"Alan Erskine" wrote in message
ond.com...
On 30/05/2011 4:14 AM, Anonymous Remailer (austria) wrote:
http://www.spaceflightnow.com/news/n1105/29junosolar/

They should've powered it with an RTG, just like Cassini. The solar
cells on this billion dollar probe will only last three years at the
most, and severly limiting the probe's effectiveness during the
mission
when its solar panels aren't viewed towards the sun. NASA and the DOE
have failed to restart plutonium production for RTG's resulting in
maimed and demasculated probes like Juno.

Cassini has now operated for almost 15 years on its nuclear power
source, the Voyagers for almost 35 years. Due to its nuclear power
the
craft will be safer since it won't have to rely on batteries during
swingbys behind Saturn. There's a good chance these probes will
operate
for quite some time still. Juno OTOH will wear out its solar panels
in
a couple of years.

All in all, a waste of time, money and effort in my opinion.



Well, Mr anonymous, the mission is only scheduled to last for three
years; where do you get the information that the PV arrays will "burn
out" in a couple of years? The arrays on ISS (the space station) are
nothing special (just silicon) and will last for 10+ years and are
exposed to much more radiation than the Juno arrays.

I should rephrase that: the power systems on the probe will wear out,
mainly the batteries. RTG powered probes can keep working for decades
even though their design life was only a couple of years. Cassini's
main mission was projected to be a mere three years IIRC. It's still
going strong and still revealing mysteries about Jupiter and its moons.
Its longevity has been a real boon for planetary science.

Juno will probably work for the intended mission duration, but I doubt
it will last long after that. That makes it expensive IMHO.