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Of Reactors and Regolith

© Robert Davis

The way I see it, the way to give a human expedition to Mars the maximum opportunity to succeed is to equip it with two things: nuclear power, and the ability to use indigenous resources.

The nuclear power is needed because, truth be told, space exploration continues to be conducted on an electricity budget that would make the average American homeowner faint in desperation. The solar panels on the original Little Rover That Could, the Sojourner rover from 1997's Mars Pathfinder mission, produced about 16 watts. According to James C. Foster over at NuclearSpace.org, that's about like the light you probably have inside your oven. Likewise he points out that the current wonder rovers, Spirit and Opportunity, enjoy a whopping 140 watts for about 4 hours each day thanks to their solar panels--100 watts of which goes to keep the wheels turning.

It is frankly a marvel what our missions are capable of doing on such a trickle of electrical power. But at the same time, there's no getting around a few facts. Sojourner traveled something like a couple of hundred feet--no more. Spirit and Opportunity, of course, are astounding everyone by breaking the mile mark. But a human being can walk a mile in no time at all. Meanwhile the solar power we've been relying on--and the rechargeable batteries that keep the show on the road when the sun is down, and that lose effectiveness over time--definitely put a cramp in our style. By the time people are walking around on Mars, exploring the planet in the inimitable way that only people can, there'll be no escaping the need for a voluminous, reliable, and constant supply of electrical power.

Nuclear power is the obvious solution. It's already been employed, small-scale, on the robotic missions with destinations beyond the reach of meaningful solar power (Mars hangs just about on the limit of that reach), in spite of the protestations of some anti-nuclear activists, and fortunately NASA is taking another step in the right direction by planning to use nuclear power on the Mars Science Laboratory rover that will launch in 2009. Plus Project Prometheus, very fortunately funded for the next fiscal year, continues to develop space nuclear power for a variety of applications, including propulsion. Of course, the Mars Science Laboratory power supply is still on the small side compared to what will be wanted for a well-equipped, manned expedition--probably less than 600 watts, whereas the needs of a manned mission will doubtless be measured in kilowatts--but it's several times more than what the current rovers can rely on, and represents a fine step in the right direction. The point is that the commitment to nuclear power in space needs to be firm, lasting--and growing.

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