Perseverance Completes Its Sample Depot After 2 Years on Mars

NASA’s Perseverance rover landed on Mars on February 18, 2020, and has since been spending every Martian sol exploring the western end of Jezero Crater, imaging the Martian surface, and—vitally—collecting rock samples that will be shipped to Earth in the early 2030s.

Now, the intrepid rover has cored, stored, and dropped its final sample from the Red Planet. The sample was deposited on January 28, nearly a year since the rover picked up its first specimen from a rock on January 31, 2022.

Perseverance had a false start when it came to Martian rock collection, but it’s now amassed 27 total samples, counting its “witness tube” sample, which contains no rock but serves as a control for the mission team to monitor any potential Earthly contamination of the alien material.

The samples all come from rocks Perseverance mission scientists determined are scientifically significant, offering information about Mars’ geological, hydrological, climatological, and potentially astrobiological past.

The 10 tubes strewn about the Martian surface—deposited in erratic zigzags in Jezero, about 15 to 50 feet apart from one another—are not the first samples due to make the many-million-mile trip from Mars. That honor belongs to 17 samples still aboard the rover.

If everything goes to plan, in 10 years Perseverance will hand off the samples still in its onboard cache to the Sample Retrieval Lander, which will put the samples in the Mars Ascent Vehicle to blast off from Mars and bring the material safely to Earth, vis-a-vis a final handoff to another spacecraft in Earth orbit. Should the endeavor occur without a hitch, it’ll be the first time humankind has ever sent something to Mars and back.

All told, this is the Mars Sample Return (MSR) mission. While the whole shebang is the compelling future of the Perseverance’s samples, we’ll have to wait for the finale—the mission is slated for no earlier than 2033.

For now, the rover can move on from the Three Forks river delta. The delta was formed several billions years ago, when water once flowed on the Martian surface, and Jezero Crater was filled with Jezero Lake.

NASA chose the location for because of its potential for astrobiology. The earliest evidence for life on Earth appears in 3.5-billion-year-old stromatolites, layers of rocky material congealed by ancient microbes. Stromatolites still form on Earth today, in shallow reef systems in Western Australia.

Since stromatolites form in shallow water flows today, for NASA it followed that Perseverance should interrogate an analogous environment on Mars. Though Mars is a dry, barren place today, the Three Forks delta and its immediate vicinity is a logical place to search for life on Mars, if it did ever exist.

Now that its sample collection is done, the rover will head farther up the delta, past an outcrop called Rocky Top and toward the top of the delta itself.

“We found that from the base of the delta up to the level where Rocky Top is located, the rocks appear to have been deposited in a lake environment,” said Ken Farley, a Perseverance project scientist at Caltech, in a JPL release. “As we ascend the delta into a river setting, we expect to move into rocks that are composed of larger grains – from sand to large boulders. Those materials likely originated in rocks outside of Jezero, eroded and then washed into the crater.”

The rover (and its associated rotorcraft, the Mars helicopter Ingenuity) will continue to make new discoveries about the planet while mission staff on Earth prepare for the big trip next decade.

Until then, the backup sample tubes will lie (hopefully undisturbed) on Jezero’s flat surface, while Percy carries its first shipment up the delta.

More: Perseverance Cored Two Martian Rocks That May Be Volcanic and Shaped by Water