Asteroid Treasure: OSIRIS-REx returns with Bennu samples
After a seven-year, 3.86-billion-mile odyssey, NASA’s OSIRIS-REx mission successfully delivered to Earth samples from asteroid Bennu.
NASA’s first sample return mission to an asteroid, the agency said some 250 grams (about 8.8 ounces) are aboard the OSIRIS-REx return capsule — the most returned by a spacecraft from any destination other than the Moon.
The sample return capsule, released from the main OSIRIS-REx spacecraft earlier today at about 63,000 miles (101,000 kilometers) away from Earth, reentered the planet’s atmosphere at 10:42 a.m. EDT (14:42 UTC) Sept. 24, going 27,650 miles (44,500 kilometers) just off the coast of Northern California. Protected by a heat shield, the capsule made its way to the Utah Test and Training Range near Salt Lake City.
Once the capsule’s descent slowed enough, a parachute was opened for it to decelerate to a mere 11 miles (18 kilometers) per hour. It opened at about 20,000 feet (6,000 meters), rather than the expected 5,000 feet (1,500 meters). According to NASA, this was a decision made by the autonomous vehicle using data it was gathering during descent.
As such, touchdown occurred about three minutes earlier than predicted at about 10:52 a.m. EDT (14:52 UTC) in the Utah desert. Notably, recent rain softened the ground a bit, providing an additional cushion for the precious Bennu samples.
The capsule was retrieved within about 90 minutes and transported by helicopter to a nearby temporary cleanroom. There, the samples will be prepared for transport to NASA’s Johnson Space Center in Houston on Sept. 25.
From there, the Bennu samples will be stored and distributed to the OSIRIS-REx science team. According to NASA, up to a quarter will be distributed to 233 scientists on the mission team, representing 38 institutions globally. Some 4% will be given to the Canadian Space Agency and 0.5% will be sent to the Japan Aerospace Exploration Agency.
NASA said the other 70% will be preserved at Johnson Space Center and White Sands, New Mexico, for scientists outside of the mission team as well as for future generations of scientists.
According to NASA, samples from Bennu could help scientists understand how Earth came to have an abundance of organic molecules and liquid water. The agency said Bennu and similar asteroids may have helped deliver those ingredients via collisions billions of years ago.
Bennu, discovered in 1999, has a diameter of about 1,600 feet (490 meters). It is considered a rubble-pile, meaning it is essentially a bunch of rocks loosely packed and barely held together by gravity.
The asteroid is also considered a near Earth object and a potentially hazardous object, since its orbit intersects with Earth’s. NASA said it has a roughly one in 1,700 chance of hitting Earth sometime between 2178 and 2290. Its greatest risk is on Sept. 24, 2182.
The OSIRIS-REx mission launched atop an Atlas 5 rocket Sept. 8, 2016, from then Cape Canaveral Air Force Station. It arrived at Bennu Dec. 3, 2018, to begin orbital surveys.
On Oct. 20, 2020, the spacecraft made its way to the surface of Bennu. When it reached the surface, the 11-foot (3.3-meter) robotic arm briefly made contact with the asteroid. A burst of nitrogen gas was released to blow particles into the sampler head before the whole vehicle backed away.
Upon inspection in the coming days, it was found that the sample collected was overflowing from the container. The team was confident that more than the required 60 grams (2.1 ounces) were collected. While the exact amount is not yet known, teams have estimated that there should be at least 250 grams (8.8 ounces) of material.
The Bennu samples were stowed in the return capsule on Oct. 28, 2020, and the spacecraft left the asteroid May 10, 2021, to begin its journey back to Earth.
About 20 minutes after the sample return capsule was released from the OSIRIS-REx spacecraft, when it was still four hours away from Earth, the main spacecraft performed short thruster firing to allow the vehicle safely fly past Earth to begin a new mission — OSIRIS-APEX.
OSIRIS-REx is an acronym for “Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer.” The new mission name replaces “Regolith Explorer” with “Apophis Explorer” — APEX.
Apophis is about 1,210 feet (370 meters) in diameter. The asteroid, also a near Earth and potentially hazardous object, is expected to make a very close pass of Earth of about 20,000 miles (32,200 kilometers) on Friday, April 13, 2029.
The OSIRIS-APEX spacecraft will enter orbit soon after the closest approach and over about 18 months investigate how the Earth encounter affected the asteroid’s orbit, spin rate and surface.
Apophis was discovered in 2004 and made headlines later that year when early estimates suggested a 2.7% probability that it would hit Earth in 2029. Later observations eliminated that possibility, as well as a possibility for impact in 2036.
In fact, NASA’s Jet Propulsion Laboratory estimates Apophis has no chance of impacting Earth anytime in the next 100 years.
Video courtesy of NASA
Derek Richardson has a degree in mass media, with an emphasis in contemporary journalism, from Washburn University in Topeka, Kansas. While at Washburn, he was the managing editor of the student run newspaper, the Washburn Review. He also has a website about human spaceflight called Orbital Velocity. You can find him on twitter @TheSpaceWriter.