The Thread For The Future Of Interstellar Propulsion

[GhostFaceSaint]

Please read this article posted July 22nd at New Scientist.com "Ion engine could one day power 39-day trips to Mars"

http://www.newscientist.com/article/dn17476-ion-engine-could-one-day-power-39day-trips-to-mars.html

Before we can even think about leaving to another solar system lightyears away we need to learn how to travel in our own solar system and the first stop is Mars. What will power are trip to Mars will probably power us to other local planets such as Venus, Jupiter, etc. What will our propulsion system look like? Will it be ion propulsion after all, and if it is; is it good enough to get us to Jupiter and beyond? What else is there available that could get us to Mars, is there something faster, or more endurable?

Please post available links to online articles addressing this topic, or, site magazines and books that have stated possible solutions to long distance interstellar travel.

Discuss.

 

[All Seeing Eye]

The future method of solar system travel will be a rail line on the moon.

It will be one huge looped magnetic rail line which will speed up a space vessel to enormous velocities and then release the vessel beyond the moons gravitational pull.
The space vessel will have on board fuel to be used to slow the vessel down as it approaches its destination such as Mars.

When it comes to the vessel returning to Earth, there will be a fuel tank in orbit around Mars which will have been sent there previously by normal methods of propulsion.
This is because the fuel tank doesn't have to get to Mars quickly because there are no people on board so the fuel tank can be sent earlier before the manned mission.

The manned mission will utilise the moon based rail system to get to Mars quickly because people are on board so the quicker the journey to Mars the better.

The return journey will be made by conventional means as there will be no rail line based system at Mars.

 

[Urge]

Could it be that some of the heat, or most of the heat produced by this system (the VASIMR system) could be turned into electricity again, and then re-used in order to help the main nuclear powerplant running longer?

Its a lot of heating going on in this system, and by making water boil close to the exhaust-pipe of the engine, where the superheated plasma exit (It would produce a lot of heat-radiation, wont it?) it can run a turbin. Perhaps even a internal cooling-system can be used to produce some extra electricity. If forexample the chamber where the argon-gas is heated needs some extra cooling, the colant-aid that is pushed around by the heat can run a dynamo as well, if it proves impossible to contain the heat completly within the chamber offcourse.

That way, the engine might be able to run longer on less uranium.

Beside that, its cool that something is happening in this field. But even a conventional ion-drive would be highly effective with a nuclear powersupply, wont it?

 

[Peter the Younger]

Beside that, its cool that something is happening in this field. But even a conventional ion-drive would be highly effective with a nuclear powersupply, wont it?

It would, but not 39 days to Mars good. Most of the estimates I've seen for Hall thrusters (the sort we used on DS1 and Dawn, I believe) come out to eight weeks one way, assuming optimal planetary alignment. That's do-able of course, but a more powerful engine like VASIMR would really open up the inner solar system to humanity.

I hope Dr. Diaz succeeds. He's been working on this thing for years.

 

[GhostFaceSaint]

Beside that, its cool that something is happening in this field. But even a conventional ion-drive would be highly effective with a nuclear powersupply, wont it?

It would, but not 39 days to Mars good. Most of the estimates I've seen for Hall thrusters (the sort we used on DS1 and Dawn, I believe) come out to eight weeks one way, assuming optimal planetary alignment. That's do-able of course, but a more powerful engine like VASIMR would really open up the inner solar system to humanity.

I hope Dr. Diaz succeeds. He's been working on this thing for years.

I am with you in hoping for Diaz to succeed because we could easily go to other planets in our solar system only a few years apart, instead of waiting another fifty years to leave the Earth we could visit Mars one year, then a year or two later visit the moons around Jupiter, or around Venus, and then beyond!

 

[Urge]

If on could reach March in eight weeks with a nuclear-powered Ion-drive, then that should work just fine, wouldnt it? It seems to me like sceptisism about launching a nuclear-powerplant into space hinders space exploration a bit. It shouldnt be that risky if its sendt up in different peaces. But then offcourse, if this new VASIMR technology might work, its good to wait annyway. The best thing would offcourse be if the scientists managed to fusion-power working together with VASIMR.

 

[Peter the Younger]

If on could reach March in eight weeks with a nuclear-powered Ion-drive, then that should work just fine, wouldnt it? It seems to me like sceptisism about launching a nuclear-powerplant into space hinders space exploration a bit. It shouldnt be that risky if its sendt up in different peaces. But then offcourse, if this new VASIMR technology might work, its good to wait annyway. The best thing would offcourse be if the scientists managed to fusion-power working together with VASIMR.

There have been protests the last couple of times we've launched an RTG powered probe, but they haven't stopped a single launch, and really the dangers they describe are incredibly improbable. We've sent up dozens of spacecraft carrying radioactive material, there's no reason to believe a full-on fission reactor would be any more dangerous (I mean, unless you fire it up while you're on the ground, but why would you do that?)

