[X] My Assistant

[vjkane]

NASA posted this update on its website today. No nuclear power for the next mission and list of acceptable candidate missions likely to come this spring:

"The National Aeronautics and Space Administration (NASA) Science Mission Directorate (SMD) plans to release an Announcement of Opportunity (AO) for the third New Frontiers (NF-3) mission no earlier than June 2008. Downselection would occur in 2009. This NF-3 AO will solicit only missions that do not require nuclear sources for power generation or propulsion.

Once the National Research Council's (NRC's) New Opportunities for Solar System Exploration (NOSSE) committee reports to NASA on mid decade NF science mission priorities in March 2008, NASA plans to release more details about allowed targets for the upcoming NF-3 AO."

http://www.spaceref.com/news/viewsr.html?pid=27162

[Mariner9]

Yeah, for the first time in my life I'm bummed that the US does not have an active nuclear weapons production program. At least then we would have supplies of plutonium around.

From what I remember reading, Alan Stern is dividing up the plutonium (that NASA gets) between the MSL, the expected ballpark requirement for the Flagship mission, and then one Sterling RTG powered Discovery class mission.

I'm not really sure why it is limited to Discovery and not allowed on New Fronteirs. One reason may be flight duration. New Fronteirs mission budgets are big enough that outer planet missions are practical (and indeed, the first 2 missions in the program are to the outer planets). An outer planets mission is likely to be operating much longer than an inner planets probe. Unlike a tradition RTG (which has no moving parts) the Stirling generators are comparatively new and I don't think anyone has tried running one continuously for 10 years.

A real shame, because I still want the New Fronteirs class Io Observer that volcanopele keeps wishing for.

[dvandorn]

Yeah, for the first time in my life I'm bummed that the US does not have an active nuclear weapons production program. At least then we would have supplies of plutonium around.

The U.S. alone has more than twenty thousand thermonuclear devices, at varying states of age and maintenance, lying around in storehouses around the world. Most of them contain a fair supply of weapons-grade plutonium. We're probably talking *tons* of weapons-grade plutonium in existence today.

How many weapons would you have to cannibalize to construct enough RTGs for, say, a dozen outer-planet missions? One? Ten? Twenty?

Is it at least *possible* that we need those outer planet missions more than we need those very few weapons (out of a large stockpile)?

It just seems to me that saying there's a shortage of plutonium is not correct. We just have to be willing to lose a few bombs out of an enormous stockpile in order to replenish the supply available for RTGs.

-the other Doug