Tuesday, April 3, 2007

Chinese moon rover

The Chinese are bent on moon exploration and I can already see a mini-space race in the making. Unlike the West, China has no issues about using nuclear energy in space as is demonstrated by their intention to power their moon rover with nuclear energy. Indeed if we are really serious about establishing colonies on Mars and on the Moon, and further afield, there is no choice but nuclear. The power that one can derive from solar energy decreases as the square of the distance from the sun. Mars is approx 1.5 AU from the sun (with a max. distance of approx 1.6 AU). This means that the power that we are able to derive from the sun is between 2.2 - 2.6 times weaker than on Earth. This means that either the solar panels need to be twice as efficient or the collecting area twice as big to get the same power as on Earth.
Batteries are also problematic. For example, if we powered the Galileo space probe using conventional batteries instead of Radioctive Thermal Generators (RTGs) and expected the same duration for the mission (70000 hours), the probe would have batteries weighing 47T! This does not include the fact that the batteries themselves need to be kept warm.
Robert Zubrin in his excellent book Entering Space, discusses the use of nuclear power in space. He goes one step further and recommends the use of an actual nuclear reactor.
Not only do we need RTG's, we need to move beyond them to actual space nuclear power reactors that use nuclear fission, rather than mere radioisotope decay, to generate tens or hundreds of kilowatts. The reason for this is very simple. On Earth, it has been said, knowledge is power. IN the outer solar system, power is knowledge.
Perhaps its time to get past the neo-luddites and start to look at nuclear power more rationally.

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