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Going To Space Inside Magnetic Bubbles
Ecyrd writes: "Those fine guys at NASA have figured out a way to hitch rides to space inside magnetic bubbles, creating both an efficient propulsion system and protection from high-energy particles. Sorta taking the Earth's magnetosphere with you as a protective cloak when you go." The propulsion in this case comes not from within, but by using the magnetic bubble as a giant solar sail.
How the hell do you make it slow down? Even if you never touched an atmosphere, you'd still need big, bulky engines to slow down so you don't splat yourself into wherever it is you're going. And it may deflect solar flares, but it damn sure isn't going to deflect a head-on collusion with anythign solid.
No, you can't tack. Tacking with a sailboat uses the force of the water to keep it bouyant and at an angle. In space you don't have that force because its space. The only way you could "tack" is if you have thrust. In that case, you might as well not use a magnetic field since it would be an opposing force. The thrust you would need to generate to tack would produce an unoptimal usage of resources to get where you wanted to go.
As for using an "unbalanced" magenetic field, well that would just cause you to spin and move in the direction of the wind.
read the rest of the thread.
Slashdot, would a spell-checker for posting be too much to ask? It's not rocket science!
This isn't so bizarre. Science fiction writers have been clinging to this concept for a long, long time. (At least, the concept of riding on mangnetic waves).
My personal favorite is Dan Simmons' vision of the Ousters with multi-kilometer wings that could 'catch the magnetic waves' and push them around in space. Like giant butterflies. Very cool. It's nice to see another of the science fiction authors' predictions coming true.
Bite my yammer.
Before you get carried away by "That's enough to accelerate a 200 kg spacecraft from a dead stop to 80 km/s (180,000 mph) in only 3 months.", remember that just 2 astronauts and their suits are heavier than that. That's without any actual spaceship.
Also later on it says
Maintaining such a bubble in space would require about 1 kW of power and less than 1 kg per day of helium propellant for the plasma source. In return, the bubble would intercept about 600 kW of solar wind power.
So... if it weighs 200 kg, and uses 1 kg per day for propellant... Isn't there a fundamental problem here...?
Good question. Whats even cooler though is how they can use the same propulsion system to stop. If they're traveling towards another star, they can gradually reduce the field in such a way that it'd bring them to a stop in just the right place. If the field was too strong, then they'd stop somewhere a little further than halfway, and if it wasn't strong enough, then they'd never stop.
You speak of 'just travelling in space' as though that really wasn't much of a breakthrough at all! Granted, this is not the technology that will send the Millenium Falcon roaring out of Mos Eisley. It's not supposed to be. In a way, this technology is more exciting than that. This technology makes the idea of a manned trip to Jupiter, etc. much more of a possibility. We can get (roaring, even) into space already, albeit clumsily. Where we go from there and how we survive while doing so is where things get really sticky. This is great news!
**>>BELCH
That occured to me also. Either you use this kind of thing on a one-way trip (good for expendable probes) or you make a sling-shot around the planet of interest and conduct your business *real fast* on the fly-by. ;) I haven't heard anything written on the concept of "tacking" upwind like you would do in a sailboat (since I believe that makes use of lateral pressure exerted on the boat from the water). The only thing left would be some other (more conventional?) thrust device, but now we're stacking up lots of extra mass to the point that the magnetic sail wouldn't work nearly as well to begin with, rending the discussion somewhat moot.
Unrelated to this, though, I have to wonder how massive the magnetic generator itself is. Sounds like they can meet the 1kW power requirement well enough, but it needs [nearly] 1kg of "fuel" (for plasma) also per day. The numbers quoted at the top for a 200kg vehicle isn't all the heavy. By the time you add yourself, a friend, and the obligatory Beowolf/Linux cluster, well, I just start wondering if it would truly attain their listed speed *or* endurance rating. Just my thoughts.
With more time to think, "tacking" certainly wasn't the right word to use, as this means progress upwind.
