Who is the Villain in Mars Sample Return?

Mars For The Rest of Us

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Who is the Villain in Mars Sample Return?<br>I bet you're wondering why I've gathered you all here.

Maciej Cegłowski<br>Jun 03, 2026

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Last month I wrote about the demise of Mars Sample Return, NASA’s most ambitious planetary science mission.<br>What fascinates me about sample return is that it’s a human mission in miniature. The goal is to land a large spacecraft on Mars and return its contents safely to Earth. The criterion for success is binary—either the sample gets back safely to Earth, or it doesn’t. The mission has a mix of American and European spacecraft launching over several synodic periods, interacting with equipment that has been pre-positioned on Mars years in advance. And the program as a whole consumes a substantial fraction of each agency’s exploration budget, spanning multiple election cycles.<br>This makes sample return a different animal from normal planetary science missions, which are set up so that there is a partial science return even if important components break, and whose costs tend to be front-loaded ahead of a single launch. For that reason, the demise of sample return may give us some clues about the political and organizational headwinds a human mission would face.<br>In my earlier post ,I described the various moving parts of the Mars Sample Return mission that died in 2026. Today I want to try swinging around the finger of blame, to see who it points at most comfortably. The various suspects have been assembled here in the drawing room. Let’s meet them one by one.<br>Donald Trump

Trump has a curious relationship with the nation’s space agency. He’s clearly interested in its achievements from a ‘national dominance’ point of view, taking obvious pleasure in NASA’s recently-completed Artemis II flight around the moon. Jared Isaacman, the agency’s new Administrator, has been sedulous about beginning every interview and public statement with praise of Trump. He’s also made getting a Moon landing in before the President’s term ends in 2029 the agency’s top priority. The flattery seems to be working. Trump keeps a model of NASA’s Mars-bound nuclear rocket on display in the Oval Office, brags about NASA, and seems happy with Isaacman.<br>But Trump’s proposed budgets for 2025 and 2026 both slashed funding for the science half of NASA, part of his administration’s broader jihad against Federally-funded science everywhere. Trump also set in motion personnel cuts that have cost NASA about 20% of its workforce.<br>Congress has pushed back against Trump’s budget cuts, keeping NASA spending fairly flat. But the political environment for science at the agency has been scarier. As the sample return mission became the most prominent and expensive line item in NASA’s science budget, there was internal concern that continuing to push for it would only start to cannibalize other programs. That zero-sum mentality removed a powerful internal constituency for the mission at NASA, and in the broader scientific community.<br>Bill Nelson

One problem with blaming Trump is timing. The sample return mission was already collapsing under Biden. So a more natural villain may be the man who oversaw the agency under the previous regime, NASA Administrator Bill Nelson.<br>Biden had the chance to nominate a dynamic new head of NASA. Instead he chose a fellow Senate dinosaur, 78 year old Florida Senator Bill Nelson. Nelson was a longtime space enjoyer best known for getting himself flown as congressional cargo on a 1982 Space Shuttle mission, back when NASA still indulged such stunts. At thta time, Nelson gained a reputation among the astronaut corps as a man enamored with his own reflection; his fellow crew members were warned never to get between the Congressman and a TV camera.<br>As NASA Administrator, Nelson treated the agency like a Cadillac Coupe de Ville on cruise control, a place where he could put his feet up and enjoy the sunset years of a long career in government. His grasp of science was minimal (at one press conference, he mortified his staff by talking about ‘the dark side of the moon’), but his love for the space program was pure. He was a man who loved a giant rocket and didn’t care who knew it.<br>Nelson mostly ignored the agency’s flagship science missions. His heart was with the Artemis moon program, and he spent his tenure making sure that Congressional money would continue to accumulate on NASA’s lunar bonfire, if necessary by cutting cheap and scientifically priceless missions like the Chandra X-Ray Observatory.<br>Nelson rarely mentioned Mars Sample Return until the program’s exploding budget started making headlines, at which point he called for commercial alternatives, then punted the problem to the next Administrator (and Administration). Nelson’s neglect didn’t kill the project, but it meant he missed the best chance to turn the program around.<br>Nelson’s biggest sin was insisting through his tenure that NASA was on track...