NASA just successfully touched down on an asteroid

 NASA just landed a spacecraft on an asteroid and, if everything went as planned, sucked up a sample of dust and rock from the surface.

From 200 million miles away, NASA and its engineering partner, Lockheed Martin, instructed the spacecraft to descend to the surface of a space rock called Bennu.

In just 5 to 10 seconds, the probe should have collected samples from the asteroid's surface. It's set to bring these pieces of Bennu back to Earth later.

OSIRIS-REx, as the spacecraft is known (short for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer), completed this "touch-and-go" operation on Tuesday evening.

The spacecraft beamed back confirmation that it had landed on Bennu's surface. When the signal reached Earth at 6:11 pm ET, about 18 minutes after the actual touchdown, Mission Control erupted in cheers and applause.

"Transcendental. I can't believe we actually pulled this off," Dante Lauretta, the mission's principal investigator, said during NASA's live broadcast of the operation. "The spacecraft did everything it was supposed to do."

It will take a few days to determine whether the probe picked up enough rock. The goal was to get at least one 2.1-ounce (60-gram) sample, which is about a small bag of potato chips' worth of mass.

OSIRIS-REx has been orbiting Bennu since December 2018, scanning the asteroid and collecting as much data as possible. It's set to leave in March 2021, samples in tow, then reach Earth on September 24, 2023.

The mission's research could be crucial over the next 100 years, since Bennu's path puts it at risk of crashing into Earth.

"Bennu is one of the most potentially hazardous asteroids, with a non-negligible chance of impacting the Earth at some point in the 22nd century," Lauretta said in September.

"Part of our science investigation is about understanding its orbital trajectory, refining the impact probability, and documenting its physical and chemical properties so that future generations can develop an impact-mitigation mission, if that's necessary."

There are other important reasons to study Bennu: As new missions go deeper into space, they will need to make pit stops to mine asteroids for resources like water, which can be split into oxygen and hydrogen for rocket fuel. The data NASA is gathering from Bennu could help inform future asteroid-mining attempts.

OSIRIS-REx is also, in a sense, a soul-searching mission. Asteroids are bits of ancient rock from the beginnings of the solar system 4.5 billion years ago. The leftover material that made the rocky planets - Mercury, Venus, Earth, and Mars - coalesced over time into asteroids, where it's largely preserved in its original form.

A rotating mosaic of Bennu captured by OSIRIS-REx in 2018. (NASA/Goddard/University of Arizona)

Some theories posit that asteroids delivered key ingredients for life to ancient Earth. On Bennu, scientists may find signs of those ingredients, cluing them in to how life arose on Earth (and possibly on Mars or Venus as well).

If successful, this mission will be one of the first to return samples of primordial rock. Japan's Hayabusa-2 spacecraft is also set to bring back asteroid samples in December.

"This is all about understanding our origins, addressing some of the most fundamental questions that we ask ourselves as human beings: Where did we come from? And are we alone in the universe?" Lauretta said.

NASA's spacecraft dropped 3,000 feet to blast asteroid dust

OSIRIS-REx's early data revealed a problem for the mission: Bennu is much rockier than NASA thought. Landing in a field of boulders puts a spacecraft at risk of tipping over and getting stranded.

To target the smoothest possible terrain on the asteroid, the OSIRIS-REx mission team chose a landing spot that's much smaller than originally planned. Its leeway is just 26 feet (8 meters), whereas the initial plan expected it to have 164 feet (50 meters).

That means the spacecraft, which is about the size of a 15-passenger van, had to target an area roughly equal to six parking spaces on the fast-spinning asteroid.

The landing spot is a relatively smooth area named Nightingale that's covered in a fine rocky dust called regolith. This is the material that OSIRIS-REx attempted to scoop up on Tuesday.

The spacecraft slowly descended about 3,280 feet (1 kilometre), manoeuvring past a two-story boulder that mission controllers call "Mount Doom". OSIRIS-REx has twice rehearsed this descent, practicing "basically everything except for the final two minutes," said Mike Moreau, a project manager.

The sequence goes like this: The spacecraft's thrusters fire, pushing it out of its kilometre-high orbit above Bennu. Then the probe deploys its sample-collection arm and points its navigation camera to the asteroid's surface. About 3 1/2 hours later - and about 410 feet above the surface - the spacecraft fires its thrusters again to push itself toward the landing site. After another 10 minutes and another 260 feet of descent, the spacecraft burns its thrusters to manoeuvre into a precise landing spot.

The whole operation seems to have gone according to that plan.

If the spacecraft's instruments had detected hazardous rocks at its landing point, the probe would have initiated a back-away burn just 16 feet above the surface.

But the spacecraft appears to have reached Bennu's surface with its sample-collection arm stretched down. Through this arm - if collection went according to plan - the spacecraft shot nitrogen gas out of a bottle, stirring up the regolith beneath it. In the disturbance, some material should have been caught in the collection tool at the end of the arm.

Shortly after touchdown, OSIRIS-REx fired its thrusters to push itself away from Bennu.

NASA will decide whether to stow the sample or try again

Once the spacecraft is back in Bennu's orbit, it will take a few days for NASA mission controllers to analyse the regolith sample it collected. If there's enough rock and dust, mission leaders will command the spacecraft to store the sample in a pod for its return to Earth.

But if the spacecraft has less than 2.1 ounces of regolith, it will try again in January, targeting a backup site on a different part of the asteroid.

"By far the most likely outcome that we will have on October 20 is we will contact the surface and come away with a large sample that exceeds our minimum requirements," Moreau said in September.

"But Bennu has thrown us a number of curveballs."

OSIRIS-REx is carrying three bottles of nitrogen for stirring up dust, allowing it three attempts to descend to Bennu's surface and collect a proper sample.

The Bennu sample should reach Earth in 2023

When OSIRIS-REx returns to Earth in 2023, it should shoot the capsule containing the samples into Earth's atmosphere. The samples should parachute into the Utah desert for NASA to pick up.

"It's going to probably be Christmas in September," Lauretta said. "The best Christmas present I've ever had, these pristine samples from asteroid Bennu that I've been dreaming - literally dreaming - about for, at that point, almost 20 years of my life."

Scientists will set about analysing the sample, but NASA will preserve some of the regolith for future study.

"These samples returned from Bennu will also allow future planetary scientists to ask questions we can't even think of today," said Lori Glaze, the director of NASA's Planetary Science Division, "and to be able to use analysis techniques that aren't even invented yet."

This article was originally published by Business Insider.

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