Propulsion methods for the Space Exploration Act

Canth · 2002-05-16 15:07:40

If the Space Exploration Act of 2002 gets passed do you think it will use an advanced non-chemical propulsion scheme to accomplish some of it's goals? Or will it use a more standard chemical system? I personally favor a nuclear electric (nuclear powered ion drive) or a nuclear thermal propulsion scheme. I like the nuclear electric idea best because of its non fuel hungryness. You will need very little fuel to be lifted from earth thus cheapening missions past the first one immensly. These systems would likely be used only once out of the atmosphere due to low short term thrust on the nuclear electric and the danger, real or imagined, of contamination by the nuclear thermal. I expect that the craft will be assembled in orbit, lifted there by more conventional means. I wouldn't think conventional propulsion means would be nearly as attractive for a reusable interplanetary spacecraft as you would have to lift all that fuel from earth, or develope the means to produce it somewhere else. Other in space propulsion it could use would be solar sails, a solar thermal rocket, or nuclear pulse propulsion. What propulsion method do you think will be used, why.
I really hope the bill gets passed, many dreams will come true because of it if it does.

C M Edwards · 2002-05-16 15:53:20

Hello Canth.

There are several goals enumerated in the act in question. Earth RLV?s, Mars RLV?s, Lunar surface-to-orbit RLV?s, OTV?s all around? (Sounds a bit like the old 90-day report they gave President Bush, Sr.? :[ ) So many, in fact, that I think it would basically leave us with the same circus of competing systems we have now, except the focus would change to high thrust propulsion systems.

As such, I personally think it?s bad legislation in its current form, but bills like this often get torn apart and reassembled a lot before their final fate is determined. Keep watching. The US Congress may yet rise above quiet desperation.

I think nuclear-electric propulsion is a wonderful idea for re-usable orbital craft. I prefer chemistry for my surface-to orbit propulsion on Earth, because it?s safer and can evolve more thrust than nuclear systems.

Question: If a nuclear thermal rocket had a meltdown in the Martian atmosphere, would there be as much damage from radioactive dispersal in the thinner air?

Hmm.

CME

Canth · 2002-05-16 22:20:25

The real question is is there anything to be considered damaged. Nobody is gonna get radiation sickness from it, it is not going to get to martian life unless it is on the surface and it is bound to be radiation resistant anyway if it is. Of course a meltdown on earth produces less lingering radioactivity than a nuclear test, even an underground one.
I too favor chemical to orbit propulsion. It is tried and true and there is currently no viable alternative, although there are some things beggining to show some promise.

Phobos · 2002-05-19 14:58:47

I just hope the fanatical anti-nuclear crowd doesn't succeed
in killing the use of nuclear power on Mars and in space. I think if an anti-nuclear proponent were to bring up the scenario of nuclear debris being spread across Mars we might
suddenly find ourselves without the advantages of nuclear power. Of course such things should be debated, perhaps it would be catastrophic for that to happen on Mars, but such
a debate would probably be killed on emotional charges rather
than intellectual ones since its already an emotionally charged
subject anyway.

Canth · 2002-05-20 16:28:18

A much smaller nuclear reactor would be required if it were only used to power a fuel manufacturer for chemical mars ascent craft. That way power can be stored up rather than used all at once. I will be quite angry if anti-nuclear people hurt mars exploration. ALL men on mars mission architectures I know of including mars direct require nuclear power.

Shaun Barrett · 2002-05-21 21:08:02

Hi C M ! It seems to me that there would be less dispersal of radioactive material in the Martian air because it's thinner and less able to support small particles. You know, like the plumes of fine dust spraying off the lunar rover wheels and dropping to the surface immediately ... no clouds of it hanging in the air like on Earth.
So I think it would tend to fall out quicker and concentrate the radiation over a smaller area. Thus making it easier to clean up.
But then again, Martian dust storms manage to spread dust quite a long way because of the lack of cleansing rainfall! But that's due to raging winds, which we hope wouldn't be blowing during a nuclear-thermal rocket lift-off!!!
Have I helped, or just made things worse?!
:0

C M Edwards · 2002-05-22 06:34:47

Ever invaluable, Shaun. I hadn't considered the consequences of yearly dust dispersal in Mars' arid environment.