I'm really thinking more of steering. The solar wind will always be radially outward from the sun. I'm thinking in terms of gaining accelleration in the plain perpendicular to the local wind vector.
THe force vector will be radially outward. To knock off a dimension, assume that we stay in the plane of the solor system. If the vessel is off of the vector, displaced by an angle theta (where 0 would be on the vector), the accelleration breaks into Fcos(theta) away from the sun, and Fsin(theta) laterally.
As far as the filed, I don't mean making the field funny, but instead to spread out the unit in some way so that the field is generated away from the center of gravity of the entire vessel. This should give a similar ability to move outward.
There would still always be accelleration outward. HOwever, if it is possible to move the vessel far enough off center, it may be possible to move outward while accellerating against the direction of orbit, enough so that the orbit decays and the craft comes inward under the force of gravity.
hawk, who could have done the math for this in his sleep 15 years ago . . .
As far as I can tell, this has nothing to do with going to space. It's talking about once you're already there. Isn't accelerating 200kg to 180,000mph in 3 months a little low to actually break out of earth's gravity? Unless they are referring to hitching a ride on the magnetosphere. But they never actually said anything about leaving earth on one of these, just travelling in space.
_______________
you may quote me
Quick question (maybe a stupid one)...
Does this miniature magnetosphere have to be turned off everytime you need to talk to your craft?
It would seem to me it might interfere a tad with radio communications...
Man, what a nifty idea. Especially if the term "solar sail" conjures up for you images of kilometer-sized sheets of gold foil.
One thing I wished the article would have explained better: How is it that plasma can expand a magnetic field in that way? I mean, I see how you could block an EM field-- we see that everyday-- but intensify it? (without increasing the coil voltage, at that). Could anyone comment?
iSKUNK!
You'd be sending equipment, not people. On the other hand, the 1kg/day propellant is a much more serious problem. It's probably not steerable enough to do a good flyby of one of the outer gas planets or their moons to pickup some hydrogen without risking falling into their gravity well. But you can find some interesting balance of weights and propulsion strengths to get out to interesting parts of space and send telemetry back, and once you're going that fast, it's a nice cruising speed.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
Ok, Is it just me or does this look amazingly like the Star Trek "Warp fields"..... Use something along the lines of the ST nacells and you get more elongation to your field. (Ok I don't know how multiple fields might interact, but there's another way to gain a little control.) Also as long as your not talking about supra liminal velocities just stick a couple of "feild generators" out on some sort of boom arm and there you have some steering control with more or less pressure being applied to one side of the craft or the other. X wing them for more than one plane of control.
For additional thrust (at least at the onset, or possibly for breaking) vent the plasma gases, that you just used to expand your field, through a nozzel.
But you've forgotten that the accel is continuous, not a single burn. As soon as you're going farther than the moon, you're saving time.
.01 m/s/s acceleration (.001*g, or 10N acting on 1000kg), a 1 AU trip takes 1,521 hours, or half as long.
With a (helluva) rocket that gets you to 50,000kph in one extended burn, a 1 AU trip (150M km) takes 3,000 hours.
With a solar sail that gives continuous (and puny)
(Neither of these take into account the time to brake, or my poor arithmetic. But plug in t = d/v versus t = sqrt (2d/a) with your favorite numbers and you get the idea.)
"You can't get something for nothing." - my grandfather, on the stock market and Reaganomics.
Easy. Just reverse the polarity!
Hmm, if I traveled into the past and wanted to leave a message for future generations, I would use a giant laser to carve the message into the moon. It would be, CHA- but then get cut off as my laser was destroyed by a 400 pound blue idiot.
"Destroy science and religion. Science would re-emerge exactly the same; but not religion." - Penn Jillette, paraphrased
You shield and direct the magnetic field such that it is flat, then you turn is sideways to the magnetic wind. Just as in sailing, instead of going straight out in front of the wind, you will tend to drift sideways. You can use this effect to decrease your orbital velocity and then let gravity pull you home.
