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By James McGovern

In a sign of how successful nuclear energy has been in powering space missions, the Voyager 1 spacecraft is expected to become the first man-made object to move beyond our solar system and cross into interstellar space.

Since its launch 35 years ago from the Kennedy Space Flight Center in Cape Canaveral, Voyager 1 has had up-close looks at several planets. It discovered two of Jupiter’s moons as well as many of Saturn’s moons. The spacecraft confirmed that Jupiter has rings and identified 16 active volcanoes on the moon Io. It also sent back the first spacecraft photo of the Earth and the moon and a portrait of the solar system.

Now, as it breaks through the outer limits of the solar system some 11 billion miles away from the sun, crossing a region known as the heliosheath before reaching the Milky Way, the spacecraft still runs on nuclear generators known as radioisotope thermoelectric generators (RTGs), powered by the radioactive decay of plutonium. RTGs convert heat from plutonium into electricity, with no moving parts. Scientists expect to continue receiving data until the Voyager 1 spacecraft stops functioning in about 2025.

Compact and lightweight, RTGs have been used on 27 space missions over the past half-century, ranging from Apollo to Ulysses and including the most recent Curiosity rover landing on Mars. RTGs are simple, highly reliable and impervious to the high-radiation environments of deep space, allowing spacecraft to operate at significant distances from the sun or in other areas where solar power systems would not provide enough power output or reliability.

Were it not for these nuclear generators, we would not have seen, through Voyager’s fine-resolution cameras, the powerful volcanoes spewing lava on Jupiter. The corkscrew-shaped magnetic field on Uranus would still be undiscovered. And we would still lack any direct evidence of whether the vast Gale Crater on Mars could have once supported microbial life.

Many will ask: Why are we spending billions of dollars up there in space when we have pressing problems down here on Earth?

Scientists say that space missions have had an enormous impact on technology and innovation, producing revolutionary spinoff technologies, ranging from digital imaging and improved kidney dialysis to collision-avoidance systems on aircraft, the benefits of which have been incalculable. These advances have produced whole industries.

Congress can help ensure enough nuclear fuel will be available for future space missions by authorizing construction of a reprocessing facility to extract plutonium from spent fuel currently stored at nuclear power plants. Often mistaken for nuclear waste, spent fuel contains plutonium and other valuable nuclear materials. A reprocessing facility similar to one operating in France could be built in conjunction with a deep-geologic repository for high-level nuclear waste.

Neil deGrasse Tyson, an author and director of the Hayden Planetarium at the American Museum of Natural History in New York, says that all U.S. space missions — spaceborne telescopes and planetary probes, rovers on Mars, the International Space Station, the recently terminated space shuttle, and telescopes and missions yet to fly — cost one-half of one penny of each tax dollar.

No other country has made such historic conquests in space — conquests that will draw to a rapid end unless there is recognition of the enduring value in space exploration. That’s going to require an understanding of the huge payoffs from the space program, owing to its advancement of science and technology and its role as an engine of economic growth.

James McGovern is an energy consultant to government and industry.

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