This artist's concept shows the Origins Spectral Interpretation Resource Identification Security - Regolith Explorer (OSIRIS-REx) spacecraft contacting the asteroid Bennu with the Touch-And-Go Sample Arm Mechanism or TAGSAM. Image Credit: NASA's Goddard Space Flight Center

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Dec. 10, 2018: Recently analyzed data from NASA’s OSIRIS-REx mission has revealed water locked inside the clays that make up its scientific target, the asteroid Bennu.

Animated GIF of asteroid growing larger
This mosaic image of asteroid Bennu is composed of 12 PolyCam images collected on Dec. 2 by the OSIRIS-REx spacecraft from a range of 15 miles (24 km). Credit: NASA/Goddard/University of Arizona

During the mission’s approach phase, between mid-August and early December, the spacecraft traveled 1.4 million miles (2.2 million km) on its journey from Earth to arrive at a location 12 miles (19 km) from Bennu on Dec. 3. During this time, the science team on Earth aimed three of the spacecraft’s instruments towards Bennu and began making the mission’s first scientific observations of the asteroid. OSIRIS-REx is NASA’s first asteroid sample return mission.

Data obtained from the spacecraft’s two spectrometers, the OSIRIS-REx Visible and Infrared Spectrometer (OVIRS) and the OSIRIS-REx Thermal Emission Spectrometer (OTES), reveal the presence of molecules that contain oxygen and hydrogen atoms bonded together, known as “hydroxyls.” The team suspects that these hydroxyl groups exist globally across the asteroid in water-bearing clay minerals, meaning that at some point, Bennu’s rocky material interacted with water. While Bennu itself is too small to have ever hosted liquid water, the finding does indicate that liquid water was present at some time on Bennu’s parent body, a much larger asteroid.

Mission Elapsed Time
Launch Date Sept. 8, 2016 | 23:05 UT
Launch Site Cape Canaveral, Florida, USA
Destination Asteroids, 101955 Bennu
Type Orbiter, Sample Return
Status In Progress
Nation United States
Alternate Names Origins Spectral Interpretation Resource Identification Security-Regolith Explorer (OSIRIS-REx), 41757, 2016-055A


Travel to a near-Earth asteroid Bennu (formerly 1999 RQ36), and bring at least a 2.1-ounce sample back to Earth for study. The mission will help scientists investigate how planets formed and how life began, as well as improve our understanding of asteroids that could impact Earth.


This spacecraft arrived at asteroid Bennu on Dec. 3, 2018.

Key Dates

Sept. 8, 2016 | 23:05 UT: Launch

Sept. 22, 2017 at 16:52 UT: Earth Flyby

Dec. 3, 2018: Asteroid Bennu Arrival

Sept. 24, 2023: Sample Return to Earth


Launch Vehicle: Atlas V

Spacecraft Mass: 3,369 pounds (1,528 kilograms)

Spacecraft Instruments:

  1. The OCAMS Instrument Suite:

    1. MapCam

    2. PolyCam

    3. SamCam

  2. OLA

  3. OTES

  4. OVIRS

  5. REXIS


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