The cold side can be cooled by radiation. It's been done. The View Factor to the 3 K of space is nearly 1.0, and the heat transfer rate goes up as the radiator temp EXP 4.
-John ============ > I don't think it is feasible... for a cooling reason :) > > Regards, > > Javier > > El 09/06/2011 22:18, William H. Fite escribió: >> I well recall the furor over Cassini-Huygens in 1997 but approval was >> ultimately granted and, of course, the launch was without incident. >> Since >> then, New Horizons, Galileo, and Ulysses have been launched with far >> less >> public outcry, despite the fact that all are powered by RTGs. Arguably, >> well-designed reactors could be even safer. >> >> While I appreciate that sensitivity to nuclear power for earth orbit >> satellites could be greater than for deep space vehicles, we may have to >> agree to disagree on the feasibility of nuclear powered satellites. >> >> On Thu, Jun 9, 2011 at 4:06 PM, J. Forster<[email protected]> 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. >>> >>> 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. >>> >>> -John >>> >>> ============= >>> >>> >>>> Perhaps in the longer term (ie. next the several decades) moving away >>> from >>>> the >>>> current wide band spread spectrum scheme to a higher power narrow band >>>> scheme >>>> might make more sense for GPS. A previous poster mentioned the use >>>> of >>>> nuclear >>>> powered satellites to achieve higher transmit powers, given the >>>> benefits >>>> of GPS >>>> that option should not be entirely discoutned in my oppinion. >>>> >>>> >>>> ----- Original Message ---- >>>> From: Magnus Danielson<[email protected]> >>>> To: [email protected] >>>> Sent: Thu, June 9, 2011 12:03:45 PM >>>> Subject: Re: [time-nuts] GPS interference and history... >>>> >>>> On 06/09/2011 07:29 PM, Burt I. Weiner wrote: >>>>> For many years the FCC has not allowed FM broadcast stations within >>>>> certain distances of each other where a 10.7 MHz frequency difference >>>>> existed. Not exactly the same thing, but did show an understanding of >>>>> what can go wrong as a result of good receiver front end selectivity. >>>>> In >>>>> AM and FM broadcasting there has also been required distances between >>>>> 1st and 2nd adjacent channels, only partially because of overload >>>>> issues >>>>> but more so because of occupied bandwidth and overlapping. I'm not >>>>> sure >>>>> how much more it would cost to build GPS receivers with better front >>>>> ends, but I'm sure it would've priced GPS devices out of the hands of >>>>> many consumer level users. The FCC under the direction of Congress >>>>> has >>>>> made (allowed) some pretty stupid moves in the past bunch of years. >>>>> In >>>>> my opinion, the FCC has forgotten what their purpose is, and being >>>>> run >>>>> by attorneys has made the situation that much worse as there are very >>>>> few attorneys that understand the un-revocable physics of the >>>>> electromagnetic spectrum. >>>> >>>> Regarding GPS receivers there today exist many different front-end >>>> approaches. >>>> In particular have single-bit and 1.5 bit samplers and direct samplers >>>> been used >>>> for many customer GPSes. The GPS receivers needed in E911 compatible >>>> phones is >>>> hardly done with lots of money, space and power-budget. >>>> >>>> Bringing too quick shift of requirements onto the GPS receiver market >>>> would... >>>> well kill it. Some degradation would be tolerated. >>>> >>>> Look forward to L2C and L5 capabilities to show up alongside Glonass >>> L1... >>>> >>>> Cheers, >>>> Magnus >>>> >>>> _______________________________________________ >>>> time-nuts mailing list -- [email protected] >>>> To unsubscribe, go to >>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>> and follow the instructions there. >>>> >>>> >>>> _______________________________________________ >>>> time-nuts mailing list -- [email protected] >>>> To unsubscribe, go to >>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>> and follow the instructions there. >>>> >>>> >>> >>> >>> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