As for the current exploration act, I hadn't previously considered the necessity of nuclear power for small outposts on Mars, but apparently there is a big one. (See the forum discussions on life support and power systems.) This one fact, coupled with the inevitability of squabbling and compromise over nuclear power, could lead to the removal or neutering of the items calling for manned missions to Mars.

We should still throw behind this bill if we expect to get anything from it. But I have a grave fear that it will not be sufficient to take us to Mars.

CME ???

C M Edwards · 2002-05-22 06:48:42

Check this out:

http://space.com/busines....-1.html

I'm starting to feel a warm place in my heart for NASA's new head accountant, Mr. O'Keefe.

CME

Canth · 2002-07-09 21:04:50

I am in favor of a small fleet of reusable nuclear electric spacecraft (use a nuclear reactor to generate power for an ion engine) which remain in space at all times except during aerobraking. Another possibility is that a mini magnetosphere propulsion system could be used instead of an ion engine. They would carry people to mars during every conjunction class mission opportunity and possibly supplies during other opportunities. The developement of a single long range spacecraft could fullfill all of the space exploration act of 2002's long range transport needs. The only other major developements required would be lunar and martian landers and likely a new vehicle to reach earth orbit. Very little developement would be required for asteroidal landings. Aerobraking would be used upon reaching mars or earth. For other targets the engines would have to be fired one way for half the trip and the other way for the other half. Conceivably such a craft could also conduct missions to the asteroid belt and other destinations. I am in favor of using in sitiu propellant production for the mars ascent/descent vehicle. I find this scheme to be the best system in terms of versatility and long range usability as well as in cost and fuel efficency in the long run. (Ion and mini magnetospere propulsion systems use very little fuel, as do their reactors.) This system could also be used as the groundwork for a colinization system for mars or a mining system among the asteroids, or both. Anyway that would be my dream system.

Canth · 2002-07-10 08:45:29

For some reason my post dosn't seem to have registered with the bumping up feature. Hopefully this post will correct the problem.

Phobos · 2002-07-10 15:22:11

This system could also be used as the groundwork for a colinization system for mars or a mining system among the asteroids, or both. Anyway that would be my dream system.

I think if we really want to colonize and utilize space to its fullest we have no choice but to go with a scheme similiar to the one you mentioned. If we don't learn how to manufacture necessities like fuel insitu and instead continue to rely on supplies being lifted off of Earth, colonizing Mars and undertaking other large space projects will remain just a dream. We have to start developing technology that allows us to be as self-reliant as possible in space without a huge need for payloads being lifted off from Earth. I think once technology matures to the point where agriculture, mining, and fuel production can all be achieved in space easily and abundantly, we can declare independence from Earth. So I think we should be working hard on those types of technologies.

Canth · 2002-07-10 17:15:11

What we really want is dependance on space not independence from earth. If terrestrial governments and people are dependent on resources obtained extraterestrially huge amounts of money will be poured into space. The quickest way to expand our presence in space is to find a resource which people back on earth will want. Look at the role of tobacco in the european settlement of america. What is needed is a cash crop.

John_Frazer · 2002-07-11 22:10:44

First of all, this newest space initiative doesn't include anything at all for nuclear thermal. Only fission power systems to power probes and possibly NEP thrusters for outer solar system exploration. Nothing big enough for manned ships, at that.
One reason for this nuclear initiative is that there is only one single RTG stockpiled for space probes, of an old design. This new program modernizes the designs, and builds more.

This probably means that there's not much there for VASIMR either. That plasma thruster is very power hungry, so it would take big nuclear power plants -far bigger than anything flown to date.

I doubt the value of VASIMR anyway. The same performance can be achieved with far less expensive R&D with nuclear thermal: First, VASIMRs designers say its variable thrust/isp allow it to thrust all the way there, vastly shortening the trip times.
Everything they claim has been either tested or planned for NTR for a long time.
First, for low-efficiency big thrust (for liftoff from Mars or the Moon or perigee-kick propulsive maneuvers) there's the O2 "afterburning" NTR. Inject O2 into the exhaust stream of an NTR, and the exhaust cools, EV and isp drops, while thrust goes up.
This gives equal capability to VASIMR, with far less new technology needed (No supercunductors or plasma handling).

