Plasma Propulsion Could Cut Time To Mars in Half 329
NEW ROCKET TECHNOLOGY COULD CUT MARS TRAVEL TIME
An agreement to collaborate on development of an advanced rocket technology that could cut in half the time required to reach Mars, opening the solar system to human exploration in the next decade, has been signed by NASA's Johnson Space Center, Houston, TX, and MSE Technology Applications Inc., Butte, MT.
The technology could reduce astronauts' total exposure to space radiation and lessen time spent in weightlessness, perhaps minimizing bone and muscle mass loss and circulatory changes.
Called the Variable Specific Impulse Magnetoplasma Rocket (VASIMR), the technology has been under development at Johnson's Advanced Space Propulsion Laboratory. The laboratory director is Franklin Chang-Diaz, a NASA astronaut who holds a doctorate in applied plasma physics and fusion technology from the Massachusetts Institute of Technology, Cambridge.
Chang-Diaz, who began working on the plasma rocket in 1979, said, "A precursor to fusion rockets, the VASIMR provides a power- rich, fast-propulsion architecture."
Plasma, sometimes called the fourth state of matter, is an ionized (or electrically charged) gas made up of atoms stripped of some of their electrons. Stars are made of plasma. It is gas heated to extreme temperatures, millions of degrees. No known material could withstand these temperatures. Fortunately, plasma is a good electrical conductor. This property allows it to be held, guided and accelerated by properly designed magnetic fields.
The VASIMR engine consists of three linked magnetic cells. The forward cell handles the main injection of propellant gas and its ionization. The central cell acts as an amplifier to further heat the plasma. The aft cell is a magnetic nozzle, which converts the energy of the fluid into directed flow.
Neutral gas, typically hydrogen, is injected at the forward cell and ionized. The resulting plasma is electromagnetically energized in the central cell by ion cyclotron resonance heating. In this process radio waves give their energy to the plasma, heating it in a manner similar to the way a microwave oven works.
After heating, the plasma is magnetically exhausted at the aft cell to provide modulated thrust. The aft cell is a magnetic nozzle, which converts the energy of the plasma into velocity of the jet exhaust, while protecting any nearby structure and ensuring efficient plasma detachment from the magnetic field.
A key to the technology is the capability to vary, or modulate, the plasma exhaust to maintain optimal propulsive efficiency. This feature is like an automobile's transmission which best uses the power of the engine, either for speed when driving on a level highway, or for torque over hilly terrain.
On a mission to Mars, such a rocket would continuously accelerate through the first half of its voyage, then reverse its attitude and slow down during the second half. The flight could take slightly over three months. A conventional chemical mission would take seven to eight months and involve long periods of unpowered drift en route.
There are also potential applications for the technology in the commercial sector. A variable-exhaust plasma rocket would provide an important operational flexibility in the positioning of satellites in Earth orbit.
Several new technologies are being developed for the concept, Chang-Diaz said. They include magnets that are super-conducting at space temperatures, compact power generation equipment, and compact and robust radio-frequency systems for plasma generation and heating.
Coordinated by Johnson's Office of Technology Transfer and Commercialization, the Space Act Agreement calls for a joint collaborative effort to develop advanced propulsion technologies, with no money exchanged between the two parties. Such agreements are part of NASA's continuing effort to transfer benefits of public research and development to the private sector.
VASIMR (Score:1)
According to proper acronymology, the true acronym should be VSIMR. If they chose the more inferior, VASIMR, for phonetic reasons, then they are a disgrace to the Russian Language.
good (Score:1)
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Re:this is important news (Score:1)
How long... (Score:4)
And better yet: How long after leaving the line before same fool disintegrates the car and is strewn over fifty square miles of ground?
Re:This is great news!! (Score:3)
Even though this technology would cut the time to Mars in half you can bet that the kids would still spend the whole time whining.
"Are we there yet?"
Nasa's simply going to have to do better :).
How fast? (Score:1)
Anyone know of a physical limit to the speed of this type of craft?
I checked the link, and I'm sorry if I missed it, but I didn't seem to spot speed numbers anywhere.
the plasma drive (Score:1)
Re:How long... (Score:1)
B. Elgin
Huzzah and kudos to NASA! (Score:2)
All this effort may be wasted (Score:4)
It constantly astounds me that world governments, with all the obvious environmental problems, refuse to whole-heartedly endorse space programs. Certainly, the lack of participation of nations in the shape of Russia (although their space program is/was generally good) is understandable, but the U.S. and other prosperous countries need to take some leadership here.
An Internation Space Station is a good start, but the political infighting regarding the development of it is discouraging. We need governments to realize that, with 6 billion people on the earth, that we don't have the resources to maintain an acceptable standard of living infinitely.
Traveling to another planet to explore, in a precursor to either inhabitation or mining, would be an even better use of this technology. I for one hope that world governments wake up (and that waking up is continigent upon public sentiment) and realize that right now is the time to radically advance our exploration of space.
Scythe
heat (Score:1)
Seriously enough, does anyone know how to support 50,000K temperature with known materials?
Cut time? Or increase time? (Score:3)
But if I want to be on Mars ASAP, which technology is going to get me there first? Conventional, tried-and-true, already-exists rockets? Or untested, not-yet-mature, haven't-built-one-yet technology?
Just launch a damn ship NOW.
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Compaq dropping MAILWorks?
More info on VASIMR (Score:5)
Scientific American ran a really detailed article [sciam.com] a few months back on Mars missions. It discussed several propulsion systems, including this plasma thingee.
