BackNASA Capsule Set to Deliver Rare Sample From Asteroid Bennu
The Osiris-REx mission is bringing home the largest asteroid sample ever collected.
PremiumThe largest sample ever collected from an asteroid is set to touch down in the desert of western Utah on Sunday.
Osiris-REx, the robotic spacecraft delivering the sample, is part of a mission of the same name launched seven years ago by the National Aeronautics and Space Administration to a space rock named Bennu. When the 20-foot-long craft buzzes by Earth this weekend, it will jettison a capsule containing rocks and dust collected from the asteroid’s surface.
The sample could help us better understand the earliest days of our solar system, 4.5 billion years ago, and perhaps how asteroids helped seed our world with the ingredients for life as we know it, according to scientists involved with the mission.
“We think objects like Bennu may have made Earth habitable," said Dante Lauretta, principal investigator for Osiris-REx and a professor of planetary science and cosmochemistry at the University of Arizona. “They might have delivered the ocean water, the molecules that are in our atmosphere, and maybe even the organic materials that triggered the origin of life on our planet."
The exact amount of asteroid material contained in the capsule is unknown, but Lauretta said he estimates that about 250 grams—half a pound or so—of Bennu is on its way.
The Osiris-REx mission wouldn’t be the first to deliver an asteroid sample to our planet. Two Japanese missions already did so from two other asteroids, in 2010 and 2020. But the size of the expected sample from NASA’s mission dwarfs its predecessors—the sample Japan brought back in 2020 was 5 grams.
“It is a big deal—this is the first time they’ve gotten a substantial amount of material," said Thomas Burbine, a planetary scientist and director of the Williston Observatory at Mount Holyoke College who isn’t currently affiliated with the mission. “This will change the way we think about asteroids."
The larger the sample, the more interesting chemistry scientists can explore by extracting molecules out of the rocky material, according to Lauretta.
If all goes well, Sunday’s livestreamed sample delivery will begin 63,000 miles above the Earth, or about one-third the distance from our planet to the moon. At 6:42 a.m. Eastern time, mission controllers will command Osiris-REx to release its capsule, which will then move through space toward Earth for about four hours while the craft that released it begins a new six-year journey toward an asteroid named Apophis.
The capsule will move into our atmosphere at a blistering speed of more than 27,000 mph at 10:42 a.m. ET. A safe touchdown is expected 13 minutes later, after several parachutes slow the capsule down to about 11 mph.
“Seeing the parachute deploy on landing day is really going to be the biggest relief," said Rich Burns, Osiris-REx project manager at NASA’s Goddard Space Flight Center in Greenbelt, Md., which manages the mission.
At its highest speeds, Osiris-REx’s jettisoned cargo will be enveloped in a superhot ball of fire that reaches 5,000 degrees Fahrenheit, but a heat shield will protect it. Burns said infrared sensors on the ground should be able to track the capsule’s descent before it is picked up by visual instruments as it nears the ground.
Its target is a roughly 36-by-9-mile ellipse-shaped area within the Department of Defense’s Utah Test and Training Range west of Salt Lake City. Helicopters are ready to help a large retrieval team quickly recover the capsule.
Jason Dworkin, Osiris-REx project scientist and senior scientist for astrobiology at NASA’s Goddard Space Flight Center, said the spacecraft is on a course to release the capsule “to the dead center of the landing ellipse."
After the capsule is retrieved on Sunday, it will be flown to a temporary clean room on the military range. There, it will be partially disassembled before being transported to a laboratory at NASA’s Johnson Space Center in Houston, where the agency curates other extraterrestrial samples, like lunar rocks and meteorites. NASA said it intends to unveil the sample next month.
Lauretta said he isn’t nervous about the expected landing and recovery, in part because the agency and Lockheed Martin Corp.’s space division—which built the spacecraft and is responsible for capsule recovery—have conducted practice retrieval exercises in recent months.
Rather, he said, some of the mission’s biggest challenges came after Osiris-REx arrived at Bennu in 2018. The 1,600-foot-wide asteroid, discovered in 1999, was chosen as the mission’s target because it was carbon-rich and could contain biochemical building blocks needed for life. Born from an ancient collision in the asteroid belt between Mars and Jupiter, Bennu also has an orbit that brings it close to Earth, making it more accessible than some other asteroids.
Yet it took the Osiris-REx team two years to map the asteroid and choose a suitable, safe area to collect the sample from on the space rock’s surface, which was unexpectedly littered with large, hazardous boulders.
The knowledge of Bennu’s surface and composition can help inform planetary defense efforts like NASA’s successful deflection of a distant asteroid during a test last year, scientists say.
“Sooner or later, one of these objects is going to hit the Earth," Burbine said. “So you want to know as much about them as you can if you want to do any mitigation."
There is a nonzero chance Bennu will impact Earth late next century—less than about 0.05%, according to Lauretta—so insights from the Osiris-REx mission could help inform future generations’ response to the potential threat.
“It’s what we call the most potentially hazardous asteroid in the solar system," he said. “But we definitely don’t want people to panic over this."
Write to Aylin Woodward at aylin.woodward@wsj.com
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