Mars Sample Return: The Critical Decision Point Awaits in 2026

NASA’s Mars Sample Return Initiative Faces Difficult Decisions

By Lee Billings edited by Dean Visser

NASA’s challenged Mars Sample Return program is at a critical junction—and is anticipated to linger in uncertainty at least until 2026—officials from the agency stated during a press briefing on Tuesday.

Commonly referred to as MSR, this collaborative endeavor between NASA and the European Space Agency (ESA) has been in development for decades. It is widely regarded as a key element for the U.S. and Europe’s upcoming interplanetary science and exploration efforts—and as an initial step toward more ambitious human missions that aim to travel to and return from Mars. The project’s first stage is already well underway: NASA’s Mars rover Perseverance has spent a significant portion of the last four years traversing a vast ancient lake bed and river delta within the Jezero Crater, where it has been collecting samples in some of the 43 cigar-sized titanium tubes it carries onboard. Scientists assert that analyzing these materials would fundamentally change our understanding of the solar system’s early history, when Mars was believed to be warmer, wetter, and likely more hospitable. In theory, the samples could even lead to the first-ever discovery of extraterrestrial life.

To successfully transport this invaluable cargo back to Earth in the early to mid-2030s, as intended, NASA’s initial MSR strategy proposed to launch a new lander around 2027–2028; this lander would rendezvous with Perseverance on the Red Planet and transfer the samples to a canister within a Mars Ascent Vehicle (MAV). The MAV would then ascend from Mars to meet up in space with an Earth Return Orbiter supplied by ESA, which would subsequently transport the sample canister back for a final descent to our planet’s surface with a parachute-assisted landing.

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However, this intricate sequence faced significant political and financial obstacles in September 2023, when a formal reassessment indicated that MSR’s projected cost had soared from approximately $4 billion to a staggering $11 billion—merely to return the precious samples to Earth no sooner than 2040. U.S. lawmakers threatened total cancellation, prompting NASA administrator Bill Nelson to pause the MSR project, subsequently leading to layoffs and increasing anxiety at the Jet Propulsion Laboratory, or JPL, which oversees the MSR initiative. Concurrently, NASA began seeking proposals for new strategies from both internal sources and external commercial entities. In October, the agency established an independent review team to evaluate 11 proposals and devise a path forward.

During Tuesday’s briefing, the findings from that independent evaluation were disclosed, presenting two potential options for a more efficient, cost-effective MSR. Both approaches aim to reduce expenses by minimizing the mass delivered to Mars. They also exhibit certain common characteristics, such as equipping the sample-retrieval lander with a simpler spare robotic arm from Perseverance’s development and redesigning the MAV to utilize a compact radioisotope power source instead of the more complex solar panels. The first alternative for deploying a sample-retrieval lander on Mars would utilize an enhanced version of a proven technology: the JPL-developed, hovering “sky crane” mechanism that successfully landed the Curiosity and Perseverance rovers. The second option would instead use an as-yet-unnamed commercial heavy-lift vehicle to bring the sample-retrieving lander to the Martian surface—most likely a variant of the substantial rockets being developed by companies such as SpaceX and Blue Origin. “Either of these two options is constructing a significantly simplified, quicker, and less costly version than the initial plan,” Nelson stated during the briefing. The sky crane strategy is projected to cost between $6.6 billion and $7.7 billion, whereas the commercial heavy-lift choice would be estimated at $5.8 billion to $7.1 billion. The ESA’s cargo-carrying orbiter could launch from Earth in 2030, with NASA’s sample-collecting lander following in 2031. The return to Earth could potentially happen as soon as 2035 or as late as 2039.

However, citing the necessity for further detailed engineering investigations—along with budgetary uncertainties and the need to consider the incoming administration of U.S. President-elect Donald Trump—Nelson statedNASA will not finalize its decision between the two alternatives until mid-2026. Furthermore, to ensure the program remains on schedule, he stated, congressional financiers would still need to allocate a minimum of $300 million to MSR in the current fiscal period—an amount that must be maintained “every year [of the program] in the future.”

“I believe it was prudent not to present the new administration with just one option,” Nelson stated, “if they [even] consider pursuing a Mars sample return—which I can hardly believe they wouldn’t.”

Nicola Fox, associate administrator for NASA’s Science Mission Directorate, shared her enthusiasm for the new strategy during the briefing. “I’m thrilled about both directions,” she said. “I think we can truly achieve this if we collaborate with our partners—with our international allies, with our commercial collaborators, with all our fantastic NASA proficiency.” The Perseverance rover, she pointed out, is “very robust and stable” on Mars and has already filled 28 of its titanium tubes with meticulously curated samples of Martian stones, sediments and air. Ten of those tubes have been stored on the planet’s surface as a contingency should Perseverance fail and be unable to reach a retrieval lander. The revised strategy proposes leaving them behind in favor of recovering a significantly larger haul: 30 tubes to be stored inside Perseverance, which we hope will still be fully functional in the 2030s. Meanwhile, Fox remarked, there are “13 intriguing tubes still yet to be filled…. We are extremely confident we can return all 30 samples before 2040—and for under … $11 billion.”

That ambition for a greater number of samples excites MSR’s chief scientist Meenakshi Wadhwa, a Mars specialist at Arizona State University. “I’m particularly pleased that the objective is to bring back as many as 30 sample tubes as early as 2035,” she states. Those samples “will tackle essential inquiries for us as humans and transform our comprehension of planet-formation processes in our solar system and beyond.”

Harry McSween, a long-time Mars sample return advocate and a professor emeritus at the University of Tennessee, Knoxville, also highlights the significance of retrieving as much material as possible. “The scientific benefit from MSR necessitates meticulously chosen samples collected from a site thoughtfully selected to address pivotal questions—not merely acquiring samples from anywhere on Mars,” he states. This stands in sharp contrast to what may be the most compelling motivator for MSR’s ongoing political backing: a rival sample-return initiative by China, which appears to involve a considerably simpler “grab and go” mission to collect some samples from a single, easily reachable location on Mars. This could enable China to potentially cross the finish line first in a hypothetical race to bring Martian materials back to Earth—but at substantial scientific expense.

Others are less convinced that Tuesday’s announcement is cause for celebration. “I’m glad to see MSR not canceled, but we need to make a decision and proceed sooner rather than later,” remarks Casey Dreier, chief of space policy at the Planetary Society. “I’m concerned that MSR has remained in limbo for such an extended period…. The proposed path forward is merely additional studies. NASA needs to commit to a mission or not and determine the next steps from there.”

To Dreier and others, the decision appears to be between a presumably JPL-led sky crane—a “stick with what you know” strategy—and a more uncertain and risky dependence on innovations from commercial enterprises. For the latter, “clearly [NASA is] discussing SpaceX, the only viable company that could undertake this capability—via Starship,” SpaceX’s in-progress, fully reusable heavy-lift vehicle, Dreier mentions. “That does necessitate Starship to be operational, however, and [to reach] Mars.” Utilizing Starship could “strengthen the argument for MSR functioning as an uncrewed demonstration mission for a future crewed Mars endeavor,” Dreier adds. This could potentially align this high-priority NASA scientific mission with the agency’s broader ambitions in human space exploration.

“I believe there’s a feasible path there,” Dreier concludes. “But that still relies on numerous uncertainties.”