OSIRIS-REx delivered on time a gift from Asteroid Bennu

On September 24, 2023, the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) spacecraft accomplished its primary mission of delivering the asteroid 101955 Bennu sample to Earth.

Detached from the mothership at 107,000 Km from Earth, the return capsule entered the atmosphere at 14:34 UTC, after four hours of a solo journey. Its heat shield protected the precious content from the high temperatures developed by the friction with air at 44,500 Kmh.

In a few minutes, the drogue parachute deployed, stabilizing the descent at subsonic speed. Then, the main chute unfurled, slowing down the capsule at 18 Kmh and allowing it to touch down safely in the Utah Desert at 14:52 UTC, within the predetermined landing zone and at the planned time.

TOUCHDOWN! The #OSIRISREx sample capsule landed at the Utah Test and Training Range at 10:52am ET (1452 UTC) after a 3.86-billion mile journey. This marks the US's first sample return mission of its kind and will open a time capsule to the beginnings of our solar system. pic.twitter.com/N8fun14Plt
— NASA (@NASA) September 24, 2023

After being passed through the planned safety procedures, the sample container will be delivered to a new curation facility managed by NASA’s Astromaterials Research and Exploration Science division, or ARES, at Johnson Space Center in Houston.

Asteroid Bennu, a time capsule in space

Bennu was discovered on September 11, 1999, by the LINEAR (Lincoln Near-Earth Asteroid Research) survey. It is classified as a B-type asteroid, an uncommon carbonaceous rock. It has a diameter of around 500 meters and resembles a spinning top.

Broken off from a Main Asteroid Belt ancient relic, Asteroid Bennu has been chosen as the target for this sample return mission because its material is so old (4.5 billion years) that it may contain organic molecules at the origin of life on the Earth, giving new hints on the formation of the Solar System.

Mosaic image of asteroid Bennu collected by the OSIRIS-REx spacecraft from a range of 24 kilometers. Credit: NASA. — *Mosaic image of asteroid Bennu collected by the OSIRIS-REx spacecraft from a range of 24 kilometers. Credits: NASA*

Its orbit crosses the orbit of Earth every six years, defining it as a Near Earth Asteroid (NEA). Since there is a small probability that it will impact the Earth in the second part of the 22nd century, Bennu is categorized as a potentially hazardous asteroid.

OSIRIS-REx is now OSIRIS-APEX

Launched on September 8, 2016, the spacecraft reached Bennu after a two-year journey in December 2018. After two years of study orbiting the asteroid, the sampling activity happened on October 20, 2020. OSIRIS-REx left Bennu on May 10, 2021, initiating his journey back home.

OSIRIS-REx's sample collector head is placed into its Sample Return Capsule. Credit: NASA. — *OSIRIS-REx’s sample collector head is placed into its Sample Return Capsule. Credits: NASA*

The mission holds two Guinness World Records: for orbiting the smallest body ever and for the closest orbit of a spacecraft to a planetary body.

With the primary mission accomplished, the spacecraft is ready for a new assignment: the close observation of asteroid 99942 Apophis. The new target is another NEA and potentially hazardous asteroid, a bit smaller than Bennu, but much denser, categorized as an S-type (stony asteroid).

Apophis closest approach to Earth of 2029. Credit: NASA — *Apophis closest approach to Earth of 2029. Credits: NASA*

Current calculations predict a close approach of Apophis to the Earth on April 13, 2029, and OSIRIS-APEX (APophis EXplorer, its new designation) will be there to witness the rendezvous and observe the dangerous body for the following eighteen months.