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Thread: Earth to Mars in 39 Days?

  1. #1 Earth to Mars in 39 Days? 
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    A six-month space journey away, Mars often seems an almost impossible planet to reach. But engineers are developing a new engine that could turn six months to six weeks, bringing the Red Planet much, much closer than ever before.

    Engineers at the Ad Astra are seeing promise in VASIMR, an ion engine that uses a radio frequency generator to heat charged particles and create greater thrust than other similar engines. Ad Astra plans to attach a solar-powered VASIMR engine to the International Space Station for tests, and, if they are successful, could use VASIMR periodically to thrust the ISS back into the Earth's orbit.

    But, if the engine were powered by an onboard nuclear reactor, its applications could be much more profound. Using 1000 times the energy of a solar-powered VASIMR, a nuclear-powered VASIMR engine could propel a manned spacecraft to Mars in a mere 39 days. Although the technology to play a nuclear reactor on a space shuttle is still a ways off, many in astrophysics feel the project holds enormous promise. NASA has provided Ad Astra with a small stipend for VASIMR development, and NASA chief Charles Bolden had high praise for the possibility of shortened space travel:


    http://io9.com/5323516/earth-to-mars-in-39-days


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  3. #2  
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    Really neat.

    Getting to Mars in less than a couple months would make such a trip much more feasible. Logistics, psychological health of the crew, bone calcium loss exposure to solar flare risk all go down.


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  4. #3  
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    I wonder what else this tech will help us do. Would it make the trip from low Earth Orbit to the Moon easier as well?
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    It would be ridiculously quick. But that is hardly the target - the Gas Giants would all be one HELL of a lot closer! We could really get to see what's under Europa's crust of ice very soon! And thoroughly exploring Titan wouldn't be far off either.
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  6. #5  
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    Don't get me wrong, these things are very cool, but it's difficult to imagine how they could get to mars in just six weeks when you look at the actual numbers for the thrust (which is about 5 N for each 200 kw engine).
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    Ever stop to think that what you accelerate you must also decelerate when you get there. so you will be accelerating half way there and solwing down the other half.
    Minor detail most wouldbe space travelers seem to miss!
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  8. #7  
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    Quote Originally Posted by fizzlooney
    Ever stop to think that what you accelerate you must also decelerate when you get there. so you will be accelerating half way there and solwing down the other half.
    Minor detail most wouldbe space travelers seem to miss!
    So traveling to Mars in forty days while Mars is at at its closest and accelerating halfway there decelerating the rest of the way would require an acceleration of 0.0262 m/sē or 0.00267g. You'd reach a top speed of somewhat over 45 km/sec,

    Assuming that your VASIMR has an Isp of 3000, you'd need a mass ratio of 20.5
    if it has an Isp of 30,000 the mass ratio drops to 1.35. Of course this is just one way. Assuming you want to return, the mass ratios change to 420 and 1.83
    "Men are apt to mistake the strength of their feelings for the strength of their argument.
    The heated mind resents the chill touch & relentless scrutiny of logic"-W.E. Gladstone


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  9. #8  
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    Quote Originally Posted by fizzlooney
    Ever stop to think that what you accelerate you must also decelerate when you get there. so you will be accelerating half way there and solwing down the other half.
    Minor detail most wouldbe space travelers seem to miss!
    You can use gravitational and atmospheric tricks for some of it. --- Probably not very helpful if you're going that fast I guess.
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    Good to grasp, adn it is feasible, we could do it the long way, I just think people are not that serious about going to mars, but they are serious about spying on us, thats sad, but it's a fact of life.
    the more science you know, the less crap you get.
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    Quote Originally Posted by kojax
    Quote Originally Posted by fizzlooney
    Ever stop to think that what you accelerate you must also decelerate when you get there. so you will be accelerating half way there and solwing down the other half.
    Minor detail most wouldbe space travelers seem to miss!
    You can use gravitational and atmospheric tricks for some of it. --- Probably not very helpful if you're going that fast I guess.
    Umm, We've aerobraked at least one Mars mission already so I think it's possible we might be able to use the atmosphere to do most of the work to slow down the ship(s).
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  12. #11  
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    Quote Originally Posted by Lynx_Fox
    Quote Originally Posted by kojax
    Quote Originally Posted by fizzlooney
    Ever stop to think that what you accelerate you must also decelerate when you get there. so you will be accelerating half way there and solwing down the other half.
    Minor detail most wouldbe space travelers seem to miss!
    You can use gravitational and atmospheric tricks for some of it. --- Probably not very helpful if you're going that fast I guess.
    Umm, We've aerobraked at least one Mars mission already so I think it's possible we might be able to use the atmosphere to do most of the work to slow down the ship(s).

    That aerobraking maneuver was to circularize an already existing orbit and required several passes though the atmosphere. Even then, it only shed a total of 1.2 km/sec.

