> Assume a cubesat with a monopole ΒΌ wave antenna at 400 mhz. >The satellite is in full sun with a 500km orbit. What is the antenna > temperature in full sun and in eclipse?
It depends entirely on its color (surface properties). If it black it will get to about 55 farenheight in the sun and to about very cold in the dark. If it is white, it will get to about -60 F in the sun (Notice that is MINUS 60) and very cold in the dark. If it is clean shiny aluminum, it could get to +250 F in the sun and very cold in the dark all assuming they have no other way to conduct away heat. Those are steady state hot temps for the surfaces given. I dont remember the cold temps, though they will all reach the same very cold temps if they never see the sun. Notice that these are steady state. A metal sphere with these colors going in and out of eclipse will never reach these extremes because of their thermal mass that cannot get that hot in 60 minutes and cool down that much in 35 minutes of dark. Our basically black PCsat (solar panels mounted to the aluminum body with good conductivity only got to about room temperature in the sun and no colder than about freezing (32 F) in the dark every 90 minutes. But it was a shock to us when we designed a flip-out solar panel for a cubesat that is exposed on both sides to space. It gets to almost boiling on the sun side and down to about -70F in the dark... EVERY orbit. SO, I assumed that a thin tiny whip antenna could not conduct very much heat to the spacecraft, so its extremes will be high. But a piece of wire can easily handle these temps. But any solder joint that cannot communicate heat to/from the rest of the spacecraft might have problems. This is an off-the-cuff answer. Doing thermal in space is a real ART! Good luck. Bob, Wb4aPR > > > > TNX in advance > > > > Nick CAPE Team > > > > _______________________________________________ > Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
