NASA’s Mars Sample Return Mission in Jeopardy as U.S. Considers Abandoning RetrievalNEWS | 21 November 2025NASA’s Perseverance Mars rover took this selfie on Mars in July 2024. The rover stands next to a rock named Cheyava Falls, which scientists say may hold clues about whether the planet ever hosted microbial life.
Right now one of the most advanced planetary explorers ever built is scouring the surface of Mars. Supported by a team of hundreds of scientists back on Earth, the Perseverance rover has traveled nearly the distance of a marathon to answer some of the biggest questions about our neighboring world: What was the planet like eons ago? Was it ever habitable? Did it host life?
One rock visited by Perseverance, called Cheyava Falls, is speckled with iron-rich minerals that might be able to answer these questions, scientists announced in September. On Earth the presence of these minerals usually means microbes that used iron in the chemical reactions essential to their metabolism once lived there. Does the same hold true on Mars? A piece of Cheyava Falls is safely tucked inside the rover’s storage cache. If it can be shipped to Earth, analysis with the full range of laboratory equipment here could tell us the answer.
But Cheyava Falls’s ride to our planet might have fallen through. The Perseverance rover is the first phase of a multistep mission to bring bits of Mars to Earth known as Mars Sample Return (MSR), and the next step is dangling by a thread. The Trump administration has proposed canceling the return portion of the endeavor. The mission’s fate, as of press time, rests with the U.S. Congress.
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The situation has dismayed scientists who have longed to get their hands on Martian rocks. “We’ve been working for so many decades to try to make this happen,” says Vicky Hamilton, a planetary geologist at the Southwest Research Institute’s Colorado branch. Now that Perseverance has scooped up prized samples, scientists are faced with the prospect of leaving them on Mars to languish. “It’s hard to watch.”
Even if the mission isn’t canceled, how to finish it remains an open question. In 2024 NASA said it was scrapping its initial, troubled plan for MSR—deemed too costly and too far behind schedule—to seek cheaper commercial approaches. The agency now has multiple options on the table but has yet to decide which course to take, if any.
Perseverance has collected dozens of rock samples during its explorations across Mars. At these 12 sites, it collected cores to be stored in its onboard sample-collection tubes. NASA/JPL-Caltech
At stake are potentially profound insights about Mars. We know that some three billion to four billion years ago Mars was warm and wet, with lakes and seas on its surface. What we don’t know is whether life ever took hold there. Can we find out?
Perseverance touched down on Mars in February 2021 following a nail-biter of a landing. After the spacecraft had torn through the Martian atmosphere and descended toward the surface by parachute, a crablike, rocket-propelled platform called Sky Crane lowered the rover on cables to the surface. It landed inside Jezero Crater, a 28-mile-wide (45-kilometer) dent in the Martian landscape. A river once flowed there, and the bone-dry delta it left behind is visible from space.
If anything ever lived on Mars, Jezero is as good a place as any to look for signs of it. It’s nearly impossible, however, to send a mission to Mars that would be capable of finding life without help from labs on Earth. That’s why scientists have been lobbying since the 1960s for a way to bring pieces of Mars here.
MSR is the culmination of those efforts. In 2000 Scott Hubbard, NASA’s first Mars program director—sometimes called the “Mars Czar”—was tasked with turning around the fortunes of an ailing program that had experienced multiple failures in the 1990s, including the loss of two orbiters and a lander. “I took the existing program down to the roots, almost a bare sheet of paper,” Hubbard says. The top priority, he says, was to find out: “Did life ever exist on Mars, and could it be there today?”
Interest in Martian life had been spurred by a now infamous announcement from the White House lawn in 1996, when President Bill Clinton declared that signs of life had been detected in a Martian meteorite found in Antarctica. That claim was later refuted—but it caused enough clamor to put the search for Martian life at the top of NASA’s agenda.
NASA put a plan in place. Rovers and orbiters would probe the planet to identify good places to look for evidence of life. Then a rover would head there to grab samples, and a third phase would bring them to Earth. In 2012 NASA announced the Mars 2020 mission, which would land a rover, later named Perseverance, to collect the samples. By 2030 a follow-up mission would collect these samples and return them to Earth at an estimated cost of slightly less than $6 billion. Perseverance launched from Cape Canaveral in Florida in July 2020. Not far behind, scientists hoped, the retrieval mission would follow.
