Mission interplanetary Using radioisotope power to explore the solar system.pdf

Available online at /locate/enconman Energy Conversion and Management 49 (2008) 382–392Mission interplanetary: Using radioisotope power to explore the solar system Gary L. Bennett * 5000 Butte Road Emmett, Idaho 83617-9500, USA Available online 21 December 2007Abstract The exploration of space both by humans and robots has been greatly enhanced and, in many cases, enabled by the use of radioiso- tope power sources (RPSs) to power and/or heat scientific instruments. Radioisotope power sources have enabled such breakthrough missions as the Pioneer flights to Jupiter, Saturn and beyond; the Voyager flights to Jupiter, Saturn, Uranus, Neptune, and beyond; the Apollo lunar surface experiments; the Viking Lander studies of Mars; the Galileo spacecraft that orbited Jupiter; the Ulysses mission to study the polar regions of the Sun; the Cassini spacecraft orbiting Saturn; and the recently launched New Horizons spacecraft to Pluto. Radioisotope heater units have enhanced or enabled the Apollo Early Scientific Experiment Package and the Mars exploration rover missions (Sojourner, Spirit and Opportunity). Since 1961, the United States has successfully flown 41 radioisotope thermoelectric generators (RTGs) to provide electrical power for 23 space missions. Published by Elsevier Ltd. Keywords: Radioisotope power; Interplanetary missions; SNAP; RTG; Thermoelectric1. Introduction Sending spacecraft into the cold, long dark night of outer space requires reliable, long-lived electrical and ther- mal power sources. For near-Earth applications solar power (e.g., photovoltaic devices) has been the preferred option because of the relative proximity of the ‘‘heat source’’ (Sun). However, as human missions have moved farther out into the Solar System or into harsh environ- ments (such as the surface of Mars or in certain lunar loca- tions), mission designers realized that a power source independent of the Sun was needed. Studies after World War II showed the benefits of nuclear power, bot