In article ,
Mike Chan wrote:
...Off hand, do you know how much solar power
one would get around Jupiter? ...

The Rosetta mission launching in a few days uses PV and its orbit
perihelion takes it out to Jupiter's orbit. IIRC, it has enough to
get 800W at Jupiter distance from Sun.

No, its solar arrays will deliver only about 350-400W at Jupiter's
distance. (Versus 8700 near Earth.) It will set a new distance record for
solar-powered spacecraft, at around 5AU; if memory serves, the previous
record was set by NEAR at a mere 2.2AU.

Solar-powered operation out near Jupiter is not impossible, merely very
difficult. Rosetta is paying heavily -- in money, in mass, in deployment
worries, in moment of inertia that makes turns difficult -- for those huge
solar arrays that make it possible.

For actual Jupiter missions, it would not be just the distance but
also the radiation environment closer to the planet. PV output in
Earth orbit degrades over time. An interesting question is if Galileo
had PV with initial output equal to initial RTG output, would the PV
output degrade faster than RTG output in the repeated passes close to
Jupiter?

Rather a lot faster, I believe, but I don't have numbers.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |