08-25-2013: BSinSF - Dangers of Space Travel

This post comes to you from South Carolina where I'm visiting my father on the way to Dragon*con. Next week's post might be a bit late because of the convention. Peacekeeper update: My wife is at about the half-way point in her grammatical review of the novel. She's been doing her best to proof during our drive through the mountains.

Space is an incredibly dangerous place and many science fiction stories seem to ignore that fact. The movie 2010 got it right but most other movies and many novels get it wrong. This edition of BSinSF talks about some of the dangers people face in space.

The vast majority of the population have no idea just how well protected they are living on the Earth's surface. They seem to forget that our home planet orbits a monstrous unshielded fusion reactor spewing forth torrential amounts of radiation. The Earth protects us in two ways from this onslaught: it maintains a powerful force field and it has a relatively thick atmosphere. The force field is the Earth's magnetic field which extends for hundreds of kilometers out into space. It deflects high energy particles away from the surface. The atmosphere provides a thick layer of shielding protecting us against many other forms of attack from space.

Radiation is a major concern in space. The international community measures radiation in Sieverts which is abbreviated as Sv. A typical person on Earth receives an annual dose of about .01 milli-Sieverts (mSv). The International Space Station is protected from most of the radiation in space because it orbits within the Earth's magnetic field. If you were to spend an entire year on the station, you could expect to receive a total dose of about 150 mSv. An astronaut on the shortest possible round-trip to Mars would receive a total dose of roughly 0.66 Sv. That's 66,000 times the radiation a person normally expects to receive. If you're on the surface of an airless world (i.e. the moon) you're exposed to this radiation. Mars has a very weak magnetic field and a thin atmosphere so living there will get you more dose than working at a nuclear plant. For comparison purposes, I work at a nuke plant and I have never received more than about 3 mSv of radiation in one year.

Things get even worse around Jupiter. Space probes working in the area have to be equipped with specially hardened electronics because the radiation field in the area would damage them to the point of failure. Biological material would not survive for long. Any ships carrying humans would have to be equipped with sophisticated heavy shielding systems.

But radiation is not the only danger in space. In order to get anywhere within a reasonable amount of time you need to travel very fast. Speeds are measured in kilometers per second and at those velocities hitting something as mundane as a fleck of paint can cause serious damage. The space shuttle has returned with dings in the windshield from hitting things like this. A marble-sized rock would do serious damage. Luckily, space is big—very very big—and the chance of hitting something is quite remote. Still, it's a danger, especially if you're traveling very fast for long periods of time. To prevent the forward section of your ship from being slowly eroded away it had better be protected by thick layers of heavy armor.

There are other things out there that are far more dangerous. Getting in the path of a gamma-ray burst for instance could be instantly fatal even light years from the source. If your ship is capable of faster than light travel, the navigational system had better be able to steer you clear of these deadly beams of radiation. There are also strange objects out there called magnetars with hyper-powerful magnetic fields. Get too close to one of these and they will not only erase all your credit cards but you could also find yourself without any iron in your body.

The bottom line—space is not a safe place to be and all science fiction writers should be aware of them. Your ship needs to be able to avoid the larger hazards as well as protect the occupants from the ever-present radiation field. If you want to keep the science right, then you need to learn about such things.