How to bring asteroids to Earth?

Our solar system is full of mysteries: how did it form? What is in it? How can we take advantage of its resources? How did life form? Asteroids found in our solar system may be the key to answering some of these questions, and a NASA mission launched in September 2016 aims to bring us closer to the answers.

The OSIRIS-REx mission

The OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security – Regolith Explorer) mission consists of a small spacecraft that has the objective of traveling to a near-Earth asteroid called Bennu and collecting samples to bring them back to Earth so they can be studied.

How was it done?

The OSIRIS-REx spacecraft, 6.2 m long, 2.4 m wide and 880 kg (without fuel), was launched from Cape Canaveral with an Atlas V 411 rocket in September 2016 and orbited the Sun for a year to get a gravity assist from Earth and reach the asteroid Bennu.

In 2018 the spacecraft reached the asteroid and began a scan of its surface to identify potential sample collection sites. This process lasted a year, until it finally approached the asteroid to collect the samples using the TAGSAM.

The TAGSAM (Touch-And-Go Sample Acquisition Mechanism) is an articulated robotic arm specifically designed for this task. Confirmation was obtained in October 2020 that the samples had been successfully collected. At least 60 g of the material was collected and placed in the capsule, the maximum capacity of the capsule is 2000 g.

In addition to the TAGSAM, OSIRIS-REx also had several cameras, a telescope, thermal, visible light, infrared and x-ray spectrometers, and other measurement instruments that allowed it to study the surface of the asteroid.

On May 10, 2021, OSIRIS-REx left Bennu to return to Earth. It orbited the Sun twice on its journey back. The capsule, which contained the samples and had a heat shield and parachutes, separated from the spacecraft, entered the atmosphere and landed at the Utah Test and Training Range on September 24, 2023, where it was recovered. It held 121.6 g of rock and dust from Bennu, more than twice the 60 g the mission set out to collect.

After completing its main mission, OSIRIS-REx headed for another asteroid, as it still had plenty of fuel on board. Renamed OSIRIS-APEX, the spacecraft is bound for Apophis, which will pass about 32,000 km from Earth's surface in April 2029; it will reach the asteroid in June 2029 to study how that close encounter changed it.

What is being done with the samples?

The sample was flown to NASA's Johnson Space Center in Houston, where it was extracted and cataloged. Up to a quarter of it went to the mission's science team, from 38 institutions around the world, and small portions were allocated to the Canadian and Japanese space agencies. The initial plan allowed two years to characterize and analyze the samples. The mission's sample analysis phase ended on September 30, 2026, but research continues. In April 2024 NASA published the sample catalog so that scientists outside the mission could request pieces.

Not all of the sample will be analyzed in the near future: about 70% of the sample is being preserved for future research around the world and even for future generations of scientists.

It is hoped that the results of the mission can (among other things): improve theoretical models and predictions about the orbits of asteroids, helping to monitor near-Earth objects and improving our understanding of asteroids that could collide with the Earth; confirm and refute observation techniques, one of those confirmed is a technique that could predict the composition and presence of water on Bennu; and help scientists investigate how planets formed and how life arose. Analyses of the samples published in January 2025 found 14 of the 20 amino acids that life on Earth uses to build proteins and all five nucleobases that store and transmit genetic information, along with abundant ammonia.