OSIRIS-REx met its asteroid

Asteroid missions are all the rage in space right now. There are currently two spacecraft getting cozy with asteroids and sending us photos to prove it. JAXA is operating the Hayabusa2 mission, while NASA’s OSIRIS-REx just moved into orbit with the asteroid Bennu on Monday.

In 2016, NASA launched an ambitious mission to study our solar system. The OSIRIS-REx mission sent a spacecraft to Bennu, a “carbonaceous asteroid whose regolith may record the earliest history of our solar system,” according to the mission’s website.

OSIRIS-REx mission launch

This spacecraft will search for the molecular precursors to life and Earth’s oceans. It also will study Bennu’s physical composition in case the asteroid comes close enough to impact the Earth in the next century. In that case, knowing its makeup will be critical for any missions sent to alter its trajectory or to break it apart.

The next step of the mission will happen soon. OSIRIS-REx began its approach to the asteroid on Aug. 24. That’s when it started sending back photos of Bennu to Earth. It started the first of four asteroid maneuvers Oct. 1, slowing the spacecraft to match Bennu’s orbit around the Sun. Once it reaches its destination, the spacecraft will spend about a year and a half surveying this never-before-visited asteroid and preparing to collect a sample of surface material for return to Earth.

During the asteroid encounter, OSIRIS-REx will be formation flying with Bennu while it maps the asteroid’s surface. The survey begins in December 2018. After the sample site is selected, OSIRIS-REx will move into position to collect a sample of Bennu’s surface material. The spacecraft’s sampling arm will then touch the surface for five seconds as part of the Touch-And-Go (TAG) sampling maneuver. This is set to take place on July 4, 2020.

Bennu, a carbonaceous asteroid

The team who organized the OSIRIS-REx mission picked Bennu for a few reasons. Bennu, a carbonaceous asteroid whose regolith may record the earliest history of our solar system, may contain the molecular precursors to the origin of life and the Earth’s oceans. Bennu is also one of the most potentially hazardous asteroids, as it has a relatively high probability of impacting the Earth late in the 22nd century. OSIRIS-REx will determine Bennu’s physical and chemical properties, which will be critical to know in the event of an impact mitigation mission. Finally, asteroids like Bennu contain natural resources such as water, organics, and precious metals. In the future, these asteroids may one day fuel the exploration of the solar system by robotic and crewed spacecraft.

OSIRIS-REx stands for Origins Spectral Interpretation Resource Identification Security and Regolith Explorer. According to the mission’s website, “The mythology of the Egyptian god Osiris loosely parallels the OSIRIS-REx mission. Osiris, in his original form, was believed to have spread an understanding of agriculture throughout the Nile Delta, hence bringing life to the ancient world. Likewise, OSIRIS-REx seeks to return samples of an asteroid that may contain organics that led to the origin of life on Earth. Osiris also had a dual role as the god of the Underworld, which mirrors the destruction that large asteroid impacts have created.”