Good if you want to be fried! (Score:2)
Ground-based launch or orbital-only? (Score:3)
Basically, is having a plasma rocket inherently more dangerous to be launching through the atmoshpere than the normal chemical rockets currenntly employed?
Lastly, I guess is the bit about "large magnets that are super-conductive in space temeperatures" imply that these rockets may not be able to leave orbit in order to keep the engine functional (or have massive amounts of cooling available to take over for atmoshperic descent).
Re:VASIMR (Score:2)
Interesting (Score:3)
If its not too large, I'd like to propose making a plasma gun ala Doom and Q3a.
'Neutral gas, typically hydrogen' neutral meaning 'non-ionised' I suppose. At least it fits with Elite and the hydrogen fuel suggested there
Wow, an actual use for plasma physics? (Score:2)
Seriously though. Are they going to take all of the propelent with them or will they collect it along the way. This is still going to take massive amounts of energy. Are they going to bring a tiny nuclear power plant with them? I suspect the enviromental people will be up in arms over this. People seem to get upset every time the word nuclear is mentioned. It will be quite a while before this is put into practice (if at all.) Hopefully it will be in our lifetime.
compare methods (Score:2)
Plasma + Air? (Score:2)
-B
Re:How long... (Score:3)
Though I wish this weren't the case, because "plasma powered landspeeder" is kind of neat-sounding.
Re:How long... (Score:2)
I assume you are referring to this [darwinawards.com] urban legend on the Darwin Arwards [darwinawards.com] web site. It's a good story, and there may be some truth [geocities.com] to it.
Next time include the reference.
Excellent (Score:5)
Rush down to your local blood center and donate some of your plasma!
count to ten
Re:Huzzah and kudos to NASA! (Score:2)
Anyone here ever hear of the Orion project? (Score:2)
Now we're talking about a plasma that doesn't look much less radiative for the crew, given the relative strengths of the ships, and certainly costs more, and goes slower... decades later... and it's a great thing? What's in a name? Nuclear == bad, plasma != bad? Mind you, the Orion project, like all space travel back then, would have used the technological equivalent of duct tape and bailing wire. Sometimes I wish I were a geek of yore...
Re:Cut time? Or increase time? (Score:5)
You have to have enough consumables to keep your crew alive for a long period of time: air, food, and water. The longer the voyage, the more mass you will have to take in order to provide for your crew, and thus the more fuel you will need to propel the extra mass...
You would need a tremendous amount of fuel using conventional propulsion methods, and the cost would be prohibitive (note we don't already have a mars mission underway!).
Doug
Re:the plasma drive (Score:3)
And it wasn't that each particle gave thrust equal to the weight of a piece of paper, it was that the *total* thrust was that of a piece of paper...
the thing is, it's extremely efficient, and considering the length of it's journey..
Re:Ground-based launch or orbital-only? (Score:2)
The article mentioned that with a plasma engine, the craft to Mars would have thrust for the entire period, as opposed to chemical rockets where it would need to shut down after a while to conserve fuel... since plasma gives you constant acceleration (while far less thrust is produced than the short bursts of power that chemical rockets provide) over the entire distance, you get there faster...
So, plasma tech probably wouldn't be feasible for ground launches - more likely to be useful in space, though, where fuel is scarce (for now) and you gotta go longer distances.
Re:heat (Score:2)
You're thinking of Deepspace-1, launched ... (Score:2)
Its an ion-propulsion driven deep space explorer - it does not use plasma fusion.
Ion propulsion is a very weak (for now) method of getting around, and yes - in the DS1 experiment, it doesn't provide much more force than the weight of paper here on Earth, but gradually over time DS-1 will reach incredible speeds.
There's more about DS-1 on the NASA pages, but I'm too lazy to go find a link for you!
Re:Huzzah and kudos to NASA! (Score:3)
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Here's my mirror [respublica.fr]
Re:Anyone here ever hear of the Orion project? (Score:2)
Ties into the same reasons that all those "get rid of nuclear waste by rocketing the crap into the sun" plans go nowhere as well.
Nuclear Reactors in space (Score:2)
There are lots of ways to play with plasmas to create engines. NASA did lots of research into this in the 60's, and then someone decided it wasn't a good idea to launch a nuclear reactor, and research basically stopped. The technology has been around for a long time though (arcjets, ion engines, electrostatic engines of various designs...)
The fact of the matter is you could build a craft the size of the shuttle that could make it to Mars and back on one tank of gas, but it would require a nuclear reactor on board. You can also collect interplanetary dust (99% hydrogen) and use it as fuel. Greenpeace, our political system, and the public in general don't like nuclear reactors. I've fantasized many times about buying an island in the pacific for the purpose of building a launch complex, and being out of the reach of governments that feel it's their duty to make sure they know where every ounce of radioactive material on the planet is, and exactly what the owner is doing with it.
Nuclear "fear" is responsible for so much...export controls on computers, testban treaties, greenpeace...but there's so much you could do with it if you could get around all the (MASSIVE) regulation.
All research on nuclear technology basically stopped in this country in the 60's. France, for instance, has far more advanced (and safe) nuclear power plants than the US because they kept working on them. At some point in this country it became taboo to have anything to do with nuclear technology.
It's sad how ignorance and fear are the driving force behind policy on this issue. *sigh*
--Bob
Re:This would be great if Mars actually existed .. (Score:3)
Q: Is there a reason that the Martian landscape, a completely different planet, so strikingly resembles the Arizona desert? (you bet your butt there is)
Q: Why do liberals find it so decidedly convenient to distract schoolchildren with prophetic nonsense about "other planets" instead of focusing their attention on the here and now where it belongs? Lots of topics of education are being outright ignored in favor of liberal subjects such as astronomy, evolution, and heliocentrism.
