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Why Nuclear Energy PDF Print E-mail
Written by Colin Deng   
Sunday, 30 January 2005

In the previous paragraphs, we discussed solar modules provided electric power for space missions on Mars. As missions become more ambitious and complex, power needs increases, scientists investigated various options to meet these challenging power requirements. One of the options was nuclear energy.

The nuclear energy comes from heat produced by nuclear fission. There are more compact ways of generating electricity from the heat produced by fission. NASA's Galileo Probe which reached Jupiter in 1995 was designed to take pictures of the planet and perform a range of scientific tests in Jupiter's atmosphere. Unfortunately, because Jupiter is so far from the sun, powering the equipment on board using solar energy would have been impossible. So, NASA came up with another solution. They designed a special self-contained power source called a Radioisotope Thermoelectric Generator (RTG).
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Radioisotope Thermoelectric Generator (RTG)

The RTG will provide power for many years, enabling mission scientists and program managers to extend the life of the spacecraft by several years and in turns reap more scientific benefits. No failures of spacecraft have been attributed by the RTG over the past 30 years in regions of space where the use of solar power is not feasible. The systems of RTG are safe, proven, reliable, maintenance free, and capable of producing either heat or electricity for decades under remote harsh environment such as in Mars exploration. The unique characteristics of these systems make them especially suited for applications when large arrays of solar cells are not practical.
The first RTG produced only 2.7 watts of electric power. The most recently designed system, the General Purpose Heat Source RTG (GPHS-RTG), generates about 290 watts of electric power. The first system that was launched, a SNAP-3B unit (SNAP, systems for nuclear auxiliary power), provided only partial power for the Navy Transit 4 satellite. DOE provided three RTGs for NASA's Cassini mission to Saturn. The Cassini spacecraft, launched to Saturn on October 15, 1997, required three GPHS-RTGs - approximately 870 watts electric. The RTGs are the only source of onboard electric power.
The first RTG from www.ne.doe.gov/ space/space-desc.html
A general purpose heat source module used in RTGs from www.en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator
With such amount of electric power provided by RTGs and solar sell at daytime, it is enough to power all of the scientific instruments, radio transmitters, and cameras on the mother ship and recharge the sub ships.

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