[X] My Assistant

[Tom Womack]

http://www.spaceref.com/news/viewnews.html?id=1237

reprints an interesting Aviation Week article suggesting a push for proposals for new Discovery-sized missions to use closed-loop Stirling cycle nuclear power systems, aiming for launch around 2013. It's unclear how the shortage of 238Pu is being resolved, though the Stirling-cycle devices use two 250W_thermal units of 238Pu for 143W output, whilst the Cassini/New Horizons RTG uses eighteen units for 285W electrical output.

http://nspires.nasaprs.com/external/viewre...ationDocument=1 is a summary of the specs of the Advanced Stirling Radioisotope Generator; http://esto.nasa.gov/conferences/nstc2007/...ations/D2P1.pdf is quite a nice presentation of the technology development.

The engineering history seems to be by way of Stirling-type cryocoolers, of which ten have been running for more than 10k hours each.

[algorimancer]

...unclear how the shortage of 238Pu is being resolved...

Seems like the Russians ought to have plenty of plutonium lying about which they'd be happy to sell to a legitimate buyer - or is there some rule prohibiting Nasa from buying Pu from foreign nations?

[Del Palmer]

Seems like the Russians ought to have plenty of plutonium lying about which they'd be happy to sell to a legitimate buyer - or is there some rule prohibiting Nasa from buying Pu from foreign nations?

NASA has bought 238Pu from Russia for years (or at least, the Department of Energy does so on its behalf).