The idea of re-engineering Mars to make it habitable has been discussed in scientific journals since the early 1970s, and made the cover of Nature in 1991, but remained for decades the preserve of an academic fringe and science-fiction writers.
Astrobiology was invented in the 1990s to provide a unified context for scientific thought about life beyond Earth. It gave NASA a way to pull together disparate research interests and align them with a topic that fascinated the public. NASA's Kepler telescope was designed to study exoplanets in the "habitable zones" of stars like the Sun, and the agency's Mars rovers Curiosity and Perseverance were sent to places that looked as if they might have been habitable in the planet's distant past.
Robin Wordsworth, a researcher at Harvard University, developed the concept of "applied astrobiology" at a workshop at Harvard in 2024. The idea reframes astrobiology as a science not just of studying habitability but of creating it—a unified context for searching for extraterrestrial life and supporting human life in space.
Dr Wordsworth has explored spreading a layer of material such as aerogel across the Martian surface. Such a layer would be transparent to visible sunlight but opaque to ultraviolet radiation and thermal infrared. Sunlight would warm the regolith below while the insulating properties would trap that warmth. Added to regolith with frozen ice and carbon dioxide, this could create a near-surface habitable zone for photosynthetic microbes.
Edwin Kite, a geoscientist at the University of Chicago running a group at the Astera Institute, has explored using solid particles—tiny iron filings optimised to reflect infrared wavelengths, or single-atom-thick carbon nanoparticles—rather than greenhouse gases. Models suggest that pumping optimised aerosols into the Martian atmosphere at just one cubic metre a minute could raise average surface temperatures by around 30°C over a few decades, potentially enough to thaw significant amounts of frozen water. Dr Kite wants to fly a precursor lander mission to release a few kilograms of particles and track their progress.
COSPAR, an international scientific body, formulates planetary-protection rules to which national space programmes pay heed. Any bit of Mars which looks unusually habitable is liable to be rated a "special region", and sending missions to special regions is not allowed. A report from America's National Academies noted that not visiting special regions would minimise or eliminate the chance of finding extant Martian life—a double bind in which the more promising a site, the less possible it is to study.
The Astera Institute is a non-profit organisation funded by Jed McCaleb, a software billionaire responsible for various blockchain innovations, and the leading funder of research into terraforming Mars. It sponsored the "Green Mars" workshop at Lighthaven, a conference facility near the University of California, Berkeley.
Pioneer Labs is a biotech company spun off from the Astera Institute, run by Erika Alden DeBenedictis. It is working on biological systems to help keep space habitats habitable, and has discussed proposing precursor missions to Mars: bioreactors on the surface loaded with Martian atmosphere and regolith to test how various microbes fare.
VAST, also owned by McCaleb, hopes to launch its first space station, Haven-1. McCaleb says two companies are developing systems for biological research to be flown on Haven-1.
Mars's southern hemisphere develops a dry-ice icecap roughly a metre thick in winter as carbon dioxide freezes out of the atmosphere. In spring, dust trapped within the opaque dry ice warms it from within, turning it translucent. Sunlight reaches the surface beneath, turning the base of the dry ice back into gas. Pressure builds until the ice bursts in little fountains, carrying dark dust that settles in distinctive "bloom" patterns. The radial patterns left behind are known as "spiders", and scientists recognise a range of araneiform erosional features created by flows of pressurised dry ice.
In the late 1990s Chris McKay, a NASA scientist, suggested a "Mars Biology Demonstrator" to grow a plant on the planet and send pictures home. NASA did not take up the idea, but a young Elon Musk found it fascinating and looked into doing it privately. He discovered that the cost of launching such a mission would be prohibitive, and so decided to create a space-launch business instead. At some point the idea of a simple flower on Mars was superseded by the idea of a new branch of humanity. Paul Wooster heads SpaceX's plans for Mars.
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