Graphic by Matthew Twombly; Source: ESA/DLR/FU-Berlin (base image of Jezero crater); Kenneth A. Farley and Vivian Sun (expert reviewers)
In September 2021 Perseverance collected its first sample, a type of volcanic rock called basalt, possibly the result of a volcano erupting into Jezero Crater after it was formed. If the stone could be analyzed and dated on Earth, it would help scientists determine the earliest time that water could have flowed into Jezero, estimated to be around 3.8 billion years ago.
Since then, the rover has been gradually making a 20-mile trek toward the rim of Jezero, traveling up the delta of the now absent river. Equipped with a sampling arm and a drill, Perseverance carries 43 cigar-size tubes into which it can deposit interesting samples it has collected, selected by scientists back home who are watching its every move.
The rover dropped 10 of these tubes at a spot called Three Forks between December 2022 and January 2023—a contingency cache in case the vehicle later failed. The most valuable samples, however, collected farther up the riverbed in locations where the prospects for life look more promising, remain onboard Perseverance. These include the Cheyava Falls tube, retrieved in March 2024, which was collected in a region called Bright Angel. “Everybody’s probably most excited about the Bright Angel samples,” says Briony Horgan, a planetary scientist at Purdue University and part of the Perseverance science team. “They have potential biosignatures in them.” The Cheyava Falls rock “has our first confident detection of organic matter,” says Perseverance’s project scientist Kenneth Farley of the California Institute of Technology. The rock’s blotches and speckles “could be associated with ancient Martian life,” Farley says. “It is the most interesting sample in our entire collection.”
Scientists get giddy thinking about what they could do with these rocks here on Earth. “We would look for a series of properties that are really hard to explain by any abiotic [nonbiological] mechanisms,” says Tanja Bosak, a geobiologist at the Massachusetts Institute of Technology and a member of the Perseverance sample science team. In other words, these samples might be our first concrete evidence of life on another world. Researchers would check for material left behind by decayed microbes, for instance, or an imbalance in two key forms of carbon, carbon-12 and carbon-13. “If you have a dead log [on Earth] with some kind of dead plant matter, you will see a lot of carbon-12,” Bosak says. Other evidence of life could include microfossils, physical shapes in the rocks themselves that might be the fossilized remains of ancient critters. “There should be some organic compounds or minerals present that we know are good at preserving microbial shapes,” she says.
Perseverance’s Sample Caching System Camera captured this close-up photo of one of its sample tubes, revealing the sample material it collected as the tube was being prepared to be sealed and stored. NASA/JPL-Caltech
It’s hard to overstate how important this discovery would be. It would constitute the first evidence of life on another world, proof that Earth was not the only place in the universe to become inhabited. We would know that with the right ingredients and conditions, life could form anywhere. The quest to bring Mars rocks home is not solely about life, though. The project could explain why the planet now has no magnetic field and barely any atmosphere—two characteristics that are probably linked. Mars’s atmosphere might have been mostly blown away by the sun billions of years ago when the planet’s core stopped generating a protective magnetic field, possibly a result of the planet cooling and plate tectonics ending.
Samples collected by Perseverance could tell us when this all happened and why. Electrons in the ground should be oriented in the direction of the planet’s magnetic field at different points in time, “like a fossil record of the field,” says Benjamin Weiss, a planetary scientist at M.I.T. and a member of the MSR sample science team. X-ray scans of the samples taken on Earth could detect these orientations, which could be matched with various data, including markings on Mars’s surface that Perseverance made when it collected the rocks. These measurements would reveal a timeline of activity in the planet’s core and maybe solve the mystery of why today Mars, compared with Earth, is such a hellhole—knowledge that could help us in the search for habitable worlds outside our solar system. Given what scientists know about Jezero Crater, there is no question that life should have been able to survive there in the past. If we find no evidence that it did, would that suggest that life struggles to arise even under the right conditions? The only way to know for sure is to finish what NASA started.
Perseverance collected the Cheyava Falls sample three months after its future was thrown into doubt. In April 2024 Bill Nelson, a former senator from Florida who was then the administrator of NASA, announced he would postpone the return portion of MSR. He cited an independent review that warned the program might end up costing $11 billion—some $5 billion more than intended—and be delayed into 2040, a decade behind the original schedule. Nelson felt the program was spinning out of control. “It was an awfully complicated plan, and this complicated plan kept getting more and more expensive,” he says. Eventually he decided that “we’re pulling the plug on this, and we’re going to start over,” he says. The decision was “disappointing and surprising” to the scientists working on the mission, Farley says. They felt a “sense that somehow everybody had let NASA down.”
