CAPE CANAVERAL, Florida (AP) – After nearly two years of orbiting an ancient asteroid hundreds of millions of miles away, a NASA spacecraft this week will try to land on an insidious, rocky surface and grab a handful of debris.
The drama unfolds on Tuesday, when the United States takes its first crack in collecting samples of asteroids to return to Earth, an achievement achieved so far only by Japan.
Mottled with names inspired by Egyptian mythology, the Osiris-Rex mission seeks to return at least 60 grams of the asteroid Bennu, the largest outside world beyond the moon.
The van-sized spacecraft aspires to the relatively flat surface of a crater the size of a tennis court called Nightingale, a place comparable to several parking spaces here on Earth. Stones as large as buildings rise above the target touch area.
“So for some perspective, the next time you park your car in front of the house or in front of a cafe and go inside, consider the challenge of navigating Osiris-Rex in one of these places 200 miles away,”
After falling out of its half-mile (0.75 km high) orbit around Bennu, the spacecraft will deliberately take four hours to reach the surface.
The action is then mixed when Osiris-Rex’s 11-foot (3.4-meter) hand reaches out and touches Bennu. The contact should last five to 10 seconds, long enough to expel nitrogen under pressure and suck up the slaughtered dirt and gravel. Pre-programmed, the spacecraft will operate autonomously during the unprecedented “touch and move” maneuver. With an 18-minute delay in radio communication in each direction, ground controllers for the Lockheed Martin spacecraft builder near Denver could not intervene.
If the first attempt fails, Osiris-Rex may try again. All collected samples will reach the Earth by 2023.
Although NASA has returned dust from comets and solar wind particles, it has never tried to sample one of the nearly 1 million known asteroids lurking in our solar system so far. Japan, meanwhile, expects to receive samples from the asteroid Ryugu in December – at most in milligrams – 10 years after the return of spots from the asteroid Itokawa.
Bennu is a paradise for asteroid pickers.
The large, black, rounded, carbon-rich space rock – taller than the New York Empire State Building – was around when our solar system formed 4.5 billion years ago. Scientists consider it a time capsule full of virgin building blocks that can help explain how life formed on Earth and possibly elsewhere.
“It’s all about understanding our origins,” said Dante Lauretta, the mission’s chief scientist at the University of Arizona.
There are also selfish reasons to get to know Bennu better.
The solar orbital asteroid, which oscillates on Earth every six years, could target us at the end of the next century. NASA puts the odds of hitting at 1 in 2,700. The more scientists know about potentially threatening asteroids like Bennu, the safer the Earth will be.
When Osiris-Rex launched the mission for more than $ 800 million in 2016, scientists predicted sandy areas in Bennu. So the spacecraft is designed to swallow small pebbles smaller than 2 centimeters.
Scientists were amazed to find massive rocks and crushed gravel everywhere when the spacecraft arrived in 2018. And from time to time, stones were seen launching the asteroid, falling backwards and sometimes ricocheting again in a space ping-pong game.
With so much rugged terrain, the engineers went up to a narrower place than originally expected. The Nightingale Crater, the main target, seems to have the greatest abundance of fine grains, but rocks still abound, including one called Mount Doom.
Then COVID-19 struck.
The team is lagging behind and moving the second and final dress rehearsal for the spacecraft to August. This pushes the sampling to October.
“Returning a sample is difficult,” said NASA Chief of Mission Thomas Zurbuchen. “COVID made it even harder.”
Osiris-Rex has three bottles of nitrogen gas, which means it can reach three times – no more.
The spacecraft will automatically retreat if it encounters unexpected dangers such as large rocks that could cause it to capsize. And there is a chance to touch it safely, but fail to collect enough debris.
In both cases, the spacecraft will return to orbit around Bennu and try again in January elsewhere.
With the first attempt finally here, Loretta is worried, nervous, excited and confident that we have done everything we can to ensure safe sampling.
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