|Nation||United States of America (USA)|
|Objective(s)||Asteroid Sample Return|
|Spacecraft Mass||4,650 pounds (2,110 kilograms)|
|Mission Design and Management||NASA GSFC / University of Arizona|
|Launch Vehicle||Atlas V 411 (no. AV-067)|
|Launch Date and Time||Sept. 8, 2016 / 23:05 UT|
|Launch Site||Cape Canaveral, Fla. / SLC-41|
- OSIRIS-REx is the first U.S. mission to collect a sample from an asteroid.
Sep 8, 2016: Launch
Sep 22, 2017: Earth flyby
Dec 3, 2018: Asteroid Bennu arrival
Oct. 20, 2020: OSIRIS-REx successfully collects a sample from Bennu
April 7, 2021: OSIRIS-REx completes its last flyover of Bennu
May 10, 2021: OSIRIS-REx began its journey back to Earth
Sep 24, 2023: Sample capsule expected to be delivered to Earth
In Depth: OSIRIS-REx
OSIRIS-REx is the third major planetary science mission for NASA’s New Frontiers Program (after New Horizons launched in 2006 and Juno launched in 2011).
OSIRIS-REx is an acronym for "Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer." The goal of the mission – collect a sample weighing at least 2.1 ounces (59.5 grams) from near-Earth asteroid 101955 Bennu (formerly known as 1999 RQ36) and then bring the sample to Earth.
The mission, developed by scientists at the University of Arizona, will give us more information about how the early solar system formed and about how life began. It will also help us better understand asteroids that could impact Earth in the future.
About 55 minutes after launch on Sept. 8, 2016, from Cape Canaveral, Florida, and after a boost by the Centaur upper stage, OSIRIS-REx separated from its Atlas V rocket and deployed its solar arrays.
At 17:30 UT Sept. 9, 2016, the spacecraft crossed the orbital path of the Moon at a range of about 240,200 miles (386,500 kilometers). Three days later, it was in orbit around the Sun. Beginning Sept. 19, 2016, the mission team activated all of its scientific instruments.
The spacecraft’s trajectory correction maneuver (TCM) thrusters were fired for 12 seconds for the first time on Oct. 7, 2016, for a course correction. The spacecraft also carries three other sets of thrusters—the attitude control system (ACS), the main engine (ME), and low thrust reaction engine assembly (LTR) thrusters—thus providing significant redundancy for maneuvers.
On Dec. 28, 2016, the spacecraft conducted its first deep-space maneuver (DSM-1), firing the main engine to position it properly for an Earth gravity-assist encounter in late 2017.
A second firing, the first to use the spacecraft’s attitude control system (ACS) thrusters, on Aug. 25, 2017, further sharpened its trajectory by changing the velocity by about 19 inches (47.9 centimeters) per second.
About a month later, on Sept. 22, 2017, OSIRIS-REx, passed Earth at a range of about 10,710 miles (17,237 kilometers) as part of a gravity-assist maneuver that tilted its orbit to match that of Bennu. During the encounter, the spacecraft took several high-resolution pictures of both Earth and the Moon.
The spacecraft got its first glimpse of Bennu in August 2018, sending back a grainy image taken at a distance of about 1.4 million miles (2.3 million kilometers). In early November 2018, OSIRIS-REx sent back detailed images showing the asteroid’s shape and some surface features.
After arriving at Bennu on Dec. 3, 2018, OSIRIS-REx mapped the asteroid in detail while the mission team searched for a safe sample collection site. One of the biggest challenges was that Bennu has an extremely rocky surface with hazardous boulders.
After a year, the mission team selected a sample site called “Nightingale” located in a northern crater 460 feet (140 meters) wide. The crater is thought to be relatively young, and the regolith, or rocks and dust, is freshly exposed. This means the site would likely allow for a pristine sample of the asteroid, giving the team insight into Bennu’s history.
On Oct. 20, 2020, OSIRIS-REx unfurled its robotic arm and, in a first for NASA, briefly touched down on asteroid Bennu to collect dust and pebbles from its surface in a maneuver known as “Touch-And-Go” or TAG.
Two days later, the mission team received images that confirmed the spacecraft had collected more than enough material to meet one of its main mission requirements – acquiring at least 2 ounces (60 grams) of Bennu’s surface material. On Oct. 28, 2020, the mission team sent commands to the spacecraft, instructing it to close the Sample Return Capsule – marking the end of one of the most challenging phases of the mission.
On April 7, 2021, OSIRIS-REx completed its last flyover of Bennu and started slowly drifting away from the asteroid. During the flyby, OSIRIS-REx imaged Bennu for 5.9 hours, covering more than a full rotation of the asteroid. It flew within 2.1 miles (3.5 kilometers) of Bennu's surface – the closest since the TAG sample collection event.
Images taken during the flyover revealed the aftermath of its historic encounter with the asteroid.
On May 10 at 4:23 p.m. EDT, the spacecraft fired its main engines at full throttle for seven minutes – its most significant maneuver since it arrived at Bennu in 2018. This burn thrust the spacecraft away from the asteroid at 600 miles per hour (nearly 1,000 kilometers per hour), setting it on a 2.5-year cruise toward Earth.
After orbiting the Sun twice, OSIRIS-REx is due to reach Earth on Sept. 24, 2023. Upon return, the capsule containing pieces of Bennu will separate from the rest of the spacecraft and enter Earth’s atmosphere. The capsule will parachute to the Utah Test and Training Range in Utah's West Desert, where scientists will be waiting to retrieve it.
“OSIRIS-REx’s many accomplishments demonstrated the daring and innovative way in which exploration unfolds in real-time,” said Thomas Zurbuchen, associate administrator for science at NASA Headquarters. “The team rose to the challenge, and now we have a primordial piece of our solar system headed back to Earth where many generations of researchers can unlock its secrets.”
After releasing the sample capsule, the main OSIRIS-REx spacecraft will have completed its primary mission. It will fire its engines to fly past Earth, putting it on a trajectory to circle the Sun inside of Venus’ orbit.
About six months after the sample capsule lands, NASA will distribute pieces of the sample to research groups around the world. A portion of the sample will also be stored at a secure location in New Mexico as a sort of insurance policy.
- NASA: OSIRIS-REx
- University of Arizona: OSIRIS-REx
- National Space Science Data Center Master Catalog: OSIRIS-REx
Siddiqi, Asif A. Beyond Earth: A Chronicle of Deep Space Exploration, 1958-2016. NASA History Program Office, 2018.