NASA Probe Will Try To “High Five” a Near-Earth Asteroid

The robotic spacecraft is scheduled for launch from Cape Canaveral Thursday evening.


The primary goal of the OSIRIS-REx mission is to retrieve a few pounds of gravel and dust from Bennu, an asteroid whose orbit brings it near Earth every six years.

If successful, the asteroid samples will be the largest amount of extraterrestrial material brought back to Earth since the Apollo-era trips to the moon.

The asteroid, called Bennu after an ancient Egyptian bird god, was discovered in 1999.

Bennu was a good target because it's relatively close to Earth, and also big enough for a visit, according to Dante Lauretta, the lead scientist for the mission, and a planetary scientist at the University of Arizona. Bennu measures 495 meters in diameter (about a third of a mile).

"We needed something that was relatively large, because when asteroids get to be around 200 meters in diameter or smaller, they tend to rotate very rapidly, sometimes as often as once every minute, and that would likely fling any of that gravel off the surface," Lauretta said.

The asteroid's gravel could contain carbon-rich material that is 4.5 billion years old, almost as old as the solar system itself.

"These asteroids could contain organic molecules, volatiles and amino acids that may have been the precursors to life on Earth or elsewhere in our solar system," said Christina Richey, a NASA scientist involved in the mission.

The probe will take two years to reach Bennu. Once there, the probe will go into orbit around Bennu, and spend another two years studying and mapping the asteroid's surface from afar.

Finally, the probe will approach the asteroid, unfold an 11-foot arm, and pick up some rock and dust.

Richey says the arm will only touch the surface for about five seconds, to minimize the chance of the probe being damaged. She likened it to a cosmic "high five."

"Our priority is to bring back at least 60 grams of pristine material," Richey said. "So once we have that, we're not going to try to touch that again. We've got it. It's getting stowed, it's getting ready to come home."

After flying back to Earth, the probe will eject a small capsule containing the samples. The capsule will fall through the atmosphere and land in Utah in September, 2023.

The samples will be brought to Johnson Space Center for storage. Scientists will get to examine and study 25 percent of the sample, but 75 percent will be stored for future scientists who may come up with better ideas and testing techniques than current technology allows.


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