NASA's New Horizons mission, which is planned for launch in January 2006, will reach Pluto and Charon -- the "double planet" -- in July 2015. And a key component for a successful mission is a nuclear space battery using plutonium, and which will carry a 'Made in Idaho' sticker. Its general purpose heat source (GPHS) will contain quadruple-encapsulated Plutonium-238 (Pu-238). According to the Idaho National Laboratory (INL), this is the only way to power a spacecraft where the Sun’s intensity is only 1 percent of what it is on Earth. It would require a solar array of about the size of a football field to power the spacecraft when it reaches Saturn. So, the only way to achieve this mission is to use another source of energy, plutonium. Read more...
Before going further, let's read on the New Horizons web site, maintained by the Johns Hopkins University Applied Physics Laboratory (JHU/APL), the reasons to go to Pluto.
Our solar system contains three zones: the inner, rocky planets; the gas giant planets; and the Kuiper Belt. Pluto is the largest body of the icy, "third zone" of our solar system. The National Academy of Sciences placed the exploration of the third zone in general -- and Pluto-Charon in particular -- among its highest priority planetary mission rankings for this decade. New Horizons is NASA's mission to fulfill this objective.
Just for your information, the picture above shows the sizes of Pluto and Charon if they were projected on the United States (Credit: JHU/APL).
And this Science Overview gives us more details about the mission.
New Horizons is scheduled to launch in January 2006, swing past Jupiter for a gravity boost and scientific studies in February or March 2007, and reach Pluto and its moon, Charon, in July 2015. Then, as part of an extended mission, the spacecraft would head deeper into the Kuiper Belt to study one or more of the icy mini-worlds in that vast region, at least a billion miles beyond Neptune's orbit. Sending a spacecraft on this long journey could help us answer basic questions about the surface properties, geology, interior makeup and atmospheres on these bodies.
For more information about this mission to Pluto and Charon, you should read about other key components of the spacecraft and browse this gallery.
Now, it's time to look at the nuclear space battery which will used for this mission.And let's start by anecdotal details provided by KIFI, a TV station from Idaho Falls.
The INL is at it again, but this time they are working on a project that doesn’t just affect our town or even the globe, it actually has a universal impact.
Scientists are making a battery that can send a spacecraft to the end of our solar system.
John Kotec, deputy manager at DOE, said, "We think it’s fascinating and fantastic. The thought of something with a 'Made in Idaho' sticker on it going to Pluto in 10 years is pretty exciting for us."
For the mission to be a success, the team at the INL has only a two-week window to get the ship up and out. That’s in 2006. If they don’t make it in time, they’ll have to wait four years for their next chance.
In other words, if this space battery doesn't work correctly next year, the New Horizons spacecraft will not reach Pluto before 2019.
Now, in "Energizing Space Exploration," the Idaho National Laboratory gives more details about its own goals, which is to provide the nuclear technology necessary for powering "the most intriguing discoveries in our solar system." Below is a diagram of the nuclear space battery that will go to Pluto, extracted from a Space Batteries Fact Sheet (PDF format, 2 pages, 470 KB).
The General Purpose Heat Source (GPHS) is the building block for the Radioisotope Thermoelectric Generator (RTG). These heat sources contain quadruple-encapsulated Plutonium-238 (Pu-238) used to produce heat, which is subsequently converted into electricity.
But why use plutonium?
In space, power is a precious commodity. In Earth’s orbit, a five-foot-square solar panel will produce about 300 watts of electricity which is about as much as an RTG. To produce the same power at Saturn, where the Sun’s intensity is only 1 percent of what it is on Earth, would require a 6,430 square foot solar array -- about the size of a football field. A launch of a spacecraft with such a solar array would not be possible. Without systems like these that enable spacecraft to operate reliably and predictably for many years in harsh environments, exploration into the far reaches of the solar system would not be possible.
Will this space battery be ready next year? Stay tuned...
Sources: KIFI, Idaho Falls, June 10, 2005; and various websites
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