Io Volcano Observer

Leonard Dudzinski, the Program Executive for NASA's Radioisotope Power Systems Program, presented details on the availability of plutonium-based power sources for space missions, on new types of Radioisotope thermoelectric generator (RTG)'s, and on a program to test one of these new types of RTGs on the next Discovery-class mission.

Currently, the plutonium used to power some of the planned upcoming missions (like the Outer Planets Flagship Mission, the Mars Science Laboratory rover, and the next Discovery mission) is purchased from Russia. New production here in the US may start up in the middle of the next decade, but that won't be enough to supply the missions planned in the NASA roadmap. To improve this outlook, new technology and more efficient RTGs will be needed. Enter the Advanced Stirling Radioisotope Generator (ASRG). This RTG uses 75% less plutonium per unit but provides 115-130% more watts than the next-generation MMRTGs to be used on the upcoming Mars rover and Outer Planet Flagship missions. Plus the ASRG weighs less and costs less per unit.

While the ASRG will be a boon for missions that require power from radioisotopes, it is as yet not flight tested. This is why the next Outer Planets Flagship mission will use the less efficient MMRTGs. NASA has decided to make two ASRGs available for the next Discovery-class mission, to be launched in 2013-2014. All previous Discovery-class missions have used solar panels for power. The cost of the RTGs will not be counted against the Discovery mission cost cap. To study the feasibility of such a plan, NASA has commissioned nine mission concept studies to see if such mission can fit within the Discovery cost cap.

And the big news: one of these mission concept studies is the Io Volcano Observer. This study is being run by Dr. Alfred McEwen of the University of Arizona (my boss). Few details are publicly available at this point on this mission concept, but the idea would be for the mission to perform multiple flybys of Io. I had thought this was a study for a New Frontier-class mission. I didn't even think of this being a Discovery-class mission.

The concept study should be finished in late September. No word on when this will be available.

Link: Radioisotope Power for NASA's Space Science Missions [www.lpi.usra.edu]