SpaceX’s Starship Could Save NASA’s Beleaguered Mars Sample Return Mission

Don’t you hate it when you leave your valuables in your car with no way to get them back—and they’re 140 million miles from Earth? That’s the prospect NASA is facing right now. Its flagship multibillion-dollar mission to return invaluable and potentially life-harboring samples of rock and dust from Mars is in trouble. The mission is facing an “unacceptable” rising cost of $11 billion and a delay to 2040 for bringing the precious payload home, said NASA chief Bill Nelson in a call with reporters this week. That wait is “too long,” he said. Instead the agency will now turn to private companies to provide it with innovative designs to revive the mission. If they can do so, the prize will be the opportunity to play a part in one of the grandest endeavors of our time, the hunt for habitability and perhaps life on a neighboring world. “We’re so close,” says Amy Williams, an astrobiologist at the University of Florida. “The scientific yield is almost unimaginable.”

Mars Sample Return (MSR), as the program is known, was dreamed up nearly three decades ago. The goal was to land a rover on Mars, collect samples of scientific interest from a location that could have hosted life and return them to Earth. The first part of the mission is underway, with the Perseverance rover currently trundling around the 28-mile-wide Jezero Crater, thought to have contained an ancient lake that dried up 3.8 billion years ago, with some two dozen samples in tow. The next phase of the mission was supposed to have launched by 2031, collecting those samples from Perseverance and launching them back to Earth on a European-built spacecraft in 2033. In September 2023, however, an independent review found that goal was unachievable, given delays and cost overruns in the program.

On April 15 NASA published a response that agreed with that assessment. The agency said it needed “out-of-the-box options” to achieve the goal of returning Perseverance’s samples to Earth. Its solution is “a surprise,” says Casey Dreier, senior space policy adviser for the Planetary Society. NASA is asking private companies to put forward ideas for how to carry out the mission at a lower cost and on a shorter time frame. The agency is seeking short proposals by May and will then make a decision this summer on which ideas to carry forward, with full proposals then expected by the fall. “It’s added no certainty or clarification to the future of MSR,” Dreier says. “The results of the internal study were ‘let’s ask if anyone else has any ideas.’” That outcome is “a bit disappointing,” he adds, given MSR was the top priority for the last two “decadal surveys” for planetary science. Such surveys are once-a-decade intergovernmental reviews that marshal communal input to task NASA and other federal agencies with major scientific goals.

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Jim Green, former chief scientist at NASA, who cemented MSR in his time as director of the agency’s Planetary Science Division, says the situation is not wholly unlike the development of Europa Clipper, a mission to Jupiter’s moon Europa that NASA plans to launch in October. “We had probably a couple hundred million dollars’ worth of studies on Europa,” Green says. “We couldn’t come to closure.” Eventually, however, NASA found a way to save costs by making Clipper a flyby mission, planning for it to zoom past Europa dozens of times rather than enter into orbit around the moon, which is deep in the grip of Jupiter’s hardware-frying radiation belts. A similar breakthrough might come for MSR. “Industry has an opportunity to weigh in with some ideas,” Green says. “This is very healthy. It’s exactly the approach it will take to get a better mission scenario.”

NASA might be soliciting ideas with one specific vehicle in mind, Dreier says: SpaceX’s massive new Starship rocket. “It’s encouraging companies to use infrastructure built for Artemis,” he says, referring to NASA’s massive effort to return astronauts to Earth’s moon. “The only conclusion you can really draw from that is they’re hoping Starship somehow is the solution here.” That could provide MSR with a whopper of a solution. NASA is already funding Starship, the largest rocket in history, to the tune of billions of dollars to ferry astronauts to the lunar surface—but Starship also has the potential to launch immense payloads off other worlds and back to Earth. “Starship has the potential to return serious tonnage from Mars within [about] 5 years,” note SpaceX CEO Elon Musk on X, formerly Twitter, on April 15 in response to NASA’s MSR solicitation. Starship’s planned heavy-lift capabilities are so immense, in fact, that the rocket could immediately simplify MSR. “You could probably just roll Perseverance into Starship and fly back to Earth,” Dreier says. Green thinks the idea of using Starship for MSR is plausible. “We need to leverage assets that we didn’t have” when MSR was first devised, he says. SpaceX is also hoping to ultimately send humans to Mars in the coming decades. “How are we going to learn to launch humans off the surface of Mars?” Green asks. MSR could provide the opportune test mission.

One prospect seemingly taken off the table by NASA is to use “Marscopters,” follow-ups to the wildly successful Ingenuity helicopter that traveled to Mars with Perseverance. NASA says that “careful evaluation of Perseverance reliability” means such a vehicle would no longer be necessary to pick up samples from the rover. Instead Perseverance would be driven back to the base of Jezero Crater in 2028, where it would remain in a dormant “quiescent state” until the arrival of the MSR retrieval mission. Then the European Space Agency’s planned orbiting vehicle would still launch “in 2030,” said Sandra Connelly, NASA deputy associate administrator for science, at a town hall meeting on April 15—presumably if an architecture not involving Starship were selected—and the orbiter would collect the samples launched from the surface.

If a solution can be found, the scientific return on offer is almost incalculable. Williams, a science team member on Perseverance, says the samples will allow us to precisely date the presence of water in Jezero Crater down to millions of years and to look for life’s possible imprints in the rocks of Mars in a way no rover alone can match. “You can’t send a synchrotron to Mars” to produce powerful particle beams to finely parse samples, she says. “They’re like one mile in diameter.” While it’s unclear precisely how far toward the question of life on Mars the samples would take us, they would be a “game changer” in our understanding of habitability on other worlds, Williams says. “These samples have the potential to revolutionize our understanding not just of Mars but of all our inner rocky worlds and our search for habitable worlds beyond our solar system,” she says.

Even without the prospect of life, the samples will be scientifically astounding, says Jack Mustard, a planetary scientist at Brown University. Jezero Crater itself lies in a much larger 1,200-mile-wide basin, called Isidis Planitia, which may have resulted from a cataclysmic impact 3.9 billion years ago. “There are aspects of solar system evolution that can only be done through the return of samples [from Mars],” Mustard says. That includes the formation of the planets themselves, the presence of magnetic fields on worlds such as Earth—and once Mars—and, in particular, the timing of giant impacts in the early solar system. “Having datable samples from another planetary body to address that question would be unbelievable,” Mustard says. “Life is a sexy topic that gets all the headlines. But at a more lasting level, it’ll be the questions about solar system evolution that the samples will answer that will be equally, if not more, important.”