T-Minus: How to not die on (the way to) Mars

The threats Mars astronauts face — and how NASA is working to solve them.
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In 1962, President John F. Kennedy told a crowd gathered at Rice University that the US wanted to put a person on the moon before the end of the decade because it was hard — but a challenge wasn’t all America was looking for with its moon mission.

In that same speech, Kennedy also talked about how a moon landing — and everything that led up to it — would expand our knowledge of the universe and environment and lead to the development of new technologies with applications far beyond aerospace.

And he was right. Not only did we learn a ton about the moon and our solar system from NASA’s Apollo program, it also laid the groundwork for modern computers and led to the development of countless inventions, from cruise control to rechargeable hearing aid batteries.

NASA’s new goal is to put boots on Mars before 2040 — but if landing on the moon was hard, safely sending people to the Red Planet is going to be downright grueling

An artist's concept of astronauts living on Mars, with habitats and other structures
An artist’s concept of astronauts living on Mars.

The moon is about 240,000 miles away from Earth, and while that’s not exactly close enough for a weekend getaway, NASA could send the Apollo 11 astronauts there and back in eight days. That’s short enough that all the food, water, and oxygen they needed could be included in the spacecraft with them.

At its closest, Mars is about 35 million miles away from Earth, and NASA estimates it’ll take about 7 months for a crewed spacecraft just to reach the Red Planet. Factoring in the return trip and the actual exploration of Mars, NASA anticipates missions lasting 2 to 3 years — and the cost of shipping supplies for a mission of that length from Earth to Mars are astronomical.

Aside from figuring out an alternative way to provide Mars astronauts with the food, water, and oxygen they’ll need to simply stay alive during the mission, NASA also needs to protect them from the many health threats they’ll face being away from Earth for so long — and some of the unique risks to life on Mars.

Here’s a breakdown of five of the biggest threats to future Mars astronauts — and what scientists are doing to overcome each hurdle between us and a multiplanetary future.

T:05 written in the style of a digital clock

No food

The problem: NASA plans to ship most of the food for Mars missions to the Red Planet, either with astronauts or before they arrive, but it hopes to supplement that prepackaged food with fresh food — this could help keep shipping costs down, ensure astronauts stay healthy, and help avoid menu fatigue.

As far as we can tell, though, there is nothing edible on Mars.  

an astronaut on a space station studying lettuce
ESA / Alexander Gerst
NASA astronaut Serena Auñón-Chancellor harvests kale and lettuce grown aboard the ISS.

The plan: Farming is an obvious solution — seeds are cheaper to ship than meals, and Mars has water and CO2 already. But Mars is not exactly an ideal environment for growing crops, even in a greenhouse.

Not only does it have weak sunlight and a limited water supply, its soil is very different from the dirt on Earth — as Zach and Kelly Weinersmith point out in their book A City on Mars, about 1% of Martian dirt is composed of chemicals called perchlorates, which can mess up your thyroid gland.

NASA doesn’t think it would be impossible to grow plants on Mars, though, so the challenge now is figuring out the best approach.

It’s studying how crops grow in the microgravity environment of the International Space Station (ISS), testing indoor gardening systems at simulated Mars habitats, and offering prizes through its Deep Space Food Challenge for Martian food system designs.

T:04 written in the style of a digital clock

Weak gravity

The problem: Gravity on Mars is only about one-third as strong as on Earth, and NASA already knows from studying astronauts aboard the ISS that spending extensive time in microgravity causes significant bone loss, muscle loss, vision problems, and other health issues. 

Most ISS missions are just six months long, too, and no NASA astronaut has been in space longer than 371 days (Russian cosmonaut Valeri Polyakov holds the overall record at 437 days). Martian gravity is much less than on Earth but a lot greater than on the ISS, so we still don’t really know how two or three years of reduced gravity is going to affect the astronauts.

Researchers watch a person suspended horizontal to the ground by straps walk on a vertical treadmill.
Research being conducted at the Exercise Countermeasures Laboratory (ECL) at NASA Glenn Research Center.

The plan: NASA’s Human Research Program (HRP) is conducting studies with Mars analogs on Earth and the ISS to better understand the problem and try to develop effective countermeasures. Some of that research will continue on the moon when NASA returns astronauts to its surface in the coming Artemis missions.

It’s likely that exercise will be at least part of the solution — ISS astronauts work out for two hours every day to slow down bone and muscle loss, and they still lose a ton of muscle mass. Researchers at NASA’s Exercise Physiology and Countermeasures lab are developing exercise routines specifically designed to help Mars astronauts stay healthy during the long spaceflight and while on Mars.

Scientists are also exploring ideas more radical than space treadmills to protect astronauts from the effects of microgravity.

UC Davis researchers have created a genetically modified lettuce that makes a hormone that stimulates bone formation, while a NASA-sponsored study at the University of Illinois Urbana-Champaign is trying to find out whether it’s possible to recreate the cellular benefits of exercise without requiring astronauts to break a sweat at all.

A NASA-sponsored team at UT Southwestern, meanwhile, is developing a sleeping bag that would prevent fluid from building up in astronauts’ heads while they sleep, aiming to prevent the vision problems created by microgravity.

T:03 written in the style of a digital clock

Space radiation

The problem: Earth’s molten metal core creates a magnetic field around our planet known as the “magnetosphere,” which protects us from solar and cosmic radiation and prevents the erosion of our atmosphere into space. 

Some other planets have magnetospheres, but Mars isn’t one of them (not anymore, anyway), which means astronauts won’t have this protection, leaving them at increased risk of developing cancer and other health issues.

a scientist holding a vial of yellow powder
University of Nevada, Reno
This pigment, found in the fungi Wolf lichen, might one day be used in a sunscreen for Mars astronauts.

