After traveling through space for more than two years and over two billion kilometers, NASA's Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) spacecraft arrived at its destination, asteroid Bennu, on Monday, Dec. 3, 2018. NASA scientists think the 484-meter-wide rock was once part of a much larger asteroid, which Space.com suggests was as large as the U.S. state of CT (which is 110 miles wide and 70 miles long), that was blown apart by some colossal collision a billion years ago.
The mission, headed by principal investigator Dante Lauretta, was planned as a mission to the asteroid then known as 1999 RQ36, an approximately 500 meter (0.5 km) diameter potentially hazardous asteroid (PHA) that has a 1 in 1800 chance of impacting Earth in 2182.
The mission is considered to be an important one because, by studying Bennu, which formed so long ago that some of the minerals inside of it are older than our solar system, scientists could get a clearer picture of the early solar system and understand how the planets formed.
Bennu - named after a mythological Egyptian deity by a third-grade contest victor - is one of the most hazardous asteroids known to NASA because of its large size and orbit.
OSIRIS-REx has a camera suite, a laser altimeter for 3D mapping, a thermal emission spectrometer to take temperature and mineral content and spectrometers to measure X-rays, almost infrared and visible light.
Meanwhile, a Japanese probe is circling an asteroid named Ryugu, about double the size of Bennu, with a plan to bring home some specks of space dust.
Scientists say that material from a carbon-rich asteroid such as Bennu could hold evidence that dates back to the beginning of our solar system 4.5 billion years ago.
"This does look a challenging surface", said Lauretta, gesturing to a blown-up image of Bennu.
The craft will obtain somewhere between 2 ounces and 4.4 pounds of soil sample from the surface of Bennu using a robotic arm that will blast the surface with a puff of nitrogen gas and collect the pieces that fly off.
Osiris-Rex is the first U.S. mission created to return a piece of an asteroid to Earth. At the time of the mission's asteroid selection in 2005, there were only 192 asteroids classified as Near Earth Objects that met NASA's proximity requirements. "Bennu is a building block of the planets that didn't end up in a planet".
OSIRIS-REx may be able to aid in preventing such events.
After backing away, OSIRIS-REx will direct the robot arm to place the collector inside an aerodynamic sample return capsule.
"But this is all dependent on the outcome of a very close approach that Bennu has with Earth in September 2135", Johnson said. It will also look for a good spot for the most ambitious part of the mission: Dropping down so close that the TAGSAM can literally touch the asteroid. Carbon is the key to the organic molecules needed for life, so finding organic molecules on a sample from Bennu would help to answer a big question about the origin of life. Bennu may be on collision course with Earth in the future.
Space agency NASA estimates its space probe will reach the distant asteroid around 5pm GMT (12pm EST) today. "But while the spacecraft might tell us some things about where we have been and where we are headed, it also can remind us of where we are right now", NASA officials said in a statement.
To achieve this, the craft will establish a gradually tighter orbit by spiralling down to a distance of roughly six feet for its retrieval mission sometime in July 2020.
Starting in October, OSIRIS-REx performed a series of braking maneuvers to slow the spacecraft down as it approached Bennu.
In addition, scientists are hoping the mission will yield more information about the source of both water and life itself within our own solar system.