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Thargoid
2002-Sep-12, 04:54 AM
Orions, NERVA, radioactive gas, etc.

What do guys think of em?

Provided that they are constructed in orbit, with the radioactive material gathered from asteroids or lunar sources, they would seem to be the next logical step in engine design. Ideal for cruising about the inner solar system on a budget.

I know that they are taboo, but the time has come to dust off this concept, IMHO.

Karl
2002-Sep-12, 05:51 AM
I did some conceptual design work on an unmanned mission with nuclear propulsion. It was difficult to design the spacecraft in a way that radiation hardened electronics could survive a mission length of a couple of years.

It's hard to imagine a very useful role for manned mssions. The hazards are too high for humans, and the radiation interferes with scientific measurements for unmanned missions.

VenusROVER
2006-Mar-28, 04:20 AM
why not

Joff
2006-Mar-28, 05:12 AM
That sounds interesting Karl. Which forms of nuclear propulsion did you investigate?

Anything that generates a radioactive exhaust would be highly undesirable in the vicinity of Earth. However this isn't the case for all forms of nuclear propulsion.

Using RTGs to power an ion drive in the outer solar system for example would be a perfectly achievable nuclear propulsion.

Van Rijn
2006-Mar-28, 05:35 AM
It's hard to imagine a very useful role for manned mssions. The hazards are too high for humans, and the radiation interferes with scientific measurements for unmanned missions.[/b]

Back in the '60s, there were concepts with a nuclear thermal rocket (like NERVA) pulling the manned section along by cable, much like a balloon and gondola. There would be some shielding, but distance was the primary method of reducing exposure. Are you saying there are fundamental problems with this concept?

antoniseb
2006-Mar-28, 01:55 PM
Please note that Karl posted his reply in September 2002. VR is doing a nice job of searching our old stories looking for interesting topics related to his interests. I'm guessing we won't see a reply from Karl.

NERVA was a project that we shelved. The engine for Prometheus (for the JIMO project) was also shelved so far. Neither concept is abandoned. Neither is something we can do with a low budget right now.

mantiss
2006-Mar-28, 05:23 PM
Anything short of fusion will most likely be constrained to RTGs No way will any fission engines be allowed anywhere. So yes, we are still decades away, if not centuries (would be about time to get some Fusion going somewhere!)

antoniseb
2006-Mar-28, 06:19 PM
No way will any fission engines be allowed anywhere.

Actually we have a program for a fission-electric propulsion program, but it is on the back burner right now. I expect it to be operating before the man-to-Mars mission.

mantiss
2006-Mar-28, 06:38 PM
Actually we have a program for a fission-electric propulsion program, but it is on the back burner right now. I expect it to be operating before the man-to-Mars mission.

I just am not a fan of fission, unless you have some way to completely contain it without exhausts and contamination? Sounds intriguing.

antoniseb
2006-Mar-28, 06:43 PM
Sounds intriguing.
Try looking here:
http://exploration.nasa.gov/programs/prometheus/

Van Rijn
2006-Mar-28, 06:51 PM
Please note that Karl posted his reply in September 2002. VR is doing a nice job of searching our old stories looking for interesting topics related to his interests. I'm guessing we won't see a reply from Karl.


Just to be clear, that was VenusROVER. (Sometimes people call me VR here as well.) I'm usually pretty good at noticing post dates, but I missed it this time. No, we aren't likely to see an answer.

antoniseb
2006-Mar-28, 07:13 PM
Sometimes people call me VR here as well
OK, I'll start abreviating him as VeRo, when I'm in a hurry. I try to stick to the full name usually.

Joff
2006-Mar-28, 07:33 PM
Yeah... I missed that it was a resurrection thread too. It's still an interesting topic but we've probably dicussed it in one form or another on quite a few threads since this one.

Bob B.
2006-Mar-28, 08:30 PM
I just am not a fan of fission, unless you have some way to completely contain it without exhausts and contamination? Sounds intriguing.
Why would the exhausts be a problem? All a NERVA-style engine is doing is heating, expanding, and ejecting hydrogen. The hydrogen shouldn't be radioactive. All that should be required is shielding of the reactor to protect the spacecraft structure and crew from long-term degradation.

Clive Tester
2006-Mar-28, 11:30 PM
Why would the exhausts be a problem? All a NERVA-style engine is doing is heating, expanding, and ejecting hydrogen. The hydrogen shouldn't be radioactive. All that should be required is shielding of the reactor to protect the spacecraft structure and crew from long-term degradation.

As I understand, solid core nuclear thermal engines offer a two- fold impulse advantage, over contemporary hydrogen/oxygen engines. Many moons ago, the NTP concept was tested to a stage where a flight ready engine was close at hand. So perhaps NTP would be the preferred option in the near term, for deep space missions of large payload mass.

I guess that we should look beyond nuclear power’s taboo status, and recognise that the debate should be purely technological. There are indeed inherent safety issues that are associated with nuclear power; we have witnessed some ecological disasters in its infancy. But technology moves on.

Ara Pacis
2006-Mar-29, 05:08 AM
I think nuclear will be the future of rocket tech in space. The reason it is not used currently is related to the international treaties. There are some political action groups that are opposed to nuclear energy in any form, but most people are simply ignorant. With new international agreements and public education campaigns nuclear space engines could become popular. I think this could happen by 2020 due to oil shocks. As energy prices increase populations will return to nuclear. This will generate a favorable climate for space nuclear.