Can SpaceX’s Starship save Mars Sample Return?

Amid the cost growth, political division, and management missteps roiling NASA and ESA’s Mars Sample Return program, it is not unreasonable to ask if there are more affordable alternatives to return these samples to Earth, namely SpaceX’s own Mars project, Starship.

The answer is almost certainly “no.” At least, not anytime soon.

This is due to the unique needs of a scientifically relevant Mars sample return campaign, the uncertain capabilities of Starship, and the one-of-a-kind nature of the samples themselves.

Mars Sample Return, as envisioned by NASA and ESA, is a multi-mission campaign. The samples are collected and stored by the Perseverance rover. Years later, a Mars Ascent Vehicle (MAV) lands nearby, into which the samples are loaded. The MAV launches the samples into Mars orbit, where they are collected by an orbiting spacecraft provided by the European Space Agency. That orbiter returns to Earth and drops the protected samples into Earth’s atmosphere, where they land in a deserted area to be collected and analyzed.

SpaceX’s Starship and Super Heavy rocket, now making tremendous progress in Boca Chica, could, theoretically, complete a sample return project in a single mission, with far more mass, for less money. It is designed to be reliable and rapidly reusable, and it can also be fueled using natural resources processed on Mars. NASA has already committed nearly $3 billion to Starship to serve as its lunar lander for Artemis, a smart move since it nets the agency a two-for-one long-term investment in Moon and Mars hardware.

But once specifics start coming into play, the uncertainties of Starship in active development become more pronounced, and a number of critical questions are revealed as unanswerable, making any reformulation of Mars Sample Return via Starship functionally impossible in a near-term timeline.

These are some of the questions that need to be answered with confidence before Starship can be considered in a NASA-directed sample return campaign:

• Will the samples be the same ones collected by the Perseverance rover?
• If so, can Starship land in Jezero Crater?
• What would Starship land on? In mockups of Starship on Mars, SpaceX shows it using launch pads. There is currently no landing pad or related infrastructure at Jezero Crater. Who builds that? When? How?
• How does Starship refuel and prepare itself for a return launch to Earth? Will there need to be a facility to refuel and prepare Starship at Jezero Crater?
• If so, how many launches and on what timeline can a Martian ground facility be established at Jezero? Who pays for that and how much would that cost? Is the local environment at Jezero Crater conducive to such a facility?

• How reliable is Starship for landing and launching from the surface of Mars?
• What is the risk tolerance for returning these samples to Earth? What reliability will NASA demand to transport these one-of-a-kind items?
• What collects the samples? Starship will create significant debris when landing and taking off, so it would need to maintain distance from the samples themselves. Are sample collection rovers needed? If so, who develops and pays for those rovers? How do they travel, deploy, collect, and secure the samples within Starship? How do they get in and out of the rocket on Mars?
• If it’s not robotic, is the proposal to have humans collect the samples? If so, how will SpaceX solve the immense engineering, social, and psychological challenges of long-duration human spaceflight to Mars? On what timeline do they aim to solve those?
• Would having humans collect the samples make Mars Sample Return more or less complicated than the current plan? Will it place more or fewer barriers to success?
• Can Starship meet stringent planetary protection requirements that preserve the integrity of both Mars and Earth environments? How are the samples protected to ensure there is no forward contamination of Earth's environment? How does Starship return the samples to Earth itself?
• If the samples collected are not the same ones already prepared by the Perseverance rover, where are they collected from? Who or what decides which samples to collect? Will they represent the same variety of geologic and historical range as the ones necessary to address the most important scientific questions at Mars? Will the scientific community be involved in their selection?
• The value of Mars Sample Return depends on the quality of the samples returned — if these are not the same samples, then who selects the landing site and why? If you’re using existing landing sites for Starship, is the local geologic area one that would answer these big questions of planetary history and the history of life?

It’s likely that some of these questions may be answered in the next decade. But probably not all of them (or even most). Starship is running behind schedule for landing on the Moon; now likely to occur toward the end of the decade.

SpaceX may ultimately establish Starship as a reliable and cost-effective access to the Martian surface. It’s just not clear when that will be and what caveats it will require. Tying this degree of schedule and hardware uncertainty to NASA’s highest near-term priority for planetary science is to relegate Mars Sample Return to a passive observer, reliant on a single private company to solve some of the most difficult engineering problems in human history.

The Planetary Society’s principles for Mars Sample Return are to prioritize the science return, to do it now, and to do it with balance within NASA’s larger portfolio. Until the questions outlined above have better answers, dependence on Starship challenges NASA’s ability to pursue the program now and to retain science as a priority. As convenient as it would be to have an external solution to MSR’s current programmatic problems, NASA remains responsible for its own destiny. The agency must forge its own path for sample return to ensure a successful and sustainable mission that addresses some of the biggest questions we have about our origins.