Mars matters because it is the closest planet that could answer one of humanity’s biggest questions: did life ever exist beyond Earth? But the planet’s importance goes well beyond biology. Mars serves as a natural laboratory for understanding how planets lose their atmospheres, a testing ground for technologies that benefit life on Earth, and a potential second home for human civilization. No other destination in our solar system offers all of these at once.
It May Hold Evidence of Ancient Life
Mars was once a warmer, wetter world with rivers, lakes, and a thicker atmosphere. That makes it the best candidate in our solar system for finding signs of past microbial life. NASA’s Perseverance rover is actively searching for those signs in Jezero Crater, a basin that was once filled by a river a quarter-mile wide. In 2024, Perseverance collected a rock sample from that ancient riverbed that scientists flagged as a potential biosignature, meaning it carries chemical patterns consistent with biological activity.
The rock is made of clay and silt, materials that on Earth are excellent at preserving traces of microbes. It’s rich in organic carbon, sulfur, phosphorus, and iron. Most intriguing are mineral formations the team nicknamed “leopard spots,” tiny patterns of two iron-rich minerals (one commonly found around decaying organic matter on Earth, the other produced by certain microbes). Together, they suggest the kind of chemical reactions that living organisms use to generate energy. None of this proves life existed on Mars, but it’s exactly the kind of fingerprint scientists have been looking for.
Adding to the intrigue, NASA’s Curiosity rover has detected methane in Mars’s thin atmosphere, including one spike of about 21 parts per billion, the largest the mission ever recorded. On Earth, microbial life is a major source of methane. On Mars, the gas could also come from water reacting with rock deep underground. Scientists have observed methane levels rise and fall with the seasons but haven’t been able to pin down the source. Curiosity lacks the instruments to distinguish biological methane from geological methane, which is one reason future missions are so critical.
A Warning About Planetary Atmospheres
Mars once had a much thicker atmosphere, possibly dense enough to support liquid water on the surface. It lost most of that atmosphere because it lacks a strong magnetic field. Without that shield, the solar wind (a constant stream of charged particles from the Sun) gradually stripped away atmospheric gases over billions of years. Scientists estimate that roughly 3 bars of carbon dioxide have been blasted off Mars over the last 3.5 billion years. Early in the solar system’s history, when the young Sun was more active, this stripping happened even faster.
This matters for Earth because it demonstrates what happens when a planet loses its magnetic protection. Earth’s magnetic field deflects the solar wind and keeps our atmosphere intact. Studying Mars gives scientists a real-world case study of atmospheric loss, helping refine models of how planets evolve over time and what conditions are necessary to keep a world habitable.
Liquid Water Still Exists There
In 2018, a team using radar aboard the Mars Express spacecraft reported evidence of liquid water trapped beneath the south polar ice cap. The radar instrument surveyed a region called Planum Australe between 2012 and 2015 and found an unusually bright reflection about 20 kilometers wide, buried under layers of ice. The signal’s properties matched those of water-bearing materials rather than dry rock or ice. The finding was confirmed across nine separate orbital passes at three different radar frequencies.
If liquid water does persist underground, it dramatically changes the picture for both past life and future exploration. Water is essential for biology as we know it, and it’s also a critical resource for any human settlement. It can be split into hydrogen and oxygen for breathable air and rocket fuel.
A Testing Ground for Survival Technology
Mars exploration has already produced a landmark technology demonstration. The MOXIE instrument aboard Perseverance proved that oxygen can be extracted from the Martian atmosphere, which is 96% carbon dioxide. In its first year of operation, MOXIE produced about 50 grams of oxygen across seven separate runs, generating 6 to 8 grams per hour. That’s a tiny amount, but it validated the concept. A scaled-up version, several hundred times larger, could produce 2 to 3 kilograms of oxygen per hour. That’s enough to manufacture the tens of tons of oxygen needed to launch a crew off Mars for the return trip home, eliminating the need to haul all that mass from Earth.
The broader push toward Mars has also driven innovations in medicine and consumer technology. NASA research originally aimed at keeping astronauts healthy has led to breakthroughs in eye surgery, cardiac devices, and cancer treatment. Technologies developed for tracking, durable materials, and imaging in extreme environments routinely find second lives in hospitals and homes.
A Strategic Location for Deeper Exploration
Mars sits at 1.5 times Earth’s distance from the Sun, placing it much closer to the asteroid belt, a vast ring of rocky bodies rich in metals and minerals. Research comparing the energy costs of reaching asteroids from Earth orbit versus Mars orbit found that launching from Mars cuts the required energy roughly in half. The median velocity change needed to reach main-belt asteroids drops from about 9.7 km/s from low Earth orbit to around 5.1 km/s from Mars orbit. That difference is enormous in spaceflight terms, where every extra kilometer per second of velocity demands exponentially more fuel.
If space-based mining or large-scale exploration of the asteroid belt ever becomes economically viable, Mars orbit would serve as the logical staging area. Its moon Phobos, orbiting just 9,000 kilometers above the surface, could function as a natural base of operations.
The Challenges Are Real
Mars is not hospitable. The Curiosity rover’s radiation detector measured an average surface dose of about 0.7 millisieverts per day. That works out to roughly 255 millisieverts per year, compared to Earth’s average background radiation of 3 millisieverts per year. An astronaut on Mars would absorb radiation at about 85 times the rate you experience on Earth. Over a typical mission lasting nearly three years (including travel time), the cumulative dose would approach the career limits set by most space agencies. Shielding habitats, possibly by burying them under Martian soil, would be essential for any long-term settlement.
The thin atmosphere, only about 1% the density of Earth’s, offers almost no protection from radiation or meteorite impacts and cannot support human breathing. Surface temperatures average around minus 60°C. These aren’t reasons to avoid Mars. They’re engineering problems, and solving them is part of why the planet matters. Every solution developed for Mars, from radiation shielding to closed-loop life support to extracting resources from hostile environments, has direct applications for surviving extreme conditions on Earth.
When Humans Might Get There
NASA is developing the technologies needed to send astronauts to Mars as early as the 2030s, with an example roundtrip mission scenario targeting 2039. The transit alone takes six to nine months each way, and launch windows open only every 26 months when Earth and Mars align favorably. A full mission would likely keep a crew away from Earth for two to three years.
Getting there requires advances in propulsion, life support, radiation protection, and the ability to live off Martian resources rather than shipping everything from Earth. MOXIE was a first step. Future missions will need to demonstrate water extraction, food production, and habitat construction using local materials before a crewed landing becomes realistic.