The report first outlines what the top priorities of a human mission to Mars should be. While this may seem pretty obvious, the primary objective of the Moon landing in 1969 was, ultimately, to place humans on the Moon and return them safely. For landing on Mars, the National Academies of Sciences, Engineering, and Medicine, which provides independent advice to the US government, recommends placing scientific aims at the forefront of such a mission.

“The first human landing on Mars will be the most significant moment for human space exploration since we first set foot on the moon over 50 years ago,” said Linda T. Elkins-Tanton, director of the University of California, Berkeley Space Sciences Laboratory; principal investigator, NASA Psyche mission; and co-chair of the committee that wrote the report, explained in a statement.

“Our report puts science at the center of what will be a remarkable achievement, and outlines the incredible knowledge we’ll have the opportunity to glean about our place in the universe, the potential habitability of Mars, and so much more.”

The top priority identified by the report is, unsurprisingly, to look for indigenous life. The goal here is to  “determine if evidence can be found on Mars of existing or extinct life, the planet’s habitability, or indigenous prebiotic chemistry”. From there, the report lays out the next priorities for a crewed mission to the planet, in order of importance:

• Water and CO₂ on Mars – Characterize the planet’s water and CO₂ cycles to understand how they may have evolved.
• Mars Geology – Characterize and map the geologic record to reveal Mars’ evolution.
• Impact on Crew – Determine the impact of the Martian environment on crew physiological, cognitive, and emotional health, and on team dynamics.
• Dust Storms – Determine what controls the onset and evolution of the major dust storms that make Mars’ atmosphere so variable.
• Explore Resources – Characterize the Martian environment for in situ resource utilization and processing needs, with an early focus on water and propellants, ultimately to explore materials that support permanent habitation.
• Effect of Mars on Genomes and Reproduction – Determine whether the Martian environment affects reproduction or the functional genome across multiple generations in at least one plant species and one animal species.
• Understanding Microbes – Determine if microbial population dynamics and the distribution of microbial species in biological systems are stable on Mars, and are not detrimental to astronaut health and performance.
• Martian Dust – Characterize the effects of Martian dust on the human body and on hardware.
• Plants and Animals in an Ecosystem – Determine the impact of the Martian environment on plant and animal physiology and development across multiple generations, as part of an integrated ecosystem of plants, microbes, and animals.
• Radiation Sampling – Characterize radiation at key locations in the crew habitat and at astrobiological sampling sites, both to contextualize sample collection and improve our estimates of the risk to future missions

In order to achieve these aims, with the top priority being finding signs of current or extinct life on the planet, the report proposes four different mission options. The first – and favored – campaign would see astronauts land on the planet for 30 sols, or Martian days, followed by a return of that crew, then a cargo delivery to the planet, followed by a 300-sol mission to the planet for a second crew. This mission is dubbed “30-cargo-300”.

Within the 30-cargo-300 mission model, there are a number of options, all with the goal of providing scientists on the planet with the maximum amount of time to study the planet in situ, as well as returning samples back to Earth where they can be further analyzed. This campaign would land astronauts in an “exploration zone” around 100 kilometers (62 miles) in diameter, with a wide array of scientific equipment to explore the planet. Depending on whether the campaign focused on looking for extinct life or current life, potentially more likely beneath the surface, the crew may use some of the initial 30 days to search for suitable drilling sites for the 300-sol mission.

“In the initial 30 sols, the crew would conduct an initial geologic field campaign and initial environmental assessments to inform subsequent scientific activities. They would collect samples from a potentially habitable site and examine them for signs of extinct or extant life, providing exciting early science return. Initial activities would also support site validation, ensuring the selected landing site meets all criteria and is safe for extended operations,” the report explains.

“This foundation supports the extended 300-sol period, during which more complex operations, such as extended EZ exploration, deep drilling, atmospheric measurements, and laboratory-based data collection, can be established in multiple locations. This structure offers the ability to preplace significant infrastructure assets and enable initial reconnaissance to adapt elements of the extended phase based on real-time findings. Longer-duration stays enable more monitoring of volatile and aerosol exchange rates (including interior and exterior) and cycles with seasonal influence, with the ideal situation being a return of a full Mars year of sets of measurements.”

Other, less favored missions include three crewed missions to separate parts of the planet, each to address different science goals. The report notes that there are human limits placed on the exploration of Mars that will need to be addressed before missions like these can take place.

“Current planetary protection guidelines would not enable humans to achieve the top science objective for Mars exploration, namely, the search for life,” the report explains. “That is largely because operations in areas termed ‘Special Regions‘ that are most likely to harbor indigenous life, or that could conceivably be contaminated by life brought to Mars from Earth, require limits on bioburden that may be infeasible for human systems.”

In short, special regions are places on Mars where indigenous Martian life could feasibly still exist. We may not want to contaminate the planet with Earth life, not least because it would make it more difficult to confirm that Mars has its own life at all. Nevertheless, if we are to find life, we may need to explore them.

“NASA should continue to collaborate on the evolution of planetary protection guidelines, with the goal of enabling human explorers to perform research in regions that could possibly support, or even harbor, life,” the report recommends. 

The team stresses that both in-situ science conducted by the first humans on Mars and further analysis back at home will be necessary for a potentially world-changing discovery of life on another planet.

“By imagining different ways that priority science could be pursued during actual human missions, our report shows there are many different options for humans to explore Mars and achieve great scientific breakthrough,” committee co-chair Dava Newman, Apollo Program Professor in the Department of Aeronautics and Astronautics at Massachusetts Institute of Technology, added. “Importantly, it also offers a synergistic review of science priorities enhanced by human exploration.”