NASA's OSIRIS-REx spacecraft is about to suck up asteroid rubble for the first time. Watch the risky maneuver live.

• NASA's OSIRIS-REx spacecraft is set to land on asteroid Bennu and collect samples of rock on Tuesday evening.
• The van-sized probe will have to maneuver past a rock field to land on a small, smooth stretch of the asteroid's surface.
• Live coverage of the maneuver begins at 5 p.m. ET on NASA TV, embedded below.

For the first time ever, a NASA spacecraft is about to try to gather up an asteroid's dusty rock.

The $1 billion OSIRIS-REx spacecraft — short for the Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer — has been orbiting asteroid Bennu since December 2018.

The 1.7-ton robot has spent much of that time looking for the perfect spot to suck up some extraterrestrial dirt in a risky "touch-and-go" maneuver. NASA has settled on a location named Nightingale, a small, unobstructed, and relatively smooth area covered in fine dust and grit called regolith.

But landing on Nightingale will be tricky.

First, OSIRIS-REx must navigate through a hazardous field of debris that drifts around Bennu before it can reach the surface. If the spacecraft makes it through unscathed, it must then successfully land in a zone roughly the area of six parking spaces. OSIRIS-REx is about the size of a 15-passenger van, so that landing needs to be close to perfect.

This will all have scientists on the edge of their seats. NASA plans to air live coverage of the event starting at 5 p.m. ET. If everything goes smoothly, NASA should get confirmation that the spacecraft collected samples from Bennu's surface at 6:12 p.m. ET.

You can catch the action on NASA TV, embedded below.

The OSIRIS-REx Twitter account will also host a livestream. On Twitter, you can ask the landing team questions by tweeting with the hashtag #ToBennuandBack.

The spacecraft is slated to leave Bennu in 2021 and return to Earth on September 24, 2023, where it should jettison a capsule full of samples into the Utah desert for NASA to pick up.

Why NASA is spending $1 billion to get a couple ounces of asteroid grit

During its sampling maneuver, OSIRIS-REx is expected to scoot up close to Bennu and extend a long robotic arm until it touches the surface. In the next 10 seconds, the probe should blast out some sterile nitrogen gas, collect regolith into a sample container, and then rocket away from the surface.

A NASA-run Twitter account for the robot has described the maneuver as a "boop" (a reference to cutely touching someone on the head).

"I'm getting ready for my boop with Bennu!" the account wrote on Sunday.

NASA hopes to get at least one 2.1-ounce (60-gram) sample, which is about a small bag of potato chips' worth of mass. But if the agency gets lucky, the spacecraft may gobble up to 2 kilograms (4.4 lbs) of dust and grit over several sampling attempts.

Understanding Bennu's composition could be crucial over the next 200 years, since the asteroid has a 1-in-2,700 chance of hitting Earth in that time. Such an impact would release the energy of roughly 1,300 one-megaton thermonuclear weapons.

"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," Dante Lauretta, the mission's principal investigator, 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, too: 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 such asteroid mining attempts in the future.

The mission may also help us better understand where we came from: Bennu is thought to be rich with carbon-based molecules, so the tiny sample OSIRIS-REx brings back to Earth may help reveal how our solar system formed and what gave rise to life on Earth.

"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.

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