Richard Binzel describes how the asteroid dirt and dust delivered by OSIRIS-Rex, with help from MIT, revealed clues to the origin of the solar system. On the morning of September 24, a space capsule the size of a mini-refrigerator fell from the sky above western Utah, containing an unprecedented package: about 250 grams of soil and dust collected from the surface of the asteroid. As the candy-striped parachute deployed to slow its free fall, the capsule plummeted to the sand, slightly ahead of schedule.
The sample return capsule of NASA's OSIRIS-REx mission touches down in the desert at the U.S. Department of Defense's Utah Test and Training Range on Sunday, September 24, 2023. The sample was collected from the asteroid Bennu in October 2020 by NASA's OSIRIS-REx spacecraft. Image credit: NASA/KeeganBarber
This is NASA's first mission to an asteroid and return asteroid samples to Earth. The mission, launched in 2016, targets Bennu, a "near-Earth" asteroid thought to have formed in the first 10 million years of the solar system. The asteroid is composed mainly of carbon and minerals and has not undergone major changes since its formation. Therefore, samples collected from its surface can provide valuable clues about the kinds of minerals and materials that originally formed the early solar system.
The sample return capsule of NASA's OSIRIS-REx mission touches down in the desert at the U.S. Department of Defense's Utah Test and Training Range on Sunday, September 24, 2023. The sample was collected from the asteroid Bennu in October 2020 by NASA's OSIRIS-REx spacecraft. Image credit: NASA/KeeganBarber
OSIRIS-REx took more than two years to reach Bennu, and then spent another two years orbiting and measuring its surface, looking for locations where samples could be collected. Among the series of instruments carried by the spacecraft is an experiment designed by MIT students - REXIS (Regolith X-ray Imaging Spectrometer). The shoebox-sized instrument is the work of more than 100 MIT students, who designed it to use X-rays to map asteroid surface material to help determine where spacecraft should take samples. REXIS is a joint project of MIT's Department of Earth, Atmospheric, and Planetary Sciences (EAPS), MIT's Department of Aeronautics and Astronautics (AeroAstro), Harvard College Observatory, MIT's Kavli Institute for Astrophysics and Space Studies, and MIT Lincoln Laboratory.
On September 24, OSIRIS-REx released the capsule through Earth's atmosphere, and the spacecraft itself embarked on a new course to the asteroid Apophis. The capsule has been transported to Johnson Space Center in Houston, where Bennu's dust will be assayed and distributed to researchers around the world for further study. The successful return of the sample is a huge milestone for mission members, including MIT's Richard Binzel, a leading expert in asteroid research and a tenured professor at EAPS and AeroAstro.
As a co-investigator of OSIRIS-REX, Binzel helped lead the development of REXIS and its integration with the spacecraft. MIT News spoke with Binzel about his first reaction after the capsule landed and recovered, and what he hopes we can learn from asteroid dust.
Q: First off: What a landing! As someone who has studied asteroids in depth from a distance, how does it feel for you to see a sample of this asteroid being returned to Earth?
A: I was holding my breath like everyone else! The opening of the parachute brings a deep breath and the soft landing is a joyful release for the entire team. You work with these people for so long, you become like a family, so you feel everything together. It's like watching your child complete the balance beam and then land firmly on the ground. While I wasn't at the landing site, many of us were "together" online watching the timeline and all the proceedings. What a journey it has been over two decades, from the time we discovered with our telescopes that Bennu was a scientifically rich and accessible sampling target, to the ever-changing mission design. MIT student involvement with the REXIS instrument began in 2010. It took six years to reach the launch pad, and now we finally see the mission complete, returning the sample to Earth.
Q: Instruments on OSIRIS-REX made measurements of asteroids in orbit. What do these space measurements reveal about asteroids? Now that the samples have been returned to Earth, what else do you hope scientists will discover?
Answer: No matter how technologically advanced the instruments on the spacecraft are, they cannot reach the capabilities of laboratories on Earth. Our instruments aboard OSIRIS-REX tell us that Bennu is rich in carbon and likely contains some of the earliest chemical records of the ingredients that make up the Earth and even life itself. But how do we know that what the measurements taken by the spacecraft's instruments while flying above the surface reveal is completely accurate and how we interpret the data? We can only ensure "ground truth" by bringing actual samples into Earth laboratories. Laboratory analysis of these samples, confirming our preliminary findings, will validate our ability to interpret asteroid data from telescopes and orbiting spacecraft. Laboratory analysis will then lead us to a deeper understanding of the chemistry, conditions and processes of how our own planetary system formed.
Q: Let's salute all the students who helped bring the instruments to the mission. Looking ahead, what does this asteroid sample -- and the spacecraft's continued trajectory -- have to do with MIT's work?
A: It's a reminder that at MIT our work is limitless. Representing MIT's motto "mensetmanus" ("mind and hands"), MIT's REXIS instrument reaches hundreds of millions of miles into space, using actual hardware designed and built by students, to fly farther than any other MIT student project before. It is an honor to have so many students involved, learning and experiencing the hard work, teamwork and dedication required to succeed in space exploration.