The motto at NASA’s Jet Propulsion Laboratory (JPL) is “dare mighty things,” and in building Mars Sample Return (MSR), it is certainly doing that. The multispacecraft mission, planetary scientists’ top priority, will collect rocks gathered by the Perseverance rover that is now exploring Mars. It will rocket them off Mars, catch them in orbit, and, as early as 2033, ferry them to Earth— where they will be scrutinized for signs of life and clues to martian history.
The cost of the mission may become altogether too mighty, however. The most recent official figure now puts it at some $6 billion, up from some $4 billion, and a leaked report suggests that, in one scenario, it could exceed $8 billion. Cost overruns for MSR and a few other large missions have already forced NASA to squeeze or delay other science missions, and calls to rethink—or even kill—MSR have grown. When an independent review of the project delivers a fresh cost estimate later this month, advocates are praying it stays well below $10 billion, which has emerged as a sort of red line for the mission. “It’s fair to say that the future of Mars Sample Return lives and dies with the recommendations of that panel,” says Casey Dreier, chief of space policy at the Planetary Society.
The increases stem in part from underestimates of how big the lander needs to be, along with the extensive steps needed to prevent earthly contamination of the samples, and vice versa. Inflation and supply chain shortages also played a role. But NASA hasn’t clarified the issues further, Dreier says. “We don’t really know what the problem is here.”
Fears for the mission escalated in July, when the Senate committee that oversees NASA spending warned it would be canceled if the agency couldn’t keep costs to $5.3 billion. The corresponding House of Representatives committee is likely to be more supportive, however. In the end Congress might work with the agency to set a new but stricter cost cap, much as it did a decade ago for the $10 billion JWST space telescope, a budget-busting mission that became too big to fail, says Allen Cutler, CEO of the Coalition for Deep Space Exploration and a former appropriations staffer focused on NASA. “Nerves have been touched. The Senate is letting NASA know that they’ve got some work to do.”
But some planetary scientists would be glad to see the Senate follow through with its threat. One is Darby Dyar of Mount Holyoke College, who serves as deputy principal investigator for Veritas, a mission selected in 2021 to map Venus with radar. Late last year, NASA delayed Veritas until 2031 or later because of staffing shortages at JPL and cost overruns with MSR and other large missions. NASA has kept the science team on a “life support” fund of $1.5 million, Dyar says, but “the team is losing people like crazy.” Meanwhile, MSR’s potential scientific return does not excite her. “Do I actually believe we’ll find signs of life in the returned samples? No.”
NASA has also postponed its next billion-dollar mission in the New Frontiers series by 3 years, and it is delaying work on a flagship Uranus probe. The damage is not confined to NASA’s planetary science division. Most prominently, the agency postponed work on the $1.4 billion Geospace Dynamics Constellation, six satellites that will study the upper atmosphere, causing universities to lay off staff hired to work on GDC instruments. “You’re cutting the artery, the lifeblood, of our science,” says space physicist Allison Jaynes of the University of Iowa. “All of NASA science is taking a hit because of the MSR burden.”
NASA has been using its smaller missions as “piggy banks” for problems with larger projects, says Sean Solomon, retired director of Columbia University’s Lamont–Doherty Earth Observatory. But MSR is not the only culprit, says Philip Christensen, a Mars scientist at Arizona State University and co-chair of last year’s decadal report, which set MSR as the field’s top priority. The price tag for Europa Clipper, launching next year to explore Jupiter’s icy moon, grew from $2 billion to $5 billion. Psyche, an asteroid explorer, gained several hundred million dollars in unexpected costs after its launch was postponed from last year to October. Dragonfly, a mission to Saturn’s moon Titan and the most recent New Frontiers selection, could cost $2.5 billion or more. And the price for NEO Surveyor, a congressionally ordered infrared telescope to chart hazardous asteroids, has risen to $1.2 billion—partly because of NASA-imposed delays to fund other shortfalls. “These missions haven’t gotten the same blame,” says Christensen, who points out that Congress has provided more money for MSR as its costs have grown.
JPL Director Laurie Leshin adds that MSR designers are looking for savings. “People think it’s getting more complex, but it’s actually getting simpler.” After the European Space Agency (ESA) scrapped its plan to build a small “fetch” rover, NASA will now rely on Perseverance itself to transfer samples to the rocket-carrying lander, with small helicopters as backups. Other simplifications include braking the lander with single-propellent thrusters like those that lowered Perseverance to Mars, rather than new ones that use two fuels; using the sample capsule itself as the nose cone on the return rocket; simplifying the containment vessel of the ESA-built spacecraft that will catch the capsule; and easing that rendezvous by launching the capsule to an orbit above the spacecraft, where it will stand out against the black of space.
Perseverance would be 10 years old by 2030, the earliest the MSR lander could arrive. But if NASA does have to cancel MSR or delay it past the end of the rover’s life, Perseverance could lay down its cache of samples for future pickup by helicopters or some other mission, Dyar says. “Once we cache the samples, nothing is going to happen to them,” she says. In the years to come, she suggests, “we can do it better, faster, and cheaper.”
No matter what, MSR shouldn’t be canceled, Christensen says. Such a move, Dreier adds, would undermine the influence of decadal surveys, pushing the field back to the time when the missions that were most politically savvy got selected. “If you allow the Senate to pick and choose what the priorities of the science community are, eventually that comes back to bite you.”
But if the new MSR cost review predicts the mission will cost something like $10 billion, Cutler thinks it may not be salvageable. That would be bad not just for Mars exploration, but also for planetary science in general, Dreier says. After all, the Senate has already said that if MSR is canceled, its money mostly wouldn’t go to science, but instead to human spaceflight and the Artemis program to return astronauts to the Moon. Artemis would be “the lion feeding on the carcass” of MSR, Dreier says. “The planetary science community is tied to MSR, whether they like it or not.”