Mike Roberto (roberto@soul.apk.net [mailto]) -GAIM: MicroBerto
Re:Ground-based launch or orbital-only? (Score:2)
Of course, I'm not taking account whether the exhaust is radioactive or not, or is water vapour or some super-yucky fluorine-based concoction...
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Here's my mirror [respublica.fr]
Re:How fast? (Score:2)
As you probably know, a body travelling with constant force in the atmosphere exhibits "terminal velocity" which is dependent on the density of the air, and also to a large extent on the turbulence of the flow. That is, a fast object (high force) hits more turbulence, so will get a relatively lower terminal velocity than a slow object.
In space, the "atmosphere" is the dust that fills space. Nowhere near as dense as air, of course, but at extremely high speeds the effective density increases. Thus, there will be a terminal velocity for a given thrust dependent on this. I doubt turbulence comes into this equation at all.
Of course, going from Earth to Mars you're going away from the Sun, so the radiation pressure assists you somewhat. On the return journey you have to fight the radiation pressure.
Disclaimer: all this is speculative rubbish.
Re:All this effort may be wasted (Score:2)
The way the planet works, all resources cycle. A simplistic example is water. When you use it up, it cycles back around and is regenerated. Everything on the planet is this way. Some things are on very fast cycles, some things are on very slow cycles. But everything eventually regenerates. When one particular thing outgrows it's potential to cycle, it stops growing. This probably includes the human population. When the earth can't support growth anymore, we will naturally quit growing or even start dying off. As morbid as it sounds, that's the way things work, and there's probably not much you can do about it.
When you travel into space, you actually remove resources from the shorter term cycles of the earth by carrying them outside our atmosphere. (They may enter into a much larger cycle of the galaxy or universe, but that's a much longer term topic.) So when you leave the earth, everything you take with you is removed from the cycles of the earth, which actually lessens the ability of the earth to support life. So probably all you are doing by travelling to space is moving one tick on the life support chart from here to wherever you go.
In the long run, though space travel is neat and fun and interesting, it is not going to solve any of the long term problems of the human species. I'm not implying that we shouldn't do it. Neatness and funness and interestingness are all worthwhile efforts. But the illusion of solving the problems of the human species through space travel is just that, an illusion.
Re:How long... (Score:2)
Do you actually think these guys get their military grade semi-classified powerplants from McDonnell-Douglas or Boeing? They go 'dumpster diving'!!
I agree.. the challenges of the Moon are greater. (Score:3)
But, the advantage to the Moon is the proximity to Earth - if things go wrong, its just a 3 day trip to the plentiful resources of Earth.
So, we refine the self-sustaining tech needed to live on Mars, using our own backyard lab (the Moon), and once that's all happening, send the tech off to Mars. Not to mention that we could probably *manufacture* half of the Mars base from the Moon, which would be cheaper and less dangerous than doing it here on Earth. Heck, we could probably use all sorts of crazy ass tech on the moon to build things better, such as nuclear technology, etc.
Seems sorta backwards to me that we're ignoring this resource and trying to get straight to Mars instead, but then again I don't know how these things are budgeted. Perhaps there are political reasons for getting th Mars before doing the Moon thing - and after all, politics drive the space program.
Re:All this effort may be wasted (Score:3)
Amen to govenrnments waking up, but I would focus on the mining rather than the inhabitation.
The next "giant step" for mankind is surely to live in space. Think space colonies, not planets. We (or USA at least) have had the technology to establish permanent habitation in space for decades. (I was looking for my old copy of O'Neil's book, but couldn't find it.) We can do this, but we do not seem to have the will.
<RANT>
You Americans really p*ss me off: you live in probably the best country in the world (OK: I have only lived and worked in half-a-dozen countries so I can't speak for eveywhere. But to all the Amricans who might have forgotten it: your country isn't half bad</RANT>
Anyhow: space colonies. I'm ready, when do we go?
Re:Cut time? Or increase time? (Score:5)
But if I want to be on Mars ASAP, which technology is going to get me there first? Conventional, tried-and-true, already-exists rockets? Or untested, not-yet-mature, haven't-built-one-yet technology?
Just launch a damn ship NOW.
You are advocating precisely the same approach that took us to the moon six times...and then no more, in almost thirty years.
Why? Because they were in a hurry. Because they wanted to hit Kennedy's arbitrary deadline. Because it was a stunt, strictly for prestige value. So instead of investing in infrastructure, they slapped together the quickest solution they could.
If you want to go to Mars once, use conventional solutions and launch now. If you want to keep going there, over and over without end...if you want to make it more than a stunt...be patient, develop the technology to support it, do it right.
Furthermore, conventional solutions, which accelerate only at the beginning and end, take time proportional to the distance. Constant-acceleration takes time proportional to the square root of the distance. This allows you to go not only to Mars but anywhere in the solar system.
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Plasma propulsion? (Score:2)
Re:All this effort may be wasted (Score:2)
Maybe not, but it's pretty vital for the continuation of the human species. When you consider threats from
The supervolcano under Yellowstone park
Asteroids
Nuclear/biological war
other stuff
there are countless ways that the denizens of Earth could one day find themselves without a planet. Ultimately, all of the above will happen, it's only a question of when and how nasty. You can sort of counter some threats (asteroids, eg) if you throw a tonne of money at them, but the chances of humanity surviving until the sun boils the Earth are bordering on zero. If there's a colony on Mars, it'll be dependent of Earth for decades (maybe centuries), but will most likely ultimately prove self-sufficient. Until it does, all humanity's eggs are in the one basket.
