NASA and ESA agree on next steps to return samples from Mars to Earth

The next step in the unprecedented campaign to return scientifically selected samples from Mars was taken on October 19 with a formal agreement between NASA and its partner ESA (European Space Agency). The two agencies will proceed to establish a sample tube repository on Mars. The sample depot or cache is located in “Three Forks”, an area near the base of an ancient river delta in Jezero Crater.

This cache will contain samples of carefully selected rocks on the Martian surface – samples that may help tell the story of Jezero Crater and the evolution of Mars, and may even contain signs of ancient life. Scientists believe core samples from the delta’s fine-grained sedimentary rocks, deposited in a lake billions of years ago, are the best clues as to whether microbial life existed when the climate on Mars was very different than it is today.

“Never before has a scientifically curated collection of samples been collected from another planet and brought back to Earth,” said Thomas Zurbuchen, deputy administrator for science at NASA Headquarters in Washington. “NASA and ESA have reviewed the proposed location and Martian samples that will be used for this cache as early as next month. When this first tube is positioned at the surface, it will be a historic moment in space exploration.”

The Sample Cache – a duplicate set of the collection Perseverance will keep on board – is part of a solid plan to ensure the mission’s success. The Perseverance rover will be the primary means of transporting the collected samples to the Mars launch vehicle as part of the campaign. The Three Forks depot serves as a backup and houses the duplicate set.

“The choice of the first repository on Mars makes this exploration campaign very real and tangible. Now we have a place to revisit and samples are waiting for us there,” said David Parker, ESA Director of Human and Robotic Exploration. “Being able to execute this plan so early in the campaign is a testament to the capabilities of the international team of engineers and scientists working on Perseverance and Mars Sample Return. The first depot of Mars samples can be seen as an important risk mitigation step in the Mars sample return campaign.”

The first step of the campaign is already underway. Since Perseverance landed at Jezero Crater on February 18, 2021, the rover has explored 13.2 kilometers of the Martian surface and collected 14 rock core samples during its first two scientific campaigns.

During its first scientific campaign, the rover explored the crater floor – a former lake bed – and found igneous rocks that form from magma deep underground or from volcanic activity on the surface. The second science campaign was highlighted by examining sedimentary rocks formed as particles of different sizes were deposited in the once watery environment.

The rover also collected an atmospheric sample and three witness tubes. Witness tubes contain material that helps identify potential terrestrial contamination in the tubes that may have originated from the rover during sampling.

“Although a significant mission milestone will have occurred once these tubes are jettisoned, it does not mean that Perseverance exploration or sample collection is complete — far from it,” said Ken Farley, Caltech’s Perseverance Project Scientist in Pasadena, California.

“Next we will make our way to the top of the delta to an area that appears geologically rich on satellite imagery, conduct scientific surveys and collect more rock cores. Mars Sample Return will have a lot of great things to choose from.”

Another important milestone is the entry of the Mars sample return program into the preliminary design and technology completion phase, known as Phase B, on October 1st. During this phase, the campaign focuses on completing technology development, engineering prototypes, evaluating software and legacy hardware, and other risk mitigation activities.