New production of the vital and specialized radioisotope fuel called Plutonium-238 (Pu-238) that powers all of the United States' deep space probes ensures the continuation of NASA's ambitious solar system exploration in this decade and beyond.

Without the little known Pu-238, the first American astronauts on the Moon wouldn't have been able to power their experiments and the New Horizons spacecraft wouldn't have survived 10 years in space to give us those breathtaking photos of Pluto last year.

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All NASA deep space probes from Voyager 1 in 1977 to the Curiosity Mars Rover in 2011 have used Pu-238 as their primary power source.

Despite its irreplaceable role as the only power source for deep space NASA missions, supplies of Pu-238 were allowed to reach a level so low existing supplies were estimated to be enough to only power three batteries. This led the U.S. Department of Energy to begin a frantic search for a quick solution. It found it in December 2015.

The DOE's Oak Ridge National Laboratory reported it had successfully produced an initial 50 grams of Pu-238. Production of this fuel will increase to 1.5 kilograms per year.

Before this welcome piece of good news, the U.S. bought all of its Pu-238 supplies from Russia since 1993. Total purchases from Russia came to 16.5 kg and was only resorted to because U.S. production of this radioisotope stopped in 1988.

DOE reported that 35 kg of Pu-238 was available for civil space uses as of March 2015 but only 17 kg was in a condition good enough to meet NASA standards for power delivery.

The main use of Pu-238 is as the heat source in radioisotope thermoelectric generators or RTGs. These generators have been used for long-term nuclear power generation in spacecraft such as Voyager 1 and 2; Cassini-Huygens and New Horizons.

In the future, Pu-238 will be used in a multi-mission radioisotope thermoelectric generator (MMRTG) for the 2020 Mars Rover mission. In addition, two additional MMRTGs will power an upcoming 2024 NASA mission.

Without the new Oak Ridge production, the U.S. would have exhausted its Pu-238 supplies in only 10 years.

TagsPlutonium-238, PU-238, NASA, voyager 1, Curiosity Mars Rover, Oak Ridge National Laboratory