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Fraser
2004-Oct-14, 05:54 PM
SUMMARY: Researchers from the University of Washington have been funded by NASA to develop a magnetized-beam plasma propulsion system (or mag-beam). Selected as part of NASA's recent Advanced Concepts study, the system would involve a space-based satellite that would fire a stream of magnetized ions at a spacecraft equipped with a magnetic sail. The researchers think they could get a spacecraft going fast enough that it could make a round trip to Mars in 90 days, as long as there was another station at Mars that could slow the spacecraft down again.

What do you think about this story? Post your comments below.

StarLab
2004-Oct-14, 07:11 PM
That doesn't seem as easy as it appears to be, I'm not sure if they could pull it off, hmm...

Spacemad
2004-Oct-14, 07:31 PM
Originally posted by fraser@Oct 14 2004, 05:54 PM
The researchers think they could get a spacecraft going fast enough that it could make a round trip to Mars in 90 days, as long as there was another station at Mars that could slow the spacecraft down again.


MARS & BACK - IN 90 DAYS!

What a headline for a newspaper report or a title for a travel agency ad.! :D

Iīd be thrilled to be able to do a journey like that! :P

I do worry all the same if it is not just headline grabbing news - I sincerely hope not! My faith in the scientists conducting the research would be severely shaken if it were! :(

Selected as part of NASA's recent Advanced Concepts study I hope it gets serious consideration & eventual financial support to see it through - this could open up the Solar System to permanent human exploration & eventual habitation. :)

lswinford
2004-Oct-14, 07:55 PM
All Right! Now we're getting somewhere!

It sort of has the "star gate" style limitations, the first mission there has to essentially plant the equipment for the return/next step staging, but this is good.

TuTone
2004-Oct-14, 08:12 PM
Wow, sounds sci-fi! Hopefully it will work perfectly w/o errors. Crazy what mere humans think of & can do.....just amazing! How does somebody comprehend stuff like that? People are just brilliant!

jamerz3294
2004-Oct-14, 08:41 PM
The physics may be sound, but the economic considerations, and the logistics would be a nightmare! It does sound like future tech sci fi, but then again, so did "From the Earth to the Moon" in the early part of the last century.

John L
2004-Oct-14, 09:13 PM
How could these beaminf stations last indefinitely as suggested for the outer solar system nuclear stations. The plasma would have to be made of some type of gas that would need to be regularly replenished. I see that as being this system's killer, although the M2P2 propulsion system will work.

StarLab
2004-Oct-15, 12:38 AM
Yeah, I was thinking about that too...longetivity, and how a craft/probe can functionally use intrastellar, interplanetary space substances/particles.

Guest
2004-Oct-15, 07:04 AM
Sounds like a good idea but I guess it would be prudent to have a base on Mars first in case of systems failure. Perhaps, it is also worth-investigating if the mag-beam is on the Martian surface for greater protection from external threats. The problem of "star wars" program was due to Earth's atmosphere. The absence of atmosphere (or nearly so) on Mars would be near-ideal for the mag-beam

Guest
2004-Oct-15, 07:06 AM
Oops! forgot to register! that's me, Alfchemist!

bunny
2004-Oct-15, 10:53 AM
Here's a question, Assuming you have all this plasma being fired at a sail, what would keep the beam generator in place? wont the generrator experience an equal force in the oppposite direction and be blasted out of orbit at 11km/sec?

antoniseb
2004-Oct-15, 11:35 AM
Originally posted by bunny@Oct 15 2004, 10:53 AM
wont the generrator experience an equal force in the oppposite direction and be blasted out of orbit at 11km/sec?
Force? Yes. Acceleration, probably not. Suppose the generator is attached to something really massive, like the moon, or an asteroid that would otherwise eventually hit the Earth, or enough solar panels to actually drive it.

bunny
2004-Oct-15, 12:22 PM
that was my point. Without it being attached to anything to stop it moving it will fly off in the opposite direction. The article said it would be in orbit. No mention of moon or being on top of a mountain or attached to any asteroid. (although you are reaching a bit there!)

GOURDHEAD
2004-Oct-15, 01:09 PM
that was my point. Without it being attached to anything to stop it moving it will fly off in the opposite direction. The article said it would be in orbit. No mention of moon or being on top of a mountain or attached to any asteroid. (although you are reaching a bit there!)

The generating station will be equipped with an orbit orientation control and maintenance propulsion system.

GOURDHEAD
2004-Oct-15, 01:30 PM
Selected as part of NASA's recent Advanced Concepts study, the system would involve a space-based satellite that would fire a stream of magnetized ions at a spacecraft equipped with a magnetic sail.

Does anyone know how a magnetic sail differs from a photon or "particle impact" sail?

