The problem is that most of the plutonium-238 was created in the last century.
The main source of energy for space missions – a radioactive isotope plutonium-238 – ends at U.S. scientists.
Such data are contained in the report of the government of the US Department of energy.
The problem is that most of the plutonium-238 was created in the last century, during the cold war. The stock of finished material may be exhausted within eight years. This, as noted in the report, “can jeopardize the ability of NASA to use plutonium batteries RPS as a source of energy for future missions.”
The engineers there are many other ways to power interplanetary probes, including batteries, fuel cells, solar energy, and even nuclear reactors. But for many reasons the best choice is plutonium-238. Among these reasons: the compactness of the battery, the half-life of the isotope, the sensitivity of electronics to electromagnetic fields and others.
“On the comet, which is crazy far from us, you will not be able to land with solar panels the size of the wing of the Airbus. The radioactive power source is fully allows you to do it,” – said the expert of NASA on the sunshine Jessica.
In the United States in 1988 had discontinued production of plutonium-238 and since then has been used accumulated reserves. In 1992 the United States signed a five-year agreement to purchase the isotope from Russia in the amount of 10 pounds. In 2012, after several attempts, the Obama administration managed to get funding to restart production of plutonium-238. However, production volumes are still insufficient.
Today, NASA remains about 35 kilograms of plutonium-238, although the Ministry of defence has a separate stock. However, as the plutonium decays, only about half of the reserves can be used. Such amounts will not be enough, for example, at the start of the mission to Saturn or Jupiter.