The Fate of NASA’s Mars Sample Return Program May Be Decided in 2026

NASA’s Mars Sample Return Program Faces Stark Choices

By Lee Billings edited by Dean Visser

NASA’s troubled Mars Sample Return program is stuck at a crossroads—and is likely to remain in limbo until at least 2026—agency officials said at a press briefing on Tuesday.

Colloquially called MSR, the joint effort between NASA and the European Space Agency (ESA) has been decades in the making. It is widely seen as a linchpin for the U.S.’s and Europe’s near-future interplanetary science and exploration—and as a first step toward more ambitious there-and-back-again human missions to Mars. Its opening phase is already well underway: NASA’s Mars rover Perseverance has spent much of the past four years trundling around a sprawling ancient lake bed and river delta within the Red Planet’s Jezero Crater, where it has stuffed samples into some of the 43 cigar-sized titanium tubes that are carried onboard. Analyzing these materials, scientists say, would at minimum transform our understanding of the solar system’s early history, when Mars was warmer, wetter and presumably more habitable. And in principle, the samples could even deliver the first-ever discovery of extraterrestrial life.

To bring this precious cargo to Earth in the early to mid-2030s, as desired, NASA’s original MSR plan envisioned launching a new lander circa 2027–2028; it would meet Perseverance on the Red Planet and transfer the samples to a canister within a Mars Ascent Vehicle (MAV). The MAV would blast off from Mars to rendezvous in space with an ESA-provided Earth Return Orbiter, which would then ferry the sample canister back for a final, parachute-slowed plunge to our planet’s surface.

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But this complex choreography ran into heavy political and fiscal headwinds in September 2023 when a formal reappraisal revealed that MSR’s estimated cost had grown from about $4 billion to as much as a budget-busting $11 billion—all to only bring the precious samples back to Earth no earlier than 2040. U.S. lawmakers threatened outright cancellation, and NASA administrator Bill Nelson put MSR on hold, triggering layoffs and exacerbating anxiety at the space agency’s Jet Propulsion Laboratory, or JPL, which leads the MSR program. Meanwhile NASA began soliciting proposals for new plans from within, as well as from external commercial companies. Last October the space agency formed an independent strategic review team to assess 11 accepted proposals and plot a way forward.

Tuesday’s briefing revealed the results of that independent assessment, giving two potential options for a speedier, cheaper MSR. Both seek to save costs by delivering less mass to Mars. They also share certain corresponding features, such as outfitting the sample-retrieval lander with a simpler spare robotic arm left over from Perseverance’s development and redesigning the MAV to use a compact radioisotope power source rather than more finicky solar panels. The first option for getting a sample-retrieval lander on Mars would employ a beefed-up version of a tried-and-true technology: the JPL-developed, hovering “sky crane” platform that landed the Curiosity and Perseverance rovers. The second would instead bring the sample-retriever lander to Mars’s surface via an as-yet-unspecified, commercial heavy-lift vehicle—most likely some variant of the massive rockets that are being developed by companies such as SpaceX and Blue Origin.

“Either of these two options are creating a much more simplified, faster and less expensive version than the original plan,” Nelson said during the briefing. The sky crane approach, he said, would cost between $6.6 billion and $7.7 billion, while the commercial heavy-lift option would range from $5.8 billion to $7.1 billion. ESA’s cargo-ferrying orbiter could launch from Earth in 2030, followed in 2031 by NASA’s sample-snatching lander. And the return to Earth could occur as early as 2035 or as late as 2039.

But, citing the need for more detailed engineering studies—plus budgetary uncertainties and a deference to the incoming administration of U.S. President-elect Donald Trump—Nelson said NASA won’t choose between the two options until mid-2026. And to keep the program on-track, he added, congressional appropriators would still need to allocate at least $300 million to MSR in the current fiscal year—an amount that would need to be sustained “every year [of the program] going forward.”

“I think it was a responsible thing to do, not to hand the new administration just one alternative,” Nelson said, “if they [even] want to have a Mars sample return—which I can’t imagine that they don’t.”

Nicola Fox, associate administrator for NASA’s Science Mission Directorate, expressed optimism for the new plan during the briefing. “I’m excited about both paths,” she said. “I think we can really do this if we work together with our partners—with our international partners, with our commercial partners, with all our amazing NASA expertise.” The Perseverance rover, she noted, is “very healthy and stable” on Mars and has already filled 28 of its titanium tubes with carefully curated samples of Martian rocks, sediments and air. Ten of those tubes have been cached on the planet’s surface as a backup in the event Perseverance breaks down and can’t travel to a retrieval lander. The new plan calls for abandoning them in favor of bringing back a significantly heftier haul: 30 tubes that will be stashed inside Perseverance, which hopefully will still be fully operational in the 2030s. Meanwhile, Fox said, there are “13 tantalizing tubes still left to be filled…. We are very confident we can return all 30 samples before 2040—and for less than … $11 billion.”

That push for a larger number of samples sounds exciting to MSR’s chief scientist Meenakshi Wadhwa, a Mars expert at Arizona State University. “I’m especially pleased that the goal is to bring back as many as 30 sample tubes as early as 2035,” she says. Those samples “will address fundamental questions for us as humans and revolutionize our understanding of planet-building processes in our and other solar systems.”

Harry McSween, a longtime Mars sample return proponent and a professor emeritus at the University of Tennessee, Knoxville, also emphasizes the importance of retrieving as much material as possible. “The scientific payoff from MSR requires carefully selected samples collected from a site thoughtfully chosen to address critical questions—not just grabbing samples from anywhere on Mars,” he says. This is in pointed contrast with what may be the most potent motivator for MSR’s ongoing political support: a competing sample-return effort by China, which appears to involve a far simpler “grab and go” mission to retrieve some number of samples from a single, easily accessible spot on Mars. This could push China first over the finish line in a notional race to return Martian materials to Earth—but at considerable scientific cost.

Others are less certain that Tuesday’s announcement is something to celebrate. “I’m happy to see MSR not cancelled, but we need to make a decision and move forward sooner rather than later,” says Casey Dreier, chief of space policy at the Planetary Society. “I’m worried that MSR has remained in limbo for so long…. The path forward they promised us is merely further studies. NASA needs to commit to a mission or not and decide where to go from there.”

To Dreier and others, the choice appears to be between a presumably JPL-led sky crane—a “go with what you know” approach—and a more uncertain and fraught reliance on innovations from commercial companies. For the latter, “obviously [NASA is] talking about SpaceX, which is the only feasible company that would take on this capability—via Starship,” SpaceX’s in-development, fully reusable heavy-lift vehicle, Dreier says. “That does require Starship to be working, however, and [to reach] Mars.” Utilizing Starship could “make a stronger case for MSR serving as an uncrewed demonstration mission for a future crewed Mars campaign,” Dreier adds. That could potentially unify this high-priority NASA science mission with the space agency’s broader goals in human spaceflight.

“I think there’s a path there,” Dreier concludes. “But that still assumes many unknowns.”