There and Back Again: How OSIRIS-REx is Returning an Asteroid Sample to Earth
A 1,614-foot asteroid has quietly been crossing Earth’s orbit around the sun every six years, and it’s now expecting a visitor.
Discovered in 1999, the asteroid Bennu may hold clues to how life began on our planet. And, in the spirit of exploration, NASA is sending a robotic spacecraft to collect a sample from this asteroid’s surface.
Follow along with this seven-year journey, cruising through space to Bennu and back.
YEAR 1: LAUNCH AND EARTH FLYBY
Led by the University of Arizona, NASA’s OSIRIS-REx, which stands for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, is beginning its journey to Bennu this September from Cape Canaveral, Florida.
Designed and built by Lockheed Martin, the spacecraft is set to launch Sept. 8, on a United Launch Alliance Atlas V 411 rocket. Mark your calendars.
“Along with the key scientific findings, with this mission, we’ll obtain data associated with how to operate a spacecraft around a planetary body the size of Bennu,” said Richard Kuhns, Lockheed Martin OSIRIS-REx program manager. “With Bennu’s low gravity, we’ll gain a clearer understanding of how to navigate a spacecraft in this type of environment – something that no one has done before.”
At first look, OSIRIS-REx may remind you of a recent 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 launch, OSIRIS-REx will orbit the sun for a year before coming back and making an Earth flyby in September 2017. Using Earth’s gravity, the spacecraft will sling shot to increase its speed and adjust course to catch up with Bennu.
YEAR 3: COME CRUISE WITH ME
Even though Bennu is a near-Earth asteroid, meaning it’s not in the asteroid belt, the spacecraft will need to cruise in deep space for two years, traveling 509 million miles to reach its destination.
For a successful rendezvous, OSIRIS-REx’s path will 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 begins to survey Bennu for two years.
Why not sample Bennu right away?
- This will be the first time scientists will see it up close. We’ll take images and thoroughly study the surface.
- To find the right type of sample. By mapping Bennu we’ll find the perfect spot to take a sample.
- We want to practice. The sample collection is a delicate maneuver and we want to take time to practice our approach.
- Because we can’t leave whenever we want. It takes time to realign with Earth and our departure window to open.
Then in July 2020, when most of the surveying is complete, OSIRIS-REx will use a first-of-its-kind sample collection method and hardware to gather surface material. The sample is collected with a touch-and-go maneuver that happens about the speed of a slow walk.
"The spacecraft doesn’t land on the asteroid; only the collection head called TAGSAM... touches the surface for about 3-5 seconds."
The spacecraft doesn’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, touches the surface for about 3-5 seconds.
“The work of implementing the sample capture is done from our mission support area in Denver, Colorado, where Juno and MAVEN are operated today,” Kuhns explained. “We’ll take the input from our navigators and science team to develop the right set of steps to get to Bennu’s surface and take the sample.”
The collected sample will be stowed safely in a return capsule for the journey home. A while later, when the time is right, OSIRIS-REx departs for Earth in March 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 a 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 off 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 scrub 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.
“By asking a fundamental science question, we’re driving innovation across a broader spectrum of technologies and activities,” said Kuhns.