The Challenges of Staying Alive in Space

Image source: ESA

There is an exciting future ahead for space travel. NASA is planning on sending astronauts back to the moon by 2024, and eventually, NASA, ESA and other international and commercial partners are planning to build orbital and surface habitats on the moon. On top of that, you also occasionally hear about colonizing Mars on the news. However, as one might expect, outer space is vastly different than the environment on Earth, and as such humans are naturally very poorly equipped to survive there. Therefore, we must face a lot of challenges to create livable circumstances for any space explorations.

Environmental Issues

As you will probably know, space is a vacuum and immensely cold. The space craft and stations thus need to be fully pressurized and heated and be able to maintain this. Anything that can damage the space craft, such as collisions with orbital debris or (micro-)meteoroids, are thus a major hazard. To protect against this, space stations utilize various methods and technologies. One simple among these is that they have curved outer surfaces, because it increases its so-called effective thickness. This means, that if a surface is struck by an object under an angle, it will behave as if the surface is thicker than it actually is. Depending on the angle, this can increase the protection to more than twice what it usually is. This has been known since the Middle Ages, during which they started building rounded towers, because these can withstand a lot more damage from siege engines than square towers. In the same vein, a cylindrical design will better protect a space craft against micro-meteoroids, than flat surfaces. Additionally, these kinds of structures also hold their shape better, meaning that these designs also help withstand the vast pressure difference between the exterior and interior of the spacecraft. 

An Overwhelming Amount of Radiation

Besides the difference in pressure and temperature, is there also a big difference in the amount of radiation on Earth versus in space. The Earth’s magnetic field and atmosphere shields its surface from a lot of radiation coming from the Sun and deep space. This is a good thing, because ionizing radiation can deal damage to all parts of the body, including the nervous system and blood forming organs. In low amounts, this will increase the risk of cancer later in life, but in large amounts, such as during a Solar flare, can have immediate and life-threatening consequences. Once we travel outside these protective boundaries, we will be exposed to this harmful radiation. It is thus important that we deploy countermeasures to reduce the exposure to radiation and its effects. 

Currently, the amount of time an astronaut is allowed to be in space is limited to 3-6 months. However, when travelling further out into space, we obviously cannot limit the amount of time an astronaut will spend exposed. Additionally, the International Space Station (ISS) resides within the magnetic field of the Earth, because of which they are only exposed to about 10 times as much radiation as they would be on Earth. Completely leaving the Earth’s magnetic field for long periods of time will thus require better protection than we deploy today. 

One way of protecting the crew is by blocking the radiation with material. The highest energetic radiation, like gamma waves or cosmic rays, can penetrate through aluminum and require a thick and dense layer of material, such as concrete, to be stopped. This causes a problem, because the heavier the shielding is, the harder and the more expensive it is to launch it into space. Additionally, the radiation will interact with the atoms making up the shielding itself, causing secondary radiation. Heavier elements, such as lead, will produce a lot more of this secondary radiation than lighter elements such as hydrogen or carbon. A lightweight plastic composed from hydrogen and carbon is thus seemingly the best solution. But even then, shields of five to seven centimeters thick can only block up to 35% of the incoming radiation, meaning that the majority of the radiation would still penetrate the shields. These types of shielding are thus combined with medicine to mitigate the effects of radiation exposure, and could be combined with other methods. One possibility is to use electromagnetic fields to curve the path of the radiation around the spacecraft, although this does require energy to generate these fields. 

The Lack of Gravity

Space Station V from 2001: A Space Odyssey

Finally, the lack of gravity or reduced gravity has effects on the human body as well. This can lead to loss of muscle and bone density, changes to eyesight and many more. Luckily, astronauts can normally re-adapt without too much issue. But with very long spaceflights, this might not be the case. Thus, the idea of creating some form of artificial gravity to prevent these issues has been floating around for quite a while. One way of achieving this, could be done by having a circular section of the space craft rotate, using the centrifugal force as a stand-in for gravity. This will sound familiar to science fiction fans, as it was featured in movies such as 2001: A Space Odyssey.

As one would expect, a lot of engineering and clever problem solving is required to keep humans alive and healthy in space. Even with our current technologies, space travel is still very dangerous, and more scientific progress will need to be made before we can truly explore and colonize the rest of our solar system and beyond.