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>gotten in their minds that RTG power is evil and dangerous RTG usage is curbed due to NASA's low supply of plutonium-238. Until more is made it makes sense to

>gotten in their minds that RTG power is evil and dangerous RTG usage is curbed due to NASA's low supply of plutonium-238. Until more is made it makes sense to design for solar powered systems. Also these are risky missions with high pricetags and erring on the side of caution using well known technologies isn't some big conspiracy. Its to avoid high-profile fails. We can try new and risky stuff in lower profile missions. Heck, Curiosity was launched just a few years ago and has 11lbs of plutonium powering its RTG. I hardly see a conspiracy here. Also RTGs add weight and cost to projects. If you don't need one, you probably shouldn't be using one - even ignoring their rarity. Missions like Juno get significant weight savings using solar. >I don't know if the cam is the problem or the transmission bandwidth, The quality of the photo has to do with the distance from Jupiter. It has nothing to do with "power." This is a spacecraft, not a gaming PC. Yes more power would mean a higher bitrate, but the bitrate it uses is good enough for the mission.

cornholio 10y ago
Sorry, but you have no ideea what I'm talking about. You are probably to young to remember but going with RTG was immensely controversial when Cassini launched, which had an 135 kbps link. Juno, on the other hand has less than 1kbps, because it needs to carry a large solar array instead of an antenna and has much less power for the uplink - data rate is proportional to the square of transmitter power. Bad publicity is the reason we went with solar on Juno and why NASA canceled ASRG.
- teh_klev 10y ago
  > Sorry, but you have no ideea what I'm talking about. You are probably to young to remember... We don't speak to each other like that here, regardless of how right or wrong the previous poster's knowledge of the subject at hand.
mikeash 10y ago
Juno is the first use of solar panels for a probe going that far out. You're right that they want to err on the side of caution using well-known technology to minimize risk. But you're missing the fact that RTGs are that well-known risk-minimized technology. If solar panels saved weight, they would have been used on past missions like Galileo. Better solar panel technology will eventually shift the balance, but we're not there yet. Juno's panels weigh 340kg. Galileo's two RTGs, which produced about the same amount of power at Jupiter, weighed 57kg each.
- drzaiusapelord 10y ago
  I was referring to the new stirling engine RTG. According to wikipedia, NASA doesn't see it being used in a mission for another decade or two due to further testing and certification. I wasn't aware solar was so heavy. Thanks for the info.
  - mikeash 10y ago
    Inverse square is a harsh mistress. With only 4% the insolation at Jupiter as you get at Earth, you need a lot of panels. Stirling RTGs sound very interesting but I'd be really worried about reliability. Definitely needs lots of work and testing to be confident in it!
tdy721 10y ago
bitrate it uses is good enough for the mission The fact is, it could be better, and it really should. It's just silly to use Solar panels in the outer Solar System. This mission was dominated by politics and not science. I think that is a very real issue. Look at Curiosity, I think it's very clear that Rover is a massive upgrade over the preceding solar powered missions.
- drzaiusapelord 10y ago
  Well, Curiosity is huge and at that point needed a power source that wasn't solar. I really am not buying that these are political decisions. I think there's more emphasis on solar and less RTG in some scenarios because everyone is worried about the plutonium situation. No use wasting plutonium on missions that frankly just don't need it.

cornholio 10y ago

Sorry, but you have no ideea what I'm talking about. You are probably to young to remember but going with RTG was immensely controversial when Cassini launched, which had an 135 kbps link. Juno, on the other hand has less than 1kbps, because it needs to carry a large solar array instead of an antenna and has much less power for the uplink - data rate is proportional to the square of transmitter power. Bad publicity is the reason we went with solar on Juno and why NASA canceled ASRG.

teh_klev 10y ago
> Sorry, but you have no ideea what I'm talking about. You are probably to young to remember... We don't speak to each other like that here, regardless of how right or wrong the previous poster's knowledge of the subject at hand.

mikeash 10y ago

Juno is the first use of solar panels for a probe going that far out. You're right that they want to err on the side of caution using well-known technology to minimize risk. But you're missing the fact that RTGs are that well-known risk-minimized technology. If solar panels saved weight, they would have been used on past missions like Galileo. Better solar panel technology will eventually shift the balance, but we're not there yet. Juno's panels weigh 340kg. Galileo's two RTGs, which produced about the same amount of power at Jupiter, weighed 57kg each.

drzaiusapelord 10y ago
I was referring to the new stirling engine RTG. According to wikipedia, NASA doesn't see it being used in a mission for another decade or two due to further testing and certification. I wasn't aware solar was so heavy. Thanks for the info.
- mikeash 10y ago
  Inverse square is a harsh mistress. With only 4% the insolation at Jupiter as you get at Earth, you need a lot of panels. Stirling RTGs sound very interesting but I'd be really worried about reliability. Definitely needs lots of work and testing to be confident in it!

tdy721 10y ago

bitrate it uses is good enough for the mission The fact is, it could be better, and it really should. It's just silly to use Solar panels in the outer Solar System. This mission was dominated by politics and not science. I think that is a very real issue. Look at Curiosity, I think it's very clear that Rover is a massive upgrade over the preceding solar powered missions.

drzaiusapelord 10y ago
Well, Curiosity is huge and at that point needed a power source that wasn't solar. I really am not buying that these are political decisions. I think there's more emphasis on solar and less RTG in some scenarios because everyone is worried about the plutonium situation. No use wasting plutonium on missions that frankly just don't need it.