http://totl.net/Gods/Cthulhu.png

Hi.

Power and Purpose in Space (http://www.nuclearspace.com/a_zubrin.html)

by Robert Zubrin, Mars Society.

Wood, wind, water, coal, oil, gas, and nuclear energy: of those major power sources, only one—nuclear—can work in space. Like it or not, humanity is going nowhere, astronautically speaking, without the power of the atom.

Continued.... (http://www.nuclearspace.com/a_zubrin.html)


http://www.nuclearspace.com/images/gallery/npr_orion_to_mars_small.jpg


What do you think? Is this guy nuts?

Zubrin's correct. Solar is limited in range and power, and chemical is limited in weight/thrust and power. Nuclear is the only route, with fusion being the goal for travel throughout the solar system.

Imagine what we could do with the existing deep probes, powered not with a 300W nuclear system, but a MW reactor...

Another Orion project?

I do not think that nuclear power in the sense of an Orion Project will be enough. There is not enough radioactives with in the earth's crust for continual expansion of interstellar flight through nuclear bombs.

Welcome to sciforums, Cthulhu.

There is another possibility of using a mix of antimatter and nuclear for propulsion. Present tests show that it can generate a good bit of extra thrust.

I don't think Zubrin is promoting a revisited Orion project, wet1. Besides, it's inefficient, especially for short distances,, technically difficult, and potentially not that safe for anyone in its wake.

Zubrin's just stating that nuclear reactors (as in electricity generating) need to be used in space, because they are the best choice, and the only choice past Mars.

Fusion engines would make Mars colonization much more feasible, cutting the travel time down a lot.

I did not connect to the link because I am at a work computer so I was left with guess to make a response.

We have a ways to go before we are technologically proficient to handle such a method. We are reaching for answers though. So hope is there that one day we may find what we seek
.

Wet1
Do you often write detailed responses to articles you haven't read? Just curious.

I think the pic was purely to add some colour. The article is mostly about RTG's and reactors. Orion is the most advanced nuclear rocket possible with today's technology and is still being studied by JPL. They don't call it a nuclear pulse engine anymore. It's now an external pulsed plasma drive under it's new politically correct terminology. 'Nuclear' Waaah! Several versions and derivatives are under contract through various companies and universities. MITEE being the most famous.
Zubrin is mostly interested in miniature space reactors for human colonisation. The SP-100 for example. Here's what he has to say about nuclear power for Mars colonisation.

Link. (http://www.spaceref.com/news/viewsr.html?pid=3212)

For those who can't read links.

It is essential that a Mars mission be conducted in a power-rich environment. There are those who say we can conduct human Mars missions using solar energy for surface power. It's possible in principle, but it's a bad idea. Solar power on Mars is weather dependant, and an extended dust storm could starve the crew of electricity. Here a power shortage is a matter of discomfort; on Mars it could be fatal. The right way to do a human Mars mission is with nuclear power, with the reactor rated to a maximum output twice that of the anticipated average crew needs. Depending on the mission plan, that means a unit or set of units with a total output between 20 and 100 kilowatts. Either way, that is very small for a nuclear reactor. One hundred kilowatts is 130 horsepower, the same amount of muscle that drives a mid-sized car.

Developing such small nuclear reactors is hardly beyond our technology. After all, we had nuclear power in the United States before we had color TV. The problem has been lack of funding due to opposition by penny pinchers on the right and anti nuclear types on the left. Both are mistaken. Space nuclear power will be an enormous cost saver. It will allow us to make our return propellant on Mars, reducing mission launch-to-orbit mass by hundreds of tons and cost by billions of dollars. It also poses no threat to the Earth's environment. At launch, a space nuclear reactor (unlike a radioisotope generator) contains no more radioactivity than the uranium that was pulled out of the environment to fuel it. It is only after starting it following landing on Mars, that a significant radiological inventory is generated. And that stuff is not coming back to Earth unless Mars heads for Earth, in which case we have larger problems.