Dont forget the nuclear core to power it. (Score:3)
It's interesting that in none of the press releases do they mention that any ship using this propulsion system would need to have a fair sized nuclear pile (likely more than Cassini's 76 pounds of plutonium) to generate the electricity needed.
Deep Space's ion drive, while having an incredible specific impulse, was pushing so little fuel at any given time that a moderate power source would work. If we're talking about driving 100 tons of cargo to Mars in a speed race however, it's going to require far, far more electricity than a solar cell could reasonably capture, and forget batteries. They can't store enough, even if they weren't damned heavy.
I'm not saying it's for better or worse, but the fact that this propulsion system would mean launching large amounts of plutonium atop a chemical rocket to get out of the Earth's gravity well shouldn't be overlooked or swept under the rug. The potential for disaster is there.
Kevin Fox
Re:All this effort may be wasted (Score:2)
Volcanos or similar natural disasters are probably more likely on another planet than they are on Earth, especially under an artifically created biosphrere.
Smaller asteroids are deflected by the excellent atmosphere of the Earth, and larger ones are reduced in size. This is a luxury we won't have anywhere else.
War? That's a human thing. It's not a matter of where we are, but who we are. If we want to solve that problem, we need to look at ourselves, not our location.
Though all our eggs are in one basket, it's a much better basket than one we are going to be able to build ourselves. My bet is that any artificial habitat we create will be destroyed long before the earth will. I'd even give 1000 to 1 odds on it.
My other question is - why are we so intent on outsurviving the Earth's willingness to let us live here? Why not just appreciate what we are given, and make the most of it? Maybe I'm just going off, but isn't the ego that drives our self preservation getting a little out of hand here?
Re:All this effort may be wasted (Score:2)
I guess in the very long run we are all dead. The Universe may be flat [nasa.gov] and will eventually run out of entropy. Then we die.
However, the rest of your argument is silly. Some points; -
Yes and no. Space travel is the future of the human species but it does not by itself solve many problems anymore than long distance sea-faring and the discovery of the Americas solved anything. But it is a key to greater prosperity and for extending the life of the Human race. We should not waste time in persuing this goal. Be fruitful and increase...
Clearing a few things up... (Score:2)
It would be much more realistic to compare performance between this and an Ion engine instead of a chemical rocket. Ion engines are a proven technology which is jets ionized Xenon instead of Hydrogen plasma. Xenon is safer to carry, but nearly impossible to collect en-route.
What I want to know is where they're getting the continual stream of power to generate the radio waves to create this plasma. This isn't trivial, and power generating and storage systems take up weight.
Mythological Beast
Re:All this effort may be wasted (Score:2)
Wrong question. What you should be asking is what's the probably of [stuff] happening in two places, compared to just one?
Though all our eggs are in one basket, it's a much better basket than one we are going to be able to build ourselves
That's certainly true now, and will be for centuries to come. But even if it's true forever, it doesn't matter. Humanity may struggle and worry on an extraterrestrial colony, but the species will survive. Which is nice.
why are we so intent on outsurviving the Earth's willingness to let us live here?
I'm tempted to give a specious answer to this one, but let me instead ask you why your descendents are less deserving of a long lifespan than you are?
you wouldn't, though (Score:2)
Most likely in a practical Mars-bound craft it'd be around 1 or 2 Gs for most of the trip.
Sudden weightlessness when the engines cut out and as the ship turns around.
Make sure everyone's holding onto the floor real quick, and kick in the engines again. Back at a constant 1 or 2 Gs.
A Case For Mars (Score:2)
I'll volunteer (Score:2)
It's not like my life is so fabulous anyway . . . worst case scenario is that I get killed. Best case scenario is that I end up doing a Good Deed. Since I can get myself killed just crossing the street, I don't see a problem here.
Not radiative (Score:2)
It's frustrating... (Score:3)
It's too bad that nothing much happened after the commendable Tom Hanks film, Apollo 13 [imdb.com] , unlike Saving Private Ryan [imdb.com] which helped get the ball rolling on the WW2 Memorial.
By all means, this is an issue to keep in mind during the coming election campaign. Simply ask the candidates where they stand on NASA funding, and let them paint themselves as either populist tax-cutters or visionary opportunists.
Re:How fast? (Score:3)
Take the distance between Earth and Mars, divided by the time to get there (v=d/s) for the average speed. Assuming 0 starting and ending speed, constant acceleration until the halfway point, and the same acceleration in the opposite direction afterwards, the top speed would probably be about twice the average speed.
Not knowing my astronomy, but looking at some stats, I'll take a rough stab and say the distance would be about 55 x 10^6 km (just for a round number [estec.esa.nl]).
So 3 months is 2160 hours.
So the acceleration would be about 12.9 m/s^2 or roughly 1.3 G.
Now, I'm sure I've miscalculated in there - and I'm not a rocket scientist (ha ha, funny joke) so I'm probably wrong... but 1.3G for continuous acceleration doesn't sound too bad. You'd come back stronger and shorter for the experience...
Re:How fast? (Score:4)
To clarify this point for those who were too busy learing C++ in school to read any Einstein:
As an object with mass approaches the speed of light, the ammount of force required to accelerate approaches infinity.
Therefore the speed of light (represented as "c") is not only theoretically impossible for a passenger vehicle to reach, but before you even get up to that speed you will reach a point where more acceleration is Not Worth The Trouble.
On top of that, there are troublesome issues of time deceleration and lots of other hard math problems that lead one to desire a better way of getting from point A to distant point B than getting a rocket to go "really really fast". Some serious thought and lots of bad sci-fi has been applied to this problem, but so far with few promising conclusions.
