The last time OSIRIS-REx was this close to Earth it was flying through the humid skies above Florida on its way to space.
On Friday, the spacecraft will pass about 10,711 miles above Earth. That’s far, but not quite as far you might think.
Sure, it’s much higher than the International Space Station – which orbits at about 240 miles. But it’s much lower than some satellites. Especially, weather satellites. Take the GOES-16. Anyone following this year’s crazy Hurricane season has seen the stunning images from space. GOES-16 is locked in a geostationary orbit 22,300 miles above Earth.
The mission’s flight dynamics team is keeping a close eye on OSIRIS-REx and the satellites around the area where it will fly through. A course correction is ready to be keyed up if there are any issues.
Why come back towards Earth? As Matthew McConaughey says, it’s gravity. Specifically, a gravity assist. By flying close towards Earth, and missing, OSIRIS-REx will be flung towards its target destination, the asteroid Bennu.
Gravity assist maneuvers give mission controllers the trajectory they need without burning precious fuel.
“The Earth Gravity Assist is a clever way to move the spacecraft onto Bennu’s orbital plane using Earth’s own gravity instead of expending fuel,” says Dante Lauretta, the mission’s principal investigator.
And that’s even more vital for a mission like OSIRIS-REx.
See, OSIRIS-REx isn’t just going to the asteroid Bennu. It’s also coming back to Earth. Late next year, the spacecraft will reach Bennu. The first phase of the mission is all about getting a feel for the asteroid. OSIRIS-REx will survey the asteroid and nail down a final landing spot to grab a sample. This 500-meter diameter chunk of space rock will be the smallest object a NASA mission has ever orbited.
In mid 2020, OSIRIS-REx will head towards the surface and grab a piece of Bennu to bring back to Earth. A device called TAGSAM will touch the surface of the asteroid. High-pressure nitrogen gas is blown at the surface to stir up the asteroid’s soil and collect the sample. All in five seconds.
OSIRIS-REx will hang out around Bennu until departure in March 2021. Two years later, OSIRIS-REx will release the sample return capsule towards Earth. This capsule will slam into Earth’s atmosphere at more than 27,000 miles per hour. At about 2 miles above the Utah Test and Training Range, the capsule’s parachutes will deploy and bring the sample to a nice, soft landing on solid ground.
The OSIRIS-REx team will grab the sample and prepare to ship it off to a special facility at Johnson Space Center in Houston, Texas. Portions of the sample will be given to NASA’s mission partners, the Japanese and Canadian space agencies. Another portion will be stored at a secure location in New Mexico as a ‘just in case’ scenario. After about six months of study, NASA will give researchers across the world a chance to study parts of the sample.
Three-quarters of the sample will also be set aside for future generation of scientists to study. Who will be armed with even more sophisticated technology to tease every possible piece of info out of the sample.