Talk:Juno (spacecraft)
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Solar Panel Output
Since Jupiter has a perihelion and aphelion distance of 4.95 AU and 5.46 AU repectively, it receives between 1/25th and 1/30th of the sunlight levels we receive at Earth's distance from the Sun. So why then does the article state:-
"The total area of the arrays is over 60 square metres (650 sq ft). This is enough to produce over 18 kilowatts (24 hp) while in Earth orbit, and just over 400 watts (0.54 hp) while on Jupiter orbit."
Surely if the solar panels could produce 18kW of power in Earth orbit, they'd produce between 600 and 720 Watts in Jovian orbit? One of these figures must therefore be incorrect! CrackDragon (talk) 20:22, 31 July 2010 (UTC)
That assumes that you have a perfectly empty vacuum. If you have any sort of intervening material - dust, gasses, etc. - that could reduce the intensity of the light received by more than just increasing the distance would. 71.134.236.97 (talk) 08:29, 8 August 2010 (UTC)
- This has nothing to do with dust, which absorbs no more than 1/10,000,000th of the light. The output drops faster because it is a non-linear function of the light intensity. Ruslik_Zero 08:37, 8 August 2010 (UTC)
- With the solar panels themselves? So if they're bathed in say, half the light intensity, they produce less than 50% of the output? CrackDragon (talk) 08:40, 11 August 2010 (UTC)
- Semiconductor behavior can alter with temperature. While not necessarily applicable to Juno's solar cells, an example would be the increase in electrical resistance with decreasing temperature often seen in semiconductors. More resistance = less efficient collection of electricity from the cells. And Juno's going to be colder at Jupiter than a satellite in Earth orbit. 147.160.136.10 (talk) 11:51, 13 September 2010 (UTC)
- With the solar panels themselves? So if they're bathed in say, half the light intensity, they produce less than 50% of the output? CrackDragon (talk) 08:40, 11 August 2010 (UTC)
Mission duration: 1 Earth year
NASA is spending $700 million on this project, and it's only lasting one year? Why not ten or more? Our weather satellites are designed to last decades. Why can't we expect similar results from Juno? Someone at NASA should get fired over this blunder.173.58.64.64 (talk) —Preceding undated comment added 16:53, 27 August 2010 (UTC).