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L. M. Prockter, R. E. Gold, R. L. McNutt, P. H. Ostdiek (Johns Hopkins University Applied Physics Laboratory), C. B. Ensworth (NASA Glenn Research Center)
The Jovian Trojan asteroids were highlighted by the recent National Academy of Sciences Decadal Study (2002) as important primitive body targets. The Decadal Study recognized that primitive bodies are the principal building blocks of the solar system, and summarized fundamental science questions relating to them, including their range of sizes, compositions, physical characteristics, locations, processes of formation and alteration, and their role in planet formation and evolution.
Exploration of the Jovian Trojans can be accomplished at reasonable cost using PARIS (Planetary Access with Radioisotope Ion-drive System) spacecraft, which enable a new class of missions to the outer solar system. These low-thrust missions launched to a high C3 are especially effective for exploring objects in a shallow gravity wells. The PARIS spacecraft take advantage of the high-efficiency of Stirling radioisotope generators (SRGs) to provide the power for an electric propulsion system. The net power-to-mass ratio enables New-Frontiers class missions to carry a significant science payload to the outer solar system.
A PARIS mission could reach the Trojan asteroids in less than 5 years using the next generation SRGs with a demonstrated efficiency of >30% and a projected specific power of >8W/kg. With the specific power of current first generation SRGs, the flight time would be increased by about 20%. The power system would generate about 900 W and the launch mass would be slightly less than 1000 kg.
We consider a mission that would orbit the largest Jovian Trojan, 624 Hektor, and then go on to orbit at least one other nearby object of the estimated 105 Trojans greater than 1 km in diameter. A candidate payload for such a mission would include wide-field and narrow-field cameras, an UV-Vis-IR spectrograph, gamma-ray and neutron spectrometers, and plasma and energetic particle spectrometers.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.