Surprising Facts About Mars from Geology to Exploration

Why Mars Matters

Mars offers a window into planetary evolution, the potential for past life, a testbed for technologies needed for human exploration, and a source of broad public inspiration that drives science and engineering forward.

Essentials of the Red Planet

Mars is smaller than Earth with roughly 38% surface gravity, a day length similar to Earth’s, an axial tilt that produces seasons, and longer seasons due to its wider orbit, creating a familiar but stretched seasonal cycle.

Surface and Geological Wonders

• Olympus Mons — The tallest known volcano in the Solar System, towering far above any terrestrial peak.
• Valles Marineris — A canyon system orders of magnitude larger than the Grand Canyon, cutting across the Martian crust.
• Basaltic plains and dunes — Vast volcanic plains dominate the surface while active dune fields show ongoing aeolian migration.

Water, Ice and Habitability Clues

Multiple lines of evidence point to past and present water activity on Mars, informing habitability questions.

• Ancient valleys and deltas — River networks and deltaic deposits indicate sustained surface runoff in Mars’ past.
• Clay and sulfate minerals — Mineralogy records aqueous environments and changing redox conditions over time.
• Subsurface ice and transient brines — Widespread ground ice and hypotheses about ephemeral salty liquids at specific sites.

Atmosphere, Climate and Weather

Mars’ climate is driven by a thin, CO2-dominated atmosphere that produces extreme temperature swings and dynamic weather.

• Thin CO2 atmosphere — Surface pressure is a fraction of Earth’s, limiting liquid water stability and thermal buffering.
• Temperature extremes — Large diurnal and seasonal temperature variations across the planet.
• Global dust storms — Planet-encircling storms can obscure sunlight and alter surface conditions for months.
• Seasonal CO2 ice exchange — Polar caps sublimate and redeposit CO2 seasonally, driving pressure and wind changes.

Exploration Milestones

A compact timeline of robotic missions that transformed our knowledge and prepare targets for sample return and human missions.

• Orbital mapping — Orbiters have mapped minerals, surface morphology and climate indicators at global scale.
• Landers and rovers — Surface missions analysed rocks, detected organics, and demonstrated mobile science across varied terrains.
• Sample caching and return planning — Recent rovers have cached samples to enable future sample-return campaigns.
• Technology demonstration — Instruments and experiments tested entry, descent, landing and in‑situ resource concepts for humans.