Ask a Scientist: Dr. Michelle Thompson discusses NASA's OSIRIS-REx

10-20-2020

Writer(s): Cheryl Pierce

Photo by Purdue University Marketing and Media

Today the world watches and waits with great anticipation to see if the NASA OSIRIS-REx Mission can collect samples from an asteroid, Bennu, that is flying by.  The mission to Bennu began in August of 2018 with the goal of collecting samples and bringing them back to Earth for scientists to study.  Because the mission began two years ago, today may be the first you are hearing about this marvel of space innovation so we have asked Dr. Michelle Thompson of the Department of Earth, Atmospheric, and Planetary Sciences at Purdue University to help answer questions. Thompson runs the LEAPS Lab at Purdue University, has worked directly with the team on the OSIRIS-Rex Mission, is currently studying samples from the Apollo Mission.

Can you briefly describe the mission?

“This mission is an incredible, unparalleled opportunity to study an asteroid up close and to bring back material from a primitive, organic-rich planetary body. The samples will represent some of the earliest solar system materials - the remnants left over after building our planets. These samples will likely contain organic molecules which may give us clues to the building blocks of life here on Earth. This mission will give us a window into the early solar system, giving us clues to how our planetary bodies formed and have evolved over time.”

What do you hope to find in the samples that return?

“I am hoping to find signatures of space weathering at the microstructural and chemical level that will explain some of the interesting spectral features on asteroid Bennu. Since this has never been done before, anything we see in these samples will be amazing and we probably will find lots of things we didn’t expect!” 

You have worked directly with the mission team and have collaborated on publications.  Can you tell us a bit about this? 

“I have collaborated quite a lot with the Space Weathering Working Group on OSIRIS-REx. We work to understand the alteration of the surface of asteroid Bennu because of its exposure to interplanetary space - a process known as space weathering. Understanding this process is very important because it changes the optical properties of surface material that we observe with remote sensing spacecraft. In order to understand the composition of these planetary bodies, we have to understand space weathering. The work I have collaborated on with the team has showed that this process operates much differently on carbonaceous asteroids than on other planetary bodies that we have studied, which is very exciting.”

Today the goal, if I have it correct, is to collect the samples.  Is there a set amount of attempts OSIRIS can make?

“Yes, today they will perform their first attempt at sampling. The goal is to collect a minimum of 60 g (though they can actually collect up to 2000 g). They can make unlimited approaches to the surface but as for touching the surface to collect the sample, they can make 3 attempts. Once they have collected material, they will measure how much they have and decide whether they need to make another attempt.”

You have collaborated with the team handling sample returns.  Can you tell us about their role in the mission?

“The space weathering working group that I collaborate with is very important because they give information about how fresh or weathered the surface is. This is important information for guiding the selection of the sampling site.”

What would samples returned from this mission mean to your science?  Would you be working with any of the returned samples?

“These samples will be transformative for myself and my research group. I have spent the last four years performing experiments on analog samples to try and understand space weathering processes in advance of sample return. I can’t wait to be able to do these analyses on the samples we bring back. I hope to work with them when they arrive back on Earth.” 

Once the sample is collected, it will have a return journey to get back to the Earth.  Is that a given?  Or is there quite a bit of risk in the return?

“Any mission in space is risky. However, the sample return capsule design is based on the Stardust mission, which successfully collected material from a comet and returned those particles safely to Earth. The success of that mission lends high confidence to the OSIRIS-REx samples making it back to Earth safe and sound in fall of 2023.”

Are there other people at Purdue who have helped?  Do you have students who also contribute?

“I have two students, Dara Laczniak and Laura Chaves who are each working on projects related to OSIRIS-REx. Dara is trying to understand how energetic particles from the solar wind can alter these materials, which is an important component of space weathering. Laura is working to understand how sulfide minerals (minerals that have sulfur in them) respond to space weathering. These minerals are an important component of Bennu. Both of these students want to work with samples brought back from OSIRIS-REx one day!”

Are there other missions like this happening at the same time?  If not, if this is successful, would this mean future missions?

“There is a mission run by the Japan Aerospace Exploration Agency (JAXA) which has completed sampling of another asteroid (Ryugu) called Hayabusa2. Hayabusa2 collected samples last year and is already on its way to Earth. Both of these missions are incredibly important because initially, scientists thought the asteroids may have similar compositions. Analysis of remote sensing data however, has shown there are many differences between the two asteroids. Having samples from both asteroids will give us an incredible opportunity to compare these bodies and help us understand why they have evolved so differently.”