Summary
Highlights
Mars captivates with its mysteries, including immense volcanoes and vast canyons. It's a world where water once existed and lost microbe empires might still thrive. Scientists believe life could be common in the universe if an independent origin of life is found on Mars. The long-held dream of human exploration is closer to reality than ever before, with predictions that the first person to walk on Mars is alive today.
Mars, easily spotted in the night sky, is the most Earth-like planet in our solar system, featuring polar caps, deserts, volcanoes, and canyons. A Martian day is only 40 minutes longer than Earth's, and despite being further from the sun, it has identifiable seasons. Formed around 4.5 billion years ago from similar materials, its early history may have resembled Earth's, raising questions about shared origins of life.
Initial probes in the 1960s dispelled popular notions of Martian civilizations, revealing a barren, cratered landscape. The 1976 Viking missions, while finding no immediate signs of large organisms, painted a picture of a cold, dry planet primarily of rocks and sand. Despite the initial disappointment, scientists continued to dig deeper, uncovering evidence of ancient water flow, suggesting a warmer, wetter past.
Mars is characterized by clear, sunny, yet extremely cold days, with an average temperature similar to Antarctic winters. Its surface area is roughly equivalent to Earth's dry land. Robotic rovers like Spirit and Opportunity, active since 2004, have provided invaluable insights into the Martian landscape. The atmosphere is thin and cold, preventing liquid water on the surface, and the planet experiences constant dust storms. The Martian sky appears amber due to dust, showcasing blue sunsets.
A journey to Mars presents immense challenges, including a six-month one-way trip, a three-year round trip, and the need to carry all supplies. Landing is particularly difficult due to the thin atmosphere and high approach speeds, requiring complex maneuvers and technologies like heat shields, parachutes, and airbags. The Martian environment is dangerously alien; without a thick atmosphere, the low pressure would cause bodily fluids to boil, and radiation levels are high. Current spacesuits are inadequate for sustained activity.
Mars features spectacular scenery on an enormous scale, such as the Valles Marineris, a canyon system thousands of miles long and six miles deep, dwarfing Earth's Grand Canyon. This colossal fissure, once filled with water, shows evidence of biblical floods. Olympus Mons, the largest volcano in the solar system, towers 17 miles high, covering an area larger than the United Kingdom. Mars also exhibits recent landslides, gullies, flash-frozen seas, and buried glaciers, indicating a more active past with abundant water.
The search for Martian life often begins with water. The Phoenix lander in 2008 confirmed the presence of water ice beneath the surface, revealing that the soil contained calcium carbonate, a compound formed in the presence of liquid water. Analogous to Earth's Atacama Desert, where life thrives in extreme dryness, scientists suggest Martian microbes might exist in protected underground environments, utilizing minimal water and unique adaptations. Seasonal changes in Mars's axial tilt might create brief periods conducive to life. The detection of methane, a gas produced by biological or geological processes, further indicates Mars is an active planet, potentially with life.
Human missions to Mars offer advantages over robotic exploration due to the ability to improvise. Future missions, like the Curiosity rover, will search for organic molecules, the building blocks of life. Discovering a second, independent origin of life on Mars would suggest that life is common throughout the universe. Alternatively, if Martian life shares Earth's genetic code, it might imply that life was exchanged between the two planets, possibly originating on Mars and traveling to Earth via meteorites.