By recovering a greater than expected weight of particles, the collection compartment of the probe had difficulty in closing, causing the cancellation of an operation which could risk the loss of more fragments. She is due to return to Earth in 2023.
NASA announced on Friday that its Osiris-Rex probe had managed to collect a very large amount of particles from the asteroid Bennu earlier this week, but there were so many that the collection compartment could not close, endangering the mission.
The probe is due to bring back dust and small pebbles to Earth in 2023, which would be by far the largest alien sample since the Apollo missions to the Moon. On condition that she manages to store them tightly for the return trip.
“A substantial fraction of the mass harvested is escaping,” Dante Lauretta, head of the mission, announced during a conference call in a tone less euphoric than his presentation on Wednesday, when the team welcomed an operation having gone “as well as hoped”.
In the meantime, the probe took pictures from all angles, and its land masters discovered with amazement a disturbing cloud of particles floating around the three-meter-long arm.
The good news is that the probe would have recovered around 400 grams of fragments, much more than the minimum desired 60 grams, and in any case several hundred grams, according to the scientist.
But 5 to 10 grams have already been observed around the arm; due to microgravity, the fragments behave like fluids.
“My big worry is that particles are escaping, we are the victims of our success,” said Dante Lauretta.
As a result, the operation of measuring the mass by rotating the device, initially scheduled for this Saturday, was canceled, as this would risk causing even more fragments to come out.
Suspense until 2023
The urgent need now is to reduce the activities of the device to a minimum, to limit leaks, and to prepare the samples as quickly as possible in the capsule located in the center of the probe.
This involves arm movement, and must be carefully prepared by engineers. It may take place on Tuesday.
The fragments are currently in the circular compartment at the end of the arm. On Tuesday, Bennu’s arm stuck for a few seconds on Bennu’s floor and at the same time blew out compressed gas, causing particles that were captured inside the arm to rise up, as if under a bell. But the arm actually sank 48 cm deep, to NASA’s surprise.
The compartment closing mechanism is blocked by stones. Is Osiris-Rex at risk of losing her treasure? The volume of the leak is not yet well known, but scientists seemed relatively confident, and said it would not be necessary to repeat a sampling operation.
“We think we’re losing a small fraction of the material, but it’s more than I would like, I’m quite worried since I saw the footage,” said Dante Lauretta. “The most prudent thing is to store it as carefully as possible to minimize any future loss.”
The probe, launched more than four years ago, is due to return to Earth in March, and land in Utah in September 2023.
“We’re going to have to wait until we get home to find out precisely how much we have, and that, as you can imagine, is difficult,” added the scientist.