NASA’s OSIRIS-REx spacecraft did its job a little too well on Tuesday, when it attempted to pick up a handful of rocks from an asteroid named Bennu more than 200 million kilometers from Earth. The vehicle did seize too much material with its robotic arm, blocking the cover at the end of the open arm – and letting some of the asteroid sample escape into space.
“We were almost victims of our own success here,” Dante Lauretta, principal investigator of the OSIRIS-REx mission at the University of Arizona, said at a press conference.
OSIRIS-REx’s mission is to bring a sample of asteroid material back to Earth so that scientists can study the rocks in a laboratory. But since OSIRIS-REx has bitten more than it can chew, its mission team rushes to store the sample in the belly of the spaceship, so that the vehicle does not lose too much material in the void. “Time is running out and no, we won’t sleep,” Thomas Zurbuchen, NASA associate administrator for science, told a press conference.
The good news is that OSIRIS-REx appears to have caught an abundant and diverse group of asteroid rocks. The team’s goal was to catch up to 60 grams (2.1 ounces) of rock on Bennu’s surface, and images from the spacecraft show that OSIRIS-REx likely caught up to 400 grams. (14.1 ounces) of material, according to the mission team. The sample includes rocks that vary in size, and some are so large that they prevented the spacecraft from sealing the sample.
Engineers are confident that rocks don’t escape too quickly, so the spacecraft should be able to store a fair amount inside the spacecraft before too much runs out. They believe they lost between 1 and 10 grams of material yesterday after moving the robotic arm. However, NASA does not plan to store the sample in OSIRIS-REx until Monday. The mission team should take the time to understand all the controls of the spacecraft and ensure that this process will always work with rocks spreading through space. It is not known how much of the sample will be lost while they wait.
There is also another complication: Simply moving the robotic arm with the sample inside causes rocks to leak outward, so the materials storage may lose more rocks. Engineers believe they could lose up to an additional 10 grams of rock just by storing the sample inside the spacecraft. But it is better to tidy up Something than to wait for everything to flow.
To collect the Bennu sample, OSIRIS-REx is equipped with a robotic arm which has a cylindrical sample collector at the end. Tuesday afternoon, OSIRIS-REx slowly approached Bennu and gently patted his surface with the collector. Upon contact, the collector blew out a bunch of nitrogen gas, shaking all the rocks and pebbles on the asteroid’s surface. Some of these rocks sprang up inside the collector, while others danced and whirled in space.
The OSIRIS-REx team couldn’t tell right away whether they had a sample or not, as they had to wait to get images of the spacecraft. But they soon realized they had a problem when they finally got a close up photo of the sample collector. The pictures show that part of the lid is stuck by a centimeter; tiny pieces of asteroid can be seen hovering around the arm.
If the sampling had gone more easily, NASA would have waited a little longer to put the material inside OSIRIS-REx. In fact, the mission team had planned to do a rotation maneuver on Saturday with the spacecraft, spinning the vehicle with its robotic arm outstretched. This would have helped the team determine how much material the spacecraft had collected. Engineers were able to measure the inertia of the spacecraft, comparing it to an earlier time when the spacecraft did not have a sample in its arm. But the spin is effectively canceled. “It would risk losing material, so it’s not a safe path to take,” Lauretta said.
This means that the OSIRIS-REx team will not really know how much sample is in the belly of the spacecraft when the vehicle returns to Earth. “I think we’re going to have to wait until we get home to find out exactly how much we have and that, as you can imagine – it’s tough,” Lauretta said. “We were looking forward to a sample mass measurement.” So it’s possible that the whole sample would drop before Monday, and we wouldn’t really know until the spacecraft returned to our planet.
The OSIRIS-REx team are also not planning to take another sample from Bennu, so that’s it. That’s why engineers are working quickly to store this sample on Monday. “I’m very confident that this has been a success – that we have more than the 60 grams of material we promised Thomas and the agency we would deliver,” Lauretta said, adding that “the most important thing is to store the sample safely. and minimize any further loss. “