Thursday, July 16, 2009

Buzz wants to go back to the future

In Buzz Aldrin's column, Time to Boldly Go Once More, the argument is made to once more make the case to colonize Mars, with the Moon perhaps as a starting point. Good idea? Maybe not so much:
Space is a very hostile place for carbon based life forms. I'm not just talking about hard vacuum and cold temperatures.
  • Weightlessness:

    The most significant adverse effects of long-term weightlessness are muscle atrophy and deterioration of the spaceflight osteopenia. These effects can be minimized through a regimen of exercise. Other significant effects include fluid redistribution, a slowing of the cardiovascular system, decreased production of red blood cells balance disorders, and a weakening of the immune system. Lesser symptoms include loss of body mass, nasal congestion, sleep disturbance, excess flatulence, and puffiness of the face. These effects begin to reverse quickly upon return to the Earth.

  • Solar and Cosmic Radiation:

    When the Sun flares, it produces x-rays, gamma-rays, and energetic particles. The energetic particles are the worst, but they are delayed compared to the X rays and gamma-rays, so you have some warning that they are coming. This gives you time to get into a 'storm shelter', a well-shielded area that you can live in for a few days until the particles die down. A good place for a storm shelter would be in the center of the ship, surrounded by the water tanks. If you don't have a storm shelter (e.g. if you are out moonwalking in just your suit) a bad solar flare can kill you by radiation sickness.

    The hard radiation (particles and x/gamma rays) from the non-flaring Sun is small compared to the galactic cosmic ray exposure. These particles come from deep space more or less continuously. Small amounts of shielding can cut out the majority of this, but the remainder will give you a somewhat increased risk of cancer. Using very conservative rules of thumb, a week in space's cosmic ray environment will shorten your life expectancy by about a day (statistically--it is very unlikely to give you cancer, but if it does, it will shorten your life by more than a day). Since space is inherently dangerous at the present state of the art, cancer due to cosmic rays is relatively small additional risk.

As you can see there are many obstacles that must be overcome before we can even consider space travel far from earth. The best place to solve these problems is in Earth's orbit. Instead of a trip to Mars the resources should be invested in the International Space Station and new platforms. That should also include capturing space objects for raw materials and volatiles for manufacturing in space.

We should continue to send robotic missions to Mars and beyond so we will have as much knowledge as possible if and when we are ready for a manned mission.

There was an almost wistful escapism in Aldrin's column - this notion that we humans could escape the planet we've ravaged and somehow occupy another planet in my kids' lifetime. I just don't see it happening. As fond as I am of the old Apollo missions (televised images of those moon landings form some of my earliest memories) and of science fiction, I'd rather us focus our monetary and natural resources on making our home planet more livable (an undertaking that should prove sufficiently daunting as it is). In the meantime, keep the International Space Station in good working order, send robotic missions to planets in our solar system, and continue to add to our knowledge base when and if human-led missions become feasible.

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