I still think a more practical system would supply energy to a photon sail, use the energy to electrostaticly accelerate plasma (ion engines), be thankful for the sail effect (until you're trying to stop), and steer the ship as you please. The thrust from the ion engines must always exceed that from the sail so you can stop when you wish. Sole sail is a soul sale!! The source of propellants and their delivery to the plasma engines remain the most difficult part of the puzzle to solve. Note that the details of the mag-sail generator at the remote site for deceleration were not treated with rigor.

John L
2004-Oct-15, 04:53 PM
Originally posted by GOURDHEAD@Oct 15 2004, 08:09 AM

that was my point. Without it being attached to anything to stop it moving it will fly off in the opposite direction. The article said it would be in orbit. No mention of moon or being on top of a mountain or attached to any asteroid. (although you are reaching a bit there!)

The generating station will be equipped with an orbit orientation control and maintenance propulsion system.
That brings back the problem I pointed out before. This mag-beam generator can be big, but if its imparting the forces described then its orbit orientation control and maintenance propulsion system will have to impart an opposite force to maintain position. If this thing is firing for weeks on end the mag-beam base will need a huge amount of fuel to maintain position AND a huge amount of gas to feed the plasma beam. I don't see this is being possible for the time scales their talking about.

lswinford
2004-Oct-15, 09:03 PM
Hmm...suppose we place three or four "propulsion" bases equi-distantly around the moon. I recall from some old Science Digest stories on mining the moon for Cesium to use in Cesium/Oxygen chemical rockets or Cesium ion engines that some people had located some possible mining areas for that--if it were a suitable fuel source for your plasma beams. Then with solar energy sources on the moon and some appropriate cabling for communications and steady energy supply, I think we could have the steady propulsion enterprise.

But even with only one site flaring for a fairly short window of opportunity, we are still miles ahead in the game from previous plans that would send a craft on a 9 months to 2.5 year journey (heavier loads require longer trips to economically send things to mars). With an orbiting propulser, you would have to shoot both ways, with possibly slightly less energy behind when on the backward swing (relatively speaking) and slightly less forward when on the forward swing of an orbiting propusive facility.

Remember too, the mission module of this (the craft going to Mars or wherever) might likely be smaller and lighter than the facility sending it. The beam that flares between the larger space base and the lighter mission module, while exerting force upon both ('equal and opposite reaction') could be used to propel the space base a little in a desired direction while opportunistically propelling the little craft in a larger way to a more distant location. In the diagram (and I know the geometry is not straight-line, but the idea can be seen) we have M-Mars, p-probe bound for Mars, L-earth's moon (Luna), E-Earth, and S-space base where the propelling beam is fired:

M--------------p---------------S--L-------E

Then the base is pushed back toward the earth, timed to miss both, and does a correcting fire to be recaptured by the moon:

M----------p-------------------------------E-------S--L

Then the moon swings around, bringing with it the space base to repeat the next propulsion cycle:

M--------p--------------------S--L--------E

Does that help?

Offworlder
2004-Oct-16, 09:59 AM
Wouldn't it be easier to mount the thrust unit in the ship.... it is essentially a plasma drive....

kdhrocks
2004-Oct-16, 10:43 AM
A question. Would there beam scatter or a coning effect like a light beam? If not you had better get a good handhold because the landing is going to be rough.
Dave

Spacemad
2004-Oct-17, 10:48 AM
I donīt pretend to understand the physics involved but surely this Mag-beam would not need to fire for "weeks on end" - as suggested:

If this thing is firing for weeks on end the mag-beam base will need a huge amount of fuel to maintain position AND a huge amount of gas to feed the plasma beam.
Wouldnīt it be enough to fire for a short period - like a chemically propelled rocket does at present - till the probe or spacecraft reaches cruise velocity, when it would coast the rest of the way,& then for the probe or spacecraft to be slowed down with an equal amount of energy when it is nearing itīs destination?

Surely the backwards propulsion would be negligible from the Mag-beam generator - like a laser beam (thatīs how I imagine the beam (rightly or wrongly!) & would therefore require little opposite correction? (Does a laser beam produce a "force" needing a counterforce to maintain its position?)

Guest
2004-Oct-18, 04:37 AM
Seems like the mag-beam system is poorly understood due to lack of details. May I suggest to Fraser that he does the same thing like that for the ion-thruster where he was able to get the comment of the leader of the team, in this case, let the team leader explain in detail how the mag-beam really works? or would work?

Hi bunny! if your problem is the opposite force that the mag-beam generator would experience, why not make it landbased? But before we tinker on our own moon, let's make sure of its stability. I don't think there's enough data about our moon to subject it to such powerful forces. The result maybe catastrophic!

