A crucial NASA mission in the search for life beyond Earth, Mars Sample Return, is in trouble. The budget has ballooned from $5 billion to more than $11 billion, and the sample return date could move from the end of this decade to 2040.
The mission would be the first to attempt to return rock samples from Mars to Earth so scientists can analyze them for signs of past life.
NASA Administrator Bill Nelson said during a press conference on April 15, 2024 that the mission as currently conceived is too expensive and too slow. NASA gave private companies a month to submit proposals to bring back the samples in a faster and cheaper way.
As an astronomer who studies cosmology and has written a book about early missions to Mars, I have seen the sample return saga unfold. Mars is the closest and best place to look for life beyond Earth, and if this ambitious NASA mission were to unravel, scientists would lose their chance to learn much more about the red planet.
The habitability of Mars
The first NASA missions to reach the surface of Mars in 1976 revealed the planet to be an icy desert, uninhabitable without a thick atmosphere to protect life from the sun's ultraviolet radiation. But studies conducted over the past decade suggest the planet may have been much warmer and wetter several billion years ago.
The Curiosity and Perseverance rovers each showed that the planet's early environment was suitable for microbial life.
They found the chemical building blocks of life and signs of surface water in the distant past. Curiosity, which landed on Mars in 2012, is still active; its twin, Perseverance, which landed on Mars in 2021, will play a crucial role in the sample return mission.
Why astronomers want Mars samples
The first time NASA looked for life in a Martian rock was in 1996. Scientists claimed they had discovered microscopic fossils of bacteria in the Martian meteorite ALH84001. This meteorite is a piece of Mars that landed in Antarctica 13,000 years ago and was recovered in 1984. Scientists disagreed about whether the meteorite ever harbored biology, and today most scientists agree there isn't enough evidence to say the rock contains fossils.
Hundreds of Martian meteorites have been found on Earth over the past forty years. They are free samples that fell to Earth, so while it may seem intuitive to study them, scientists can't say where these Martian meteorites came from. Moreover, they were thrown from the planet's surface by impacts, and those violent events could easily have destroyed or altered subtle evidence of life in the rocks.
There is no substitute for bringing back samples from a region known to have been hospitable to life in the past. As a result, the agency is facing a price tag of $700 million per ounce, making these samples the most expensive material ever collected.
A compelling and complex mission
Returning Martian rocks to Earth is the most challenging mission NASA has ever undertaken, and the first phase has already begun.
Perseverance collected more than 20 rock and soil samples and deposited them at the floor of Jezero Crater, an area that was likely once flooded and could have harbored life. The rover places the samples in containers the size of test tubes. Once the rover has filled all the sample tubes, it will collect them and take them to where NASA's Sample Retrieval Lander will land. The Sample Retrieval Lander contains a rocket to get the samples into orbit around Mars.
The European Space Agency has designed an Earth Return Orbiter, which will rendezvous with the rocket in orbit and collect the basketball-sized sample container. The samples are then automatically placed in a biocontainment system and transferred to an Earth Entry Capsule, which is part of the Earth Return Orbiter. After the long journey home, the access capsule will parachute to the Earth's surface.
The complex choreography of this mission, involving a rover, a lander, a rocket, an orbiter and the coordination of two space agencies, is unprecedented. It's the culprit behind the rising budget and long timeline.
Returning samples is worth a lot of money
Mars Sample Return has blown a hole in NASA's budget, jeopardizing other missions that need funding.
The NASA center behind the mission, the Jet Propulsion Laboratory, has just laid off more than 500 employees. It's likely that Mars Sample Return's budget was partly to blame for the layoffs, but it also came down to the Jet Propulsion Laboratory being overcrowded on planetary missions and facing budget cuts.
Over the past year, an independent review board report and a NASA Office of Inspector General report raised deep concerns about the viability of the sample return mission. These reports described the mission design as overly complex and noted issues such as inflation, supply chain problems, and unrealistic cost and schedule estimates.
NASA is also feeling the heat from Congress. For the 2024 budget year, the Senate committee has cut NASA's planetary science budget by more than half a billion dollars. If NASA cannot keep costs under control, the mission could even be canceled.
Think outside the box
Faced with these challenges, NASA has called for innovative designs from private industry, with the aim of reducing mission cost and complexity. Proposals must be submitted by May 17, which is an extremely tight schedule for such a challenging design effort. And it will be difficult for private companies to improve on the plan that experts from the Jet Propulsion Laboratory had to draw up for more than a decade.
A major potential player in this situation is the commercial space company SpaceX. NASA is already working with SpaceX on America's return to the moon. For the Artemis III mission, SpaceX will attempt to land humans on the moon for the first time in more than 50 years.
However, the massive Starship rocket that SpaceX will use for Artemis has only completed three test flights and needs much more development before NASA can trust it with a human payload.
In principle, a Starship rocket could return a large load of Martian rocks in a single two-year mission and at a much lower cost. But Starship comes with major risks and uncertainties. It's not clear if that rocket can return the samples Perseverance has already collected.
Starship uses a launch pad and must be refueled for the return journey. But there is no launch pad or gas station at Jezero Crater. Starship is designed to carry people, but if astronauts go to Mars to collect the samples, SpaceX will need a Starship rocket even bigger than the one it has tested so far.
Sending astronauts also comes with additional risks and costs, and a strategy that involves using humans could be more complicated than NASA's current plan.
With all these pressures and limitations, NASA has chosen to see if the private sector can come up with a winning solution. We'll know the answer next month.
This article is republished from The Conversation, an independent nonprofit organization providing facts and trusted analysis to help you understand our complex world. It was written by: Chris Impey, University of Arizona Read more: Chris Impey receives funding from the National Science Foundation and the Howard Hughes Medical Institute.
