Nuclear fission

[Stargazer]

According to an article over at space.com, JPL is considering other Prometheus (their nuclear fission programme) projects than a Jupiter Icy Moons Orbiter, to be sent instead of, or before, JIMO. The ideas include orbiter missions to the Moon, Venus and Near Earth Asteroids, for example. It's not entirely clear if they would scrap the JIMO in favour of one of these projects, or do them in addition to it. Anyway, here's a link:

http://www.space.com/businesstechnol...te_041210.html

[Tormod]

Thanks for the link. It seems we have to wait at least 10 years for the launch of the JIMO mission then. Oh well.

[Stargazer]

Well it's still great to see that they're still working on this. I believe it to be important if we're going to explore and colonise the solar system more seriously.

[BlameTheEx]

Stargazer.

You may be mistaking the intent of these studies. They are ALL inner planet missions. There is not a hope in hell that they won't report back saying that solar power is the better option. I suspect politics here with NASA looking for a way of postponing JIMO until it is ether forgotten, or solar power has been developed to the point that it can be used even as far out as jupiter. This might not be NASA's preferred option, but it could easily be NASA's preferred fall back position.

I gave detailed argument against nuclear power within the inner planets here (the second post):

http://www.hypography.com/sciencefor...read.php?t=412

In short this is the situation. Within the inner planets you can get a lot of power for little mass by one of two methods:

1) Use a fission reactor.
2) Concentrate sunlight onto solar cells using fresnel lenses or mirrors (with no gravity ether can be made very light indeed).

However a little thought will show up the problem. Ether method results in a lot of waste heat to dissipate. The bulk of the generator's mass will be cooling.

Solar power is easier to cool because:

A) Efficiency levels are likely to be higher. There just wont be as much waste heat.

B) Solar cells can be small, and well separated from each other. That means the waste heat will have to be piped much smaller distances before it is dissipated.

I need hardly point out the reliability and safety benefits of solar power. I have already pointed out the lower development costs (At least the lower development costs paid by NASA).

[Stargazer]

Originally Posted by BlameTheEx

You may be mistaking the intent of these studies. They are ALL inner planet missions. There is not a hope in hell that they won't report back saying that solar power is the better option.

Yes, they are. However, this is also within the Prometheus programme, which means the aim is to develop fission reactors for use in space. These scaled down projects suggested would be done to demonstrate the technology of nuclear fission.

I suspect politics here with NASA looking for a way of postponing JIMO until it is ether forgotten, or solar power has been developed to the point that it can be used even as far out as jupiter. This might not be NASA's preferred option, but it could easily be NASA's preferred fall back position.

I think JPL would like to develop these technologies - it's usually the shortsighted politicians who wish to keep things down, or that's how it feels like, anyway.

In short this is the situation. Within the inner planets you can get a lot of power for little mass by one of two methods:

1) Use a fission reactor.
2) Concentrate sunlight onto solar cells using fresnel lenses or mirrors (with no gravity ether can be made very light indeed).

However a little thought will show up the problem. Ether method results in a lot of waste heat to dissipate. The bulk of the generator's mass will be cooling.

Solar power is easier to cool because:

A) Efficiency levels are likely to be higher. There just wont be as much waste heat.

B) Solar cells can be small, and well separated from each other. That means the waste heat will have to be piped much smaller distances before it is dissipated.

I need hardly point out the reliability and safety benefits of solar power. I have already pointed out the lower development costs (At least the lower development costs paid by NASA).

Yes solar power has its place in space exploration - however that place is not everywhere.