[Stargazer]

A mission not completely unlike JIMO, I suppose, could be launched for Neptune in 2016 or 2018 to arrive in 2035. It would study Neptune, obviously, and also its moons, especially Triton seems to be of great interest. It is believed that Triton originally was a Kuiper object captured by Neptune. This spacecraft will make use of nuclear fission as its energy source, like the Jupiter Icy Moons Orbiter. I would like to see a few more probes to ride along, for example one to be hurled into the atmosphere of Neptune, and one to land on Triton. Or why not do a close flyby of Triton right through one of those geysers. It would be great to bring something like that back to Earth...

Anyway, here's an article with some more info:
http://www.spacedaily.com/news/outerplanets-04m.html

[Tormod]

Cool. This would be great. There are currently no missions out there to take overwhen Cassini drops dead so this would be something to look forward to. It took 25 years to realize the Cassini mission so I only wish they had thought of this before.

[Stargazer]

Originally Posted by Tormod

Cool. This would be great. There are currently no missions out there to take overwhen Cassini drops dead so this would be something to look forward to. It took 25 years to realize the Cassini mission so I only wish they had thought of this before.

They could do it much faster, if they got more funding to do it. If this becomes real, they should build four of them, of which JIMO would be one, the other three would be sent to Saturn, Uranus and Neptune.

[BlameTheEx]

Stargazer

Don't build up your hopes too high. JIMO has yet to be designed, yet alone funded.

There is a lot of assumed infrastructure that is not yet in place. It will ether need a launch vehicle of a size that doesn't currently exist, or space assembly from smaller modules using human expertise or robots that are not currently available ether.

It wouldn't surprise me if the project is delayed or downsized.

For myself, I question if nuclear powered drives are the way to go at this time. Solar power is undergoing major development for commercial utilisation of near space, at zero cost to NASA. It might make more sense, from a budget point of view, to explore the inner planets where solar power is available.

Outer planet missions could be limited to gravity assisted missions of the current type, with conventional low-power nuclear generators to power the instruments. They could even be boosted towards the outer planets with solar powered ion drives. I can imagine boosting towards the sun to maximise solar power, then swinging around Venus, and outwards.

[Tormod]

Originally Posted by BlameTheEx

For myself, I question if nuclear powered drives are the way to go at this time.

Why? Cassini is nuclear powered.

Originally Posted by BlameTheEx

Solar power is undergoing major development for commercial utilisation of near space, at zero cost to NASA. It might make more sense, from a budget point of view, to explore the inner planets where solar power is available.

This is in fact happening as we speak - SMART-1 is in orbit around the moon to which it travelled with less than 80 kilos of xenon gas as propellant (the power came from the solar panels). ESA's BepiColombo mission to Mercury in 2012 will be based on the same engine, although a larger one.

The only problem is that it takes longer to get around, but the cost is much, much lower.

[Stargazer]

Originally Posted by BlameTheEx

Stargazer

Don't build up your hopes too high. JIMO has yet to be designed, yet alone funded.

There is a lot of assumed infrastructure that is not yet in place. It will ether need a launch vehicle of a size that doesn't currently exist, or space assembly from smaller modules using human expertise or robots that are not currently available ether.

The Crew Exploration Vehicle needs some sort of launcher, maybe they could use that one?

For myself, I question if nuclear powered drives are the way to go at this time. Solar power is undergoing major development for commercial utilisation of near space, at zero cost to NASA. It might make more sense, from a budget point of view, to explore the inner planets where solar power is available.

Yes but why limit ourselves to the inner planets just because solar power would be availible? Why not use nuclear fission for the outer planets?

[BlameTheEx]

Originally Posted by Tormod

Why? Cassini is nuclear powered.

Not exactly. Cassini used standard rocket power for drive. It has nuclear power for instruments and communication, but that is no new development. The question is of the development of the much higher powered nuclear generators needed to power ion drives.

Originally Posted by Stargazer

Yes but why limit ourselves to the inner planets just because solar power would be available? Why not use nuclear fission for the outer planets?

Nuclear power might be ideal for the outer planets, but the development will be costly to reduce the risk of pollution. Regardless the risk will never be reduced to zero.

In the end it all comes down to budget. Do we want to go all out for regular missions to the outer planets, or are the occasional opportunities where planets are in position for gravity assisted boosts sufficient? More important, will the funding be available?

Naturally Solar power is more appropriate for the inner planets, but I believe that commercial development will lead to a time when they are adequate for the outer planets too - at least for occasional missions. NASA can only find money for so many missions, and there is plenty left to do without bothering the outer planets. Why not wait till solar power is ready for the outer planets?

[Tormod]

NASA is of course not the only agency here. ESA is currently working on planetary exploration programs, and are evaluating whether to go to the outer planets or keep working on Mars.

[Tormod]

Originally Posted by BlameTheEx

Not exactly. Cassini used standard rocket power for drive. It has nuclear power for instruments and communication, but that is no new development.

Cassini used rocket power for the launch, then gravity assists to bring it out to Saturn. But the craft itself is nuclear powered, like I said. It carried about 35 kilos of plutonium 238 at launch, more than any other craft to date. Yes, not a new technology (nuclear powered craft have been used since 1961, AFAIK).

Originally Posted by BlameTheEx

The question is of the development of the much higher powered nuclear generators needed to power ion drives.

I am interested in this. SMART-1 uses xenon gas and solar electricity. Will ion drives for outer planet research require nuclear power? Why is there a question about this - is it a matter of funding? Safety?

Here is some background on the Cassini nuclear powered systems, with detailed information:
http://saturn.jpl.nasa.gov/spacecraft/safety.cfm

[Stargazer]

Originally Posted by BlameTheEx

Nuclear power might be ideal for the outer planets, but the development will be costly to reduce the risk of pollution. Regardless the risk will never be reduced to zero.

There are risks with everything. If we didn't do stuff despite those risks and doing them after trying to reduce the risks as much as possible, then where would we be now?

In the end it all comes down to budget. Do we want to go all out for regular missions to the outer planets, or are the occasional opportunities where planets are in position for gravity assisted boosts sufficient? More important, will the funding be available?

Naturally Solar power is more appropriate for the inner planets, but I believe that commercial development will lead to a time when they are adequate for the outer planets too - at least for occasional missions. NASA can only find money for so many missions, and there is plenty left to do without bothering the outer planets. Why not wait till solar power is ready for the outer planets?

I don't think we should wait at all, and I don't think solar power can be efficient for the outer planets. If you want plenty of power, then fission is currently the way to go in my opinion - and in a few decades maybe replaced by fusion. I do look forward to the day we have such an abundant energy production that we can produce antimatter in large quantities - space ships using that as fuel will be very efficient. Also, soon the outer planet wont be enough, I see a future where there will be more space crafts to the Kuiper belt and the Oort cloud, and within hundred years, perhaps, the first interstellar space probe (that is, the first one with a reasonable chance to reach a nearby star within a reasonable timeframe, so that would exclude Voyager and Pioneer.)

I think most national space programmes are underfunded, whether NASA, ESA or Russia. I think we as a species are using our time and resources on lots of useless and wasteful things. Exploring space is not one of them :-)