Of course, space nuclear power would save us no money if we simply decided not to go to Mars. But that would mean giving up that fundamental searching quality that makes us human, which would be a loss we could afford even less.

Actually, while guessing at the contents, I did not think my responce contained much detail.

One of the main hold backs to the whole nuclear in space thing has been proponets frightened out of their minds at the idea of having to self destruct a rocket in flight carrying nuclear material. It does not matter that it is not active nor that they wait until it is on its way to power up the reactor. It is the idea that a global contamination from radioactives could result from small amounts. True not total divestation because of the limited amount.

The whole nuclear thing drives people into fits if there is any possibility for contamination. It immeadately brings mutated babies, ect to the forefront as the thing to rally against. No matter the fail safe design, the planning that went into it to prevent just such from happening, the mass fear that nuclear power carries is a taint that is hard to seperate from the item.

It is very true that any manned mission to Mars, depending on solar would face the possiblity of no power for possibily a couple of months, not to mention the need for more panels to collect less available sunlight in the same area that we would get here on Earth. Global sand storms have been recorded many times. There is even one posted in the Astromony section from last year, I think.

There is another possibilty for power source, depending. That of geothermal. The necessary equipment and its weight would make it almost not an option at this time, provided that such a heat source could be found.

I am much in agreement that nuclear will have to have some place in the mission as a power source. Considering the length of travel time and mission time that power will be needed, at present it is the only realistic application that offers hope of filling the goals needed.

For planetary exploration, I like the idea of those nifty nuclear ramjets. New Scientist did a story on them a while back. I believe several groups, including some Australians, are working on the things, including developing a probe to function in Jupiter's atmosphere.

Basically it's a tube. Air comes in the front, and the tube inside is lined with uranium rods; heated air pushes out the smaller aperture at the back. To get air passing through and forced out the smaller back end it needs to get up some speed.

Considering the length of travel time and mission time that power will be needed, at present it is the only realistic application that offers hope of filling the goals needed.

:o
What about wind turbines? Simple, light and robust. Air density may be lower there but it does get pretty blustery.

While a good idea, I suggest that there will be problems with wind power energy sources, much the same as here. That the wind will not always blow, will not always be consistant, and that most probably dust will make it a nightmare to maintain.

It would be easy to make lightweight blades, as you could streach plastic over a lightweight frame. Also, how many would be needed might also be a problem in mass that would be needed to be boosted all the way there would add needed propellent to the flight to get it there. Anything we come up with will always have to have that as a consideration.

Without water, it would limit the mission length. Adam has recently posted an article that suspects that water may not be there on Mars at all. Fuel cells make water but not near the amount to replace what would be lost, even in a closed, recyling loop.

The reason that the water is so critical is that it will determine the length of time the mission may last. With available water it is feasable to go a year on Mars while waiting for the orbits to realign to the most convient fuel saving return trip. With out the water the mission is limited, once again by the fuel consideration for the return flight.

Having a better propulsion system is a wall we have reached. It is now needed.

I suppose a nuclear rocket does have the advantage of dual usage. Aswell as a NERVA type rocket reducing travel time by about half, it could also be converted to a power station on site. Nuclear electric engines are a step in the right direction for dual usage as they provide both thrust and in-space electrical systems power. With further development they can improve on performance I guess. Maybe nuclear power is the best option as you say. Theres nothing out there in imminent danger of getting irradiated. Space is a wasteland awash in radiation. So why don't people support it? The public I can understand. They distrust everything and everybody. Having no comprehension of a science is no reason is in their minds for them not to be totally and unreservedly against it. What I don't understand is why politicians and their scientific advisors are so against nuclear rockets. Can't they see the benefits? Is it really penny pinching from the right and anti-nuclear extremism on the left holding us back? Why haven't others spoken up as candidly as this Zubrin charactor? Sorry, it just sounds too much like a silly conspiracy theory to me.

