Two years and two months after its launch, NASA’s OSIRIS-REx space probe is slated to approach its target: the asteroid Bennu.

OSIRIS-REx or short for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer is expected to arrive at around 12 p.m. EST on Monday, Dec. 3. Similar to last week’s InSight landing on Mars, NASA will broadcast the historic event live on several online channels, including its official website and YouTube.

The special broadcast will begin at 11:45 a.m. in case the space probe arrives early to 12:15 p.m. EST.

OSIRIS-REx Mission To The Asteroid Belt

OSIRIS-REx will not actually land on the surface of Bennu on Monday, but it will carefully approach the asteroid to perform a thorough survey of the space rock. Upon arrival, NASA revealed that the probe will position at about 12 miles away from Bennu to collect data, including its mass, topography, and composition.

The process will take a couple of weeks and it will see the space probe make flybys repeatedly around the asteroid. If successful, OSIRIS-REx will be the smallest object to be orbited by a spacecraft.

However, the space probe’s main mission will not begin until next year. After surveying Bennu, OSIRIS-REx will move into position to collect samples of the asteroid’s surface material using its robotic arm.

The spacecraft will perform a series of TAG, or touch-and-go, in which it will touch the surface of the asteroid for five seconds. It will collect at least 60 grams of samples from the asteroid. If needed, it can make up to three sampling attempts, according to Asteroid Mission.

OSIRIS-REx was launched on Sept. 8, 2016, onboard the Atlas V rocket from Cape Canaveral, Florida. NASA expects to study Bennu over18 months. The space probe will depart the asteroid in March 2021 and fly back to Earth, carrying samples it will have retrieved from Bennu.

OSIRIS-REx is expected to arrive back home in Sept. 2023.

Why Bennu

Bennu, formerly known as 1999 RQ36, is a diamond-shaped asteroid that completes its orbit around the sun every 1.2 years. It is only around 500 meters in diameter, but it is considered to be a potentially hazardous asteroid that could collide with Earth sometime in the 22nd Century.

The space rock is of great interest to scientists because it is believed to be a piece that broke off from a larger, carbon-rich asteroid between 700 million and 2 billion years ago. Scientists think that it came from the Main Asteroid Belt between Mars and Jupiter, but drifted closer to Earth because of the gravitational interactions between planets.

NASA hopes that Bennu can act as a “time capsule” that preserved information about the early years of the solar system.