Second, NTR can equal the performance of VASIMR in the part of the flight where VASIMR throttles down, for low-thrust, long duration, high efficiency travel.
Shut off the rocket, run coolant through the pile into a power turbine, for a closed cycle power plant (designed by Pratt & Whitney) to power ion thrusters (already extensively tested, and flown).

This dual mode (really triple mode) NTR can do everything VASIMR claims, with everything involved relying on well known, tested or even flown equipment.

For the real kicker, the performance cited for VASIMR (3 months to Mars) can be beaten with an even earlier, well known (if unpopular) method.
The 10 meter, HLV boosted Orion engine module gets a ship of a few hundred tons to Mars, ~45% of the mass being cargo, on a 6 week trajectory. This was 1960s technology... simple, dumb, and supposedly as cheap as the booster to get it off the ground.
If "clean" bomblets can be made for the low altitude part of the flight, then we've got hundreds of tons to Mars in 6 weeks, with one HLV shot. (compare that to Mars Direct! It even inlcudes an escape module for the crew during launch, unlike Mars Direct...)
If the "clean" bombs can't be made, then we take 5-6 launches to do the same thing. Unfortunately making the mission that much bigger, and requiring space assembly, but for what a ship!

Phobos · 2002-07-12 00:42:59

The 10 meter, HLV boosted Orion engine module gets a ship of a few hundred tons to Mars, ~45% of the mass being cargo, on a 6 week trajectory. This was 1960s technology... simple, dumb, and supposedly as cheap as the booster to get it off the ground.
If "clean" bomblets can be made for the low altitude part of the flight, then we've got hundreds of tons to Mars in 6 weeks, with one HLV shot. (compare that to Mars Direct! It even inlcudes an escape module for the crew during launch, unlike Mars Direct...)
If the "clean" bombs can't be made, then we take 5-6 launches to do the same thing. Unfortunately making the mission that much bigger, and requiring space assembly, but for what a ship!

Damn it, having the possibility of the Orion around is like being immersed in cold water up to your chin when your almost dead of thirst, but can't sip of the cool waters. I've never heard of the "clean bombs", but even if they could be proven to be 100% reliable and safe to the environment, they'd probably be lobbied out of existence by nuke foes. If such "clean" bombs could be made to work, I guess we'll just have to plan on launching the mass of a few extra Earth Firsters that have chained themselves to the hull.

Byron · 2002-07-12 06:23:48

The 10 meter, HLV boosted Orion engine module gets a ship of a few hundred tons to Mars, ~45% of the mass being cargo, on a 6 week trajectory. This was 1960s technology... simple, dumb, and supposedly as cheap as the booster to get it off the ground.
If "clean" bomblets can be made for the low altitude part of the flight, then we've got hundreds of tons to Mars in 6 weeks, with one HLV shot. (compare that to Mars Direct! It even inlcudes an escape module for the crew during launch, unlike Mars Direct...)
If the "clean" bombs can't be made, then we take 5-6 launches to do the same thing. Unfortunately making the mission that much bigger, and requiring space assembly, but for what a ship!
Damn it, having the possibility of the Orion around is like being immersed in cold water up to your chin when your almost dead of thirst, but can't sip of the cool waters. I've never heard of the "clean bombs", but even if they could be proven to be 100% reliable and safe to the environment, they'd probably be lobbied out of existence by nuke foes. If such "clean" bombs could be made to work, I guess we'll just have to plan on launching the mass of a few extra Earth Firsters that have chained themselves to the hull.

Good analogy there, Phobos...that's pretty close to how I feel about the *marvelous* possibilities of the Orion...just think...Earth to Mars in 6 weeks!!! Oh, such sweet dreams....

I have an idea: why don't we pass the hat around to buy some little island in the Pacific (location kept secret) and build a lauching pad for the Orion there, and blast off to Mars before the Earth Firsters have a chance to chain themselves to the spacecraft...lol..

B

Phobos · 2002-07-12 21:53:30

Good analogy there, Phobos...that's pretty close to how I feel about the *marvelous* possibilities of the Orion...just think...Earth to Mars in 6 weeks!!! Oh, such sweet dreams....
I have an idea: why don't we pass the hat around to buy some little island in the Pacific (location kept secret) and build a lauching pad for the Orion there, and blast off to Mars before the Earth Firsters have a chance to chain themselves to the spacecraft...lol..

