Somewhere between the orbits of Mars and Earth, NASA’s OSIRIS-REx spacecraft is nipping home with precious cargo: a 250g sample of material from the asteroid Bennu.
In six months a capsule containing this sample will conclude its 600-million-kilometre, seven-year round trip by blasting through Earth’s atmosphere for a parachute-assisted landing in the Utah desert.
It will mark the end of the United States’ first return asteroid sampling mission.
NASA has now confirmed it’s in the final stages of preparation for the landing, including planning the spacecraft’s return trajectory and sample capsule recovery.
Precision is key to this process. First, the return of OSIRIS-REx requires a perfectly-timed rendezvous with Earth in orbit.
When the spacecraft flies past the earth, it will eject the sample capsule which will plummet to the US Defense Department’s Utah testing range.
Failure to calculate return angle correctly also puts the craft in jeopardy. In October, Mike Moreau from NASA Goddard Space Flight Centre observed “If the capsule is angled too high, it will skip off the atmosphere. Angled too low, it will burn up”.
NASA will then recover the capsule and transport it to a sterile site. As part of this process, air and soil samples from around the landed capsule will be taken for contaminant verification. Within the ‘clean room’ the sample canister will be extracted for transport to NASA’s Johnson Space Centre.
Testing for contaminants is an essential quality-control process as polluting the asteroid samples with Earth water or organisms would hinder scientific analysis. NASA is hoping to learn whether precursor chemicals for life on Earth arrived express from ancient asteroids.
The sample will then be divided and sent to a network of global study teams.
“There are two things pervasive on Earth: water and biology. Both can severely alter meteorites when they land on the ground and muddle the story told by the sample’s chemistry and mineralogy,” says one of OSIRIS-Rex’s project scientists, Dr. Jason Dworkin. “A pristine sample could provide insights into the development of solar system.”
Fascination with asteroids as sources of life has become prominent in recent years with several projects returning samples to earth. Japan’s Hayabusa missions returned material from the Itokawa and Ryugu asteroids. Recent analyses of the Ryugu samples detected traces of uracil – a nucleic acid used in bodily protein manufacture – and Vitamin B3.