    A spaceship approaching Mars will pick up 5 km/sec just from falling through Mars' gravity (that's not including the initial velocity difference). It will have to get down to 3 km/sec to have a chance of entering any kind of orbit. It would have to be done in one pass. (if you don't drop enough speed there won't be a second pass.)
    "Men are apt to mistake the strength of their feelings for the strength of their argument.
    The heated mind resents the chill touch & relentless scrutiny of logic"-W.E. Gladstone


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    This is pathetic, and enraging. Project Orion was the perfect solution to get us to Mars...over thirty goddamn years ago. By now we would have a successful colony on mars, manned or unmanned, because nuclear propulsion could get us there in mere weeks.

    Who do we have to thank for its termination? Why are we more than twenty years behind what could have been? You can thank bureaucracy! Not only does it make inter-planetary travel plausible, it makes interstellar travel plausible. Hell, with properly outfitted devices, interstellar communication would even be doable by way of amplification "buoys" throughout space. On an even bigger plus side, project Orion would have been magnitudes cheaper (hilariously the "reusable" vehicles we have now cost more than the throwaways NASA once used).

    No matter what the application, Project Orion was what would have propelled us to a space faring race. I'm so disgusted with humanity it makes me sick. If we really cared about going to mars we would have been there forty years ago!
    Om mani padme hum

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    how often does a space shuttle explode in our atmosphere, Darius?
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    How is that relevant? Playing coy hardly suits a forum discussion. So far all explosions have been the result of terribly poor management, and the successful launch of an Orion craft would be relatively easy. Remember, each accident (so far) has been the cause of management giving the go-ahead when engineers go "um, there's a problem"

    On top of this, the design of Orion-class vehicles would be remarkably different from the design of a modern "reusable" one. Being more the size of a small city, the chances for something to go wrong would have to be zero (none of this "Go ahead anyway" bullshit).
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    wow. and in the event of an accident... what then? what would happen to the continent it lifted off from?
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    Nuclear weapons used for this purpose aren't even a thousandth that powerful. Stop buying into the hollywood generated image that a nuclear weapon can end all life. Even a 50 kiloton bomb, or even a 100 kiloton bomb, ejects the grand majority of its energy out into space, leaving very little of it (as a percentage) to do actual damage. The burning up of an Orion craft doesn't necessarily mean a triggering of nuclear detonations, either, given how modern nukes are designed. If that even would be a problem (it isn't), special designs could be taken into account to disable them.

    By all accounts, launching and traveling by this method is safer and cheaper.
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    No, I just read the page, it made claim that the payload overall would be approximately the equivalent of a bomb rated at 10megations... and the issue is when it explodes in the upper atmosphere, and we have a neutron bomb on our hands...

    But also consider if they all went at the same time, all those massive number of warheads. the fallout would be multiplied if the bomb cores were forced together, it would create a larger bomb.
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  19. #18  
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    Yeaaah...my advice is to stop watching so much TV.
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  20. #19  
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    and spend more time on internet forums ?
    "Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
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  21. #20  
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    Given my leave of absence from this special hell, I don't believe that applies to me in any way whatsoever.
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    Quote Originally Posted by Darius
    Yeaaah...my advice is to stop watching so much TV.
    and my advice is to learn some of the physics behind it, possibly read about it, before you spout bullshit. I read the wiki, and repeated the information on it. here, the page on the neutron bomb, outlining the effect that the Drive you speak of is specifically designed to do... Please, learn to think before you speak Darius.
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  23. #22  
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    I wasn't suggesting you stop reading, I was suggesting you stop grasping at straws for Hollywood-Esq scenarios. No such explosion would be possible.
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    Quote Originally Posted by Arcane_Mathematician
    wow. and in the event of an accident... what then? what would happen to the continent it lifted off from?
    We aren't talking about fireworks or sticks of dynamite here. Nuclear weapons don't all detonate when one goes off nearby. At worst, the ship would crash and break up. The nuclear bombs that act as fuel would be in containers sturdy enough to survive any possible crash without releasing radioactive materials.
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    Quote Originally Posted by Janus
    So traveling to Mars in forty days while Mars is at at its closest and accelerating halfway there decelerating the rest of the way would require an acceleration of 0.0262 m/sē or 0.00267g. You'd reach a top speed of somewhat over 45 km/sec,

    Assuming that your VASIMR has an Isp of 3000, you'd need a mass ratio of 20.5
    if it has an Isp of 30,000 the mass ratio drops to 1.35. Of course this is just one way. Assuming you want to return, the mass ratios change to 420 and 1.83
    The problem is that although the ISP is very high, the trust is so low it will probably take you longer than 45 days just to get up enough velocity to leave earth orbit.
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    What happens if one detonates prematurely? While it's still in a position with the others? I KNOW that a fission bomb placed next to another fission bomb will most DEFINITELY detonate when the first goes off. There's a lot that could, in all right, go wrong. One glimpse at our stellar record of shuttle launches would tell you that shit happens, and you have to plan for the shit that may happen.

