Robert Zubrin: the importance of space for mankind.

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Oodain
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09 Jan 2012, 4:31 pm

iamnotaparakeet wrote:

Oodain wrote:

mars is a far cry from interstellar travel but in that scope a nuclear thermal rocket of any kind would be desirable to purely chemical rockets,
that or ion engines but the true issue will always be liftoff from earth, when in space very little is required.

Chemical rockets are proven technology though, and having a six month one way travel time for a conjunction class interplanetary transfer is not too long a time for transit. Having nuclear thermal rockets, as per Asimov's The Martian Way may indeed sound cool, but why not stick to what works when we're first starting out, and then develop yet more later - especially on Mars and away from the smothering bureaucracies of Earth.

its old tech, mainly abandoned due to political reasons,

but even ion engines will be a lot faster than chemical rockets outside the atmosphere.

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iamnotaparakeet
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09 Jan 2012, 4:36 pm

Oodain wrote:

iamnotaparakeet wrote:

Oodain wrote:

its old tech, mainly abandoned due to political reasons,

but even ion engines will be a lot faster than chemical rockets outside the atmosphere.

Ion engines and other technologies which have high exhaust velocity and yet low fuel exhausted per time have the potential for having a high final velocity, but the time it takes to accelerate is extreme. By the time it's managed to outpace a chemical rocket system's initial velocity, the chemical rocket system's payload will have already landed. If you have a chemical system with an ion system tacked on, it could give a little extra velocity, but I think it would be more weight than it's worth. If you could have a system with high fuel exhausted per time as well as high exhaust velocity, that would be pretty good.

Oodain
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09 Jan 2012, 4:59 pm

the VASIMR ion tug will be able to reach mars in 39 days, the intiial engine tests are being done on the iss where they will replace the altitude thrusters currently in use.

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iamnotaparakeet
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09 Jan 2012, 5:08 pm

Oodain wrote:

the VASIMR ion tug will be able to reach mars in 39 days, the intiial engine tests are being done on the iss where they will replace the altitude thrusters currently in use.

That is actually a pretty good travel time. If the numbers in the Transorbital Railroad lecture are correct though, then it would cost 1.25 billion, a fourth of the shuttle's previous cost, to send 15 capsules to Mars, with various payloads, per year. How many VASIMR ships would travel per year for that annual price?

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09 Jan 2012, 5:15 pm

They should use proven chemical rocket technology to get the materials [the return vehicle, a microfactory that produces rocket fuel and other necessities from Martian resources, the habitat, construction vehicles, nuclear power generators, etc] required beforehand there long before Humans set foot. As stated by Zubrin in his Mars Direct plan there would be several launches in the years leading to the Human mission, which I feel should opt for the VASIMIR so as to limit the time in interplanetary space for the actual astronauts. But when it comes to just sending materials there the expense of a VASIMIR system is not really worth it. The whole premise behind Mars Direct is an immediate launch utilizing proven technology at minimum of cost and risk. Each launch would contribute to a permanent Human presence as the factories and habitats will still be active after the explorers leave. This will eventually mean that Mars will have a network of stations and back up stations with return vehicles linked by simple roads cleared of rocks that could be built by remotely controlled robots. Much work will be needed to be done remotely in this manner, to limit radiation exposure for people working there. At least until better suits are developed or early efforts to thicken the atmosphere prove successful

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Oodain
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09 Jan 2012, 5:24 pm

iamnotaparakeet wrote:

Oodain wrote:

the VASIMR ion tug will be able to reach mars in 39 days, the intiial engine tests are being done on the iss where they will replace the altitude thrusters currently in use.

dunno but the fuel cost is vastly reduced and the engines themselves are far more mechanically reliable than chemical engines.
only downside in my eye is the inability to ever achieve liftoff from earth or mars, chemical rockets would have to do there.

as vigilans said materials are not time sensitive so if they are sent ahead they could be sent using the absolute cheapest method,
i imagine large bulk ships coupled together in orbit with an ion engine, the acceleration time would be no issue since there would be no humans aboard.

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09 Jan 2012, 5:56 pm

Vigilans wrote:

That might actually be a pretty good idea, although more and more it's sounding like Red Mars. Well, except their ship was conventionally propelled. The using of cheaper systems to deploy supplies and equipment prior to a human mission was there already though. A good idea is a good idea though.

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09 Jan 2012, 7:17 pm

The only way to get to Mars is with a single launch that gets us there before the funding is cut.

Oodain
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09 Jan 2012, 8:09 pm

russia plans to have the first comercial space station up in 5 years
there are plenty of private competitors who are just now starting to get a foothold,
cutting the funding will only slow things down, not stop them.

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10 Jan 2012, 2:26 am

Oodain wrote:

That's rather cool, a miniature space race between private Russian and American space companies.

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10 Jan 2012, 7:06 am

Oodain wrote:

they already are,

radioactive materials are handled by everyone from medical proffesionals to companies making smoke detectors and watches.

for something as controlled as a space launch i dont see why that should be a problem.

Of one of Zubins Salt Water Rockets blew up on the launch pad (something that has been known to happen) it could contaminate an area of hundreds of square miles. The Zubin rocket is not safe to launch from the ground. If it is going to be built and used, then Zubin-ships will have to be constructed and deployed from orbit. I read up on the idea and it is as clever as the dickens, but it is just to dangerous to be used on the ground. You are aware, I assume, that plutonium even when it does not fission is probably one of the most poisonous substances ever created. A small speck can kill.

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10 Jan 2012, 11:18 am

ruveyn wrote:

Oodain wrote:

Zubrin's aerospace company makes patents on loads of technologies and if I remember correctly the only reason why the NSWR was brought up was due to androbot2084's marketing style gibberish about "darkloards of attooomic poooooooweeeeer!". But to consider this seriously though, if Dr. Zubrin's NSWR is ever to be made, it would probably be best to be built in orbit of Pluto anyway. Also, in the wikipedia article, U235 could be used just as well as plutonium and it would probably be better to use simply due to the chemical toxicity you referred to.

Oodain
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10 Jan 2012, 1:30 pm

all true,

there are some radioactive gasses that can be used as well,

though to be honest i am not sold on any one method for interplanetary travel,

its liftoff thats important and the only way to make that seriosuly cheap would be a linear accelerator or renewable rocket fuel.

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iamnotaparakeet
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10 Jan 2012, 1:39 pm

Oodain wrote:

Build the ship in orbit, launching cargo and other stuff that wouldn't be damaged by extreme acceleration using electromagnetic accelerator cannons, and launching everything else and personnel using chemical rockets like SpaceX's Falcons. Apart from Kepler 22b, we don't even know too many possibly habitable planets (such that they aren't, for certain, a gas giant, and that they are within the habitable zone of their host star), so we need to know for certain the destination prior to the construction of such ships. For now, we should focus on Mars, the Earth's moon, and the moons of the gas giants of our own solar system.

Oodain
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10 Jan 2012, 1:41 pm

i used interplanetary for a reason :wink:

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10 Jan 2012, 1:43 pm

We should only focus on interstellar space travel because it forces the advancement in technology.

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