Plutonium for Martians

24 Nov 2011

Whatever life forms are on planet Mars, they will have to deal with plutonium-238 produced by American atomic research labs if the Mars Science Laboratory Curiosity mission succeeds. The launch is scheduled for Saturday, November 26th from Cape Canaveral, Florida.

The plutonium-based radio-isotopic generator that powers the Curiosity robot will become an out-of-commission vehicle on the Martian surface after 23 months of activity and exploration. It will leave a lot laboratory waste and its 4.6kg of 238Pu. The half-life of 238Pu is 87.7 years. 264 years after its production, it gives off another 12.5%. If Mars is the subject of colonization experimental within the next century, pioneers risk being exposed to radioactive contamination of human origin dating from 2012 or 1975 with the landing of the Viking probes. Do not forget that the surface and the atmosphere of Mars have been poisoned by at least 5 other crashed probes each powered by a plutonium battery amounting to hundreds of grams.

The Curiosity mission may not succeed. In the statistically improbable but however possible case of an explosion after takeoff, NASA is tempering concerns saying that the plutonium containers are resistant and the thickness of the protective shields is 20% thicker than previous missions. The dose to the most exposed people after the disintegration of the launcher would not be more than an annual dose of natural radiation. Actually, if the plutonium were sprayed and inhaled, it would have carcinogens effects even with the slightest dose. In case of an accident near the launchpad, special control instruments would be able to perform atmospheric analysis. If necessary, exposed populations would shelter themselves in closed spaces. Despite the comforting talk from NASA, who relies on feedback from four decades ago, Robin des Bois reminds them that in 1964, an American spy satellite containing 1kg of 238Pu accidently disintegrated at an altitude of 31 miles of which its contents contaminated the atmosphere. As for 1968, an American meteorological satellite containing a generator of 2kg of 238Pu crashed into the Pacific Ocean somewhere off of Santa Barbara.

Another accident possibility could be a misguided trajectory where the rocket and Curiosity robot would crash on the ground, or more likely in sea, like the Soviet probe to Mars in 1996. A few hours after its launch in November 1996 from Baikonur Cosmodrome Base, it plunged into the Pacific Ocean.

In 1992, the United Nations National Assembly adopted a principle limiting nuclear energy sources on space missions that could not adequately use other sources of non-nuclear energy.

But, the treaty of 1967 on the Principles Governing the Activities of States in the in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies, says that these activities will be conducted so as to avoid the harmful effects of contamination. 100 countries including the United States ratified this treaty. Robin des Bois estimates that the deposit and abandonment of plutonium or its dispersion in the case of Mars may lead to harmful contamination. It constitutes as such a violation of the treaty founder of space law.

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