Planetary Geologist

Planetary geologists are foundational to Mars exploration because they interpret the alien landscape in ways that determine where rovers go, where landers touch down, and ultimately where humans might one day live. In NASA's Mars Science Laboratory mission, planetary geologists analyzed orbital data from the Mars Reconnaissance Orbiter's HiRISE camera and CRISM spectrometer to select Gale Crater as the landing site for the Curiosity rover, identifying it as a location where ancient water-deposited sediments could reveal habitability history. These scientists then guided Curiosity's traverse across the Martian surface, reading rock layers the way a field geologist reads roadside outcrops, identifying mudstones at a location called Yellowknife Bay that confirmed a once-habitable freshwater lake environment. The same process played out for the Perseverance rover in Jezero Crater, where planetary geologists recognized the ancient river delta as a prime location where biosignatures might be preserved — directly shaping the Mars 2020 mission's sample caching strategy for the planned Mars Sample Return campaign, a joint NASA-ESA effort designed to bring those rocks to Earth laboratories for deeper analysis.

Beyond guiding individual missions, planetary geologists contribute to the longer pipeline of Mars colonization by building the geological maps and resource assessments that future human missions will depend on. ESA's Mars Express mission and NASA's MAVEN orbiter have provided data that planetary geologists use to reconstruct Mars's volcanic and tectonic history, identifying regions of relatively recent volcanic activity and mapping subsurface water ice deposits using the SHARAD and MARSIS ground-penetrating radar instruments. This matters enormously for colonization planning because water ice is considered the most critical in-situ resource — it can be processed into drinking water, oxygen for breathing, and hydrogen for rocket propellant through a technology framework called In-Situ Resource Utilization, or ISRU, which NASA's Artemis and Moon-to-Mars architecture programs are actively developing. Planetary geologists help identify where those ice deposits are most accessible, which lava tubes might provide natural radiation shielding for habitats, and which geological formations indicate stable ground suitable for construction.

As Mars exploration moves toward crewed missions, the role of planetary geologists will evolve from remote analysis to direct field science training and real-time mission support. NASA's analog research programs, such as field campaigns in Iceland's volcanic terrain, the Atacama Desert, and the Arctic's Devon Island through the Haughton-Mars Project, already embed planetary geologists in simulated Mars exploration scenarios to develop protocols for how astronaut-geologists will conduct rapid terrain assessments under time and suit constraints. These scientists also work closely with engineers designing drilling systems like the one carried aboard ESA's ExoMars Rosalind Franklin rover, which is designed to drill two meters below the surface in search of organic molecules protected from radiation — a depth and target chosen specifically from geological reasoning about where life-relevant chemistry might be preserved. In every phase of Mars exploration, from selecting the first landing ellipse to deciding where to sink the first permanent habitat foundation, planetary geologists translate a foreign world's rocky record into actionable human knowledge.