Re:How fast? (Score:2)
For a current look at the density around earth, check out NASA's Spaceweather site [spaceweather.com]. You can find graphs of the solar wind's speed, density, composition, and polairity at the ACE Solar Wind Observatory [noaa.gov] site. Look under ACE Plots.
News Flash! (Score:2)
News Flash: NASA Issues Press Statement About Propulsion System They Have Been Working On Since 1979
"We are researching it, and we think it will work," says top NASA spin-doctor, "although we will not be launching anything like this anytime soon. We are very excited about it, and the opportunities it will create."
This astounding news came on the heels of an earlier report from NASA (last year) when they said, "we are researching it, and we think it will work, although we will not be launching anything like this anytime soon. We are very excited about it, and the opportunities it will create."
When nothing happens again, we will be there.
Re:Dont forget the nuclear core to power it. (Score:2)
Re:All this effort may be wasted (Score:2)
I understand that is your question. But what is the relevance of it? I'll just throw out a WAG (Wild Ass Guess) at some numbers, to see what our odds are.
Let's suppose that the natural time for the Earth to support humans is about 4,000,000 years barring a natural disaster, or human stupidity. Let's say that through a natural disaster, that is shortened to 10%. That's only 400,000 years. Though no one knows exactly how long we'll last, I'll throw that out as a guess.
Based on our intelligence and the illusion of wonderful technology, as well as the stability of whatever society we create on another planet, let's say we are able to survive 10,000 years. That's still 40 to 1 odds that the Earth people will out survive the space people. So there's a 2.5% chance that having our eggs in two baskets is of any use, assuming our technology is good enough to succeed in the first place. (Keep in mind these are wild ass guesses, make up different numbers if you like.)
Now the assumption that our technology and knowledge is sufficient to create an arificial biosphere is a big assumption. Just as a stupid example, let me throw in carpenter moths and jelly donuts.
In order to make jelly donuts, you need strawberries. When you grow strawberries, in is natural for spider mites to eat the stalks. The natural cure for this is to have carpenter moths kill the spider mites. So without carpenter moths, you can't have jelly donuts.
What is the point of this stupid example? The point is that the Earth is very very complex. Everything from the smallest amoeba to the largest oak tree is necessary to make it work properly. So regardless of how much time and effort we put into an artificial biosphere, the odds of self-sufficiency are almost null.
Why are your descendents less deserving of a long lifespan than you are?
I believe that they are just as deserving as I am. And if the universe agrees with me, they will get what I think they deserve. But my point is, that I think we are misdirecting our efforts if the point of space travel is an extended life span.
As I said above, I'm not implying that we shouldn't explore space. I think it's fun, it's interesting, and I'd love to take the trip. But I still think the odds of extending our lifespan by doing it are somewhere close to zero.
Re:VASIMR (Score:2)
That said, /. had an article on the possibility of warp drives last year (sorry, no url. try a search).
Re:heat (Score:3)
Re:This would be great if Mars actually existed .. (Score:2)
The bad news is that the Martians have landed.
The good news is they're eating fanatical, conservative, off-topic,
Re:Run out of entropy? Please reread your physic b (Score:2)
OK, let's get the physics straight:
The Earth radiates more energy to space than it receives from the Sun. (The -- small -- extra energy comes from radioactive decay within the Earth.) We do not live off the energy from the Sun.
The difference is in the "quality" of the energy or, more precisely, it's entropy. The Sun is a much hotter object than the Earth; the entropy of the Sun's energy is therefore much less than the entropy of the energy when it is radiated from the Earth. (A system that receives the heat dQ (in a reversible process) increases its entropy by dS = dQ / T where T is the absolute temperature.)
The Earth therefore has a "negative entropy surplus" (talk about double negatives!).
Negative entropy means order. (A system's entropy is proportional to the logatithm of the number of states it can have. Less entropy is therefore fewer states or more order.)
Order means complex structures. Complex structures like life, like you and me.
You are right about the Universe dying the entropic death if it is expanding or flat (see my reference above), but not if it is contracting. But in any case we die. Somebody please figure out a way to create new universes before that happens.
IAAP.
And let's use rockets to go to another star... (Score:3)
Let's see, we can work on developing constant acceleration technology that makes travel time proportional to a logarithm of the distance, or we can keep screwing around with old burst acceleration technology (rockets) that makes time directly proportional to the distance.
Once we have the good constant acceleration engines, we could go anywhere we wanted in the solar system. The Pluto round trip takes only about 7 times as long as the Mars round trip (I assume simplified trajectories; real space travellers would use quicker ones). At a very reasonable 0.01 g, that means a month and a half for the Mars round, under a year for the Pluto round.
Or we could, as you say, just launch a damn ship NOW... and have another Apollo that leads nowhere. Woohoo! Another plastic flag and some footprints on a dead world for us to not visit for decades! That's something to get excited about, isn't it?
Re:Dont forget the nuclear core to power it. (Score:2)
Of course, that raises two problems: First, there would need to be a casing to slow it down. One solution is form the payload into two counterrotating flywheels.
The second is the horrendous gyroscopic forces would interfere with changing orientation. Rotating a flywheel 90 degrees perpendicular to its initial orientation requires exactly the same amount of energy as it took to spin it up in the first place.
Hmm, maybe three pairs of counterrotating flywheels along the three dimensional axes.
Now try to stick a person in it...
Kevin Fox
Some points NASA glosses over (Score:2)
- You still need reaction mass, which you have to carry with you. Plasma propulsion just gives you better exhaust velocities, so you get more impulse for your reaction mass.
