NASA tests crazytech flying saucer thruster, could reach Mars in days NASA has tested an "impossible" electric space drive that uses no propellant – and found it works even when it is designed not to. EmDrive space motor The EmDrive space engine ... a long time coming This has sparked immediate skepticism of the technology. The system is designed to use microwave energy reflected along a …
With a claimed 2.5kW to produce about 3/4 of a Newton, and about 10kN needed to balance the mass of a small car against gravity, your flying car is going to need about 40 000HP. The good news is that an RR Trent 900 exceeds this comfortably. However, as the Trent produces about 300kN of thrust on its own account, it really isn't worth the bother of messing around with large amounts of microwaves as well.
If this works, maybe the "2G" version of the EmDrive will work as well...
http://en.wikipedia.org/wiki/EmDrive
http://www.buildtheenterprise.org/80-ton-lifter-possible-in-6-years-interview-with-emdrive-inventor
"BTE-Dan: You describe a 2nd generation of EmDrive which uses a superconducting microwave cavity where 1kW of input power is capable of lifting 3 tons of mass. Of course if this worked it would be mind blowing. When do you think a prototype of a 2nd generation EmDrive could be built given adequate funding of a development project?
Roger: A prototype 2G thruster, giving 3kN for 1kW microwave input could be available in 3 years. A large prototype 2G thruster giving 800kN [80 metric ton-force] for an 80kW input would take 6 years."
So if we fire this 2G thruster for 1 second then we have used i kJ of energy (1kW for 1 second). On the other hand, we have produced a force of 3 kN for 1 second. If the mass of this craft is such that the 3 kN thrust for 1s causes the craft to move to a height of 1m against gravity, then we have produced a potential energy of 3kJ with the 1kJ input. Wonderful! Three times better than a perpetual motion machine!
Except they didn't get the same result on the control, the control produced significantly less thrust. Now that thrust on the control might be a measurement error, but the difference between control and experiment indicates something is going on. And it's not like this is the first time the experiment was tried.
The fact that they got ANY result from the control shows that they had a problem of SOME sort. And unless they repeated both experiment and control, each set up again from scratch each time, and the results from each were similar each time (but different between control and experiment), it could simply be that the instrumentation problem was weaker on one occasion than the other.
I'm with others on this. I'd love it to be verified - it would not only be potentially revolutionary, but throw a spanner in the works of current orthodoxy - rarely a bad thing. But frankly this feels a lot like cold fusion did when it was first trumpeted. Sorry - exceptional claims (apparent violation of conservation laws) require exceptional evidence, and I'd say the jury is still decidedly out.
These gadgets were tested in a vacuum chamber, but THE DOOR WAS LEFT OPEN because their RF amplifier contained cheap capacitors that would not survive a vacuum.
This will almost certainly be attributed to thermal effects, perhaps the power wires heating up.
Or maybe their GPS has a loose connection (joke alert, yes, I know...)... LOL.
You have to read other sources, good as El Reg is, to learn more of the back story on this. I've read extracts from the actual paper that mention that they used a vacuum chamber, but were forced to leave the door open because the electrolytic capacitors in the RF amp were not vacuum certified. So the experiment was a last minute thing, obviously, performed in a vacuum chamber with the door open.
GZ: "...tank of water heated by a ground based tight laser beam makes a good interplanetary engine..."
Ah, the issue is bringing mass to orbit. Energy isn't really the issue, as it can be sourced from nuke or solar cells. The issue is having to throw mass out the back to make it go forward. In other words, the tank of water needs to be left on the ground.
The average insolation at the orbit of Mars is about 40% that of the Earth in very rough terms. A typical rooftop solar panel installation in the UK is around 2.5kW peak, but that's with atmospheric losses. So a top of the head, no maths or calculator estimate, is around twice that of a typical UK roof, possibly quite a bit less for the sort of solar cells you would use for a spacecraft.
I'm sure someone will come along with an accurate estimate in a few minutes.
Not that big at all really, quite doable.
I'm not quite the rocket scientist you were hoping for but here's a couple of pence worth;
NASA have PV panels that can hit over 40% efficiency, nearly double that of most commercial high end panels so a space craft fitted with them is going to perform fairly well.
The only thing that will need a bit of calculating is the turnover point for deceleration, as the inverse square law will have to be taken into account, so the turnover point will necessarily be less than half way in order to ensure sufficient braking at Mars to avoid either overshooting or smacking into mars.
The only thing that will need a bit of calculating is the turnover point for deceleration
Off the top of my head, use a Bussard collector to pick up ionised hydrogen along the way, store it somehow (a tokamak since you're generating a magnetic field anyway? an aerogel-like substance?) and then use it somehow (mixed with LOX?) for the "descent" stage to provide more thrust than could be achieved by the outbound engine.
Nothing wrong with hybrid systems I guess. If you can make a solar panel that doubles as a sail (like a parachute, or perhaps a neat origami structure) you could probably get useful thrust for part of the journey out of that. Maybe if you could get LCDs working, you could vary the albedo of the sail so that you can transition between converting solar power to electricity and direct propulsion, depending on what you need at any point along the journey.