Also, you're quite right; once you get beyond Mars, the power from solar cells drops of precipitously. If we don't have reactors powering our spacecraft, we can forget about exploring the outer solar system or harvesting the asteroids.

 

[Meredith]

A good prototype would be an Earth-Moon cargo shuttle powered by a VASIMR engine with electricity supplied by Solar arrays. It would rendezvous with probes parked in medium earth orbit and slowly move them into lunar orbit and then it would make it back to earth and pick up more probes or supplies.

 

[skep155]

Im excitedly waiting for the results of the Kepler Mission and other planet finding missions to return. You can bet that if we find an earth sized planet orbiting within the habitable zone of one of the Alpha Centauri stars there will be a big rally to send a probe there. If the programme had lots and lots of money then given a few decades im pretty confident we could build something that could get up to 10-12% the speed of light. That would give us a 40 year journey. Bussard Ramjet, Nuclear Pulse Propulsion, Solar Sail/Starwisp etc, we just need to find the most feesible one.

 

[John O.]

A good prototype would be an Earth-Moon cargo shuttle powered by a VASIMR engine with electricity supplied by Solar arrays. It would rendezvous with probes parked in medium earth orbit and slowly move them into lunar orbit and then it would make it back to earth and pick up more probes or supplies.

The only problem is that the VASIMIR engine has models pulling 50, 100 and 200 kW. 200 kW is a heck of a lot of power to get out of a solar array. With increasing efficiencies it's certainly possible but they'd still be humongous arrays. I'm not sure it's feasible for a craft that does a lot of maneuvering. Even with significant increases in efficiency, that's about 2 and a half times the power output of the ISS array, so it'd probably be comparable in size to that.

Beside that, its cool that something is happening in this field. But even a conventional ion-drive would be highly effective with a nuclear powersupply, wont it?

It would, but not 39 days to Mars good. Most of the estimates I've seen for Hall thrusters (the sort we used on DS1 and Dawn, I believe) come out to eight weeks one way, assuming optimal planetary alignment. That's do-able of course, but a more powerful engine like VASIMR would really open up the inner solar system to humanity.

I hope Dr. Diaz succeeds. He's been working on this thing for years.

I've seen some of the white papers on VASIMIR and I have a hard time believing these sensational claims - I mean the thrust is like orders of magnitude higher than conventional electric propulsion engines (ion, hall, MPD) but it's still about 5 N... and the device is extremely complex. I think the biggest breakthrough associated with and attributable to VASIMIR is the popularization of the idea of the helicon excitation mode for ion production in a low pressure plasma. There are other, simpler, more versatile applications of the concept currently in development, though.

 

[sojourner]

Space Zombies!!!!!!


BRaaaiinnns!

 

[Bill Morris]

A physicist who actually worked for Westinghouse on a long-since-canceled project for nuclear rockets mentioned that a fusion rocket would create 10 million times as much energy per particle used in thrust than the best chemical rockets.

When accelerating at 1 G, a vehicle's speed increases to 79,000 mph in one hour, 1.9 million mph in one day, and .5 c in about six months. You couldn't do that with a chemical rocket, because most of your fuel is used up carrying fuel. With fusion, there's a chance, even though it might take more propellent than you could scoop up with Bussard ramscoops, but adding ion propulsion to the contraption would rein that issue in, as well. Funding for such a thing? Ha!

And for getting to the next star engineers probably wouldn't want to try for that much speed but maybe .2 c or so and coasting most of the way, which is okay for a robotic mission expected to take several decades (to get there and pay for!).

But it means a manned mission to Mars could have artificial gravity at least for the part of the trip with constant acceleration, just not with chemical stinkboats. Fusion or maybe even positrons. Of course, scaling that back and taking more time to get there is cheaper.

And the polywell guys say that if that reactor works it could be configured as a fusion rocket. I don't know the details of that--how much power could be expected or even if it would require a dedicated propellent tank. It might just use its own fusion products in that scenario. I don't know.

 

[KJbushway]

Could there be some kind of Rail gun shooter on the moon for ships? Of course dampers for the crew is needed, but that can be achieved with todays tech. A nice catapult in the direction you want, and since you stay a constant speed you could become faster

 

[Bill Morris]

There have been some gravity-modification experiments going on. First the ESA finding:

http://www.prweb.com/releases/2006/03/prweb364473.htm

And it seems those results have since been replicated and that further research is going on in various labs around the world.

http://www.prweb.com/releases/2006/08/prweb424020.htm

http://blog.lib.umn.edu/daigl024/discussions/2008/01/update_on_esa_gravity_research.html

They say the effect is a hundred million trillion times higher than what GR predicts, even though the achieved practical effect is still too small to affect space travel at this early stage of such research.

But the idea is to be able to do for spacecraft what O'Brien did for Deep Space Nine to move it near the wormhole, which was to lower the inertial mass with a static warp field so that thrusters could easily move it. I assume that's what they have in mind for spacecraft as an ultimate goal.