- What do they intend to use to power the thing? The classic plan is to use a nuclear reactor. This scares a lot of people, especially since this might require a rather large reactor. (Hydrogen fusion has often been suggested, but that doesn't work yet.)
- There's no indication that NASA is anywhere near building flight hardware, or even has an engine running on a static test stand.
It's a reasonable idea, but the PR piece is so uninformative that it looks like NASA turned somebody's annual progress report into a press release.Re:All this effort may be wasted (Score:2)
The total mass of all cargo placed into space is less than maybe 2 or 3 million lbs. And that includes the fuel in the upper stages that for the most part ends up back on earth again. The lower stages of course don't count because they never leave the planet.
Sound like a lot? It aint. Each day, over one hundred tons of mass (in the form of meteors, solar ejecta, etc) arrive on Earth, adding to its weight.
Eg, Earth gets stocked with the equivalent mass of 50 years of space travel in a week. And this continues each day.
Asteroid Mining can save our planet by putting cheaper access to the resources we need in hand, allowing us to get materials without ploughing up the land and destroying wilderness. If anything, resource friendly environmentalists should be 100% behind space exploration, because it's the most reallistic way to save the planet.
What's the energy source? (Score:2)
Re:All this effort may be wasted (Score:2)
I just had a chat with the universe, and he does not agree with you. HAH!
oh, right *forehead thwack* (Score:2)
Re:All this effort may be wasted (Score:2)
Just thought I'd throw in a twist.
Not! Re:All this effort may be wasted (Score:2)
a) the total amount of metal in one asteroid, Eros is greater than the entire mineable surface of the earth. And there are probably millions of asteroids where that came from...
b) solar energy is an unlimited source of energy, which is available 24x7 in orbit and is relatively easy to tap.
c) the actual, real underlying cost of putting a man into orbit is similar to the cost of crossing the atlantic (it sounds nutty, but the cost of rockets is completely dominated by building each one by hand and then throwing it away afterwards, it's a bit like building a 767 and then trashing it after one flight; the fuel cost is only a few tens of dollars per pound)
d) there's plenty of water and carbon up there- where do you think the earth got its carbon from? It condensed out of the body of a supernova.. as did the asteroids.
Re:How long... (Score:2)
That example is probably lacking, but it's more or less the truth. Plasma drives (and most drives for space travel, actually) would provide a slow, constant push at the ship, and since there's no wind resistance in space, the more you push, the faster you go (with the terminal velocity being the speed of light).
Agreed, though, this could be pretty neat if it was a more powerfull drive. :)
What about launch from lunar orbit? (Score:2)
First of all, although only a dozen people ever got to walk on the moon, there were another dozen who at least got to orbit the moon (including preparatory missions like Apollo 8 & 10 as well as the command module pilots) This way you are outside of the Van Allen Belts, but still close enough to home that other vehicles could get you to your "spacecraft" without having to burn fuel to get there in the first place.
In many ways it is too bad that the Jupiter rocket was never built (that was to follow the Saturn V... and talk about a monster rocket!) One of the early proposals was to send people to the moon by building a large earth-orbiting space station and then sending the moon craft directly from a docking bay of a space station. Von Braun pushed for the method eventually used (with a direct take-off from the ground, and everything brought with them). Had the orbiting station been built (for admittedly more money), at least there would have been an established infrastructure to build upon for future missions.
Unforunately all we got out of all the money spent by NASA for a space infrastructure is Kennedy Space Center (which still is an accomplishment) and a bunch of souviners scattered over Australia when Skylab came crashing down. Oh, and I can't forget the 5 space shuttles. Wow! What a marvelous space infrastructure to really go places!
Re:All this effort may be wasted (Score:2)
I was just talking with a family member from El Salvador about this very topic. The US should be happy that the most exciting piece of news is Bill Clinton's sex habits.
Meanwhile, elsewhere, people are starving. Really starving, not being comparatively well-fed US homeless.
If wishes were horses (Re:When you consider) (Score:2)
If you're going to wish for a new technology to be "flawless and is able to be implemented in a cost effective manner" without going through the intermediate research steps, then also wish for a pony.
One makes as much about sense as the other.
Sorry if this sounds like a flame, but it's important to make the point: Ya gotta invest in the research to get the final product. (And, typically learn a whole lot on the way, giving rise to new technologies undreamt of earlier.)
NASA gets around half a percent of the US Federal budget. We need more research like this, and some of the most promising ideas need to be tested as part of the Deep Space series of engineering test beds. I'd rather have my tax money used for these purposes than the usual government boondoggles.
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Re:All this effort may be wasted (Score:2)
One major problem with space colonies is artificial gravity. Without gravity the human body deteriates, the bones reject calcium and become very brittle and muscles attriphy. Sure we can simulate gravity by creating angular velocity to cause the frame that one would be on to experience centrifugal and centripetal forces but right now that is quite the pipe dream.
Think not? Well look at the rate the ISS is going up, and the design of the thing. Not to mention its expected life span, if everything went up on time, is 5 years! Sure we have the technology, and the money but unfortunately the people are unwilling, uninformed, apathetic, or just stupid. Not to mention, at this point all of the money that is going towards a big space project is going towards the ISS.
I would love it if the government were to support more scientific research, and huge engineering projects like building space colonies. Unfortunately the government doesn't seem too interested in what could be created from that. They seem to have forgotten that Tang wasn't the only thing that came from the space program. Microprocessors and certain plastics are just two major advances that came from the Apollo program alone.
That and the fact that the people are too interested in scandels and eye candy issues to notice the importance of science, or they fear it. Don't forget that last year the Kansas school board banning the teaching of evolution as truth.