There were concerns about the project elsewhere, though. Some scientists thought the sample-return project was taking attention and money away from other planetary science endeavors. “I’m on record for having criticized Mars Sample Return,” says Paul Byrne, a planetary scientist at Washington University in St. Louis. “There was a concern that if it had continued the way it was going, it could have eaten all the money for other missions.” Still, he wants it to happen—just at a more reasonable price. The planetary science community is nearly unanimous about the mission being a top priority. “We have decades of people pointing to this and saying this is the thing we want to do now,” Byrne says. “I don’t know if the community can be any louder or more fervent.”
This composite image shows the 33 sample tubes the Perseverance rover had filled as of July 2025, when it had spent 1,574 Martian days (or sols) on the Red Planet. Its collection includes 27 rock cores, two samples of regolith (Mars dirt, made of mixed rock and dust), and one atmospheric sample. The remaining three tubes are witness tubes, which Perseverance used to check how clean its sampling system was. NASA/JPL-Caltech
Bringing the samples home will require pulling off some unprecedented feats. Humanity has never attempted to launch a spacecraft from the Red Planet. The original plan was to send a lander carrying a small fetch rover built by the European Space Agency, which would collect Perseverance’s samples and load them into a rocket. That rocket would then be launched into Mars orbit, where another orbiting European vehicle would dock and collect them. But NASA scrapped the idea in 2022 because the fetch rover was deemed too heavy for a safe MSR landing.
So Nelson asked for other ideas. NASA put out a call to commercial companies and other branches of the agency, and by the end of 2024 about a dozen proposals had come in. Elon Musk’s SpaceX and Jeff Bezos’s start-up Blue Origin both submitted proposals; the details are unknown, and neither company responded to a request for comment, but SpaceX’s proposal involves using its huge Starship rocket, which is still in development. U.S. launch company Rocket Lab also submitted a proposal. Rocket Lab CEO Peter Beck claims the company could do the mission for $4 billion with a return in 2031 if it were given the go-ahead soon. That’s cheaper and quicker than many scientists at NASA had imagined. “We need to get on with it,” Beck says. “Pick a path, and let’s go.”
Because the proposals arrived at the end of the Biden administration, Nelson, who stepped down as NASA administrator in January 2025, decided to let the Trump administration make the choice in mid-2026. The delay means NASA might not be the first to bring Mars rocks to Earth, if it manages the feat at all. China aims to launch its Tianwen-3 mission to Mars in 2028 and bring samples to Earth by 2031, albeit with a much simpler mission that would collect samples from a single location.
In May 2025 the Trump administration released its proposed 2026 budget for NASA. The plan called for widespread cuts, scrapping existing space missions, shelving many climate programs and ending Mars Sample Return—which the administration described as “financially unstable”—in favor of one day sending humans to Mars. Now the project’s fate rests with Congress, which must decide whether to follow Trump’s recommendation or rescue the beleaguered mission.
A selection of raw images captured by Perseverance since it landed on Mars in 2021. NASA/JPL-Caltech
In the meantime Perseverance continues to trundle across Mars. Its plutonium power source has 10 years of juice left, putting a hard deadline on handing off the samples to a stationary MSR lander if there is no fetch rover. “If construction does not begin in the next two years, I don’t think it’s going to make it,” Farley says. “It takes four or five years at the very least to build a mission. So we’ll know pretty soon what our fate is going to be.”
The sample tubes packed inside the rover can last up to half a century. If MSR is canceled or postponed again, Perseverance could drop them somewhere on the surface in the hope that some future mission—perhaps even a human expedition—collects them. Or maybe another country, such as China, might decide to grab them. “Why not?” says Jim Green, former NASA chief scientist and director of NASA’s Planetary Science Division from 2006 to 2018. “There’s nothing on [the tubes] that says ‘Property of the United States.’”
For now Perseverance keeps storing rocks that might never be picked up. It’s now outside of Jezero Crater, heading to a region that scientists think might contain some of the oldest material yet encountered by the rover, dating back more than four billion years to the dawn of the solar system. It has fewer than a dozen sample tubes waiting to be filled.Author: Clara Moskowitz. Jonathan O'Callaghan. Source
