NASA’s Osiris-Rex spacecraft successfully scooped up rocky space dust from the asteroid Bennu on Friday. But in a sense, it completed its task too well: Scientists quickly realized that the spacecraft’s sample-collecting arm had gathered so much material that its valves wouldn’t close. That was leading the dust to leak back into space.
“Time is of the essence,” Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA, said.
So this week, the mission team instructed Osiris-Rex to store its sample inside the designated return capsule ahead of schedule. On Thursday, NASA confirmed that the spacecraft had successfully done so.
“I am extremely happy with the sample that we’ve collected,” Dante Lauretta, the Osiris-Rex mission lead, said in a briefing on Thursday. Scientists are pretty sure the spacecraft stashed at least 2 pounds (1 kilogram) of asteroid dust, also called regolith, he added.
That’s far more than the mission’s minimum goal of 2.1 ounces, which is about the mass of a small bag of potato chips. The leaking that occurred before the sample was stored away was only a matter of “tens of grams,” according to Lauretta.
Once Osiris-Rex returns to Earth in 2023, it’s set to drop the capsule holding the asteroid material into the atmosphere. Then the capsule should parachute down into the Utah desert for NASA to pick up. It will be the agency’s first sample collected from an asteroid.
Maneuvering a spacecraft 200 million miles away
To collect its asteroid sample, Osiris-Rex had to fly through a dangerous rock field and give Bennu a kind of cosmic high-five — it touched the surface for just six seconds.
The day after that brief landing, the spacecraft beamed images of its precious cargo back to NASA, but the scientists saw debris drifting away. The mission team had previously planned to spend a couple weeks assessing the sample, but they feared losing too much material to the vacuum of space. So they rushed the storage process, working day and night for two days to ensure the sample-collection arm could properly secure the sample inside the capsule.
The arm’s wrist had to align properly with the capsule so they’d fit together, which sounds simple, but because the spacecraft is 200 million miles away, every command and response faced an 18-minute lag.
By Tuesday, the probe’s arm had successfully placed its leaky sample-collecting head into the open capsule. To make sure it was locked in, the team directed the arm to tug on the collector head once more and make sure it was securely fastened.
By the following day, the team had detached the sample-collecting head from its arm and sealed the return capsule shut.
‘The more the merrier’ when it comes to sample material
Osiris-Rex is expected to begin its long journey home in March 2021. It’s slated to return the storage capsule to Earth on September 24, 2023. Within days of the sample’s landing in Utah, the team hopes to start analyzing it at NASA’s Johnson Space Center in Houston, Texas. NASA will also preserve some of the regolith for future study.
“These samples returned from Bennu will also allow future planetary scientists to ask questions we can’t even think of today and to be able to use analysis techniques that aren’t even invented yet,” Lori Glaze, the director of NASA’s Planetary Science Division, said.
That research could be crucial over the next 100-plus years, since Bennu’s path puts it at risk of crashing into Earth.
“Bennu is one of the most potentially hazardous asteroids, with a non-negligible chance of impacting the Earth at some point in the 22nd century,” Lauretta said last month. “Part of our science investigation is about understanding its orbital trajectory, refining the impact probability, and documenting its physical and chemical properties so that future generations can develop an impact-mitigation mission, if that’s necessary.”
There are other important reasons to study Bennu as well: As new missions go deeper into space, they will likely need to make pit stops to mine asteroids for resources like water, which can be split into oxygen and hydrogen for rocket fuel. The data NASA is gathering from Bennu could help inform future asteroid-mining attempts.
Similar research could also look at asteroid samples from Japan’s Hayabusa-2 spacecraft, which is set to bring its material back to Earth in December.
The large volume of regolith that Osiris-Rex collected means NASA will be able to send the alien rock to more laboratories for more experiments than would have been possible had it collected just the minimum 2.1 ounces.
“My goal is to get the sample out to as many qualified laboratories around the planet as possible as quickly as possible,” Lauretta said. “There’s great discoveries to be made, and we it looks like we have abundant sample, so the more the merrier.”