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Perseverance and sample tube
A selfie taken by the Perseverance rover showing one of its sample tubes on the ground. NASA is still working to figure out how to get those samples back to Earth effectively. (credit: NASA/JPL-Caltech/MSSS)

NASA looks for an MSR lifeline

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For more than half a year, dark clouds have hovered over NASA’s Mars Sample Return (MSR) program. Last September, an independent panel concluded that the current approach to returning samples being collected by the Perseverance rover was behind schedule and far over budget, with cost estimates as high as $11 billion. That prompted an internal NASA reassessment of the MSR program that, coupled with uncertainty about spending levels for the program in 2024, led to slowing work on much of MSR and, in February, laying off 8% of the staff at JPL, the lead center for MSR (see “MSR at serious risk”, The Space Review, February 12, 2024).

“The bottom line is that $11 billion is too expensive and not returning samples until 2040 is unacceptably too long,” Nelson said.

That uncertainty persisted last month even with the long-overdue completion of a fiscal year 2024 spending bill and, days later, the release of the administration’s fiscal year 2025 budget proposal. The 2024 spending bill directed NASA to spend at least $300 million—the amount in the earlier Senate version—on MSR in 2024, and up to $949.3 million, the agency’s request. However, the bill cut planetary science spending by more than $660 million, giving the agency little room to spend more than the minimum on MSR without cutting other programs.

The 2025 request, meanwhile, punted on MSR: it listed only “TBD” for the program in the proposal, with NASA stating it would amend the budget request once its review of the program was over. “That’s astonishing. I’ve never seen anything like that before,” said Casey Dreier, chief of space policy at The Planetary Society, in a webinar on the budget proposal by the Aerospace Industries Association a couple weeks after the proposal was released.

The Mars science community hoped for some clarity when the agency announced it would discuss its plan forward for Mars Sample Return April 15. That announcement, though, did little to disperse the clouds hanging over the program for months.

That review, by the MSR Independent Review Board Response Team, or MIRT, examined more than 20 architectures but ended up recommending an approach much like the previous design that included a Sample Retrieval Lander, developed by NASA, and an Earth Return Orbiter, built by ESA. The main technical difference was the inclusion of a radioisotope thermoelectric generator (RTG) on the lander, which previously was solar powered, to make lander operations more robust. (Including the RTG, the report noted, made little change to its price but it meant there would be no room for helicopters based on Ingenuity; those were intended to fetch samples from a cache on the surface as a backup to getting them directly from Perseverance.)

The MIRT study agreed with the assessment by the earlier independent review that the cost of this approach was between $8 billion and $11 billion. To minimize peak annual costs—the 2022 decadal survey had recommended that MSR cost no more than 35% of the overall NASA planetary science budget in any given year—NASA stretched out the program, launching the orbiter in 2030 and the lander in 2035, which would allow samples to be returned in 2040.

NASA, though, is looking for alternatives. “The bottom line is that $11 billion is too expensive and not returning samples until 2040 is unacceptably too long,” NASA administrator Bill Nelson said in a call with reporters to discuss the MIRT report.

He announced that NASA would seek proposals for mission studies that could carry our MSR faster and/or cheaper than the plan the MIRT developed. The day after the announcement, NASA issued a call for proposals for “Rapid Mission Design Studies for Mars Sample Return”. NASA would seek proposals, due to NASA by May 17, for 90-day studies to be conducted by industry from July to October. NASA said it the announcement it would make “multiple” awards of up to $1.5 million each for the studies.

Nicola Fox, NASA associate administrator for science, said at the briefing that NASA was looking for new approaches, but not necessarily new technologies, for MSR through the new studies. “What we’re looking for is heritage,” she said. “What we’re hoping is that we’ll be able to get back to some more traditional, tried-and-true architectures, things that do not require huge technological leaps.”

The role of the MIRT “was not to go out and find this creative, new approach to MSR. It was to respond to those specific recommendations,” Connelly said.

A particular area of interest is the Mars Ascent Vehicle (MAV), the rocket carried on the Sample Retrieval Lander that would launch into Mars orbit the canister that, as currently designed, would carry 30 tubes of samples. “As the Mars Ascent Vehicle (MAV) design and mass drives mission complexity and cost, NASA is particularly interested in studies that include or describe a smaller MAV or an alternative to a MAV,” the solicitation states.

