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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.
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.
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...
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.
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
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'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!
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
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
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?
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.
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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.)
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we've been talking around the office about this since it came up, so we have a few ideas already :)
first of all, there would have to be some other kind of drive in order to leave orbit in the first place, or even simply for steering, so that could be used for braking, etc.
then there's the option of the "2010" gravity-braking slingshot gambit, whereby one who is travelling at breakneck speeds whips around a nearby planet - optionally skipping off the atmosphere - slowing down enough to enter orbit at the target planet. the same trick can be used simply enough to steer - NASA's been doing it for years - or to head back in toward the sun after building up a velocity heading out
let's say you're headed for venus, but the cheapest way to get there would be to build up a good velocity by heading out towards jupiter first, then whipping around big J, turning off the magnets (or turning down the power) and coasting back towards the sun, catching venus on the way. this isn't all that efficient, since you can build up enough speed whipping around the earth-moon system a few times, but you get the idea - especially if the planet you're aiming for won't be on this side of the solar system for another 90 years (hello pluto!)
on the topic of longer distances - say another star - it's a simple matter of heading out on the solar wind, and using the other star's push to brake.
the problems we see remaining involve being in interstallar space, outside the influence of any solar wind. sure, the velocity would be nice and constant, but short of another drive system, there's little to use for acceleration, steering, etc.
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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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I like you, Stuart. You're not like everyone else, here, at Slashdot.
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.
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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
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.
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