Aah, change is good. -- Rafiki
Yeah, but it ain't easy. -- Simba
Of course, we still don't have a cheap way to get to orbit. Thanks, NASA.
At any rate, to answer a few questions I've seen posted here:
1) Yes, the basic concept of a solar sail is sound. It has been tested, and it works.
2) Yes, the acceleration is low, but it is continuous. That fact, plus the fact that you don't have to carry (much) fuel, put's you WAY ahead of any chemical rocket solution.
3) The magnetosphere wouldn't hurt the crew or the onboard electronics: you just put the lifesystem inside a Faraday cage.
4)And YES, you could come back from a mission to, say, Mars, using this technology. Travel between planets is accomplished by establishing yourself in an eccentric orbit that passes through the orbital path of both your origin and your destination. So you can use the magneto-sail to push out away from the planet, establish your orbit, then turn it off when you reach the "top" of your curve, and fall back in. Then turn the sail on again when you need to brake.
Depending on the location of various planets, you could also use the sail to travel out, develop alot of speed, and then slingshot around another planet to turn yourself around and head back home.
"Research is what I am doing when I don't know what I am doing." -- Wernher von Braun
I have been reading alot about alternative propulsion as of late, and this seems by far the most realistic approach. While we are not going to see this in action for some time, it opens a ton of possibilities for countries like China that are just venturing into manned space flight.
With the amount of money the US Government has tied up in the Shuttle program, it is unlikely that they will even attempt implimenting this kind of technology on anything other than a "Test Platform" for at least 10 or so years. However, a country like China that is relatively new to the "Space Race" could easily use this kind of technology to attempt large scale interplanetary expiditions, with a far shorter time-line than competing countries.
Wouldn't it be something if the Chinese were the first to put a man on Mars? Don't laugh, it could happen.
I am become Troll, destroyer of threads
I suppose I'm going to have to give the proper response to this: You keep the bubble on full the whole way.
Assuming two stars of equal solar wind, half way there, you're not being accelerated by the wind of either star, but you're coasting along at your highly accelerated rate. As you approach the other star, its solar wind begins to dominate, slowing you down to a neat stop at your destination.
THEN you turn off the bubble!
In a real example, Just adjust your bubble up or down as you go, according to the difference in solar winds.
"You can't get something for nothing." - my grandfather, on the stock market and Reaganomics.
This could be interesting. It's quite easy to manipulate the shape of a magnetic field (cf the torus-shaped fields used in fusion experiments). Maybe it doesn't have to be a bubble. Maybe it could be disk-like, and thus present a wide area for less energy than they figure for a spherical bubble. Hmmmmm....
"You can't get something for nothing." - my grandfather, on the stock market and Reaganomics.
Still, it ends up going REALLY fast :)
I've seen several questions about how to 'tack' back into the solar wind to get back to earth. With a conventional solar sail its pretty straight forward.
A conventional solar sail works by reflecting particles/light/etc and simple action/reaction. to go out to mars for example it is angled in a way to reflect particles away from itself to increase it's orbital speed; faster orbital speed puts the vessel in a higher orbit in the solar system. Coming back simply means angling the sail the other way so that the reflected particles slow the orbital speed untill the orbit lowers back to earth.
My understanding with a magnetosSPHERE sail is that it cannot by it's nature 'tack' back into a lower orbit as it is sphere shaped; It acts much like a parachute rather than a flat sail.
To tack such a vessel back you either have to figure out a way to 'flatten' the magnetic sphere into more of a disk shape that can act as a conventional flat sail. The other alternative is to use a planet's gravity to 'slingshot' you back the way you came.
You could probably 'flatten' a magnetic sail by using a large torsional (donut-shaped) ring to create the magnetic field. Older magnetic sail designs I have seen used a superconducting cable in a loop which naturally repelled itself and created such a shape but these early designs did not incorporate the 'plasma boosting' the new design displays.