So, short of creating a static warp field, but getting ahead of current state of the art, I'm just wondering if some scheme llke setting up a centrifuge consisting of a superconducting, pressurized plasma of some heavy metal within a spacecraft could have sufficient effect on the inertial mass of the entire vessel to make it easier for its propulsion system to move the craft. The folks already working in this area perhaps have similar and probably better ideas on that.

It's like a modern-day version of inventing the wheel to make it easier to move things by rolling rather than dragging.

 

[sojourner]

^I am guessing that the problem with this idea is that the mass of the power generator you would need would out pace the reduction in mass provided by the device. A problem you don't have on ground based experiments where the power generation is most likely outside of the loop.

 

[Bill Morris]

Which highlights the need for antimatter if it comes down to that. What (at
least I) don't know is if reducing inertial mass by 90% would enable FTL with antimatter fuel. If the lightspeed limit is tantamount to just bucking wind resistance (of an all-penetrating kind), then mass reduction might be hoped to be a game changer. This notion kind of borders on Trek tech. But even it only for planet-hoping and asteroid mining, net reduction of mass sounds very attractive.

And I still think that positrons are just as good as antiprotons for use as antimatter fuel. They're both messy and require pointing gamma radiation away from the crew, as well as development of magnetic storage bottles, but offer the same power-to-weight ratio, while positrons are much easier to produce and use, not that I would suggest using antimatter to reach orbit.

 

[John O.]

Which highlights the need for antimatter if it comes down to that. What (at
least I) don't know is if reducing inertial mass by 90% would enable FTL with antimatter fuel. If the lightspeed limit is tantamount to just bucking wind resistance (of an all-penetrating kind), then mass reduction might be hoped to be a game changer. This notion kind of borders on Trek tech. But even it only for planet-hoping and asteroid mining, net reduction of mass sounds very attractive.

And I still think that positrons are just as good as antiprotons for use as antimatter fuel. They're both messy and require pointing gamma radiation away from the crew, as well as development of magnetic storage bottles, but offer the same power-to-weight ratio, while positrons are much easier to produce and use, not that I would suggest using antimatter to reach orbit.

I hesitate to answer anything in the realm of relativity and QM with a strict, "no that wouldn't work", but 'no' in terms of the way the light speed issue is understood - reducing inertial mass with some sort of quantum field or something wouldn't allow you to go superluminal if you're talking about a finite reduction. If by some really bizarre technology you could actually reduce your inertial mass to zero, then I'm tempted to say yes, you could. Any finite mass object, though, cannot be accelerated to beyond the velocity of light.

A physicist who actually worked for Westinghouse on a long-since-canceled project for nuclear rockets mentioned that a fusion rocket would create 10 million times as much energy per particle used in thrust than the best chemical rockets.

When accelerating at 1 G, a vehicle's speed increases to 79,000 mph in one hour, 1.9 million mph in one day, and .5 c in about six months. You couldn't do that with a chemical rocket, because most of your fuel is used up carrying fuel. With fusion, there's a chance, even though it might take more propellent than you could scoop up with Bussard ramscoops, but adding ion propulsion to the contraption would rein that issue in, as well. Funding for such a thing? Ha!

And for getting to the next star engineers probably wouldn't want to try for that much speed but maybe .2 c or so and coasting most of the way, which is okay for a robotic mission expected to take several decades (to get there and pay for!).

But it means a manned mission to Mars could have artificial gravity at least for the part of the trip with constant acceleration, just not with chemical stinkboats. Fusion or maybe even positrons. Of course, scaling that back and taking more time to get there is cheaper.

And the polywell guys say that if that reactor works it could be configured as a fusion rocket. I don't know the details of that--how much power could be expected or even if it would require a dedicated propellent tank. It might just use its own fusion products in that scenario. I don't know.

All of this is certainly true... it's just that, those declarations - about energy per particle and available power, etc - in terms of progress towards the final product of a working spacecraft with an engine that works, and is safe, and reliable, and understood well enough that we're willing to put people on it - it's a wide gap. The amount of comprehension towards the final product that it takes to know that fusion or nuclear rockets would produce a lot more power than chemical rockets, is akin to how close to the final product of an Intel core i7 processor that it was when some mathematician at Bell Labs in like 1962 did some theoretical calculations for how many computations per second you could do "IF" you could get 200 million transistors on one chip. It's a thought experiment, really. The nitty gritty details like - if you're injecting hydrogen gas into a combustion chamber where a fission or fusion reaction is going to superheat it so u get awesome rocket performance (a nuclear thermal rocket), how do you keep the injectors from corroding and breaking up if the temperature of the gas mixture at the injector surface is, oh say, 50,000 kelvin - when rocket engines today even only see temperatures upwards of 2,000-4,000 Kelvin? Even ion engines only see temps on their nozzles around 20,000 K. There are probably 3 dozen fundamental technological issues like that to be resolved before a nuclear thermal rocket or a fusion rocket is a viable potential vehicle - and then like hundreds of other more minor issues. It sucks engineering's sloooooooooow work.