Bringing Humans to Mars is a Challenge

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A NASA view of possible human-led Mars exploration. NASA

In the late 1960s, the United States proved to the world that it was possible to land humans on the Moon. Today, decades after that first mission, people are again looking to travel to another world, but it's not just to the Moon. Now, they want to walk on Mars. Innovations in spacecraft, materials, and designs will be needed to accomplish such a mission, and those challenges are being met by new generations of engineers and scientists. Visiting and colonizing those worlds will require complex spacecraft not just to get people there, but to safeguard them once they arrive.

Today's rockets are far more powerful, far more efficient and far more reliable than those used on the Apollo missions. The electronics that control the spacecraft and that help keep the astronauts alive are changing all the time, and some of it gets used every day, in cellphones that would put the Apollo electronics to shame. Today, every aspect of manned space flight has become substantially more evolved. So why, then, have humans not been to Mars YET?

Getting to Mars is Difficult

The root of the answer is that the scale of what a trip to Mars is incredibly big and complex. The challenges are formidable. For example, nearly two-thirds of Mars missions have met with some failure or mishap. And those are just the robotic ones! It gets more crucial when people start to talk about sending people to the Red Planet! 

Think about how far they will have to travel. Mars is about 150 times farther away from Earth than the Moon. That may not sound like a lot, but think about what that means in terms of added fuel. More fuel means more weight. More weight means bigger capsules and bigger rockets. Those challenges alone put a trip to Mars on a different scale from simply "hopping" to the Moon (which takes a few days at the most).

However, those are the only challenges. NASA has spacecraft designs (like Orion and Nautilus) that would be capable of making the trip. Other agencies and companies have plans to go to Mars, such as SpaceX and the Chinese government, but even they aren't quite ready yet to make the leap. However, it's quite likely that some form of a mission will fly, perhaps within a decade at the very earliest.

Mars missions in the future.
An artist's rendition of SpaceX's interplanetary transport system approaching Mars carrying a crew. SpaceX, donated to public domain.  

However, there's another challenge: time. Since Mars is so far away, and orbits the Sun at a different rate than Earth, NASA (or anybody sending people to Mars) must time launches to the Red Planet very precisely. Mission planners have to wait until the best "window of opportunity" when the planets are in the correct orbital alignment. That's true for the trip there as well as the trip home. The window for a successful launch opens up only every couple of years, so timing is crucial. Also, it takes time to get to Mars safely; months or possibly as much as a year for the one-way trip. 

While it may be possible to cut the travel time down to a month or two using advanced propulsion technology currently under development, once on the surface of the Red Planet the astronauts will need to wait until Earth and Mars are correctly aligned again before returning. How long will that take? A year and a half, at least.

Dealing With the Issue of Time

The lengthy timescale for travel to and from Mars causes problems in other areas as well. How do the travelers get enough oxygen? What about water? And, of course, food? And how do they get around the fact that they are traveling through space, where the Sun's energetic solar wind is sending harmful radiation around the spacecraft? And, there are also the micrometeorites, the debris of space, that threaten to puncture the spacecraft or spacesuit of an astronaut.

The solutions to these problems are trickier to accomplish. But they will be solved, which will make a trip to Mars doable. Protecting the astronauts while in space means building the spacecraft out of robust materials and shielding it from the Sun's harmful rays.

The problems of food and air will have to be solved through creative means. Growing plants that produce both food and oxygen is a good start. However, this means that should the plants die, things will go horribly wrong. That is all assuming you have enough room to grow the volume of planets needed for such an adventure.

Astronauts could take food, water, and oxygen along, but enough supplies for the entire trip will add weight and size to the spacecraft. One possible solution might be to send materials to be used ON Mars ahead, on an uncrewed rocket to land on Mars and be waiting when the humans get there. That's a very doable solution that several mission planners are considering.

food production on Mars in the future.
An artist's conception of a food production unit on Mars with the cutaway showing the plants colonists would need.  NASA

NASA is confident that it can overcome these problems, but we are not quite there yet. SpaceX says it's getting ready. The plans from other countries are less knowable, but they are serious about Mars, as well. Still, the plans are still very much theoretical. Over the coming two decades mission planners hope to close the gap between theory and reality. Maybe then, humanity can actually send astronauts to Mars on long-term missions of exploration and eventual colonization.

Updated and edited by Carolyn Collins Petersen.