-- Greg
Slashdot, would a spell-checker for posting be too much to ask? It's not rocket science!
Can someone who understands the actual physics of this propulsion explain it in terms that someone with some physics knowledge could understand? I'd like to know how they really get magnetic field amplification from plasma.
The same approach would let you fly from Earth to, say, Mercury.
"Research is what I am doing when I don't know what I am doing." -- Wernher von Braun
Tacking works on a sailboat because the keel has the water to push against, so the vector of the force exerted by the wind that would push the boat in the wrong direction has a contervailing force. A spacecraft wouldn't have the equivalent. To return, I presume that you'd do it the same way as you got to whereever you are (assuming that it's near a star): unfurl the sail and let the star accelerate you, then drop the sail when the solar wind from the destination exceeds that of the star you're using. Of course, IANASS (I am not a solar sailor)
Since the moon doesn't have a magnetosphere couldn't you put types of these machines on the moon as power plants.
:-)
You have one of these machines on an extremely long slanted pole. Slanted meaning slighty up from the moons surface. When you turn it on the solar wind pushes on it. You have a tether to a generator. The tether pulls on it creating power. Once at the end of the pole the machine turns off. The small amount of gravity on the moon pulls it back. Once it is back in its starting position it turns back on and the process starts over.
Sort of like a windmill, moon style
I had remembered that a black sail would work as well, but after a few minutes of drawing vector diagrams, I can't see how.
Replying to someone else's point about using several bubbles tethered together: I can get some tangential thrust if one is 'shaded' by the other, so the rear one receives solar wind only on one side. There is also a torque that will tend to spin the tethered bubbles, but this can probably be counteracted by clever uses of magnetic fields reacting against the solar magnetic field. This isn't very efficient in terms of sail area to useful thrust ratio, however.
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
tacking uses two forces (the wind and the resitance of the water). In space, you have solar wind and you have grvity. *should* work... Oh, and this is not well thought through at all, so you may have to > /dev/null
--The knowledge that you are an idiot, is what distinguishes you from one.
Actually, I suspect that it went the other way. Trek fx creators probably based the looks of the warp bubble on the shapes magnetic fields take. And the looks are sorta similar, but I can't see why you think the concepts are ...
TO be honest, this was the _first_ thing I thought of.
:)
:)
Magneto's force-bubbles.
Nice to know Real Life imitates art. Although, somehow, I don't think he's filling them with plasma, as even Magnus needs to _breathe_.
Damn, I am a Marvel Comics Geek.
Redhawk
Even if there's no way to take a trip home with it, would it be a cheaper way to build the ISS and shoot up satellites?
I don't know if this technology would be a candidate for interstellar spacecraft, but if it is, you could always just push off from the destination star to start the trip back.
I wonder what the "terminal velocity" of this system would be? If you start off close to a star and just sail away, how fast would you be going when the acceleration finally peters out?
MSK
It doesn't use radio for communications. It uses IR.
-- Anne Marie
It sounds like you could just bolt this new device to the floor of a shuttle's cargo bay and have yourself an interplanetary cruiser. That would make shuttle trips to places like L1 or a lunar base not only viable, but downright dirt cheap, and missions to Venus, mars and the asteroids well within reach. I am not too sure on how it works, but there is a technique that sailing ships used to travel into the wind (tacking?) for the return journeys. The biggest concern would become cargo space for life support: air, food and water, rather than fuel. The future is finally with us!
One really exciting use for this would be to attach drives like this to asteroids. This would first and foremost serve to save the Earth from any imminent collisions but would also allow you to re-position juicy asteroids closer to home, etc. All you need to do is bolt the coil and a power generator to the surface, and voila'! the rock will be moving 180,000 km/sec within umpteen units of time.
