve and identify the key vibrational absorption features of silicate, carbonate, sulfate, phosphate, oxide, and hydroxide minerals. OTES is also used to measure the total thermal emission from Bennu, which drives the requirement to measure emitted radiation globally. Based on the performance of Mini-TES in the dusty surface environment of Mars, OTES is resilient to extreme dust contamination on the optical elements.

REXIS

The Regolith X-ray Imaging Spectrometer (REXIS) will provide an X-ray spectroscopy map of Bennu, complementing core OSIRIS-REx mission science.[32] REXIS is a collaborative development by four groups within Massachusetts Institute of Technology (MIT) and Harvard University, with the potential to involve more than 100 students throughout the process. REXIS is based on flight heritage hardware, thereby minimizing elements of technical risk, schedule risk, and cost risk.

REXIS is a coded aperture soft X-ray (0.3–7.5 keV) telescope that images X-ray fluorescence line emission produced by the interaction of solar X-rays and the solar wind with the regolith of Bennu. Images are formed with 21 arcminute resolution (4.3 m spatial resolution at a distance of 700 m). Imaging is achieved by correlating the detected X-ray image with a 64 x 64 element random mask (1.536 mm pixels). REXIS will store each X-ray event data in order to maximize the data storage usage and to minimize the risk. The pixels will be addressed in 64 x 64 bins and the 0.3–7.5 keV range will be covered by 5 broad bands and 11 narrow line bands. A 24 s resolution time tag will be interleaved with the event data to account for Bennu rotation. Images will be reconstructed on the ground after downlink of the event list. Images are formed simultaneously in 16 energy bands centered on the dominant lines of abundant surface elements from O-K (0.5 keV) to Fe-Kß (7 keV) as well the representative continuum. During orbital phase 5B, a 21-day orbit 700 m from the surface of Bennu, a total of at least 133 events/asteroid pixel/energy band are expected under 2 keV; enough to obtain significant constraints on element abundances at scales larger than 10 m.

TAGSAM

The sample return system, called Touch-And-Go Sample Acquisition Mechanism (TAGSAM), consists of a sampler head with an articulated arm.[33] An on-board nitrogen source will support up to three separate sampling attempts for a minimum total amount of 60 g of sample. The surface contact pads will also collect fine-grained material.

Highlights of the TAGSAM instrument and technique include:

OSIRIS-REx II

OSIRIS-REx II is a proposed mission concept by NASA that, if funded, would make it a double mission collecting samples from the two Moons of Mars for return to the Earth. Mission planners stated that this mission would be both the fastest and least expensive way to obtain soil samples from the moons.[35]

Gallery

  1. ^ Brown, Dwayne; Neal-Jones, Nancy (January 15, 2014). "NASA RELEASE 14-017 - NASA Invites Public to Send Names on an Asteroid Mission and Beyond". NASA. Retrieved January 16, 2014. 

See also

References

  1. 1 2 3 4 "NASA To Launch New Science Mission To Asteroid In 2016". NASA.
  2. 1 2 "OSIRIS-REx Factsheet" (PDF). University of Arizona.
  3. ↑ "NASA Plans Asteroid Sample Return". Aviation Week.
  4. 1 2 OSIRIS-REx brochure.
  5. 1 2 Buck, Joshua; Diller, George (2013-08-05). "NASA Selects Launch Services Contract for OSIRIS-REx Mission". NASA. Retrieved 2013-09-08.
  6. 1 2 "NASA Selects United Launch Alliance Atlas V for Critical OSIRIS REx Asteroid Sample Return Mission". PRNewswire. 5 August 2013.
  7. ↑ NASA to Launch New Science Mission to Asteroid in 2016 (05.25.2011)| NASA
  8. ↑ Brown, Dwayne; Neal-Jones, Nancy (31 March 2015). "RELEASE 15-056 - NASA’s OSIRIS-REx Mission Passes Critical Milestone". NASA. Retrieved 4 April 2015.
  9. ↑ "OSIRIS-REx Mission Selected for Concept Development". Goddard Space Flight Center.
  10. ↑ "NASA Aims to Grab Asteroid Dust in 2020". Science Magazine. 26 May 2011.
  11. 1 2 3 4 Kramer, Herbert J. "OSIRIS-REx". Earth Observation Portal Directory. Retrieved 2015-04-20.
  12. ↑ "UA gets $1.2M to aid in asteroid mission". Tucson Citizen. 26 May 2011.
  13. 1 2 Wolchover, Natalie (27 May 2011). "NASAcronyms: How OSIRIS-REx Got Its Name". LiveScience. Retrieved 2015-05-12.
  14. ↑ Moskowitz, Clara (30 May 2011). "The OSIRIS REX: NASA Chooses Threatening Asteroid for New Mission". Space.com. Retrieved 2015-05-12.
  15. ↑ Travel to Bennu on the OSIRIS-REx spacecraft!
  16. ↑ "NASA Invites Public to Send Artwork to an Asteroid". NASA. February 19, 2016. Retrieved 2016-04-01.
  17. ↑ Milani, Andrea; Chesley, Steven R.; Sansaturio, Maria Eugenia; Bernardi, Fabrizio; et al. (2009). "Long term impact risk for (101955) 1999 RQ36". Icarus 203 (2): 460–471. arXiv:0901.3631. Bibcode:2009Icar..203..460M. doi:10.1016/j.icarus.2009.05.029.
  18. ↑ OSIRIS-Rex Infosheet (PDF)
  19. ↑ "Physical properties of OSIRIS-REx target asteroid (101955) 1999 RQ36. Derived from Herschel, VLT/ VISIR, and Spitzer observations.". December 2012.
  20. ↑ "Earth Impact Risk Summary for 101955 Bennu". Near Earth Object Program. NASA's JPL. 5 August 2010. Retrieved 2013-04-29.
  21. ↑ OSIRIS REx, The Mission.
  22. ↑ "Integration of the OSIRIS-REx Main Propellant Tank". dslauretta. 16 December 2014. Retrieved 2015-04-20.
  23. ↑ OSIRIS-Rex Instruments
  24. ↑ "The Instruments of OSIRIS-REx". The University of Arizona. Retrieved 2014-11-20.
  25. ↑ OCAMS – THE EYES OF OSIRIS-REX
  26. ↑ OLA
  27. ↑ "OLA, Canada's Contribution to OSIRIS-REx". Canadian Space Agency (CSA). 4 March 2013. Retrieved 2014-10-15.
  28. ↑ Canada Contributes to NASA’s OSIRIS-REx Mission. NASA News. 17 July 2014.
  29. ↑ Canada to Invest in Space Exploration with New Laser. "Kelowna Now". 17 November 2015.
  30. ↑ OVIRS
  31. ↑ OTES
  32. ↑ REXIS
  33. ↑ TAGSAM
  34. ↑ PI's Blog
  35. ↑ OSIRIS-REx II to Mars: Mars Sample Return from Phobos and Deimos. Elifritz, T. L. (2012)

External links

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