As usual, can't log-in...

Alfchemist

Planetwatcher
2004-Oct-18, 07:55 AM
This conceipt sounds remotely like an episode of Star Trek the Next Generation I remember.

They had two inhabited star systems a few light years apart, and a ship incapible of warp drive as the test subject. One station fired what they called a solatron wave at this ship which was in line with the other star system. The solatron wave carried this ship into warp, and the ship traveled on this wave to the other system, which in theory would fire a disapating wave to take the ship out of warp.

Bunny is onto a point which will need to be further researched and tested.
Having an orbital satelite fire a mag-beam may cause the satelite to move the opposite direction. This could be compensated for by having the mag-beam bi-directional. Then the same amount of force is emitted in each direction which will not knock the satelite out of orbit.

Now wheither or not one of the mag-beams is pushing a ship really doesn't matter as far as affecting the position of the satelite goes. The force causing the acceleration of the sail is from the velocity of the mag-beam. It's not as though a spring or simular device is propelling the craft, so there is no back force from the sail, only from when the beam is fired.

But even a bi-directional mag-beam could slow a satelite's orbital speed, causing early orbital decay. I suppose additional means of forward thrust for the satelite would have to be figured out.

I don't think a constant mag-beam stream would be required for the entire journey. If so then for all the energy it would require, you might as well build a multistage super-rocket based on the Saturn V conceipt.

No, I would think such a device may fire for a few minutes, or perhaps a few hours to get the ship to speed, and let it coast, until it was close enough to it's destination for a counter mag-beam to be fired to slow it down.

Otherwise, again, you would have to fire one mag-beam to accelerate for the first half of the journey, and the other to slow it down for the second half.
And again, for the amount of energy that would take, you might as well have three super Saturn V rockets attached to the ship, each with as many as a dozen stages, with one or two more attached to the front to act as retro-rockets to slow the craft down as it neared Mars.

It's easy to see how crazy that type of idea is, but on the other hand with current rocket velocity technology, if you had a rocket or number of rockets big enough and could carry enough fuel, it would actually be possible to make a one way trip to Mars in just over three weeks. (assuming Earth and Mars were near their once in 26 month close point) That would make for a less then fifty day round trip, instead of ninety.

So while a ninety day round trip to Mars sounds impressive, it really is not unreachable. As it is, the last probe took around 180 days to reach the red planet, but used a very limited amount of fuel.
A much faster trip is totally realistic, if only it were possible to carry enough fuel.
But such a rocket would basicly be a flying fuel can.

On the other hand the mag-beam into a sail does sound intreaging. Even workable if an emitter could be attached to the ship itself.
Then, depending on the maximum possible speeds, an intersteller probe using this means of propulsion may not be out of the question.

bunny
2004-Oct-18, 12:23 PM
Any small thrust applied for a long time will generate a large input. If the thrust being applied to the sail is small it may be feasible (as iswinford suggested) to let gravity of the earth and moon keep the satelite captured. The vessel will need a constant beam to accelerate it to such high speed making fuel a significant concern.


Here is an idea. Design a huge solar sail that will act as a solar panel to power a magnetic acceleration ring at its centre. Some solar wind will pass through the centre of the ring and be accelerated towards the sails of your mars-express. This force will be counterbalanced by the effect of the solar wind on the large collecting panels.

Artsa Da
2004-Oct-18, 04:14 PM
Originally posted by bunny@Oct 15 2004, 10:53 AM
Here's a question, Assuming you have all this plasma being fired at a sail, what would keep the beam generator in place? wont the generrator experience an equal force in the oppposite direction and be blasted out of orbit at 11km/sec?
Bunny makes a good point:


Another good point would be how would we keep the beam focused enough and on target to interact with the space craft's sail? Due to the beam spread at distance the efficiency would decrease.

There is also the problem of orbital motion to consider even if it is on an asteroid or the moon. The beam would have to shut down when it past into the shadow of the earth which would decrease efficiency even more.


And then we would have the problem of a single thruster for a single space craft.

wstevenbrown
2004-Oct-18, 08:12 PM
Find a pebble,say, the size of Deimos or smaller. Send a robotic mission there, in three stages:
1) Convert a portion of the pebble to mirrors and/or light funnels to concentrate the sunlight available at Mars-orbit distance.
2) Convert a portion of the pebble into solar-driven power collectors/storage devices. Amorphous Si solar cells, LiH or NiH batteries, you know the drill.
3) Send habitation module, beam-forming/aiming equipment to parking orbit.