Let's just assume the m2p2 drive will make it. The next holdup will be attaining orbit. I predict that either one- something similar to m2p2 is developed to launch cheaply using the Earth's own magnetic currents. Launches would take place at one of the magnetic poles (finally, a use for Antarctica!) and will be simple and sturdy like the m2p2. OR two- the application of the cavitation bubble can be used for building up hypersonic speeds (escape velocity) without much friction and without fighting gravity. A damned Mack truck could attain orbit with a system like that.
One further thing strikes me as curious about this. I know it's pretty far-fetched, but the [douglas adams/joseph campbell/tim powers] tainted conspiracy theorist within urges me to mention it; The name m2p2 bears a close resemblance to the city 'machu pichu' one of the absolute most vexing mysteries in human history. The architects of that ancient city were able to bring large rocks (massing dozens of tons each) to a remote South American mountain peak many miles from the quarry of origin. When you ask yourself "did they use m2p2 to build machu pichu?" and take into account the permutations and perversions of language drift, a suspicious coincidence in phonemes comes to light... I wonder if a band of space adventurers stumbled back in time and tried to leave us a message or hint?
:)Fudboy
:)Fudboy
I guess I'm only a Fudboy, looking for that real Transmeta
That guy's not kidding about becoming the furthest man-made object from the sun. 80km/s may not sound like much after three months, but note that, amazingly, acceleration will remain constant because the size of the bubble will increase as the pressure of the solar wind decreases.
I did a little bit of math, and came up with 392 days to pass Pluto's orbit, at which time the probe would be travelling at a speed of almost 350 km/s. That's more than 0.01c, so we'd have to start figuring in relativistic effects, but damn that's fast.
Note: I'm on my co-op term now, so please excuse any mathematical mistakes as my brain has been turned off.
It may look like I'm doing nothing, but I'm actively waiting for my problems to go away.
--Scott Adams
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Can some one with a better grasp of inter-planetary physics comment on whether you could use the space shuttle to launch small vehicles using this technology?
I know the space shuttle doesn't _really_ travel in space by some people's definition but how much force does it take for a comsat or something of that mass to get away from Earth if launched from the shuttle bay? If nothing else a test vehicle to demo the theory could be hoisted up and turned on to see if the idea works in practice.
What about the same idea from the space station? And/or use it to help sheild parts of the space station and help it mantain orbit using less power?
=tkk
Bill Gates - Creationist?!?
I wonder if you could slingshot around the earth towards the sun, and fire up this sucker near a solar flare to see how far it would shoot you out of the solar system. The force on your magnetic field would be insane which would either kill you or propel you like mad out of the solar system. Suddently this makes lots of things in the solar system managable. Think robots dispatched into space to latch onto asteroids and propel them to near earth orbit (dangerous terrorist weapon OR raw material mining?), because most asteroids are further off you could slingshot an asteroid around a planet with one of these and send it back towards earth or keep it in orbit around the moon. The scifi implications of this stuff will keep people thinking for years to come.
http://www.livejournal.com/users/cixel
Who wants to come back? I'm outta here. Alpha C, here I come!!!
I am quite civilized, and I should be brought a beer immediately. -- Bruce Sterling
If this were sent to another solar system, it would use the Earth's sun to get it half way or so then it would use the solar wind from the destination star to slow it down. It would be like running _into_ the wind. This would slow it down, and bring it to a stop.
Also, there are other ways of slowing down. Using gravity would be one example. They use it now for boosting the speed of satellites and other space equipment. But remember that this can be used to slow something down. Much like the way things are drawn into the sun, or a black hole, or a planet. Remember the comets that struck Jupiter not too long ago? Obviously they slowed down enought to fall into Jupiter's gravity well.
Getting back from trip out to the planets could use the same principles. Get a boost from a planet and redirect back to Earth, turn off the sail. Get closer to Earth then hit the brakes by turn the sail back on.
Without gravity to assist on the accelerations (whether positive or negative) many other alternative ways could be devised to slow down and stop. I'm sure you don't lack the creativity to come up with other means. (maybe a magnetic cannon or something)
A force radially away from the sun does very little for you. The solar wind force cancels a tiny portion of the solar gravity, with the result you end up in an orbit just slightly larger than before you turned on the sail.
