Mars Will Have to Wait

Recently — really, over the last 15 years — there has been a lot of fuss about going to Mars. That effort has stalled along the way, especially because the development of Starship has been more difficult than expected. Still, the idea of making the journey in the next decade or so remains alive.

But after consulting many subject matter experts — that is, Youtube videos — I am highly skeptical. In fact, I would be surprised if a human landing on Mars happens in my lifetime. And even if it does happen, it will likely be Apollo-style: go there, plant a flag, and come back. Not a permanent station, and certainly not “colonization.”

You may think that is too pessimistic, but hear me out. There are two major practical reasons why I think a human journey to Mars is unlikely in the short term, or at least suicidal if attempted.

First, the length of the journey, combined with the low-gravity environment, creates an unsolved medical problem. The human body can function without gravity for a short time, but it continuously degrades without Earth-level gravity. Physical exercise can slow this process, but it cannot stop it. Astronauts’ stays on the International Space Station are usually limited to 6 or, at most, 9 months because this is about the maximum time the human body can endure weightlessness without lasting damage. After returning to Earth, astronauts spend several months in rehab to recover and regain full control over their bodies.

A realistic trip to Mars would take 9 months — maybe 6 with much better propulsion technology — but then there would be no medical facility waiting. You would want astronauts to be at their best when they reach Mars. Instead, you would have a crew already struggling with physical decline, and that is before spending another year or so on Mars, which has about a third of Earth’s gravity, and then making the return journey. So, just from the perspective of keeping the human component alive, there is already a massive problem.

The next problem is the machinery. Mars is a long way from Earth-bound maintenance infrastructure. You cannot call a repair truck halfway to Mars. The challenge is to build a machine that works as needed in an unknown, hazardous environment for a long period of time. And our experience with this is limited.

Space stations are kept in very low Earth orbit for a reason: the thin atmosphere clears debris relatively quickly, Earth’s magnetic field offers some protection from radiation, and spare parts can be delivered. Journeys significantly beyond LEO can still be counted on two hands, plus one finger for Artemis II, and they lasted only days. Going to Mars would be completely different. It would require sustaining life and the mission for years, with current propulsion technology, without support from Earth.

It is the complete lack of supporting infrastructure that makes a trip to Mars so difficult and dangerous. Over such a long time frame, it is likely that something unfixable will break. Fueling up Starship and aiming it at Mars would be like setting out across the Atlantic Ocean in a canoe. It is not technically impossible, but you will very likely die.

Of course, these are engineering-level difficulties that can, in principle, be solved. It would help greatly to have a better rocket engine for deep-space travel. Chemical rockets are good for getting from Earth’s surface to orbit, but they are not a great solution for traveling between planets. With the current state of the art, we cannot do much better than a Hohmann transfer of 9 months to Mars, and only when Earth and Mars align, which happens every 26 months.

With a nuclear thermal engine, like project NERVA, this could be reduced to 5 months — still a long time in space. Compare that with a hypothetical engine that could accelerate continuously at 1g. Then the journey to Mars would take 3 days. That would solve all the problems described above and make an Apollo-style mission immediately possible. While running an engine for a few days may not sound too difficult, a rocket engine that can do so is pure fiction and will surely not happen anytime soon.

The other direction to look in is building more infrastructure in space. A major step in reaching the last untouched places on Earth, such as the poles or Mount Everest, was to establish stores of supplies before the expedition that actually tried to reach the pole or the summit. Something similar might work in space too.

The moon is an obvious target, but there are also ideas about launching a space station into an orbit around the sun that visits both Earth and Mars. Astronauts could travel with it and “hop” to Mars when it flies by. The focus then would not be so much on getting to Mars, but on surviving in space. That gives us a clear ladder: a moon station, a solar-orbit station, and so on. But it is not a direct ticket to Mars.

So, will we see a human on Mars? In the long run, sure. But the idea of simply aiming a rocket at Mars in the next decade does not seem plausible. Forcing the issue would likely end in disaster. Instead, we should take it step by step, with the moon as the straightforward — and still very challenging — target.