The US is a great country, but it has some fundamental flaws that need to be overcome before we can truely do what needs to be done.
By the way, Washington DC still has one of the highest, if not the highest, murder rates in the US. Funny thing though, unless you given specific permission by the government it is illegal to own or have a firearm in DC. Also, NY has a very high murder rate and they banned handguns and made it a pain in the *** to own a firearm..
Oh, a good place to look, and contribute if you really feel that space travel and colonization is as important as I think it is is the Mars Society. www.marssociety.org. At a recent speech of theirs that I went to they were discussing a private attempt to fund a manned trip to Mars. Cool stuff.
Back to the blackboard! (Score:3)
d = (at^2)/2
t = sqrt(2d/a)
a = 2d/t^2
d = 2.8 x 10^10 m (halfway)
t = 45 days (halfway)
t = 45*24*60*60 s
t = 3.8 x 10^6 s
t^2 = 1.5 x 10^13 s^2
a = 2.8 x 10^10 m / 1.5 x 10^13 s^2
a = 0.004 m/s^2
or roughly 0.0004 g, with your assumptions.
At 1.3*g, it would take about two days.
Re:All this effort may be wasted (Score:2)
Of course, now London alone has a population greater than that.
The problem is that this sort of thinking doesn't properly account for the march of technology. Higher agricultural yields, among other advances, have allowed the population of the UK and indeed the entire planet to bloom over the last few centuries, and while there are obvious problems to deal with & I'm not disregarding those problems, the problem isn't nearly as bad as Malthus expected it would be. Not by a long shot.
I agree with this poster's point, but not his rationale. We *do* need to explore space, but not because the onlysalvation for earth is by terraforming other planets. That sounds like a worthy & ambitious goal, but one that would be centuries at best to realize. We need something a little more immediate than that go get people motivated.
No, the real reason we need to get out into space and onto Mars is because exploration of new areas has been one of the biggest engines of development over the last 500 years or so. Consider for example the famed American Frontiersman, the men & women that went out into the west and had to use their ingenuity & determination to survive & build a new nation. This character takes every form from Lewis & Clark and Davy Crockett to the gold prospectors & modern day Silicon Valley entrepreneurs -- all of whom went out on the edge of society -- literally -- to find their fortune and build a new world.
This is the sort of thing we need to be encouraging. Consider that, for the most part, the old world was stagnating 500 years ago (Renaissance notwithstanding), and the exploration & settlement of the Americas & Far East, with the accompanying cross pollination of cultures, technologies, and resources, as well as the explorers need to innovate to persist, brought about greater advances in the span of a few hundred years than was seen over the course of the previous couple of thousand.
This is the sort of advance that I think space exploration -- specifically but not exclusively of Mars -- can bring. The propulsion technologies that cna get us there are only the tip of a very large iceberg, and no one alive today can really grasp what a few decades of living out in space will bring. Consider that the settlers are going to have to find creative ways of supporting themselves in a land with no plant or animal life, very little water or oxygen, limited direct human contact, etc. Their one big asset will be their brains, and I can't wait to see what those pioneers will come up with.
Apply that to the old Malthusian argument. It isn't the physical space that another continent or so worth of land is going to provide that will make room for further comfortable population blooming. It's going to be the way we taught ourselves to live on almost nothing out in space, knowledge that will surely make its way back home, that is going to be the protector of future generations. And it won't take centuries to achieve -- just a few years out on our own...
Personally, I'm still hoping to be one of the first to go :)
________________________
Ho hum. Since I've gone this far, I might as well mention the Mars Direct Plan [nw.net], which can get us there now with current non-exotic technology, on an affordable budget, quickly and safely. The plan is well thought out and fully executable -- all we need is the will to do so. If government (NASA) won't help, then perhaps private concerns can guide us to the stars. Any takers?
This thing is gonna be NOISY (Score:2)
What an interesting way to be able to track a space craft! presumably you would be able to tell how well the engine is running by 'listening' to the 'sounds' it makes?
How cool!
Re:Dont forget the nuclear core to power it. (Score:2)
Has there been any research done on this? Is it even remotely feasible?
Another poster mentioned that the gyroscopic forces would make maneuvering difficult (i.e. impossible,) but maybe it would still be suitable for interstellar trips, which might spend more time travelling straight?
Re:Clearing a few things up... (Score:2)
The Ion Engine uses an electric current or catalyst to strip one or more valence electrons from a high-Z gaseous element such as xenon or argon. These electrically charged atoms, ions, are still relatively cold. All that's left to do is accelerate them in the direction opposite to the direction of thrust you need. This is accomplished using the electrical potential of a high-voltage cathode grid. A steady stream of cold ions emerge, and Newton's second law does the rest. The challenges are primarily ones of building large scale high voltage "tubes" and getting the ions to accelerate past the grid instead of just glomming onto it.
In the Plasma Engine, heat is used to excite the gas until thermal collisions strip the electrons from a low-Z gas such as hydrogen, thereby creating a neutral cloud of plasma made up of free electrons and protons. This gas is sent to a second stage where it is inductively heated by magnetic fields (the microwave oven analogy, except using magnets instead of klystron tubes as the "heating" element). The high temperatures created here results in high nozzle pressures (remember PV=nRT?), which causes the plasma to blow out of the hole in the end of the rocket, similar to the way hot gases blow out of the ass end of the familiar chemical rocket. But in the case of the Plasma engine, the nozzle is a third magnetic field. The technical difficulties here are to build high-strength custom magnetic fields, contain the very hot plasmas, and manipulate the plasma, not to mention the immense amount of electric power needed. (Others have already addressed that issue.) Also, the potential for catastrophic failure modes is much greater.