    Nuclear fallout, though you may not care about it, is a disaster that, if it could be avoided, at this point, WILL be avoided, and with good reason. Testing nuclear weapons in the upper atmosphere is a horrible idea, for the reasons of the page I linked in my last post. The theories behind this Drive are okay, but the actual application is much trickier and has some issues, namely the radioactive fallout produced as it jettison's itself off the planet, something you can't just ignore. Every explosion would produce, in accordance with it's design, a massive abundance of neutrons that would rain down on the Earth until it leaves the atmosphere. The cone that these particles would fall in gets progressively wider, too, as the ship gets higher.

    As great as an interplanetary drive as it is, it's got massive drawbacks that won't allow it to come into being, and the 'bureaucracy', as you so nicely put it, saved as many as hundreds of millions, if not billions, of lives that would have surely been lost due to radioactive fallout and neutron-bomb effect during the test phases.
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    Quote Originally Posted by Arcane_Mathematician
    What happens if one detonates prematurely?
    People fly collections of nuclear weapons around in planes all the time, with little worry about them going off before they're meant to.
    While it's still in a position with the others? I KNOW that a fission bomb placed next to another fission bomb will most DEFINITELY detonate when the first goes off.
    Oh? How do you know that? I want a source on that claim, because it sounds like bullshit to me. It seems much more likely that the other bombs would simply break up without detonating. We're talking about very small nuclear bombs, so a premature detonation inside the ship probably wouldn't even vaporize everything. Instead, you would have broken pieces of ship raining down on the launch area. Scold your engineers, and then send work crews out to pick of the pieces.

    The theories behind this Drive are okay, but the actual application is much trickier and has some issues, namely the radioactive fallout produced as it jettison's itself off the planet, something you can't just ignore. Every explosion would produce, in accordance with it's design, a massive abundance of neutrons that would rain down on the Earth until it leaves the atmosphere. The cone that these particles would fall in gets progressively wider, too, as the ship gets higher.
    So far as I know, no one is planning to power these with neutron bombs. Yes, nuclear weapons produce some neutron radiation, but it wouldn't be the deadly radpocalypse that you seem to imagine. It's assumed that it will be launched from an uninhabited area.

    As great as an interplanetary drive as it is, it's got massive drawbacks that won't allow it to come into being, and the 'bureaucracy', as you so nicely put it...
    I never said anything about a 'bureaucracy'.
    ...saved as many as hundreds of millions, if not billions, of lives that would have surely been lost due to radioactive fallout and neutron-bomb effect during the test phases.
    I'm going to go out on a limb and guess that you don't know jack shit about how to calculate how dangerous the fallout would be based on bomb size, altitude, and type. You just have a vague "nuclear=scary" mentality.
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  28. #27  
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    Quote Originally Posted by Arcane_Mathematician
    What happens if one detonates prematurely? While it's still in a position with the others? I KNOW that a fission bomb placed next to another fission bomb will most DEFINITELY detonate when the first goes off. There's a lot that could, in all right, go wrong. One glimpse at our stellar record of shuttle launches would tell you that shit happens, and you have to plan for the shit that may happen.
    Terminator movies aside, causing Uranium to undergo a chain reaction isn't the same technical problem as setting off a keg of gunpowder. If I remember right, it is mostly about smashing two pieces of fissile material together with strong enough kinetic force. That part is simple, but there's no reason to expect that a nearby nuclear explosion would smash the two parts together in the right way to set them off.

    They'd probably undergo "predetonation" of some sort.

    Quote Originally Posted by http://en.wikipedia.org/wiki/Nuclear_chain_reaction

    Predetonation

    Detonation of a nuclear weapon involves bringing fissile material into its optimal supercritical state very rapidly. During part of this process, the assembly is supercritical, but not yet in an optimal state for a chain reaction. Free neutrons, in particular from spontaneous fissions, can cause the device to undergo a preliminary chain reaction that destroys the fissile material before it is ready to produce a large explosion, which is known as predetonation. To keep the probability of predetonation low, the duration of the non-optimal assembly period is minimized and fissile and other materials are used which have low spontaneous fission rates. In fact, the combination of materials has to be such that it is unlikely that there is even a single spontaneous fission during the period of supercritical assembly. In particular, the gun method cannot be used with plutonium
    The free neutrons from the nearby nuclear explosion would probably cause this effect to happen.

    Also, you need a critical mass of uranium/plutonium all in one place to get a chain reaction going. The nearby nuclear explosion would probably split up that mass, so it wasn't all in one place anymore.
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