To get anywhere, you need a component of force along your direction of motion. In 'traditional' solar sailing, this is achieved by putting the sail at 45 degrees to the solar radiation. If the tangential force acts in the direction of your motion, your orbit steadily grows. If it acts against your motion, your orbit shrinks.
So far as I can see, this proposal produces an approximately spherical 'sail'. This would not allow tilting the sail to produce a force component along the orbit. However, they don't discuss the shape of the bubble, so I may be going astray here.
As an aside - from memory, there is about 10 times as much pressure available from the sun's light as from the solar wind. This method doesn't use the light, whereas 'traditional' solar sailing does. This advantage is likely overwelmed by the ability to make a large 'sail' cheaply and lightly with the bubble method.
(My solar sailing experience is limited to setting an undergraduate assignment on the topic some years ago.)
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
But then they would lose the magnetic shield that the propulsion system gives them. Worse, coming back they would have to counteract the force exerted by the solar wind.
--locust
Call me when they find something that makes getting out of the gravity well as easy as this thing sounds like it is.
I'm trying to teach myself to set people on fire with my mind... Is it hot in here?
The article didn't go into this, but how would a vessel equiped with such a propulsion system return to Earth?
Could it tack back into the solar wind for the return trip?
NecroPuppy
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Godot called. He said he'd be late.
I like you, Stuart. You're not like everyone else, here, at Slashdot.
Wouldn't it be something if the Chinese were the first to put a man on Mars? Don't laugh, it could happen.
would that make Mars the Red Planet?
---
I post links to stuff here
The one immediately obvious drawback is that it is relatively slow. Another question that comes to mind is the effects of such a strong magnetic field on electronic devices within the field. Or for that matter, the effect on biological systems within such a field, especially over long periods of time.
But if nothing else, the team at NASA has apparentely developed an inexpensive solar radiation shield, especially useful for deep space exploration or space habitat use during solar storms. . . .
This sounds cool, but from the sound of it, it only works one-way!
The article talks about family flying saucers, but it doesn't mention how you get back after you zip off to Jupiter. Of course, considering some of the loony stuff happening on Earth lately, maybe you can't blame them for conveniently forgetting a return path.
We want endless gardens of data, where the bits can flower, flourish and reproduce. -- Andy Mueller-Maguhn
If you need 1kW just for a 200kg craft it means that the power requirements for a manned 30 tonne mission will be pretty high. Where do you get all that power? Solar panels are heavy and not very efficient.
I guess this calls for unpopular power sources such as radioisotope thermoelectric generators.
----
Stop worrying about the risks of nuclear power and start worrying about the risks of not using nuclear power.
There is no such force in space
In a word, gravity.
Yes, it's the force the water applies to the keel, counteracting the sideways force of the wind which allows a sailboat to sail upwind. FYI sailing on water the vessel moves forward by using the wind to generate lift (like an airplane's wings) to pull it forward, whereas space sailing movement is generated by action/reaction (like a rocket motor) so they are two completely different methods.
The 'keel' a solar sail uses to get closer to the sun is the sun's gravity itself. As the solar sail changes it's speed by reflecting particles in the direction it's traveling and causing an opposite reaction away from that direction (i.e. slowing itself) the lower orbital speed makes it fall towards the sun.
The best way to explain it may not be by words; so try the solar sail simulator java applet and see for yourself.
A conventional solar sail will sail 'to windward' like a Farr 40, whereas a magnetospheric sail sails to windward like a Morgan OutIsland.
-- Greg (S/V Scirocco)
PS: In the future please double-check that you are 'right' before calling someone else 'wrong'.
Slashdot, would a spell-checker for posting be too much to ask? It's not rocket science!
Eatrh's a dump.
Heck, even the whales are leaving -didn't you ever see Star Trek IV: The Voyage home or read The Hitchhikers books.
