It feels like we’ve been 10 years away from a Mars landing for about four decades now, yet the Red Planet remains a frustratingly distant speck in our telescopes. While the Moon was a three-day hop, Mars is a brutal, seven-month trek that we can only even attempt every couple of years when the planets align.
This isn’t just a matter of building a bigger engine; it’s a massive gamble involving everything from deep-space radiation that fries human DNA to the simple fact that landing a heavy ship in a thin atmosphere is like trying to park a bus on a sheet of ice. Even in 2026, we’re still wrestling with the reality that sending a crew out there might currently be a one-way trip to a very expensive crater. Here’s why it just hasn’t happened yet (and probably never will).
Mars is impossibly far away.
The distance between Earth and Mars changes constantly as both planets orbit the sun, ranging from about 55 million to 400 million kilometres apart. Even at the closest point, getting there takes around seven months using current technology. That’s seven months in a small spacecraft with the same few people, eating recycled food and breathing recycled air, with no possibility of emergency evacuation if something goes wrong. The moon is only three days away, which is why we managed that in the 1960s, but Mars is an entirely different scale of difficulty.
@astro_alexandra Here’s four reasons why we haven’t sent humans to Mars yet! #space #nasa #planet #solarsystem ♬ original sound – ASTRO ALEXANDRA 🪐
You can’t just turn around and come home.
Once you launch towards Mars, you’re committed to the journey. The planets only align properly for travel every 26 months, so if you want to come back, you either need to stay on Mars for over a year waiting for the return window or bring enough fuel for an immediate return, which would require a spacecraft so massive we can’t currently build it. Most mission plans involve astronauts spending 18 to 20 months on Mars before the planets align for a return journey, making the total mission around three years long.
Radiation will kill you slowly.
Earth’s magnetic field protects us from cosmic radiation and solar radiation, but Mars has no such protection, and neither does the empty space between here and there. Astronauts on a Mars mission would be exposed to radiation levels far beyond what’s considered safe, significantly increasing their cancer risk and potentially causing immediate damage to their nervous system and organs. We don’t have adequate shielding technology that doesn’t make the spacecraft too heavy to launch. Some proposals suggest using water or food storage as radiation shields, but we haven’t proven these solutions work well enough for a multi-year mission.
Landing on Mars is genuinely terrifying.
Mars has enough atmosphere to create problems during landing, but not enough to slow you down effectively with parachutes alone. The “seven minutes of terror” that NASA talks about for rover landings would be even worse with humans on board. You need a combination of heat shields, parachutes, and rockets to land safely, and everything has to work perfectly in sequence with no possibility of human intervention because of the communication delay. We’ve successfully landed robots, but a spacecraft large enough for humans and their supplies would be much heavier and harder to land safely.
Bringing enough supplies is a nightmare.
A crew of four would need roughly 30 tons of food, water, and oxygen for a three-year mission if you couldn’t recycle or produce anything on Mars. Launching that much mass is extremely expensive and difficult. Current plans rely on producing water and oxygen from Martian resources and growing some food on the surface, but these technologies haven’t been proven at the scale needed. If your water recycling system fails or your greenhouse dies, people die, and there’s no resupply mission coming to save you.
The cost is astronomical and nobody wants to pay.
Estimates for a crewed Mars mission range from 100 billion to over $500 billion (£431 billion), depending on the approach. That’s more than most countries are willing to spend on a space mission, especially when the scientific return could largely be achieved with robots for a fraction of the cost. NASA’s entire annual budget is around $25 billion, so a Mars mission would require either massive budget increases sustained over decades or international cooperation on a scale we’ve never achieved. Politicians struggle to fund projects that won’t show results until long after they’ve left office.
Low gravity will wreck astronauts’ bodies.
Mars has only 38% of Earth’s gravity, and the journey there involves months of zero gravity. Astronauts lose bone density, muscle mass, and experience cardiovascular changes even on short space station missions. A three-year Mars mission would cause severe physical deterioration that might be irreversible. We don’t know if astronauts could even survive the high-gravity stress of returning to Earth after that long in low gravity. Some might be permanently disabled by the experience, which raises serious ethical questions about sending people on a mission that could cripple them.
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We haven’t solved the mental health problem.
Spending three years in a tiny spacecraft and Mars base with the same few people, completely isolated from Earth with a 20-minute communication delay, would be psychologically brutal. You can’t leave, you can’t get privacy, and any interpersonal conflicts could become dangerous when you’re trapped together. Antarctica research stations and submarine crews give us some idea of the challenges, but those missions are shorter and evacuation is theoretically possible. We need to select crew members very carefully and provide psychological support systems we haven’t fully developed yet.
The technology gaps are bigger than you’d think.
We need closed-loop life support systems that can recycle air and water with near-perfect efficiency for years. We need reliable power systems for Mars that work during dust storms that can block solar panels for months. We need spacesuits that are more flexible and easier to use than current designs because astronauts will need to work outside regularly. We need medical equipment and training for a doctor to perform surgery or handle emergencies with no possibility of specialist consultation. Each of these problems is solvable individually, but solving all of them together for one mission is the challenge.
We’re still arguing about whether it’s worth doing.
Some scientists argue that robots can do everything humans can do on Mars for far less money and risk. Others say human exploration is essential for making the discoveries robots might miss and for inspiring the next generation. There’s also debate about whether we should focus on the moon first as a testing ground and stepping stone, or whether that’s a waste of time when Mars is the real goal. Without a clear consensus on whether human Mars exploration is a priority, it’s hard to maintain the political will and funding needed for such an expensive, long-term project. Until we collectively decide it’s genuinely worth doing, we’ll keep planning missions that never quite happen.