A 1,614-foot asteroid has quietly been crossing Earth’s orbit around the sun every six years.
Discovered in 1999, the asteroid Bennu may hold clues to how life began on our planet. In the spirit of exploration, NASA sent a robotic spacecraft to collect a sample from its surface.
Nearly five years later, NASA’s Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) is on its way back to Earth after successfully collecting rocks and dust from the surface of the asteroid on Oct. 20, 2020.
Year 1: Launch And Earth Flyby
Designed and built by Lockheed Martin, NASA’s OSIRIS-REx began its journey to Bennu on Sept. 8, 2016. OSIRIS-REx’s science team is led by the University of Arizona and its mission management is handled by NASA’s Goddard Space Flight Center.
At first look, OSIRIS-REx may remind you of another space traveler, the MAVEN spacecraft. And you would be right. OSIRIS-REx draws many of its structures, subsystems and software from MAVEN and other famous spacecraft Lockheed Martin-built like Juno and Stardust – talk about a track record of reliability.
Following the launch, OSIRIS-REx orbited the sun for a year and made an Earth flyby in September 2017. The spacecraft increased its speed using Earth’s gravity and adjusted its course to catch up with Bennu.
Year 3: Come Cruise With Me
For the successful rendezvous, OSIRIS-REx’s path needed to slowly intersect with Bennu’s orbit around the sun. It’s similar to track, where runners from the inner and outermost lanes meet at the straightaways.
This phase of the journey is where the spacecraft surveyed Bennu for two years.
Why not sample Bennu right away?
- We wanted to study the surface thoroughly. This was the first time scientists saw it up close.
- By mapping Bennu, we found the perfect spot to take a sample.
- We also wanted to practice. The sample collection is a delicate maneuver, and we wanted to take time to practice our approach.
- We couldn’t leave whenever we want. It took time to realign with Earth and for our departure window to open.
Year 5: TAGing Asteroid Bennu
Then on Oct. 20, 2020, when most of the surveying was complete, OSIRIS-REx used a first-of-its-kind sample collection method to gather surface material. The sample was collected with a touch-and-go maneuver that happened at the speed of a slow walk.
The spacecraft didn’t land on the asteroid; only the collection head called TAGSAM (Touch and Go Sample Acquisition Mechanism), attached to a 10-foot long robotic arm, touched the surface for about 3-5 seconds.
"Our nation has explored the solar system and landed on multiple bodies, but this was the first time we have attempted to collect a sample of an asteroid. Even though Bennu has posed many challenges, the team made it look easy," said Lisa Callahan, vice president and general manager of Commercial Civil Space at Lockheed Martin. "Although there's more to do before we are fully successful, the TAG event went just as planned and I couldn't be prouder of the team."
The collected sample has been stowed safely in a return capsule, ready for the journey home. OSIRIS-REx officially departed to head back to Earth in May 2021.
Year 7: Utah, I'm Home!
On Sept. 24, 2023, after a 4.4-billion-mile round trip, the spacecraft will near Earth and eject the sample return capsule, sending it on a direct course to a specific location in the Utah desert. The spacecraft will perform a final maneuver that will divert it from Earth and send it far out into deep space.
The capsule, based on the successful Stardust comet mission, will reach a top speed of 27,700 mph as it reenters Earth’s atmosphere. This will be the second fastest man-made object to return to Earth after the Stardust capsule.
The heat shield, which will see temperatures up to 5,300 degrees Fahrenheit, will head off most of the velocity. Then, at supersonic speeds, a parachute will deploy and ultimately bring the capsule to a soft landing.
After a seven-year journey to Bennu and back, mission scientists will open the capsule at NASA’s Johnson Space Center in Houston and begin to study the sample material in hopes of better understanding the building blocks of our solar system.