The plan: The effect of radiation on astronauts is already a top concern for NASA. On the ISS, astronauts are exposed to about 100 times more radiation than they would be on Earth, so NASA has limits for how much time they can spend on the ISS over the course of their careers. Even so, the space station is still well inside the cozy protection of the magnetosphere — outside it, things get hairier.

NASA’s radiation limits, which were set in 2014, are far more conservative than other space agencies, and crewed missions to the moon and Mars simply wouldn’t be possible under them, so it’s now trying to determine new ethical limits based on the latest data and input from experts.

There will still likely be a gap between the new limits and the amount of radiation astronauts would be exposed to during Mars missions, but researchers at NASA and beyond are developing strategies to minimize this exposure, including radiation-shielding vests and a special Mars sunscreen.

Building Mars shelters underground, in ancient lava tubes, or below natural rock overhangs could also help protect astronauts from radiation. In the more speculative category, NASA is even considering ideas to create an artificial magnetosphere on Mars, which would not only help address the radiation problem, but also, over time, give the Red Planet a thicker atmosphere.

T:02 written in the style of a digital clock

No liquid water

The problem: Astronauts need water for drinking, farming, hygiene, and rocket fuel to return home — but there’s essentially no liquid water at all on the surface of Mars. Water is heavy and incompressible, so carrying it all from Earth would be very costly.

an image of the surface of Mars with a bit of ice exposed
NASA / JPL-Caltech / University of Arizona
NASA’s Mars Reconnaissance Orbiter spotted this subsurface ice, which was exposed by a meteorite impact.

The plan: Mars may be a dry, dusty planet, but there’s actually tons of water on Mars — locked in the form of ice, mostly below the surface. 

The majority of Martian ice is near the planet’s poles, but temperatures there are too cold for astronauts. In 2017, NASA launched the Subsurface Water Ice Mapping (SWIM) project to (you guessed it) map the subsurface water ice on Mars using orbiting spacecraft. The data from this and other missions have found vast deposits of ice buried near the equator.

NASA will use these maps when picking a landing site for future crewed Mars missions. The ideal location would be near a large deposit of ice that astronauts could access through digging or drilling and also as close to the equator as possible to help them stay warm.

Any water astronauts capture on Mars (except that used to make rocket fuel) can be recycled repeatedly using systems like the ones on the ISS, which recover 98% of the water used on the space station.

T:01 written in the style of a digital clock

An unbreathable atmosphere

The problem: Mars has a very thin atmosphere, and it’s 96% carbon dioxide with just 0.16% free oxygen. Earth’s atmosphere is 100 times thicker and about 20% oxygen. If you tried to breathe on the surface of the Red Planet, you’d suffocate almost instantly. 

Astronauts could bring oxygen with them and recycle some of it, like they do on the ISS, but the cost of shipping enough for multiple years would be enormous.

a golden box being lowered into a spacecraft
NASA / JPL-Caltech
NASA researchers loading the MOXIE instrument into the Perseverance rover.

The plan: Carbon dioxide is one carbon molecule and two oxygen molecules, which means there is oxygen on the Red Planet — NASA just needs to figure out how to extract it from the CO2.

NASA developed MOXIE — a toaster-sized device that hitched a ride to Mars aboard the Perseverance rover in 2021 — to test making breathable oxygen from Martian air. Once on the Red Planet, MOXIE used electricity to split CO2, successfully generating the first oxygen on Mars.

This was a very small scale experiment, but NASA is now using insights gleaned from MOXIE to develop a larger system that could be sent to Mars ahead of crewed missions. The plan for that device is to make liquid oxygen, too, which could be used as rocket fuel for return missions.

The bottom line

That’s a lot of threats to Mars astronauts, and this list isn’t even exhaustive. 

Astronauts may also have to contend with months-long dust storms that sometimes cover the planet, damaging equipment and blocking sunlight from reaching the solar panels powering life support systems. (This is one reason why NASA is exploring the potential of sending nuclear reactors to the Red Planet.)

Being isolated with just a few other people so far from home for so long could impact Mars astronauts’ mental health, too, so NASA’s Behavioral Health and Performance team is researching ways to ensure astronauts stay mentally healthy during missions.

It is going to take a lot of work (and money) to solve these problems, but NASA believes it’ll be worth the effort.

Not only could crewed Mars missions improve our understanding of the solar system and potentially even lead to the first discovery of extraterrestrial life, the research going into them could have a positive impact on life here on Earth, too, just like the Apollo program did.

In 2021, for example, NASA’s Space Radiation Element — the division of the Human Research Program focused on combating space radiation — joined a White House initiative to cut cancer death rates in America by 50% by 2047.

“Scientists at NASA have been studying cancer for decades, focusing on understanding risks to astronauts,” said NASA Administrator Bill Nelson. “Through this initiative, NASA will work with agencies and researchers across the government to help end cancer as we know it.”

NASA is also hopeful that the technologies being developed to feed Mars astronauts could contribute to ending hunger on Earth by revealing ways to grow crops in inhospitable locations with limited resources.

“In addition to meeting needs for long-term deep space missions, the judges [of NASA’s Deep Space Food challenge] also considered the potential use of the technology here on Earth, where food insecurity is a significant problem in harsh environments,” said Denise Morris, program manager for NASA’s Centennial Challenges.

Ultimately, putting boots on Mars by 2040 will definitely be hard, but if NASA can pull it off, we could be reaping the benefits for decades to come.

We’d love to hear from you! If you have a comment about this article or if you have a tip for a future Freethink story, please email us at [email protected].

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