Humanity’s biggest and most ambitious plan to search for extraterrestrial life is about to go back to the drawing board.
NASA and the European Space Agency (ESA) have been working on a strategy to fly a set of Mars rocks, carefully collected by the Perseverance rover, back to Earth for study. But a new independent assessment of the plan says it can’t be done on current budgets and schedules. The entire project will probably cost between US$8 billion and $11 billion — far more than the roughly $4 billion estimated in a previous independent review report, issued three years ago. And there’s a “near zero probability” of the missions launching in 2027 and 2028, as the space agencies had hoped. Even pushing the launch dates out to 2030 would still cost between US$8 billion and $9.6 billion, the report estimates — comparable with the cost of building the James Webb Space Telescope, the single most expensive astronomy project in history.
The report, released on 21 September, stresses that Mars sample return is strategically important to the space agencies, in that it would demonstrate US and European ‘soft power’ at a time when China has also announced plans to bring back rocks from Mars. The mission is also scientifically important: it is the culmination of a decades-long quest to search for life beyond Earth. But the current plan is unworkable, according to the report, which was commissioned by NASA and led by a former NASA manager, Orlando Figueroa.
NASA says it will put current plans on hold and come up with an alternative strategy by early next year. “It’s going to take a little time for us to assess the path forward,” says Lori Glaze, head of NASA’s planetary-science division in Washington DC. The recommendations from the report are “big”, she says. “They’re not things that can be answered overnight.”
In a statement, ESA said it is evaluating how it can adjust its plan while still achieving the overall mission objectives. “We are conducting preliminary studies to assess all options given the various scenarios and will inform member states and coordinate with NASA on the outcome as soon as possible.”
A valuable collection
As currently envisioned, a Mars sample-return mission would involve NASA building a lander that would fly to the Red Planet to grab up to 30 rock samples, as well as a rocket that would blast off from the Martian surface to carry them into orbit around Mars. ESA would build the spacecraft to retrieve the precious cargo from orbit and fly it back to Earth.
Scientists can analyse the rocks in much greater detail in laboratories on Earth than with the compact instruments available on robotic rovers. The analysis would include hunting for ‘biosignatures’, molecules or other signals of past life in the samples. “These measurements are difficult to do remotely,” says Daniel Glavin, a planetary scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “You really want the samples back and in the lab.”
NASA’s Perseverance rover has already collected a bevy of samples from Mars’s Jezero Crater and has even placed ten sealed tubes, containing rock cores, on the ground for possible retrieval. The rover continues to travel around Jezero, gathering more samples that make its collection increasingly valuable as time goes on, the report says. The rocks gathered so far formed in an ancient river delta and lake that were probably once similar to life-friendly environments on Earth.
Mars sample return was one of the highest-ranked priorities recommended for NASA in the last two planetary ‘decadal’ surveys — reports, put together with input from the research community, that aim to guide the direction of US planetary science for the following ten years. But the project has struggled to remain affordable as engineers have refined the designs for the various spacecraft that would be part of the mission. The earlier independent review, which NASA commissioned from experts outside the agency specifically to head off problems with unexpected cost increases, recommended spending $3.8 billion to $4.4 billion on the sample-return project.
But that was before engineers had a full sense of what would be involved and hence how much it would cost, Glaze says. And NASA’s Jet Propulsion Laboratory in Pasadena, California, which would lead much of the Mars sample-return project, has struggled with an overstretched work force. This led NASA to delay last year’s planned launch of a separate mission, a spacecraft destined for the asteroid Psyche.
There are also questions about how to balance the cost of Mars sample return against other missions in the $3.2-billion budget for NASA’s planetary-science division. The most recent decadal survey, released in 2022, recommended limiting the cost of Mars sample return to no more than 35% of the division’s overall budget. That’s a big challenge as the agency also tries to keep funding going for other priority projects, such as the Dragonfly mission to Saturn’s moon Titan, slated for later this decade, and a mission to Uranus next decade.
That means all eyes remain on how to pay for Mars sample return. “The community knew that prioritization of a multi-mission effort and the single most ambitious effort in the history of planetary sciences would have challenges,” says Bethany Ehlmann, a planetary scientist at the California Institute of Technology in Pasadena who helped to lead the most recent decadal survey. “That’s why the [survey] highlights the importance of NASA working with Congress to augment the budget and figure out the appropriate funding profile to get Mars sample return done.”
This article is reproduced with permission and was first published on September 27, 2023.
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