Permanent Human Settlement of the Earth, Space and Ocean Frontiers

Wednesday, June 07, 2006

Space Radiation - Are There Solutions?

Space Radiation, in space agency parlance – is the “long pole in the tent”. In other words, if we can’t first understand it then solve it, mankind will never get beyond low earth orbit. If we do not fully understand and solve this problem starting now, there will never be a moon base and there will never be a Mars expedition of off earth settlements – ever. That makes the solution very important!

And what are those solutions? Here are five that have been suggested.

USE NUCLEAR ROCKETS: If we can speed up our space voyages, it exposes our crews to less radiation while in space. The less time spent on getting from point A to point B means less risk. Then we can use the methods below on the surface of the planets to mitigate the on site exploration risk.

SPACE VEHICLE SHIELDING: This is actually the least practical of all the suggestions. If one can put enough shielding around a spacecraft, one can shield out much of the space radiation. However, in the case of the “heavy primaries”, it would require one massive shield. Mass in space is always a significant problem: how does one get it there and then, once the spacecraft is shielded, then where does one get all the energy to accelerate and then decelerate it? It is possible to employ a small asteroid and burrow down to its core, using the asteroid as a shield, then propel the asteroid like a spacecraft – but, the energy required to do this is well beyond our technology.

REGOLIOTH SHIELDING: If one can pile up enough in situ shielding atop a planetary base, it is possible to shield the offending energies out. On the surface of the Moon or Mars, this is not a serious problem. One simply piles up enough regolith (the off-earth word for ‘soil’ or ‘dirt’ – which have different meanings off-earth) on top of the habitat to shield it out. It is the least expensive and most (pardon the pun) down-to-earth method. Unfortunately, the Hollywood image of the domed colony is out.

THE HIGH VOLTAGE SHIELD: It may be possible to duplicate a mini-magnetosphere by arranging a series of spherical balloons over and around the colony structures as shown in the illustration above. These spheres are then charged with very high voltage – on the order of 50 million volts. This voltage would then – like the earth’s own shielding mechanism – direct the high energy particles away and to ground. Such a system is in the planning stages now.

But what about those long space voyages between planets? There are concept drawings for this kind of shielding as well. But, any high voltage shield comes with its own pre-packaged demons.

There is also a well known risk associated with exposing living cells to high voltage fields. There are cancer risks and others suggested by the anecdotal evidence. I did a study at Oklahoma State University where I indirectly exposed mouse epithelial cells to a coil that was transmitting only 110V 60HZ wall current. The cells did very poorly. After the experiment, the cells also showed distinct chromosomal aberrations. If we expose our crews to fields of an energy many times that, there is a suggestion that it may actually be worse for them than the space radiation. It is important to point out, however, that this idea is only conjecture and needs much study before these high energy shields are actually employed and crews exposed.

STEM CELL REPLACEMENT THERAPY: I have heard a suggestion that one could conceivably actually replace the stem cells of the inner brain if they are killed en-route, caused either by a solar storm or just from day-to-day chronic space radiation exposure. In this scenario, astronauts would give medical scientists a sample of their own stem cells from their inner brain before launch. The scientists would then culture them and grow up several batches. They would then launch these brain stem cells along with the crew. A port would be fitted in the astronaut’s skull and if necessary, they could inject themselves with new brain stem cells. In this way, they could look the universe in the eye and say, “Bring on your worst!” and still survive in a relatively healthy condition. What this therapy does not address is the other myriad cancers in the body that will invariably be triggered by the radiation exposure.

The bottom line question is simple: can we go to the moon and mars and build bases there and live without being killed or badly injured by space radiation? The answer is: no one knows the answer to that question today. However, it is a near certainty that we will figure it out. I would guess that a combination of several or even all the above methods will eventually be employed in a kind of hybrid strategy to defeat this problem.