Pass that hat over here. I'll put a few centavos in it. When we build our island and install our own little government on it, we'll put huge signs everywhere warning that the beast is gonna launch regardless of how many people chained themselves to it. It'll be entertaining to watch how many people in self-afflicted bondage get cold feet as the countdown marches toward zero.

Phobos · 2002-07-12 22:53:09

Good analogy there, Phobos...that's pretty close to how I feel about the *marvelous* possibilities of the Orion...just think...Earth to Mars in 6 weeks!!! Oh, such sweet dreams....
I have an idea: why don't we pass the hat around to buy some little island in the Pacific (location kept secret) and build a lauching pad for the Orion there, and blast off to Mars before the Earth Firsters have a chance to chain themselves to the spacecraft...lol..

Pass that hat over here. I'll put a few centavos in it. When we build our island and install our own little government on it, we'll put huge signs everywhere warning that the beast is gonna launch regardless of how many people chained themselves to it. It'll be entertaining to watch how many people in self-afflicted bondage get cold feet as the countdown marches toward zero.

Aetius · 2002-07-13 21:12:29

As much as the occasionally Luddite opinions of radical environmentalists annoy me, I have grave reservations about using Orion-class propulsion systems anywhere this side of the Asteroid Belt. The electromagnetic pulse would surely wreck havoc on satellite constellations. The EM pulses would also cause temporary damage to the ozone layer, just as gamma ray bursts (GRBs) from distant galaxies do (but worse). As I understand it, 'pure' (nuclear fallout-free) fission bomblets are physically impossible to make. There will always be other, 'side' reactions that generate neutrons.

I totally support the use of other nuclear power and propulsion systems, though. Most people who are adamantly opposed to any use of nuclear power tend to rely on irrational arguments...nuclear energy is like black magic to them, and we're on the side of the mages.

Maybe you guys could just lease part of Christmas Island from the Australians. I hear the Russians are building a spaceport there. If members of the Earth Liberation Front chain themselves to the rocket, please give them the middle finger for me...right before you press the big red 'LAUNCH' button.

Phobos · 2002-07-14 20:57:50

I totally support the use of other nuclear power and propulsion systems, though. Most people who are adamantly opposed to any use of nuclear power tend to rely on irrational arguments...nuclear energy is like black magic to them, and we're on the side of the mages.

God knows that's the truth. Considering the New Age/Pagan theology some radicals espouse, it's probably not to far from being literal when you claim nuclear energy is like black magic to them. Not that I have anything against Pagans or New Agers in general. Anyways, I forgot about the affects of EMP blasts. Damn, I guess were stuck to just dreaming.

Aetius · 2002-07-15 03:35:02

Hey, no joke...I am a neo-pagan myself. No offense taken. Polytheists are no different from monotheists (or atheists, for that matter) in the sense that they encompass the entire political spectrum. My politics are obviously farther to the Right than, say, a Wiccan who espouses Dworkinite radical feminism and utters slogans like, "Fight the evil Patriarchy and its evil spawn, the scientific method which rapes Mother Nature."

Yeah, I think that's pretty scary, too.

Phobos · 2002-07-16 19:59:18

I think paganism is often misunderstood and wrongfully debased. Even though I'm not really a pagan, I find it liberating reading about pagan spiritual ideas. They have far more vitality to them then the dead dogma that's present in most of the major religions today. And I often feel that same spiritual affinity with nature that I think a lot of pagans do. It's not so much the environmentalists' concern for nature that I despise, but rather, their often anti-human, and more often than not, facist ideas. It's no secret how willing a lot of these fanatics would be to completely subjugate us to their authority if they had the chance.

Aetius · 2002-07-16 20:52:48

I agree. I abhor the wanton destruction of the natural environment, or anything else. But a balance must be struck between the needs of an advanced technological civilization, and the needs of the ecosystem which sustains its denizens. I simply disagree with the more extremist elements of the environmental movement, who seem to value plants and animals more highly than people. The fascist undertones, combined with the misanthropic sentiments voiced by some of its rank and file, are big turn-offs to me.

