Congressional supporters of the Mars Sample Return (MSR) mission have buckled to pressure from the Trump administration to kill the centerpiece of NASA’s exploration plans over the next decade. Although the compromise bill released this week only officially covers this year’s expenditure, few people think the mission will be revived in the next few years. There have been enough signs this was likely, and contingency planning must be well underway, but so far, alternatives to the project remain uncertain.
Despite the improved sophistication of instruments carried to Mars since the Viking Landers added water to Martian soil in the 1970s, many experiments require equipment that would be prohibitively expensive to send 90 million kilometers (56 million miles), let alone touch down safely. If we really want to know what Mars rocks contain, particularly possible signs of biological activity, we need to bring them back here to study.
Recognition of this saw the Mars Sample Return mission declared NASA’s highest planetary science priority back in 2011. The first part of the mission has already happened and been a major success. The Perseverance Mars Rover has collected samples of the most interesting rocks and dust it has encountered and stored them in 33 sample tubes. However, estimated costs have blown up for the mission plan to land on Mars, retrieve the canisters, and return to orbit to rendezvous with the Earth Return Orbiter, which would bring the samples back to Earth.
In 2024, NASA acknowledged that the original design for collecting the cannisters was unaffordable at $11 billion, and put out a call for suggestions for a way to do it more cheaply. An adjusted version had a new estimate of $7 billion, but faced both skepticism that the price was realistic and the challenge of squeezing into NASA’s budget when other projects were also suffering overruns.
Proposals that some people claim would be cheaper still have been submitted. For example, Dr Robert Zubrin founded the Mars Society in 1998 to promote the idea of exploring the Red Planet. He has been pushing a design he says will get the samples for a fraction of the cost of NASA’s plan. Zubrin claims it is only the desire to collaborate with other space agencies that has tied NASA to expensive options, but has won little support.
Proponents of alternative retrieval missions will presumably continue to put them forward. If they can’t convince NASA administrators or Congress that their prices are realistic, they can always try to interest private sponsors. So far, however, for all the billionaires hyping Mars as a priority, no one has shown a serious interest in retrieving the samples out of their own pocket.
The MSR is expensive and high-profile enough that it has become the subject of Congressional negotiations, which have played out in spending bills, rather than being left to administrators to sort out. In the context of the Trump administration’s aim to cut NASA’s budget by almost half, however, its prospects have been bleak for a while.
Scientists who have devoted their careers to the MSR are understandably distressed. “This is deeply disappointing,” Dr Victoria Hamilton, chair of NASA’s Mars Exploration Program Analysis Group, told Science. “When we’ve got memos coming out saying we want to be the dominant power in space, I wonder how we leave something this ambitious behind.”
The compromise spending bill does include $110 million for “Mars Future Missions.” This will explore goals such as better ways to land on Mars, an ongoing challenge given the lack of atmosphere to slow spacecraft down. Past missions have tried a variety of approaches; identifying the best one for an object heavy enough to take off again will be useful for an MSR in the distant future. In the shorter term, the same work might allow landers that might carry more powerful analytic instruments to do the research on site.
Free from water damage, Perseverance’s caches should survive erosion from dust storms for a long time, so that if technology improves or priorities change, the MSR could be revived in years or even decades’ time.
One of Perseverance’s sample tubes on the Martian surface looking like a light saber.
For the moment, Perseverance and Curiosity will continue their journeys, conducting what analysis they can with the instruments they have, and Perseverance still has a few tubes to store any particularly promising rocks. The more interesting the samples look, the greater the pressure to bring them back. However, if the rocks described last year as step 1 on NASA’s Confidence of Life scale were not enough to save the MSR, it’s hard to see what will. “A rock with a potential biosignature is awaiting return now,” Professor Bethany Ehlmann of the University of Colorado, Boulder, noted to Science.
What happens next?
If all the money MSR would require is spent on other space exploration projects, several missions currently in limbo could all go ahead. That could include Perseverance-style rovers visiting parts of Mars we have yet to explore, seizing the window for a Uranus orbiter and the habitable worlds observatory. A spacecraft that would wait in orbit until the chance came to intercept a future interstellar visitor like 3I/ATLAS has also attracted great enthusiasm, and would require a small fraction of the MSR’s budget.
Competition between these ideas will intensify, but in the current environment, it is far from certain that much of the MSR savings will go into space exploration of any sort, although this year’s budget is surprisingly positive.
The Earth Return Orbiter is being built by the European Space Agency (ESA), and work on it is more advanced than the lander. ESA is exploring ways to avoid wasting what has been done by turning the orbiter into another mission to study Mars from above.
The Chinese National Space Administration also wants to collect Mars samples and, barring accident, is now almost certain to get them first. However, their version involves simply picking up whatever rocks are handy after touching down in 2031, and blasting straight back up. If Mars has signs of life, they’re unlikely to be widespread, so the chances of getting the right rocks this way are low. The same goes for other questions Perseverance’s samples might answer. Martian geology is diverse, and collecting from a single landing site means getting a narrow slice, and not necessarily the best bits.
Before China’s mission, some planetary scientists’ hopes rest with the Japanese Space Agency’s plan to grab a sample from Mars’s moon Phobos. With a fraction of Mars gravity, it’s much easier to grab samples from something that small, and this could contain Martian material thrown up by asteroid impacts.
Meanwhile, enthusiasts may talk a big game about building permanent bases or even cities on Mars, but the inability to retrieve a few rocks shows how distant those goals remain.
Source Link: US Just Killed NASA's Mars Sample Return Mission – So What Happens Now?