Then send the operators, and a wagonload of pioneers will soon follow!
Yes, there's a solar-sail effect from capturing sunlight. If you're on a massive body, and only redistributing the energy available to that surface, who cares? There is also a counter-thrust opposing the transmitted beam, but here it's a matter of scale. Find net references to the Yarkovsky Effect to really put them into perspective at proper scale. I can't help being enthusiastic about what's unfolding for our third-generation descendents! Okay, maybe second-generation. Regards, Steve ;)

Artsa Da
2004-Oct-18, 08:52 PM
Originally posted by Planetwatcher@Oct 18 2004, 07:55 AM
This conceipt sounds remotely like an episode of Star Trek the Next Generation I remember.

They had two inhabited star systems a few light years apart, and a ship incapible of warp drive as the test subject. One station fired what they called a solatron wave at this ship which was in line with the other star system. The solatron wave carried this ship into warp, and the ship traveled on this wave to the other system, which in theory would fire a disapating wave to take the ship out of warp.

Bunny is onto a point which will need to be further researched and tested.
Having an orbital satelite fire a mag-beam may cause the satelite to move the opposite direction. This could be compensated for by having the mag-beam bi-directional. Then the same amount of force is emitted in each direction which will not knock the satelite out of orbit.

Now wheither or not one of the mag-beams is pushing a ship really doesn't matter as far as affecting the position of the satelite goes. The force causing the acceleration of the sail is from the velocity of the mag-beam. It's not as though a spring or simular device is propelling the craft, so there is no back force from the sail, only from when the beam is fired.

But even a bi-directional mag-beam could slow a satelite's orbital speed, causing early orbital decay. I suppose additional means of forward thrust for the satelite would have to be figured out.

I don't think a constant mag-beam stream would be required for the entire journey. If so then for all the energy it would require, you might as well build a multistage super-rocket based on the Saturn V conceipt.

No, I would think such a device may fire for a few minutes, or perhaps a few hours to get the ship to speed, and let it coast, until it was close enough to it's destination for a counter mag-beam to be fired to slow it down.

Otherwise, again, you would have to fire one mag-beam to accelerate for the first half of the journey, and the other to slow it down for the second half.
And again, for the amount of energy that would take, you might as well have three super Saturn V rockets attached to the ship, each with as many as a dozen stages, with one or two more attached to the front to act as retro-rockets to slow the craft down as it neared Mars.

It's easy to see how crazy that type of idea is, but on the other hand with current rocket velocity technology, if you had a rocket or number of rockets big enough and could carry enough fuel, it would actually be possible to make a one way trip to Mars in just over three weeks. (assuming Earth and Mars were near their once in 26 month close point) That would make for a less then fifty day round trip, instead of ninety.

So while a ninety day round trip to Mars sounds impressive, it really is not unreachable. As it is, the last probe took around 180 days to reach the red planet, but used a very limited amount of fuel.
A much faster trip is totally realistic, if only it were possible to carry enough fuel.
But such a rocket would basicly be a flying fuel can.

On the other hand the mag-beam into a sail does sound intreaging. Even workable if an emitter could be attached to the ship itself.
Then, depending on the maximum possible speeds, an intersteller probe using this means of propulsion may not be out of the question.
Planetwatcher,

You would have to have same mass moved by each beam. An example would be firing a mortar shell in one direction and a blank in the other. The amount of recoil would be equal to the (mass of the (mortar shell)*velocity of shell plus the (exhaust gasses)*velocity of the gas from the one side) minus the mass of the exhaust gasses * velocity of the gas from the other side. An unbalanced equation would equal recoil or in otherwords if you aren't pushing against something you'll go in that direction.

lswinford
2004-Oct-20, 08:00 PM
A couple of things might help. First, if we had multiple beam sites, say numerous points distributed about the moon. Then we could provide some angular balance and control, each one swiveling in compensation for orbital motion and lunar rotation. This gives some support (picture legs on a stool) and offers more time with a beam trained on its target to gain a more optimum speed. Second, as I vaguely alluded to earlier on, for fastest speeds we would need to have a similar array at the other end (a martian moon, orbiting station, etc.) to apply the brakes (along the lines of that fun little 'warp' example someone gave a bit ago). There we are with travel to Mars about as difficult for early European colonists to arrive in the Americas--but with no "Indians" to fight (crossing my fingers in hope).

BTW: Once we get mechanics and productive machinery living and working in space, I bet we would not be relying on solar cell arrays as much. I suspect that we would find far greater efficiencies boiling a metal (or even flashing a gas) at the focus of a decent parabolic mirror (or mirror array), and this turning a turbine (which turns a generator). I'll bet we'll be applying such mechanical generation needs to crank out more energy from the received sunlight once we have someone around to replace some blades or patch some tubing when its needed. Putting half the received solar energy to work will probably trump a similar mass set out in a passive direct solar conversion array that ecks out a quarter less of that power potential.