That could include, the request stated, returning a smaller number of samples. While NASA’s current approach calls for returning 30 tubes, the agency is willing to consider concepts that could return as few as ten. It added, though, that returning “as many scientifically valuable samples as possible returned is desired” will be one metric NASA will use to judge mission designs, alongside cost and schedule.

NASA says it is particularly interested in alternatives to the Mars Ascent Vehicle rocket, a key driver in the size and cost of the overall MSR architecture. (credit: NASA/JPL-Caltech)

“We want real solutions”

The announcement and subsequent solicitation left as many questions as answers about the future of MSR. Many of those came up during a meeting April 24 of the Mars Exploration Program Analysis Group (MEPAG), a group of scientists that provide input to NASA on its Mars exploration efforts.

One issue was why, after nearly half a year of work, the MIRT adopted an architecture for MSR that was little different from the earlier plan. “Our role was to respond to all of the recommendations of IRB-2,” said Sandra Connelly, deputy associate administrator for science and leader of the MIRT, referring to last year’s independent review, which was the second for the program. “Our role was not to go out and find this creative, new approach to MSR. It was to respond to those specific recommendations.”

That was done outside of any consideration of any budgetary limitations on the effort, including whether up to $11 billion would be acceptable. “This is what the MIRT recommended in terms of an architecture that fit within the recommendations of the IRB,” she said. “Because of the constraints that we are in, the environment we’re in, we’re not moving forward with this architecture right now.”

The hope is that the industry studies, as well as separate internal studies at NASA and JPL, will come up with less expensive and faster approaches for MSR. But the agency has not publicly set a goal for cost and schedule for MSR.

“We don’t want to put cost bogeys out there because we know that, if you put a cost bogey out there, there will be solutions that come in that fit within that cost bogey,” Connelly said. “We want real analysis, we want real solutions and we want to know what they’re really going to cost so we can make informed trades.”

“There has been industry interest that’s been commented on and shared, and we’re hopeful it will be viable,” she said, without commenting on whether NASA had enough evidence to suggest that industry concepts could sharply reduce costs and pull in schedules. There has been speculation, for example, that SpaceX has offered approaches using its Starship vehicle, but with few, if any, details (including how Starship would pull off the round trip to Mars.)

Scientists also questioned NASA’s willingness to accept as few as ten sample tubes. That is linked to a cache of ten tubes that Perseverance left behind in a region called Three Forks as a contingency in case something prevented Perseverance from returning to the sample retrieval lander.

At MEPAG, though, scientists argued that those samples aren’t the best ones to be returned, with better ones on Perseverance as it continues to climb out of Jezero Crater. “When it comes to the decision about exactly which samples will be loaded onto whatever spacecraft leaves the surface of Mars, that will be something where there will be scientific community conversations,” Lindsay Hays, acting lead scientist for MSR at NASA headquarters, reassured the audience.

Connelly, though, said returning only the samples at Three Forks was an option. “If that’s the easier solution, we don’t want to prohibit that,” she said. “Having science that is good enough is better than having no science.”

“I worry that, when we make certain decisions, that we’re cutting to the bone and, in this case, potentially amputating JPL,” Garcia said.

So, what if the studies don’t reveal any alternatives with significant cost and schedule reductions? “There is a possibility that we won’t come up with something,” Connelly said, “in which case, we’ll have to evaluate at that point in time how we’re going to move forward as an agency.”

She reiterated at the MEPAG meeting, though, that Nelson “strongly believes that 2040 and $11 billion is not acceptable.”

NASA administrator Bill Nelson told House appropriators he was “quite sanguine” about the future of MSR despite current problems. (credit: NASA/Joel Kowsky)

Is MSR worth it?

For now, MSR will not be spending much. NASA said at the announcement of the MIRT study that it would allocate $310 million for the program in the current fiscal year, just above the minimum allowed in the bill. NASA officials said at the MEPAG meeting that the $10 million increase above that floor was intended to go towards the industry studies.

