America’s Osiris-Rex spacecraft has completed its audacious tag-and-go manoeuvre designed to grab surface rock from an asteroid.
Radio signals from 330 million km away confirm the probe made contact with the 500m-wide object known as Bennu.
But the Nasa-led mission will have to wait on further data from Osiris-Rex before it’s known for sure that material was actually picked up.
The aim was to acquire at least 60g, perhaps even a kilo or more.
Because Bennu is a very primitive space object, scientists say its surface grit and dust could hold fascinating clues about the chemistry that brought the Sun and the planets into being more than 4.5 billion years ago.
“The team is exuberant; emotions are high; everyone is really proud,” said principal investigator Dante Lauretta from the University of Arizona, Tucson.
“[But] we have some work to do to determine how much sample we have collected.”
Assuming there is a suitable sample safely aboard, the probe will be able to package it for return to Earth, scheduled for late 2023.
If not, the mission team will have to configure Osiris-Rex for another go.
The spacecraft made its sample bid in a narrow patch of terrain on Bennu dubbed Nightingale.
It descended slowly to the target zone over a period of four and a half hours, squeezing past some imposing boulders on the way down.
Osiris-Rex used what some have described as a “reverse vacuum cleaner” to make its surface grab.
More properly called the Touch-and-Go Sample Acquisition Mechanism, or Tag-Sam, this device is a long boom with a ring on the end.
The idea was to push the ring into the surface and at the same moment express a stream of nitrogen gas to kick up small fragments of rock.
Controllers have sensors on Osiris-Rex to report back on all the sampling actions but they need time to assess precisely what might have been caught in the sampling ring.
One way to do this is to photograph the ring. They’ll do this.
But they’ll also spin the spacecraft. Any extra mass on board will change the amount of torque required to turn the probe. The technique can reveal the amount of dust and grit in the sampling ring to within 10 grams or so.
Osisris-Rex took pictures all the way through its descent but could not send any of these back because of the constrained bandwidth from so far away.
Nasa promises to release some photos on Wednesday.
