The power produced is a function of cable length so you send more than you think you need and wind in/out as required. So as long as we could guesstimate the cable configuration within a reasonable margin, the rewind button could cover unanticipated fluctuations.
Amen. The tether and other gubbins would probably work out heavier than an RTG but at least the Friends of the Earth won't be chaining themselves to the booster. This nuke issue is one which reasonable minds can differ. I was just at the European Mars Society conference and the French presenters are very comfortable with presenting nuclear power options whereas others nationalities readied their crucifixes/garlic/mirrors/wooden stakes at the mention. Power requirements are more acute in orbit owing to the thirsty radar module so photovoltaic arrays are needed only for cruise where the tether isn't likely to generate much juice. If more power were available, you could get a better data rate. The tether itself would be a valuable science >and< engineering project. I suspect more pixels will be lit up on this issue anon. Paul At 04:33 16/10/2001 -0700, you wrote: >----- Original Message ----- >From: "Paul Lavin" <[EMAIL PROTECTED]> >To: <[EMAIL PROTECTED]> >Sent: Tuesday, October 16, 2001 2:13 AM >Subject: Re: Europa Orbiter's nuclear power source > > > > > > At 14:08 15/10/2001 -0700, you wrote: > > >The Europa website did a lot of research in 1999 into the possibility of > > >utilizing Jupiter's radiation belts as a power source -- and found that > > >while Jupiter's radiation is just fine for chemically poisoning both >living > > >cells and electronics, it's an extremely lousy energy source. Even if we > > >had a miracle substance that could totally absorb all the energy of any > > >charged-particle radiation htting it and turn it into electricity, it >would > > >take several hundred TONS of the stuff to soak up enough power from > > >Jupiter's radiation belts to run Europa Orbiter. > > > > > > Eh? what about generating power from a tether? Surely that would weigh > > less than several hundred tons... but perhaps more than an RTG. I keep > > thinking about the news value of an RTG making an unscheduled Earth >reentry > > vs the furore caused by a falling reel of cable... > >The main problems with this idea, I suspect, are: (A) we really don't know >yet just how much power would be generated by a tether in the Jovian >environment; (B) the spacecraft still needs power from another source >during its initial cruise to Jupiter; (C) the tether would have to be >reeled back up before insertion into Europa orbit; and (D) this whole setup >(including ejectable solar panels to power it during its cruise to Jupiter) >would probably end up weighing a lot more than an RTG. The time is not yet >ripe for this technique. > >By the way, www.aero.org/conferences/sc-lv/pdfs/08-Hughes_W.pdf containes a >presentation on Glenn Research Center's tests this year on the Stirling >nuclear generator design now planned for Europa Orbiter. The weak point of >Stirling generators is that they depend on moving parts -- which are the >bane of space missions -- but these tests showed that (A) the Stirling >continued to function perfectly during the strong vibrations of a simulated >launch; and (B) its own vibrations didn't interfere significantly with >spacecraft pointing ability, despite the fact that it cycles at 81 Hertz. >The Stirling weighs as much as an RTG, but it uses only 1/4 as much >plutonium. > >== >You are subscribed to the Europa Icepick mailing list: [EMAIL PROTECTED] >Project information and list (un)subscribe info: http://klx.com/europa/ Paul Lavin +44 (0) 7775 886420 mobile +44 (0) 20 7291 0991 London office +44 (0) 1582 462720 home office +44 (0) 1582 462536 fax == You are subscribed to the Europa Icepick mailing list: [EMAIL PROTECTED] Project information and list (un)subscribe info: http://klx.com/europa/
