Mars
The red planet — target of rovers, orbiters, and future human missions.
Overview
Mars is a cold desert world with the largest volcano (Olympus Mons) and canyon (Valles Marineris) in the solar system, plus polar ice caps of water and CO₂.
Why It Matters
Mars is the most explored planet beyond Earth and the leading candidate for past or present microbial life and future human settlement.
Scientific Explanation
Mars lost its magnetic field ~4 Ga, allowing solar wind to strip its atmosphere. Surface pressure is 0.6% of Earth's. Rovers found ancient river valleys, lake beds, and organic molecules — but no confirmed life. Perseverance caches samples for eventual return to Earth.
Historical Background
Percival Lowell imagined canal-building Martians (1890s). Mariner 4 (1965) revealed craters, not canals. Viking (1976) searched for life; results remain debated.
Visual Explanation
Compare Mars' thin atmosphere, rusty iron-oxide surface, and dry river channels to Earth's blue world — same laws of physics, different outcomes.
Key Discoveries
- ✦ Mariner 9 maps global geology (1971)
- ✦ Curiosity finds ancient habitable lake at Gale Crater
- ✦ Perseverance collects first sample-return cores
- ✦ Subsurface water ice mapped across mid-latitudes
Important Astronomers
Related Missions
Reflection Prompt
Should humanity become a multi-planetary species starting with Mars? What ethical obligations follow?
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