Mission Cup 2021 Semi Finalist: OSIRIS-REx – TAG You’re It

The Mission:

NASA’s OSIRIS-REx mission was launched on the 8th of September 2016, with its target being the near-Earth asteroid Bennu. It’s the first U.S. asteroid sample return mission and is due to return to Earth in 2023 with primitive asteroid samples. The samples provided from this mission will help scientists understand the processes that were occurring in the early Solar System, improve our understanding of asteroids that could pose a threat Earth, and potentially reveal clues into the origins of life!  

OSIRIS-REx is an acronym which outlines the objectives of the mission: 

  • Origins (O): Return pristine samples of Bennu which is a carbon-rich asteroid to study the minerals and organic matter present in the asteroid. This could possibly provide clues to the origins of life! 
  • Spectral Interpretation (SI): Define the properties of Bennu that be used as a comparison with telescopic data of asteroids. 
  • Resource identification (RI): Map the chemistry and mineralogy of Bennu to understand its geological history and provide context to the samples the mission will bring back to Earth.  
  • Security (S): Measure the Yarkovsky effect on Bennu. The Yarkovsky effect is the force exerted on an object when sunlight is absorbed and released which, in the case of Bennu, is thought to be the reason behind the change of the asteroids orbit over time. 
  • Regolith explorer (REx): Determine the physical and chemical proprieties of the material at the surface of Bennu (regolith)

Why Bennu?

Asteroid Bennu was selected as the target for the OSIRIS-REx mission for a number of reasons. One reason is Bennu’s proximity to Earth. Bennu is classed as a Near-Earth Object (NEO) and every 6 years it comes within 0.002 AU of the Earth (which is very close)! Bennu also orbits the Sun in a similar plane to Earth making it an easier target to launch to. Another reason Bennu was selected is because it potentially poses a threat to Earth as it has been estimated that Bennu has a 1-in-2700 chance of impacting the Earth in the 22nd century! Scientists therefore want to gather as much information about Bennu as possible so they can be better informed on how to deal with any threat that Bennu could pose in the future. One of the reasons that sample scientists, such as myself, are excited that Bennu was selected is due to its composition. Asteroids are split into different types based on their chemistry (for example, Bennu is classed as B-type asteroid). The most primitive asteroids (i.e., the asteroids that haven’t changed much since they formed at the start of the Solar System ~4.5 billion years ago) are carbon rich. These particular asteroids contain organic molecules, amino acids, and volatiles that may provide clues into the origins of life! 

An image of asteroid Bennu taken by the OSIRIS-REx spacecraft (Credit: NASA).

Mission Updates:

OSIRIS-REx successfully collected rocky material from the surface of Bennu at the Nightingale sample site on the 20th Oct 2020. Nightingale is located in a crater in the northern region of Bennu. It was chosen as the primary sample site as the crater is thought to be relatively young and regolith is freshly exposed allowing for a pristine sample to be collected. 

OSIRIS-REx has a novel sample collection method called the Touch-and-Go (TAG) Sample Collection manoeuvre (SAM) which means instead of landing to collect a sample, OSIRIS-REx could essentially just fist-bump Bennu to retrieve a sample. When the TAG-SAM made contact with Bennu it released a puff of nitrogen gas which disturbed Bennu’s fragmented surface causing rocky pieces, dust and pebbles to be kicked up from the asteroids surface and then collected. To see how it works you can check out this YouTube video courtesy of NASA. You can also watch footage of the sample collection here

NASA’s OSIRIS-REx team confirmed that the spacecraft collected more than the target amount of material (which was 60 grams). OSIRIS-REx collected so much sample that it’s sampling head couldn’t close properly! But thankfully the OSIRIS-REx team managed to sort the issue and secure the sampling head, all while the spacecraft was ~205 million miles from Earth! With the samples now safely intact, OSIRIS-REx is set to return them to Earth on the 24th September 2023. 

The Nightingale sampling site for OSIRIS-REx (Credit: NASA/Goddard/University of Arizona).
Image taken by OSIRIS-REx during it’s successful TAG-SAM to collect samples of Bennu (Credit: NASA).

Why I Nominated OSIRIS-REx:

For my PhD I study a type of meteorite called a chondrite. Chondrites are the oldest known rocks are come from asteroids. Some asteroids, like Bennu, haven’t changed much since they formed ~4.5 billion years ago making them scientifically valuable to study.  Asteroids are fundamental to our understanding of how our Solar System formed and the OSIRIS-REx mission will provide scientists with key clues and insights into this as well as improve our understanding of asteroids that could pose a threat Earth, and potentially reveal clues into the origins of life! What’s not to like about this mission?! Make sure to vote for OSIRIS-REx in the semi-finals of Mission Cup 2021! 


Head over to our twitter page @EarthSolarSystm to cast your vote in Mission Cup 2021!

About aimeesmith1995

I am a 2nd year PhD student at The University of Manchester studying the formation of chondrules in the early Solar System. I experimentally reproduce chondrules in the lab using a furnace to determine the temperatures and cooling rates required to form the various types observed in chondritic meteorites.
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