Shaun Barrett · 2002-07-17 01:14:35

I agree with your sentiments on this topic. Although in my own mind, I feel like I'm a greenie of sorts, I am a great believer in more and better technology.
Everything needs balance, doesn't it? I am not willing to sacrifice our ecosystem on the altar of technological progress ... that is obviously the way to self-destruction. But nor am I willing to abandon technological progress for the sake of an unrealistic and patently unattainable agrarian utopia. (As I've submitted elsewhere, you can't go back to some kind of imagined rural idyll because it was never like that in the first place! Life on a medieval farm was grindingly hard and technology has lifted many of us out of that type of miserable existence.)
In any case, it's not technology that's caused most of the environmental damage so far. It's been the unmitigated greed and self-interest of the many morally bankrupt people who have used that technology without scruple to enrich themselves.
This is a problem I think is virtually insoluble ... the avaricious and power-hungry nature of many of the people who get into positions of wealth and influence. I suppose their very nature makes them more likely than most of us to actually reach these positions! Sorry to repeat myself again, but it's very relevant here. Mark Twain (I believe) once said something to the effect that the last person in the world you should ever vote for, is someone who puts him/herself up for election!! I've always thought this simple observation sums up the flaw in democracy - the career politician whose own self-interest is all that matters to him/her.
Technology, then, in my view, is a good thing. And in the hands of rational people with some sort of conscience, it will almost always result in improvements in the human condition.
Oops! This thread is getting way off track! Before Adrian gets here to pull us into line, I'll try to steer us back onto the straight and narrow by reiterating my support for the sensible application of nuclear energy in space exploration. (Phew ... do you think he noticed anything was amiss?! )
Having said that, I can't support nuclear fission propulsion systems inside Earth's atmosphere. But out in space ... sure, let's go for it! .... Nuclear thermal, nuclear electric ... the sky's literally the limit!!

Palomar · 2002-07-17 11:00:02

My politics are obviously farther to the Right than, say, a Wiccan who espouses Dworkinite radical feminism and utters slogans like, "Fight the evil Patriarchy and its evil spawn, the scientific method which rapes Mother Nature."
Yeah, I think that's pretty scary, too.

*Mmmm-hmmmm. And Wiccans of this sort make their pronouncements and statements on computers, powered with electricity, in a home or office with artificial heating and cool [comfort], after having gotten a snack from the refrigerator and maybe after having taken a nice hot shower courtesy their water heater and modern indoor plumbing, and later will get into their cars to go to the coven meeting. Yeah, down with the 'evil spawn' of Patriarchy! Riiiight.

I can't understand people who yap against technology and the scientific method, but yet insist on having the luxuries and benefits of it. They're hypocrites.

I used to work in Albuquerque, NM. Native Americans would check into the hospitals, same as everyone else, when in pain, very sick, requiring surgery, etc. Yes, they might have the tribal medicine man come to visit [which, hey -- if it gives them emotional comfort, that too can speed the healing process, why not?], but still they rely on and want the modern sterile surgical techniques, the wonder medications which relieve pain nearly instantaneously, physical comfort measures, etc. Only a fool would refuse these things. I bring up the Native Americans only because we have so many white folks [I'm white myself, and my maternal great-great grandmother was full-blooded Native American] in northern NM [and elsewhere] who have this notion that all Native Americans rely solely on their medicine men, are great believers in herbal/natural remedies [and use ONLY them], sit in sweat lodges night after night, etc., etc., i.e. some romantic ideal/notion that they are absolute nature worshippers like the wannabe whites. Maybe some Native Americans are this way, but many aren't.

--Cindy

Phobos · 2002-07-17 18:47:40

Everything needs balance, doesn't it? I am not willing to sacrifice our ecosystem on the altar of technological progress ... that is obviously the way to self-destruction. But nor am I willing to abandon technological progress for the sake of an unrealistic and patently unattainable agrarian utopia. (As I've submitted elsewhere, you can't go back to some kind of imagined rural idyll because it was never like that in the first place! Life on a medieval farm was grindingly hard and technology has lifted many of us out of that type of miserable existence.)

The thing I never grasp is why it's such a prevalent view that technology is incompatible with an ecologically healthy planet. It'll be technology that ultimately delivers the clean energy and high standard of life that is compatible with ecological health. Killing technological progress and going back to the farm so to speak would only make things more ecologically disasterous!

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