Facts Worth Sharing
- NASA’s OSIRIS-REx spacecraft will return a sample of asteroid Bennu to Earth in 2023.
- Asteroids, comets, and other small worlds are leftover planet-building materials from the birth of our solar system. Some may have brought water and the building blocks of life to Earth.
- Sample return is important because certain kinds of scientific experiments can only be done on Earth. OSIRIS-REx's samples will help us understand the solar system's early days.
Why We Need OSIRIS-REx
Our solar system is filled with countless asteroids, comets, and other small worlds left over from the disk of dust and gas that formed the planets 4.5 billion years ago. We think some of these worlds slammed into early Earth, bringing water and carbon-containing materials called organics here that formed the basis of life as we know it.
On Earth, weather and geological processes constantly alter the surface, but that's not the case on asteroids, which have remained largely unchanged. By studying them, we see what our infant solar system was like. Bennu is a near-Earth asteroid containing carbon and water. Although modern spacecraft instruments can tell us a lot about other worlds, there are certain kinds of experiments that can only be done on Earth.
What we really need is a sample, so OSIRIS-REx—a backronym that stands for Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer—will bring us one in 2023. The spacecraft launched in September 2016, arrived at Bennu in December 2018, and successfully collected a sample in October 2020.
OSIRIS-REx will also help us learn more about defending our planet from dangerous asteroids. Small worlds like Bennu, which is just 500 meters (a third of a mile) across, can have their orbits altered by small forces like heat emission in ways we don’t fully understand. These forces can add up over time and mean the difference between an asteroid missing Earth or slamming into it. OSIRIS-REx will study one of these forces, called the Yarkovsky effect.
In 2013, The Planetary Society, University of Arizona, and MIT held a naming contest for asteroid Bennu, which until then had been called 1999 RQ36. We also collected names to travel aboard OSIRIS-REx through our Messages from Earth program. If you sent your name, you can look up your certificate here!
The OSIRIS-REx mission is projected to cost $1.16 billion over 15 years. The Planetary Society has additional context to help you fully understand this number.
How OSIRIS-REx Works
OSIRIS-REx is a van-sized spacecraft weighing more than 2 metric tons, with half of that weight in fuel. It has a 3-meter-long sample arm and solar panels that fold back, giving it extra room to maneuver near Bennu’s surface and protect it from debris kicked up during sample collection. The spacecraft's small instrument deck is packed with science gear to study Bennu’s composition, map the surface, and more.
Upon arrival, OSIRIS-REx found that Bennu was much rockier than expected, with no areas that met the mission's original safety criteria for collecting a sample. Fortunately the spacecraft navigates with high precision, comparing the view from its cameras to stored images of Bennu’s landscape. This allowed scientists to settle on a sample location no larger than a few parking spaces.
In October 2020 OSIRIS-REx high-fived Bennu with a cylindrical device called TAGSAM at the end of its sample arm. Upon touching the asteroid, TAGSAM fired a blast of nitrogen gas into the surface, stirring rocks and soil into a collection chamber. The operation was so successful, a flap on the sample collection chamber was jammed open by asteroid material!
OSIRIS-REx will leave Bennu in May 2021 and return to Earth in 2023, where it will drop the sample collection capsule into our planet’s atmosphere. The capsule will land via parachute in the Utah desert.
OSIRIS-REx touchdown on Bennu video This video shows 82 images captured as NASA's OSIRIS-REx spacecraft touched the surface of asteroid Bennu to collect a sample on 20 October 2020. The sample head touches Bennu's surface for 6 seconds while a bottle of nitrogen gas stirs rocks and soil into a collector. The spacecraft then backs away using its thrusters, as debris fills the camera view.Video: NASA/Goddard/University of Arizona
How You Can Support OSIRIS-REx
Planetary Society co-founder Carl Sagan once said that when you’re in love, you want to tell the world. Space missions like the [Mission] are dependent upon sustained public enthusiasm from people like you. You know your audience best; we've got tools to help.
Tell the World
- Spread the Facts Worth Sharing at the top of this article on social media
- Send this page to others using the short URL planetary.org/osiris-rex
- Share pretty pictures of Bennu and OSIRIS-REx
- Find out why missions to asteroids, comets, and other small worlds like Bennu are so important
- Stay up to date on OSIRIS-REx and other missions by signing up for The Downlink, our weekly newsletter
- Find out how The Planetary Society is working to reduce the cost of sample collection with PlanetVac
Ready to take your next steps as a space advocate? Become a member and find out how you can take action in your community and government.
OSIRIS-REx in Recent Articles, Newsletters, and Podcasts
Even Sagan would be amazed by multitudes we now know our cosmos may hold. Learn more, plus get your scoop on the week’s space news.
Catch up on news from across the ghoul-axy and beyond.
The leader of the OSIRIS REx asteroid sample return mission shares more details of last week’s encounter in an exclusive interview, while we also learn about the proposed mission to look for life on Saturn’s moon Enceladus.