NPR:
Over the past half century, plutonium-238 has powered such NASA
robotic spacecraft as
Voyager
1 and
2,
Cassini, and
New Horizons, which have traveled to Jupiter, Saturn,
and beyond. Although not the same plutonium isotope that is
used for bombs, plutonium-238 was only produced in the US
during the cold war years. Now the US, whose supply of
238Pu made it the only country to have sent
spacecraft beyond Mars, is running out of the fuel and has not
made plans to produce more. In the past, NASA, which uses
238Pu, has split the bill with the Department of
Energy, which makes and handles the material. But Congress is
balking at allocating the requested funding to DOE. Little time
remains: The supply is expected to run out by 2022, and experts
predict that production of new plutonium won’t be fully
up and running before 2020.
