The Perseverance rover will cache about half the 14 rock cores that it has drilled as early as November. Some of these samples could be returned in a future sample return mission.
Mission planners called the cache a safeguard for the sample return mission. It provides a backup location that a future lander could land at to retrieve samples.
Perseverance landed in Jezero Crater on February 18, 2021. Its mission includes scouting for conditions that would have been suitable for life. This includes collecting samples that could be returned to Earth for scientists to analyze with sophisticated instruments that aren’t available on Perseverance.
The sample return mission could bring the samples back as early as 2033 – a minimum of twelve years after Perseverance landed. NASA’s Mars probes have a pretty good track record for outlasting their initial planned missions once they reach Mars.
(Yes, many missions to Mars have failed. However, NASA has the best success rate out of the space agencies that have sent multiple missions to Mars.)
However, NASA has no guarantees that Perseverance will last long enough to reach a good spot for the sample return mission to land. Sometimes rovers get stuck in sand pits. The Spirit rover never made it out of one.
This could explain NASA’s reasoning for wanting the backup cache even though it officially didn’t say so out loud.
“This is our backup sample cache, just in case the rover itself can’t deliver samples,” said Jim Bell of Arizona State University during a presentation at the recent 2022 Mars Society Conference. The presentation was live-streamed in the below video.
Jim Bell is the principal investigator for Perseverance’s Mastcam-Z camera system. The Mastcam-Z camera can zoom, take video, and produce 3D photos to inspect distant objects that scientists might be interested in studying.
“Mastcam-Z will be the main eyes of NASA’s next Mars rover,” Bell said before Perseverance landed on Mars.
The sample return mission will include two mini-helicopters similar to Ingenuity, which became the first flying machine to operate on Mars. The two helicopters will be capable of carrying samples back to a “base” that includes a launcher to return the samples to an orbiting spacecraft that can return to Earth. They can visit multiple caches of samples if they need to.
Mission planners intend to create the first cache in a region known as Three Forks, a relatively flat place that is suitable for helicopter landings. Perseverance still has a way to go and will likely perform scientific experiments along the way. It is currently collecting samples of regolith.
Because mission planners try to stay flexible enough to allow the rover to investigate an interesting object or detour around an obstacle, they couldn’t announce exactly when it would reach Three Forks and deposit the first cache. They only said as early as November, though it might get pushed back to December.
Perseverance carries 43 titanium tubes. NASA expects to fill as many as 38 of them with rock samples that could be returned to Earth. So far, it filled 15 of them with samples, one of which is an “air sample” from a failed rock sample collection. Perseverance also failed to properly seal one of the samples.
The sample return mission will be a collaboration between NASA, ESA, and JPL. If all goes as planned, the orbiter will launch as early as 2027 and the lander could launch in 2028. The returned samples could bring scientists closer to answering longstanding questions about any hypothetical past or present life on Mars – such as whether life ever existed.