Something needs to be done about that huge sun that keeps washing radiation all over the solar system. It could hurt someone. :)

Never fear. An anti-nuclear movement has already taken up the cause it seems.

No More Sun! (http://sitereview.org/?article=967)

:bugeye: :m:

good, this is the best way for us to currently power spacecraft. Plus, I remember an article about a specific isotope of americium which would make nuclear drives extremely efficient and quicker than any other type of possible fuel.

Americium-242. A foil reactor engine estimated to have a Mars transit time of 2 weeks. Wouldn't it be nice if a couple of hundred billion dollars was invested in actually taking these ideas off paper.

http://www.sepp.org/weekwas/2001/Mar24.htm

Here's a link that mentions it.

In the article, the researchers demonstrate that the fairly rare nuclear material americium-242 (Am-242) can maintain sustained nuclear fission as an extremely thin metallic film, less than a thousandth of a millimeter thick. In this form, the high-energy, high-temperature fission products can escape the fuel elements and be used for propulsion in space. [Obtaining such fission-fragments is not possible with the better-known uranium-235 and plutonium-239 nuclear fuels; they require large fuel rods, which absorb fission products.]

Another important note: "He found that of the known fission fuels, Am-242 is the front-runner, requiring only 1 percent of the mass (or weight) of uranium or plutonium to reach its critical state."

More bang, and less weight. Gotta like that.

One question, how does this compare with fusion potentials? I had always thought that fusion would produce more impulse with less fuel than fission can. Perhaps the numbers usually compare uranium/plutonium, and they aren't the best of fissionables to use? And what fusion would be best in the weight vs power issue?

Theoretically 1 GRAM of Americium-242 can replace 1 TON of chemical propellant.

You have to remember that Los Alamos and others are working on a shoestring budget nowadays. The fact that they didn't investigate Am-242 earlier and some middle eastern country thought to try it first is a clear indication of how low they've sunk. Fusion is just another type of nuclear reaction. As is antimatter-matter annihilation. Cutting edge science like nuclear technology needs cash and support to advance significantly. Nuclear has neither.

Isreal has excellent universities and research institutes. I don't think that really shows badly on Los Alamos and the other labs at all.

Then why didn't anybody in the US investigate AM-242 as rocket fuel? There are hundreds of possible nuclear engines for them to explore but their research must be very confined for them to never have looked at other fissionable heavy elements outside of Uranium and Plutonium.

Check this:
http://www.sciforums.com/showthread.php?threadid=15169

Then why didn't anybody in the US investigate AM-242 as rocket fuel? There are hundreds of possible nuclear engines for them to explore but their research must be very confined for them to never have looked at other fissionable heavy elements outside of Uranium and Plutonium.
The nuclear test ban treaty, and (correct me if I'm wrong)the fact that due to atmospheric contamination, you couldn't launch very many.

You'd have to use chemical rockets to get to orbit. Nuclear engines are strictly space only. Also, correct me if I'm wrong, but nuclear would be like ion, where the higher impulse is over a longer period of time than chemical, so you don't have the thrust per second needed to get out of the gravity well. Chemical has a bigger immediate punch, but nuclear has a long term steady thrust with much less fuel weight and usage.

Sounds like the Test Ban Treaty needs some ammending then. I read over that lengthy archaic script a few years back and couldn't help laughing. I don't recall the exact wordage but there was a paragraph citing the risk of "contaminating space" as a reason for the ban on nukes in space. I'm not sure if this actually applies to reactors but I do know many authorities have assumed it does. It isn't very explicit. Still, what do you expect from a manuscript nearly half a century old. They only knew a fraction of what we do today and nuclear power is still in it's infancy as a science. I wonder where we might be today if we'd embraced nuclear power rather than shunning it. I think the 'possibility of ammendment' to the treaty for spaceflight applications were written in there somewhere.