The announcement also did away with the “TBD” in the 2025 budget proposal. NASA would now seek $200 million for MSR in 2025, using funding that had originally been allocated for “Planetary Decadal Future” studies of future missions recommended by the planetary science decadal survey.

Some in Congress, particularly in California, are not happy with those plans. “These funding levels are woefully short for a mission that NASA itself identified as its highest priority in planetary science and that has been decades in the making,” said the state’s two senators, Alex Padilla (D) and Laphonza Butler (D), in a statement the day of the announcement.

Two days after the announcement, Nelson appeared before a House appropriations subcommittee to discuss the agency’s 2025 budget proposal. Among the participants was Rep. Mike Garcia (R-CA), who had similar concerns about the effects of the proposed MSR budget on JPL, concerns that transcend party lines. “It’s probably one of the only times I’ve agreed with [Rep. Adam] Schiff and been on a letter with Representative Schiff,” he said, referring to a prominent House Democrat whose district is adjacent to JPL.

Garcia was critical of the funding decisions that led to JPL’s layoffs in February and feared the budget could lead to more. “I worry that, when we make certain decisions, that we’re cutting to the bone and, in this case, potentially amputating JPL.”

Nelson reiterated that MSR was “extremely important” for the agency. “I am quite sanguine about the future,” he said, citing the upcoming studies by industry as well as within NASA and JPL, along with expectations that budget caps for NASA and other non-defense discretionary agencies will be lifted after 2025. “Let’s see what we come back with in the answers this fall.”

“The whole value of our US-European partnership for Mars Sample Return is to bring back a scientifically selected, diverse set of samples,” Glaze said, contrasting MSR with China’s plans. “That’s significantly different from a ‘grab-and-go’ sample.”

There are other factors that come into play. NASA officials said they expect to make decisions about the future of MSR in early 2025 after evaluating the various studies. That could come, though, in the midst of a presidential transition, which may at a minimum delay those plans or prompt another review of them.

The current baseline of 2040 would also mean that the samples would likely come back years after China conducts its own Mars sample return mission, expected in the early 2030s. “That is why the administrator is wanting us to find a solution that returns the samples before 2004,” Connolly said at the MEPAG meeting.

She and Lori Glaze, director of NASA’s planetary science division, argued MSR would be more scientifically valuable than Chinese plans, which appear to be focused on grabbing whatever material is available at the landing site rather than more carefully curated samples being collected by Perseverance.

“The whole value of our US-European partnership for Mars Sample Return is to bring back a scientifically selected, diverse set of samples,” Glaze said, that can address key scientific questions. “That’s significantly different from a ‘grab-and-go’ sample.” She added NASA briefly considered that approach as an alternative to the current MSR architecture, and “that was not acceptable.”

Agency leadership, all the way up to Nelson, emphasized that scientific importance of MSR, pointing to recommendations in the last two decadal surveys backing the effort. “I’m very optimistic, as I talk to our scientists, that it can be done,” Nelson told House appropriators.

Some scientists at the MEPAG meeting, though, started to question the value of MSR, particularly if the program is limited to returning a small number of samples, like the Three Forks cache, that may not be as scientifically valuable as once expected. They argued, for example, that the Three Forks cache is no longer the best set of samples that could be returned based on what Perseverance has collected despite earlier declarations that it was “return worthy.”

That extended to MSR itself: at what point, one participant said, should the scientific community reconsider its support for the mission despite the endorsements in the decadal surveys given the potential changes to the mission.

“I think that’s a legitimate question, a legitimate conversation to have. I think it's premature to have it now,” said Vicky Hamilton, chair of MEPAG. “We don’t know what these industry studies will come up with. We don’t know what NASA’s response to those studies will be.”

She added, though, that the decadal survey recommended MSR continue with no major increase or decrease in scope. Should NASA recommend sharply reducing the scope of the mission, like the number of samples returned, “we have an opening there to say that the scope has been decreased so much that the community no longer believes this is what we should be doing.”

That time was not now, she concluded. “This is the top decadal priority. We have supported that and should continue to do so emphatically until it is 110% clear that we cannot do that in good conscience. And we cannot make that decision until we know what NASA’s proposed path forward is.”

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