Hmm, I wonder if one could operate a fusion reactor, create all the energy you need to run the plasma engine, plus use the byproduct, helium, as your reaction mass. (But we haven't achieved sustained fusion yet..)
Yes! (Score:2)
Lenny
Re:All this effort may be wasted (Score:2)
Point about matter/energy conversion. (Score:2)
True. They cycle...
A simplistic example is water. When you use it up, it cycles back around and is regenerated.
Not true. They don't all recycle. They go from the state of matter to energy. For example, we incinerate many thousands of millions of tons of household and industrial waste every year - leaving some ash to sprinkle on a road and heat.
We don't yet have the ability to convert energy (heat or any other kind) into matter.
We have to get more raw materials.
Re:A Case For Mars (Score:2)
I'm just saying that I'd rather see something - anything sustained rather than another flash in the pan. (No matter how brilliant that flash might be.)
Military Applications (Score:2)
Let's start the cold war all over again. Come on, it'll be fun.
My mom is not a Karma whore!
Re:Huzzah and kudos to NASA! (Score:2)
Re:How long... (Score:2)
Re:heat (Score:2)
Of course, that's what the TV guy said.... but it's believable. A plasma is not that thin.. plasma at densities necessary to generate the required thrust would be rather high-energy one way or the other.
Re:heat (Score:2)
It has the ability to not store heat energy at all. It doesn't like to heat up, and cools instantly. It radiates heat away as fast as it comes in.
"heat energy" is not a 'thing' to be reflected.. it is just a measure of the amount of particle activity in a given closed system.
Re:heat (Score:2)
A hydrogen plasma is basically a proton cloud... and the magnetic field would push things in the appropriate direction.
Hmm. I wonder if they put the swarming electron cloud to use as well..... like tokemak (sp?) reactor..
Re:What about launch from lunar orbit? (Score:2)
It is signifantly easier to bring material back to earth than it is to put it up into space....
What is out there that we could concievably use? Moon base sounds great to me.
Re:Second Post! (Score:2)
Re:Some questions (Score:2)
One is those plasma globes.. you know,I'm not entirely sure. There could be a small amount of plasma there.. I believe there is even.. that's what those ribbons are. They are extremely thin though.
Second.. is temperature. Temperature by itself is not a meaningful number... total heat energy is what is important.. temperature is just a measurement of 'heat density' (sort of).
In other words, if I drop a 500 degree red-hot horseshoe into your cold bathtub.. you'll still have a cold bathtub.... but if I drop a 45 degree 1 ton weight into your bathtub (so to speak) you will find a market increase in the water temperature.
The ribbons in your plasma globe may be at 50,000 degrees.. but there are so few of them that the average temperature inside the globe is still basically room temperature, which translates in to even less energy than the air in the room, as the globe contains trace amounts of gas (it's partial vacuum, rarified rare gas..)
Re:An even faster propulsion system (Score:2)
as far as I can recall, we have yet to produce anything but infinitesmal quantities of anti-particles, and those are wiped out instantly. WE have yet to even be able to create any of note, let alone isolate and contain them.
Certainly, they *could* be contained within some kind of magnetic field or something.. but sheesh.
Believe me.. if they had the ability to actually 'store' antimatter in any kind of quantity, someone would have one *HELL* of a bomb on their hand. It would meak nukes look like firecrackers.
Re:Cut time? Or increase time? (Score:2)
Yours is the rationale behind NASA not using aereospike technology: nobody ever flew an aircraft using it. Too bad it's simpler, more efficient and cost effective than nozzle rockets we use today. At last they are using it for X33, but it was a private corp idea, that (the new) NASA selected because it was more innovative than the other 2 projects.
Another really funny example: Mars Polar lander used the 'old trusted rocket technology" to brake in the martian atmosphere, instead of the exotic aereobrake and ballons the previous lander used. We all saw how old technology was better than the new one in that case... (SPLAT!)
To summarize: Keep it Simple. If the new technology is simpler that the old, it's probably more secure.
Ciao,
Rob!
Re:Einstein? (Score:2)
I was simply trying to explain some the problems of reaching light speed in terms the layman could understand. With that goal in mind, everything you mentioned concerning relative dimensions fits under what I described as "other hard math problems". :)
Re:All this effort may be wasted (Score:2)
Your numbers seem quite reasonable, but you're assuming that we're talking about two centres of population; Earth and Somewhere Else. In our solar system colonies on Mars, Titan and Europa will some day (however far into the distance) will be possible, and I don't think it's unreasonable to assume that within the next five or six decades we'll be able to 'see' extrasolar, Earthlike(ish) planets. We're hundreds of years away from generation ships, but I'm not prepared to say they won't happen.
The point is that the Earth is very very complex.
Absolutely. And even if Mars is totally dead (which it most likely is), its weather is sufficiently complex that it will never be taken for granted. But what we're initially looking at isn't an entire earthlike biosphere with trillions of species, but an atmosphere that will be made denser over a couple of hundred years. The flora and fauna will be added gradually, and evolution'll ultimately finish the job.
I believe that they are just as deserving as I am. And if the universe agrees with me, they will get what I think they deserve.
As a father, you may think that your offspring are entitled to a long and successful life, but if you lock them in the closet until they're 18 and then expect them to become CEO of a Fortune 500 company then you're sorely misguided.
More than ever before, our descendents' quality of life is affected by decisions -- long and short term -- that we make today.
Thanks... (Score:2)
Thanks for the reference meloneg!