Originally posted by Fraggle Rocker
You are all joking about how stupid it is to talk about polluting space. Our ancestors said the same thing about Lake Superior. Never underestimate the ability of the human race to foul its own nest. It was mesolithic people who killed off all the megafauna that managed to survive the end of the ice age.

Good point. But would even a fleet of fusion driven ships transporting goods throughout the solar system even be able to approach what radiation naturally occurs? It's something to keep in mind though...especially the danger of backwash from other ships.

I notice that the Star Trek series and movies have quietly forgotten about the subspace ecology issue that resulted in a Star Fleet directive to never exceed Warp 5 during the last years of TNG. Shame on them. Roddenberry would not be pleased.

Wasn't that a certain part of the galaxy, not all of it? Anyway, your point is valid...we as a species need to learn how to use resources without abusing the environment around us, even in space. Just look at the clutter that surrounds the planet...

The ramjet idea has been around for a while. We can not at present make such a device. Techonolgy has yet to catch up with the idea. Certainly one ahead of its time.

To set out a feild of such magnitude is beyond us. What would we do with those small pebbles and chunks of matter that randomly float in space? At near c speed even a grain a sand would take on a whole different aspect when viewed as a potential incoming bullet.

I've thought a little bit about how well it would work to use a ramjet-like device as a vacuum cleaner to clear orbit of the smaller, more dangerous junk. Would such a magnetic field be able to grab flecks of paint?

http://www.islandone.org/APC/

read it, read it all

Originally posted by Fraggle Rocker
Once you accelerate to a good percentage of c, Bussard ramjets become practical. (Giant collectors that scoop up interstellar hydrogen.) This is only applicable to interstellar travel, you'd never get to the threshhold speed planet-hopping.
I don't think that interstellar travel will ever be practical with current technologies. It would take a tremendous amount of energy to get a space ship up to the speed of light, and even then it would take you years and years to get anywhere. Maybe if we had some sort of really great suspended animation technology that would allow you to spend a few hundred years in stasis during the voyage…

What if in the future time is irrelevant for those that travel between stars? Then interstellar flight at sublight speeds is ok. This means the only things that are going to spend hundreds of years in interstellar flight are going to be robots. If feel humans did not evolve to live in space: it is up to our progeny to do that.

like I said http://www.islandone.org/APC/ has got everything you need to know about space propulsion

I believe in Wormholes :D ... I think we could easily make ones that will transmit information over infinite distances. Wormholes that can move large matter are another thing they may require more energy then is possible to make. A wormhole wide enough to move light (1um wide lets say) would weigh a billion tons and would have the same gravitational field as the earth within 2 meters of it!

Now we're reading about electrons that can sense each other's feelings once they've participated in a covalent bond together or something like that. (Subatomic particles must be female, guys would never do anything like that!) Change the state of one and the other changes instantly no matter how far away it is. Sounds like the basis for FTL communication, even if it's difficult to imagine applying it to transportation
It was used to teleport a photon(woo whoo). I've said this elsewhere on here, I'll look it up.

When you consider the near infinite quantities of cosmic and solar positive particulate radiation out there the notion of humans polluting space becomes farcical. The Sun could swallow the Earth without a hiccup and spews out ungodly amounts of radiation every second and has done so for billions of years. It's hardly the only star out there either. All the fissionables on Earth (and the Earth itself in fact) are nothing more than embers from a Super Nova. The only way we can mess up space is by filling orbit with debris which becomes a traffic hazard. That's a serious concern and one being addressed. All those careless astronauts who lost nuts and bolts or even dropped spanners. Old modules. Dead satellites. It all drifts endlessly if high enough or eventually burns up. The technology is now being developed to clean it up. Project Orion is a lazer sweep which looks like becoming big buisness. Deeper space might some day get cleaned by garbage ships after callous space yachties space their litter rather than store it. A garbage ramscoop might become big buisness. It could be dumped into the Sun or recycled after that.