OSIRIS-REx Plays TAG with Asteroid Bennu; Now on It’s Way Home

After four years in space and two years of chasing and tracking it’s prey OSIRIS-REx made its final plunge toward the asteroid Bennu, giving it what can only be described as an interplanetary boop. The boop was part of a maneuver called Touch-And-Go, or TAG. The mission team had been slowly working toward this point, having conducted several orbital observations, recon flybys, and rehearsals over the past two years. The spacecraft has been operating in the vicinity of the asteroid since December of 2018.

A animation of the Matchpoint rehearsal procedure which was performed in August. (Image credit: University of Arizona)

The TAG maneuver itself was particularly genius, as such a sequence could be used in various environments. This turned out to be useful when on approach it was discovered that Bennu was much rockier than anticipated. With new information in hand and in impressive set of sensors, OSIRIS-REx’s team was able to map the asteroid down to 5 cm resolution and define four areas which would be suitable for the TAG procedure. The team chose the Nightingale area.

A animation of how the TAGSAM head collected the sample of Bennu. (Image credit: University of Arizona)

After having used nitrogen to blow dust from the surface into the TAGSAM, OSIRIS-REx is now slowly drifting back into its original orbit. Once the team has determined that enough sample was collected to be considered a success, it will head back to Earth for a 2023 landing.

Asteroid Bennu (101955 Bennu) is a cabonaceous (C-type) asteroid of the Apollo group of Near-Earth Asteroids. It is about 460 m across at its equatorial region or about the height of the Empire State Building in New York. It is an active asteroid, meaning that it sheds rocks as it moves through space. These rocks fly into orbit around the asteroid and then return to the surface. There are two charts which index the danger of particular known asteroids to Earth. The Sentry Risk Table and the Palermo Technical Impact Hazard Scale. Bennu is rated as the second most dangerous known asteroid on both scales, with future close approaches to Earth happening in 2060, 2135, and 2192.

The most important aspect of this mission is that Bennu is as old as the Solar System. Bringing back a sample will provide scientists with the opportunity to look back to the very formation of the Solar System. This will potentially give them a better picture of how life developed on Earth and not elsewhere as well as unveil some of the mysteries around how the solar system formed.

Next Horizons Spaceflight sends its congratulations to the TAG Team and wishing you every success in returning the sample to Earth!