The evidence is clear -the fungi have reached us and now it's time to go.
Dirt doesn't need luck.
Ita erat quando hic adveni.
okay, who else has visions of comic book supervillain magneto and his magnetic bubbles?
:)
magneto put all kinds of fun things into space with his bubbles - space ships, people, asteroids, the Avengers: West Coast mansion...
maybe the guys at nasa aren't just watching Star Wars movies, but reading comics, too
- Entertaining Bits from the Ancient Kernel Tree
The stuff they propose making solar sails out of is quite thin, the space debris is just going to punch a small hole in the sail. Your efficiency will drop a hair, but nothing catastrophic is likely to happen.
I wouldn't worry about the sail so much as I would the struts and lines connecting the sail to the rest of the craft. Sure, the odds are really low that one will be severed, but if they weren't designed properly it could cause real problems.
jim
I've wrestled with reality for 35 years and I'm happy to say, I finally won out - Elwood P. Dowd
Most conceptual solar sail designs assume the material is fairly thin, and anything that hits it would (generally) hit at a pretty good clip and just leave a hole shaped like it. No real tearing or shattering. Most of the holes left would be fairly small and not really impact performance significantly. For big holes, bring a repair kit along with you.
"That's Tron. He fights for the Users."
Ok, the working concept for a craft powered by solar wind involved a 300m wide sheet of 0.1mm thick carbon fiber fabric, or something like that. From an engineering standpoint, that is hellishly complex. The torque forces on something that would have to be small enough to launch complete by rocket, with a fold-out sail that enormous, are phenomenal. In addition, the solar sail's thrust is inversely proportional to the square of the distance from the sun, while the magnetic bubble expands as the wind gets more rarified, so the net thrust is the same at any distance.
The fuel efficiency of this thing is pretty respectable, too. 1 kg per day is a little expensive over the course of a long mission, but they expect their efficiency to improve, and they would also probably also not need the full power field during cruising legs of the trip.
The safety issue is the icing on the cake. This kind of thing would also make explorations of Jupiter easier, since Jupiter's equivalent of the Van Allen radiation belts give an exposure on the order of 5x a lethal human dose just to pass through at a speed reasonable for assuming a low orbit. Granted, there's not much on Jupiter for a human to walk around on, but if the radiation is 5x the lethal human dosage, your flight hardware needs to be very heavily shielded. This magnetic field frees up a lot of weight, which in turn increases the fuel efficiency.
Now if only they could find a way of sailing upwind in the solar wind stream. You can do it with a properly configured sailboat, usually within about 45 degrees from the wind direction, give or take a few degrees depending on various specifics. If they could do it with solar sails, you'd have a viable human-transport system. Otherwise, the best return mechanism you could use would be to go out on full power, swing around a planet (without stopping) and power down to just enough to protect the crew, and drift back on momentum.
WARNING: there is a trojan on your
Do the math. If I have a 200kg probe, and I expend 1 kg of its' mass a day for the sail/shield, then we're talking about a **100** kg probe which can accellerate for 100 days. . .
if you're running into a star, it would have its own solar (stellar?) wind, so you'd coast to a stop.
..then start accelerating in reverse!
- Entertaining Bits from the Ancient Kernel Tree
So you end up wth a hole a few inches, or feet
at worst, in sail square kilometers large.
No one would notice it.
No significant ind force to enlarge the hole.
>you can't exactly 'tack' against the solor wind...
Are you sure? Extend the lines on one size of the sail. The craft will be
off-center, and you should get outward and lateral thrust
as dictated by the cosine and sine of the angle at which the
craft protrudes.
I expect you could similarly steer with the magnetic sail by shifting the
generation unit relative to the main craft, creating such
an angle.
These won't give you outright directional control, but they could affect
the direction of your outward motion from the wind, or your
inward fall from gravity . . .
And the return trip could come by decelleration in orbit, and then
steering along the trajectory . . .
hawk