Asteroid Bennu Sample Return Mission!

In the October 2016 and February 2019 issues of Apsley Backroads, we wrote about the launch of a spacecraft called OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer) to a near-Earth asteroid called Bennu. The OSIRIS-REx mission is NASA’s first sample return mission to an asteroid. And it was successful!


  • launched in September 2016
  • arrived at Bennu in December 2018, spent some time mapping the asteroid’s surface, then went into orbit around Bennu
  • made a brief touchdown on Bennu’s surface in October 2020 to collect samples from the surface
  • started heading back to Earth in May 2021 with the samples safely stowed in a capsule
  • dropped off the capsule to land in the Utah desert in September 2023
  • headed away from Earth on its way to another asteroid, Apophis
  • had a name change to go with the new mission: OSIRIS-APEX, or OSIRIS APophis EXplorer

The sample capsule landed safely in the Utah desert. It was then transported to Houston for study and sample distribution. Credit: NASA/Keegan Barber

Once the capsule landed, the OSIRIS-REx team carefully prepared it for transport to Houston, Texas. The capsule contains around 250 grams of material from the surface of Bennu. Most of the material will remain in Houston for study and for retention for future scientists. Canada will get about 4% of the sample, or around 10 grams, in return for providing an instrument on the spacecraft, a laser called the OSIRIS-REx Laser Altimeter, or OLA. MacDonald Dettwiler & Associates (MDA), an aerospace company in Brampton, built the OLA.

The contents of the capsule were revealed on October 11. The volume of the sample can fit a coffee mug. The grains seen in the image vary—some are carbon-rich, some are sulphur-rich, some contain water, and some are metallic. Scientists think that asteroids laden with water collided with Earth and supplied Earth’s first water sources. Credit: NASA

Like Bennu, Apophis is a near-Earth asteroid, and its orbit will bring it close to Earth in 2029. OSIRIS-APEX will arrive at Apophis in 2029 and visit for about 18 months. Unfortunately, OSIRIS-APEX doesn’t have another lander to capture surface material and return it to Earth.

While Bennu and Apophis are both asteroids, they have different compositions, which is why scientists are interested in studying them. Asteroids and meteoroids are from “families.” Some families are rocky, and some are metallic. Apophis is a chondrite, which means it is stony with no metals. Bennu is more carbon-based, the type of asteroid thought to deliver water to the solar system, hence, possibly contributing to the formation of life. When studying Bennu, scientists will be looking for evidence of amino acids, the building blocks of life. They will also be trying to learn more about the formation of the solar system around 4.6 billion years ago, since asteroids are remnants from that time, untouched by weather and other erosion processes. Finally, scientists hope to learn about deflecting asteroids that come too close to Earth.