Was this message relayed through a probe out about 3 light-months? -John
================ > On 6/9/11 1:06 PM, J. Forster wrote: >> Ha! >> >> Nuclear power in space is poltically utterly impossible in the US. There >> is huge opposition to RTGs, never mind even the thought of reactors. > > Hmm.. when I was working on Prometheus aka Jupiter Icy Moons Orbiter > (JIMO) there was a guy from NASA HQ who gave a talk at the Lunar & > Planetary Institute about flying reactors. His basic idea was that > there is a fraction of people who will object to ANY nuclear power in > orbit, be they 1 ounce Radioactive Heating Units (RHUs.. pretty much in > every Mars mission we've flown) or RTGs or full on nuclear reactors > (JIMO was going to fly a 300kWthermal/100kW electrical reactor being > developed by the folks who do submarine reactors) > > So therefore, the "incremental pain" from flying a reactor is small. > > > >> >> Solar is not really practical either. The sun puts out about 1 KW/Sq.M >> in >> EO, and solar cell efficiency is<20%; so 10 KW needs 50 Sq.M of >> stabilized pointing cells. > > > A bit more than 1 kW/sq m (thats more like earth surface).. I think 1.3 > is more of a typical number above the atmosphere.. > > > 30% is more like what we get with triple junction enhanced solar cells, > I think, but there's a whole lot of factors that go into it. > > In any case, there are lots of commercial COMSATs in GEO with tens of kW > of solar panels (yes, many, many square meters). The power available on > those things (to those of us used to deep space scientific missions) is > gargantuan.. They're running more than a hundred TWTAs with hundreds of > watts each. And the L band ones (Sirius/XM) are BIG tubes. > > > But, for instance, Juno, which is on it's way to Jupiter has solar > panels that are enormous (since it's NOT nuclear powered). ABout 60 > square meters which produce just under 500W at the orbit of Jupiter > (5AU, so 1/25th what they generate at earth).. > > That would be about 200W/square meter in earth orbit (which I concede is > about your 20%) > > > >> >> -John >> > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
