When NASA’s OSIRIS-REX spacecraft touched the surface of an asteroid on Tuesday to gather a sample of rocks and dirt, the operation proceeded smoothly, to the glee of the mission’s operators 200 million miles away on Earth.
But the biggest question remained unanswered: How much of the asteroid did OSIRIS-REX pick up? Did it manage to gather any samples at all?
On Wednesday, the mission managers released a video of the sampling mechanism hitting the surface of the asteroid, within three feet or so of where the spacecraft had been aimed.
“I must have watched about a hundred times last night,” Dante Lauretta, the principal investigator of the mission, said during a news conference on Wednesday. A burst of nitrogen gas kicked up a cloud of rocks and dirt, as hoped.
“You can see that particles are flying all over the place,” Dr. Lauretta said. “We really did kind of make a mess on the surface of this asteroid, but it’s a good mess.”
The chances that spacecraft managed to capture a sizable sample “have gone way up,” he said.
Orbit of the
OSIRIS-Rex
spacecraft
Retract
sample arm
6:49 p.m.
Eastern
Begin descent
5:50 p.m.
North
pole
Move solar panels
into a Y shape
5:36 p.m.
ASTEROID
BENNU
Collect
sample
6:12 p.m.
Begin collecting
infrared data
3:51 p.m.
Point navigation cameras
2:43 p.m.
Extend sample arm
2:10 p.m.
Fire thrusters
to leave orbit
1:50 p.m.
Rotate spacecraft
1:24 p.m. Eastern
Retract
sample arm
6:49 p.m.
Orbit of the
OSIRIS-Rex
spacecraft
Begin descent
5:50 p.m.
North
pole
ASTEROID
BENNU
Collect
sample
6:12 p.m.
Begin
collecting
infrared data
3:51 p.m.
Point
navigation
cameras
2:43 p.m.
Extend sample arm
2:10 p.m.
Fire thrusters
to leave orbit
1:50 p.m.
Rotate spacecraft
1:24 p.m. Eastern
It will still be a few days before scientists can confirm how much material was trapped within the sample collector, which resembles an automobile air filter.
“There’s an incredibly clever physics experiment that the team has designed here called the sample mass measurement,” Dr. Lauretta said during the NASA Television broadcast on Tuesday.
The robotic arm with the sample collector at the end will be extended and then the spacecraft will be nudged into a spin on Saturday. “We’re measuring a property called the moment of inertia,” Dr. Lauretta said.
The scientists will compare the rate of spin to what they measured before collecting a sample. Just as a skater with outstretched arms holding a barbell would spin slower than a skater holding nothing, OSIRIS-REX will spin slower depending on how much material was picked up.
Scientists are hoping for at least a couple of ounces, but it could be more than four pounds.
“The precision, just like everything on this program, is phenomenal,” Dr. Lauretta said. “We’re talking tens of grams of precision on a measurement on a spacecraft hundreds of millions of miles away.”
If by unlucky chance OSIRIS-REX came up empty on Tuesday, it can try two more times.
The collection of the asteroid sample is the climax of the $800 million mission, which launched four years ago. The spacecraft has been making detailed observations of Bennu — a rock as wide as the Empire State Building is tall — for two years, mapping features of its surface as small as a couple of inches wide. It even discovered that Bennu was shooting debris from its surface into space.
The mission’s controllers selected a spot inside a crater near Bennu’s north pole that they named Nightingale. The spacecraft, 20 feet wide and about the size of a sport utility vehicle, had to navigate carefully to the target site, which is only 26 feet in diameter. In addition, it had to avoid a wall of rocks on the eastern edge of the crater. That included a pointy pillar nicknamed Mount Doom, which is as tall as a two- or three-story building.
However, despite the risks, Nightingale offered the greatest potential scientific payoffs, with unobstructed fine-grained material that appears to contain carbon-rich minerals.
Asteroids, mostly located in orbits between Mars and Jupiter, are bits that never coalesced into a planet, and planetary scientists hope that the samples from Bennu could shed light on what the young solar system was like when it formed 4.5 billion years ago. Asteroids like Bennu, which possesses carbon-rich minerals, may have provided the building blocks for life to arise on Earth.
The asteroid is also being studied because its orbit could cause it to collide with Earth late in the 22nd century. The likelihood of such an occurrence is low, and the asteroid is not large enough to end human civilization should it occur.
OSIRIS-REX — the name is a shortening of Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer — is to leave the asteroid next year and drop off the sample, which will parachute to a landing in Utah on Sept. 24, 2023.
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