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Overflowing with names inspired by Egyptian mythology, the Osiris-Rex mission seeks to bring back at least 60 grams of asteroid Bennu, the greatest otherworldly loot from beyond the moon.
The pickup-sized spaceship points to the relatively flat middle of a tennis-court-sized crater called Nightingale, a place comparable to some parking spots here on Earth. Rocks as big as buildings loom over the target landing zone.
“So for perspective, the next time you park your car in front of your house or in front of a coffee shop and walk inside, think about the challenge of driving Osiris-Rex to one of these places 200 million miles away.” . said NASA Deputy Director of Projects Mike Moreau.
Once it leaves its 0.75-kilometer-high orbit around Bennu, it will deliberately take four hours for the spacecraft to reach the bottom, just above the surface.
Then the action escalates as Osiris-Rex’s 3.4 meter arm reaches out and touches Bennu. The contact should last five to 10 seconds, long enough to shoot pressurized nitrogen gas and suck up the beaten dirt and gravel. Programmed in advance, the spacecraft will operate autonomously during the unprecedented touch-and-go maneuver. With an 18-minute delay in radio communication each way, spacecraft builder Lockheed Martin’s ground controllers near Denver cannot intervene.
If the first try doesn’t work, Osiris-Rex can try again. The collected samples will not reach Earth until 2023.
While NASA has recovered comet dust and particles from the solar wind, it has never attempted to sample one of the nearly 1 million known asteroids lurking in our solar system so far. Japan, meanwhile, hopes to obtain samples from the asteroid Ryugu in December, in milligrams at most, 10 years after bringing back the particles from the asteroid Itokawa.
Bennu is a paradise for asteroid collectors.
The large, round, carbon-rich black space rock, taller than the Empire State Building in New York, existed when our solar system was forming 4.5 billion years ago. Scientists consider it a time capsule filled with pristine building blocks that could help explain how life formed on Earth and possibly elsewhere.
“It’s about understanding our origins,” said the mission’s chief scientist, Dante Lauretta of the University of Arizona.
There are also selfish reasons to get to know Bennu better.
The solar-orbiting asteroid, which passes close to Earth every six years, could point us toward the end of the next century. NASA estimates the probability of impact to be 1 in 2700. The more scientists know about potentially threatening asteroids like Bennu, the safer Earth will be.
When Osiris-Rex took off in 2016 on the more than AUD $ 1.128 million mission, scientists envisioned sandy stretches at Bennu. So the spacecraft was designed to ingest small stones less than 2 centimeters wide.
Scientists were surprised to find massive rocks and coarse gravel all over the place when the spacecraft arrived in 2018. And occasionally pebbles were seen exiting the asteroid, falling, and sometimes bouncing again in a cosmic game of ping-pong.
With so much rugged terrain, the engineers were quick to target a narrower spot than originally intended. The Nightingale Crater, the main target, appears to have the highest abundance of fine grains, but rocks still abound, including one called Mount Doom.
The team stayed behind and advanced the second and final touch-and-go dress rehearsal for the spacecraft until August. That brought the sampling to October.
“Returning a sample is difficult,” said NASA science mission chief Thomas Zurbuchen.
“COVID made it even more difficult.”
Osiris-Rex has three bottles of nitrogen gas, which means that it can land three times, no more.
The spacecraft will automatically reverse if it encounters unexpected hazards such as large rocks that could cause it to overturn. And there is a chance that it will land safely, but not accumulate enough debris.
In any case, the spacecraft would return to orbit around Bennu and try again in January elsewhere.
With the first attempt finally here, Mr. Lauretta is concerned, nervous, excited “and confident that we have done everything possible to ensure safe sampling.”
