Mission to Neptune

[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]

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]

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

 

Why? Cassini is nuclear powered.

 

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]

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]

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.

 

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]

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).

 

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]

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 :-)

[Tormod]

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?

 

There is a deeper meaning in this question which is very important. Good call.

[BlameTheEx]

SMART-1 uses xenon gas and solar electricity. Will ion drives for outer planet research require nuclear power?

Not necessarily. Most of the boost can be applied while the craft is still within the orbit of the inner planets - where solar power is the better option. The remainder can be a mixture of gravity assisted boosts, and a little conventional rocket power - the same as always. Then again, the solar power assembly used for the initial boost can still be used once it gets Jupiter. It will just provide far less power. Perhaps still enough for manoeuvring with a lower velocity ion drive, and powering instruments.

 

Why is there a question about this - is it a matter of funding? Safety?

 

Yes, and yes, but also I see problems in development.

 

You are not comparing like with like. Casini used radioisotope thermoelectric generators. These were a good choice for powering the instruments - given that solar power was not a viable alternative at the time. The demand was for 600-700 watts. While RTG's are viable for powering instruments it is not suggested that they are valid for powering ion drives. The power requirement for the JIMO is pencilled in at about 100,000 watts. Current RTG's would be far too heavy for such a task. If nuclear power is to be used for ion drives, it will be a totally new technology. The plans are for a fission powered generator.

 

There is a real difference. Cassini used 3 RTG's, and if more power had been needed more RTG's could have been added. If a RTG had failed, it would be no great problem - there is redundancy. For the JIMO project there will be and can only be one fusion power source. One huge source of heat that must be dissipated. It is heat dissipation that will be the problem. Presumably there will be a large array of delicate cooling fins connected by heat pipes. I would like you to consider the development and deployment of this array. Can it be launched as a unit? If not, can it be assembled in space? How can it be made reliable? Leaks due to meteorite damage, mechanical stress during launch, thermal stress during operation, or radiation damage are all possible. So are blockages.

 

There is plenty of information on ion drive development, and it's all going well. There is plenty of information on lightweight fission generators for space, and again it seems no great problem. Plenty of studies have been made. But for cooling - Where are the contracts for research and development? Where are the estimates of the cooling assembly's weight? All I have seen is an artists impression of what the cooling fins will look like.

 

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 :-)

 

But do you think that this underfunding will end in the near future? If so, and you are proved right, I will look right foolish, but frankly pigs would fly. NASA must learn to live with the funding politicians supply, not the funding that they promise. As for funding outside the USA - who is even promising such budgets?

[Stargazer]

But do you think that this underfunding will end in the near future? If so, and you are proved right, I will look right foolish, but frankly pigs would fly. NASA must learn to live with the funding politicians supply, not the funding that they promise. As for funding outside the USA - who is even promising such budgets?

No, I suspect that it wont end anytime soon. I have no idea what it will take to have the people in charge realise how important it is. Maybe we should start relying on the private sector for space colonisation.

[BlameTheEx]

No, I suspect that it wont end anytime soon. I have no idea what it will take to have the people in charge realise how important it is. Maybe we should start relying on the private sector for space colonisation.

 

What can I do but agree? But is the private sector going to be interested in fusion? Right now there is lots of private sector involvement in space, but it is 100% solar powered. There are no private concerns planing missions to the outer planets for commercial gain in the near future. Not at least private concerns that have that sort of money. Could you offer a business plan that would attract investors? If NASA is to rely on developments from the private sector it can only go for solar power - because that is what private industry IS developing.

[Tormod]

Blame, I think your posts here are very good. Thanks.

[Stargazer]

What can I do but agree? But is the private sector going to be interested in fusion? Right now there is lots of private sector involvement in space, but it is 100% solar powered. There are no private concerns planing missions to the outer planets for commercial gain in the near future. Not at least private concerns that have that sort of money. Could you offer a business plan that would attract investors? If NASA is to rely on developments from the private sector it can only go for solar power - because that is what private industry IS developing.

I didn't meant to say that NASA would wait for the private sector to develop things, I meant that the space colonisation could very well be done by the private sector. I think they will have to take small steps out in space. Virgin Galactic and Bigelow Aerospace are great examples of this, where they will achieve suborbit and LEO for tourists and probably companies and research institutions to rent modules in Bigelow's space station for example. Then pretty soon I predict the time is ready for spaceships that can go around the moon for a short cruise, and then after a while there will be bases on the surface of the moon. All this time they will move around in the inner solar system, where nuclear fission is not necessary for most purposes. And regarding the Prometheus project, NASA is working together with private companies to develop the reactor, as they have with the other projects.

[BlameTheEx]

And regarding the Prometheus project, NASA is working together with private companies to develop the reactor, as they have with the other projects.

 

What exactly do you mean here?

 

It would be no new thing for NASA to pay private companies for research. Nor will it surprise me that private industry has made useful developments that can be applied to space. Always we take what we already know and then using it as a base for development. Are you suggesting that private industry IS directly funding development of fusion power specifically for space? I doubt it. NASA will have to pay the vast bulk of any project to adapt our knowledge of earth bound reactors for application in space.