Monday, July 13, 2015

Exploring Pluto and Other New Horizons With Nuclear Energy

The following is a guest post by Richard Rolland, an intern in NEI's Nuclear Generation Division.


Richard Rolland
Like many of my colleagues in the scientific community, I’m looking forward to viewing pictures of Pluto and its moons from the images taken by the space probe New Horizons on Tuesday morning. My excitement is enhanced by the knowledge that these pictures are made possible by nuclear power. New Horizons is powered 100% by nuclear power with a radioisotope thermal electric generator.

The two most common power sources for space probes today are solar power and RTGs. The benefits of solar power rapidly decrease the further a probe travels away from the Sun.  While radioisotope thermal electric generators (RTGs) function by utilizing the heat created from radioactive decay to produce electricity no matter the location. As we venture further into the depths of interplanetary space, nuclear power provides our space probes with a reliable source of electricity no matter the distance. With an RTG strapped to a space probe, it can venture wherever we wish.

Not only is the distance unrestricted, but the mass utilized in RTGs is trivial. The nuclear material that will power New Horizons for years to come will be less than 2.5% of the total mass of the spacecraft. Lowering the mass of the RTG allows it to carry additional scientific equipment.
Artist's conception of New Horizons approaching Pluto.
RTGs have been utilized before in some of NASA's most important missions. RTGs provided electricity for instrumentation and equipment while the Apollo astronauts were exploring the surface of the Moon. Even Voyager 1 and Voyager 2, which were both launched in 1977, are still operable due to the long-life of RTGs. The new Mars rover relies on a RTG to provide electricity. With an RTG on board, you never have to worry about a dust storm blocking sunlight and rendering the rover temporarily inoperable.

The nuclear industry has more to offer than electricity for space exploration. Nuclear thermal propulsion has the potential to cut the time it takes to travel to other planets in the solar system. Using nuclear thermal propulsion would cut travel time to Mars in half compared to today’s methods. It has been estimated that a probe, with some small advances in material science, would be able to employ nuclear thermal propulsion to reach Pluto in 6.5 years without a gravitational assist; while New Horizons took 9.5 years with a gravitational assist.

As we look to the future of space exploration and the pictures of Pluto, let us not forget the nuclear physics that made it possible. During the twentieth century, some of America’s most extraordinary accomplishments, splitting the atom and entering space, have been combined to allow for a future that humans once only dreamed of. Let’s continue with RTGs and bolster the research of nuclear thermal propulsion to make reliable and faster space exploration a reality.

EDITOR'S NOTE: For some, the arrival of New Horizons near Pluto represents the culmination of a career. That's the case with NASA mission scientist Andy Cheng, who has marked several life milestones as the probe traveled to Pluto. It's also important to point out that the RTG that's powering New Horizons relies on Plutonium-238, an isotope that's in short supply these days. While there's more than enough of a stockpile for now, NASA is looking at alternatives.

1 comment:

Anonymous said...

The Department of Energy's national laboratories play an important role producing the PU 238 and assembling and qualifying the RTGs for NASA. Truly a great team effort!