-- A seven-year journey from Florida to Utah began tonight.
That extraterrestrial rendezvous will see the probe essentially vacuum up a bit of Bennu's surface and fly it back home to Earth, where it can then be studied for years to come, one of the mission's leading scientists told ABC News.
Bennu was not selected at random, said Dr. Jeffrey Grossman, the mission's program scientist at NASA.
The 500-meter-wide space rock (just over the size of the Empire State Building) was, “very carefully chosen because it’s going to help us achieve many of our planetary goals,” chief of which, he said, is "to better understand the origin of the solar system."
The asteroid, scientists think, "preserves material that formed during the very first formation of the solar system."
It may also hold the keys to understanding more about the origins of life on Earth, since so-called B-type asteroids such as Bennu are likely to contain organic material, Grossman said. That kind of material, "could have played a role in the origins of life -- here and perhaps elsewhere."
"Perhaps this mechanism works elsewhere, which would surely influence the thinking about how common life might be," Hawley said.
Scientists also hope that the mission will provide them with a better understanding of forces that push asteroids around. In turn, this would allow them to better predict the trajectory of asteroids, and whether they pose a hazard to Earth.
Convenience was also a factor, since Bennu is actually fairly close to Earth. But that doesn't mean it's going to be a quick trip.
While it is a near-Earth asteroid, and crosses Earth's orbit every six years, Grossman said, it will still take almost two years to reach the space rock -- with the probe arriving sometime in August 2018.
Upon arrival, OSIRIS-REx will spend almost two more years taking measurements and picking the best spot to vacuum up some surface material.
Once that spot is selected, the vacuum will power up (hopefully in July 2020), and take a sample -- for just 3 to 5 seconds.
But scientists don't want to come back empty-handed, so they've built in some extra capacity.
“If unsuccessful on the first try, we can actually make three tries, but we’re confident we’re going to do it on one," Grossman told ABC News.
Scientists are aiming to collect about 60 grams of material, but they have the trunk space for as much as 2 kilograms.
The spacecraft will bid Bennu adieu around March 2021 and then head home.
Because of orbital mechanics, scientists know the exact day to be waiting for it in the Utah desert: Sept. 24, 2023.
The craft will re-enter the Earth's atmosphere at a blistering 27,000 miles per hour, Grossman said. But when it will plop down in Utah at a leisurely 11 miles per hour.
And while that will all be seven years in the future, OSIRES-REx's impact on humanity could be long-lasting.
While scientists have planned to study the craft's vacuumed-up material for two years, Grossman predicts that the rock chips and dust will be the subject of investigation for decades, noting that the original samples from the moon are still being studied today.
"These treasures we get on our sample-return missions are a legacy for science, which goes far beyond the mission," Grossman told ABC News. "People will study these samples using techniques that have not even been invented yet, and answering questions we haven’t thought to ask.”
ABC News' Gina Sunseri contributed to this report.