For the first time ever, a NASA probe has performed a sample-snagging operation on an asteroid in deep space.
The agency’s OSIRIS-REx spacecraft spiraled down to the surface of the near-Earth asteroid Bennu this afternoon (Oct. 20) to grab material that mission team members hope harbors clues about the solar system’s early days and the rise of life on Earth.
“We did it!” OSIRIS-REx principal investigator Dante Lauretta, of the University of Arizona, said during a webcast that provided updates about today’s maneuver. “We tagged the surface of the asteroid, and it’s up to Bennu now to see how the event went.”
The goal was to collect at least 60 grams (2.1 ounces) of dirt and gravel from Bennu’s rubbly surface. It could take up to 10 days to determine if OSIRIS-REx achieved this aim, mission team members have said. And it’s not a disaster if the asteroid haul turns out to be a little light; the probe can go back down for two more tries if need be.
Lauretta and his fellow OSIRIS-REx scientists and engineers watched over today’s asteroid sample-snatching attempt from a mission operations center at Lockheed Martin Space in Littleton, Colorado. (Lockheed Martin built the spacecraft for NASA.) And while the mood was certainly jubilant, the impact of the ongoing COVID-19 pandemic was clear.
For example, everyone wore facemasks and maintained appropriate social distancing for much of the event. While there were some hugs after news of OSIRIS-REx’s asteroid touchdown, they were few in NASA’s live webcast, with hand sanitizer clearly on hand after such celebrations.
“This is one of those moments where we’re all aware of COVID-19,” NASA astronomer Michelle Thaller of the Goddard Space Flight Center said in the webcast just after touchdown. “Because I want the hugs and the high fives and everything, but we’re all going to keep each other safe.”
The $800 million OSIRIS-REx mission launched in September 2016 and arrived at the 1,640-foot-wide (500 meters) Bennu in December 2018. The probe has been taking the asteroid’s measure ever since, mapping its surface in incredible detail to prepare for today’s maneuver.
That work has revealed a world far more rugged than the mission team had expected. House-sized boulders stud Bennu’s surface, limiting the available options for a safe sample grab. The team eventually homed in on a small crater called Nightingale as its top choice, because the site sports relatively fresh and fine-grained material that hasn’t been exposed to the harsh deep-space environment for long.
But Nightingale is surrounded by hazards, including a big outcrop the mission team nicknamed “Mt. Doom.” There are obstacles within the crater as well, so the spacecraft targeted a relatively flat, boulder-free area just 26 feet (8 m) wide — quite an ambitious goal, considering that OSIRIS-REx is the size of a 15-passenger van and the original mission plan envisioned a touchdown zone 165 feet (50 m) wide.
“So, for some perspective: The next time you park your car in front of your house or in front of a coffee shop and walk inside, think about the challenge of navigating OSIRIS-REx into one of these spots from 200 million miles away,” Mike Moreau, OSIRIS-REx deputy project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said during a news conference last month.
It currently takes more than 18 minutes for commands to travel from Earth to OSIRIS-REx, so Moreau and his colleagues cannot control the probe in real time. The craft therefore performed today’s operation autonomously.
Shortly before 2 p.m. EDT (1600 GMT) today, OSIRIS-REx fired its thrusters to get out of orbit around Bennu and head down toward the surface. At 6:12 p.m. EDT (2212 GMT), the probe “kissed” the asteroid for about 10 seconds with its sample-collecting mechanism, which is affixed to the end of OSIRIS-REx’s 11-foot-long (3.4 m) robotic arm.
During the brief touchdown, the spacecraft blasted Bennu’s surface with nitrogen gas. This stirred up dirt and rock that could then be collected by the arm’s sampling head, which mission team members have likened to an older car’s air filter.
We should expect OSIRIS-REx’s first images of the operation to start coming down to Earth tomorrow morning (Oct. 21), mission team members said.
The OSIRIS-REx team will spend the next week or so assessing how much asteroid material was collected. The probe’s handlers have expressed confidence that this first attempt will succeed; OSIRIS-REx’s sampler was designed to snag at least 150 grams (5.3 ounces) and could theoretically get up to 4 kilograms (8.8 lbs.) of material if everything went perfectly.
But if OSIRIS-REx is deemed to have come up short on collected material today, another attempt could be made, at a backup site known as Osprey, as soon as January 2021. A third try would be possible, too, if needed; the probe carries three bottles of surface-disturbing nitrogen gas.
Those are contingency plans, however. If things went according to plan today, OSIRIS-REx remains on course to depart Bennu in March 2021. The collected samples are scheduled to land here on Earth, encased in a special return capsule, in September 2023.
Scientists will then study the material in labs around the world, scrutinizing the stuff in far more detail than OSIRIS-REx, or any other single probe, could do on its own in deep space. Asteroids are building blocks left over from the planet-formation epoch, so such analyses could reveal key insights about our solar system’s very early days, NASA officials have said.
In addition, Bennu is rich in hydrated minerals and carbon-containing organic compounds. Asteroids like it may have helped Earth become habitable long ago, seeding our planet with the ingredients needed for life as we know it.
“And also, having the samples back here on Earth allows us to preserve them for future generations to come and allows for future explorers to analyze the samples using techniques and instruments that haven’t been invented, and to ask questions that we don’t even know to ask yet,” Lori Glaze, director of NASA’s Planetary Science Division, said during today’s webcast.
Getting these samples down to Earth is OSIRIS-REx’s top priority. But the mission also has other goals, as indicated by its full name — “Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer.”
For example, observations the probe has made while orbiting Bennu should help scientists better understand how asteroids move through space, NASA officials have said. This information could improve trajectory projections for potentially hazardous asteroids, a category that includes Bennu. (There’s a 1-in-2,700 chance that Bennu will hit Earth during a close approach in the late 2100s, researchers say.)
OSIRIS-REx’s sample won’t be the first pristine asteroid material brought down to Earth by a space mission. Japan’s Hayabusa probe returned some grains of the stony asteroid Itokawa in 2010, and its successor, Hayabusa2, recently grabbed pieces of the carbon-rich rock Ryugu. The material from Ryugu is scheduled to land on Earth this December.