Will Mars Colonists Ever Be Able to Come Home?

Jan de Vries · 2026-08-13

The idea of living on Mars has captured our imagination for decades. But there's a question that rarely gets the spotlight it deserves: once you land on the Red Planet, can you ever really leave? Harry Margulies digs into this very issue, exploring whether Mars colonisation is humanity's greatest adventure or, in reality, a one-way ticket. The conversation usually starts with the excitement of setting foot on another world. We picture the first settlers, the domed habitats, and the rust-colored horizon. It sounds like the ultimate frontier. But beneath that romantic vision lies a harsh biological reality that could change everything about how we plan for life beyond Earth. ### The Gravity Problem Here's the thing: Mars is much smaller than Earth. That means its gravity is only about 38% of what we're used to. If you weigh 150 pounds on Earth, you'd tip the scales at just 57 pounds on Mars. That might sound fun at first, but it's a nightmare for the human body. Our bones and muscles are built for Earth's pull. In low gravity, they start to waste away. Astronauts on the International Space Station already deal with this, and they're only up there for six months at a time. On Mars, you'd be living in that state permanently. After a year or two, your bone density could drop to levels that make standing up on Earth a serious risk. The real kicker? No one knows if the damage is reversible. Once your skeleton adapts to Martian gravity, coming back to Earth might not just be difficult—it could be physically impossible without breaking bones just by walking. ### A One-Way Mission by Default So, what does this mean for the first wave of settlers? It means that even if the rocket technology improves, even if we solve the fuel problem, and even if we figure out how to launch from Mars' surface, the human body might simply say "no" to the return trip. This turns the whole idea of colonisation on its head. We're not just sending explorers anymore. We're sending permanent residents who will never see Earth again. That's a heavy psychological burden, but it also changes the economics of the mission. You don't need to pack for a return journey, which saves a ton of weight and money. But you do need to commit to building a self-sustaining city from day one. ### What Settlers Would Face - **Radiation exposure**: Without a thick atmosphere, settlers are constantly bombarded by cosmic rays. Long-term exposure increases cancer risk significantly. - **Isolation**: Mars is, on average, about 140 million miles from Earth. A message takes up to 20 minutes to arrive, so real-time conversation is off the table. - **Mental health**: Being stuck in a small habitat with a handful of people for years, with no way home, will test even the strongest minds. These aren't just minor inconveniences. They're existential challenges that require us to rethink what a successful mission looks like. It's not about planting a flag and coming back. It's about building a new branch of human civilisation that may never reconnect with its roots. ### So, Is It Worth It? Margulies doesn't give us an easy answer, and that's probably the right call. There's something deeply inspiring about pushing beyond our limits, but there's also a moral weight to sending people off knowing they won't return. As we get closer to actually making this happen, we need to have an honest conversation about what we're asking of these pioneers. In the end, Mars might be our greatest adventure, but it could also be the point of no return. And that's a trade-off we all need to understand before we sign anyone up for the journey.