In recent years, space agencies around the world have been planning large-scale research missions. They all require an enormous amount of energy to be carried aboard the spacecraft. And if near the Sun it is still possible to get by with power from solar panels, then at long distances this approach will no longer work and there is an urgent need for powerful energy carriers, the main of which has almost ended at NASA.
It is worth noting that a couple of years ago we already wrote that NASA could suffer such a fate. The fact is that a radioisotope thermoelectric generator (RTG) is used on board the spacecraft, which draws the energy released during the decay of radioactive isotopes of plutonium-238. The advantage of using radioactive material is that there are no moving parts in a battery based on it, it does not require maintenance for several decades, and it is quite enough to power small research vehicles. But there is also a minus: the production of plutonium-238 is extremely expensive and labor-intensive. In addition, most of its world reserves were depleted during the Cold War during the arms race, and the United States completely stopped producing plutonium-238 in 1988, starting to buy it from Russia.
But the US stocks have come to an end: NASA now has less than 34 kg of plutonium-238 left. Since it decays quickly, only about half of it can be used for space missions. The available amount of material is no longer sufficient to equip a mission of the Cassini level, which required almost 22 kg of plutonium-238. Realizing the seriousness of the situation, the United States resumed production of plutonium-238 several years ago, but during all this time it received only about 100 grams of the substance. Another 100 grams will be received by the end of this fall.
At the same time, according to the data provided by the Accounts Chamber, the production of the rare element is not so rosy. As explained by Ralph McNutt, a leading scientist at the Johns Hopkins University Applied Physics Laboratory, “There is no reactor for production. It's taken apart. The cooling tower was demolished in the early 90s. For the production of plutonium-238, neptunium-237 is used, where during the year targets are bombarded from it and a small amount of plutonium-238 is obtained. The production itself is still in an experimental phase."
Nevertheless, the US aerospace agency remains optimistic. According to one of the leaders of NASA Jim Green, “I think we are in good shape for the coming decades. Our plans are to build up a stockpile of plutonium and not allow it to limit our future missions.”
Vladimir Kuznetsov
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