Anyway, this sounds very interesting. Let's hope that they can continue to test and maybe one day get something up there that can be tried out for real, and not just in the realm of sci-fi or "possible, but not practical" systems...
"that's the easy part."
There is _no_ difficult part, it is only the combination that causes issues - we know how to launch a few tonnes of kit successfully, we know how to land on Mars, we know how to keep men alive, we know how to return them to Earth, but each of these requires weight, pushing the launch weight up to levels that will move the Earth in its orbit...
The Dawn spacecraft, currently in transit twixt Vesta and Ceres has two 18 sq. metre solar arrays which combined produce 10kW at 1AU and 1300W 3AU out in the Asteroid Belt. Inverse square and that's about what you'd need for 2.5kW at Mars distance.
Earth to Mars takes around 9 or 10 months on the cheapest ballistic transfer orbit depending on exactly when in the launch window they're sent, the Indian and Nasa probes launched back in November are due to arrive this September. Even quite modest continuous thrust can cut that by a lot, but it also greatly extends the launch window so you don't need to wait until the planets are exactly aligned and can launch at almost any time.
Nuclear power is what this thing is made for.
This device means that, finally, a lot of sci-fi novels have just become simple fiction, not sci-fi anymore. Spaceships flying between planets at will, without the need for reaction mass - we have just passed a singularity in space exploration and human civilization expansion and the world at large have barely even noticed. Wow.
fission plants, even small ones, are very heavy, that already rules them out. Besides, when will the guyz on el reg understand, nuclear is evil, nuclear is evil, nuclear is EVIL ?????
I had a chat with the blokes over at ITER the other day and, the only reason the ITER project exists is to extend life of current nuclear facilities.
Seriously, if you believe nuclear fission is an acceptable solution for anything but human extinction you are completely deluded.
#idiocracy
"when will the guyz on el reg understand, nuclear is evil, nuclear is evil, nuclear is EVIL ?????"
Or...
"The sun is EVIL! It could destroy the earth if it went super-nova!"
Seriously, take your tin foil hat off. Modern nuclear fission technology is safer than most other generation methods, and the only one which could allow a significant reduction in carbon emissions while providing current and future power requirements.
If 18 sq. meters of solar panel produces enough energy for 720mN of thrust then we can say such a space craft produces 40mN/m^2 pressure.
Solar sails produce 8.25μN/m^2 after losses, according to wikipedia. It should be noted that sails are simpler and probably lighter than an EmDrive + panels.
If this is true then it's great news! However something tells me that a photovoltaic panel working at 40% efficiancy shouldn't be able to collect 5000x more energy than a reflective sail working at 90% efficiancy.
"a photovoltaic panel working at 40% efficiancy shouldn't be able to collect 5000x more energy than a reflective sail working at 90% efficiancy."
Use both. A toroidal mirror-sail concentrating lots and lots of sunlight in a smaller solar panel (or another different device for energy production, e.g. a stirling engine) and you have the best of both worlds. That is, if the results obtained insofar are not a rounding error. Crossing my fingers on that part.
With a little bit of luck we could be sending fecking tourists to Mars in a few decades!!!
"However something tells me that a photovoltaic panel working at 40% efficiancy shouldn't be able to collect 5000x more energy than a reflective sail working at 90% efficiancy."
A solar cell absorbs the incident photons, collecting X% of hν of energy from each. A solar sail absorbs the incident photons and then re-radiates them; it doesn't get access to anywhere near the same amount of energy.1 It's the difference between burning hydrogen and nuclear fusion.
1. I'm not actually sure where a solar sail gets its energy from. My instinct is it keeps some of the energy delivered by the photons - i.e. re radiates them at a lower frequency. But that would mean a perfect reflector wouldn't experience radiation pressure, which seems wrong.
I'm not actually sure where a solar sail gets its energy from.
The Wikipedia article seems decent. Basically, EM radiation - regardless of whether you consider it as wave or particle - has momentum, even though photons are massless. Since it has momentum, it will transfer some of that to a surface it encounters. A perfectly reflective surface would gain momentum through elastic collision; a perfectly absorptive one through a completely inelastic one. (Of course any real surface will be partly reflective and partly absorptive.)
The actual quantum-scale interactions are more complicated, but you can just say "EM radiation has momentum" and at the macro level it's quite straightforward. The calculations are simple for perfect absorption and perfect reflection.
It's surprisingly small! .01g will get you 400,000,000 kilometers (the maximum distance Mars is ever from Earth) in 2.2 months in a straight line run (turning around halfway). At .001g, it would take about 7 months. Continuous acceleration ROCKS, even if it's minuscule.
In a real trip to Mars, you couldn't do a straight-line trip with this kind of drive - you'd plonk one into orbit conventionally, and then use the thrust to gradually raise the orbit until it intersects Mars. I'll leave it to someone with better skills to estimate how well that would work, but I think it's quite practical.
On the other hand, all sorts of things are practical with magic tech - let's not put the cart before the horse.
I'm not a rocket scientist so, being basically lazy, I Googled up this site:
http://www.cthreepo.com/lab/math1/
If I'm doing this right, an acceleration of 0.1G would get you Earth to Mars at nearest approach in 5.5 days and at their farthest, 15 days (plus a bit extra on that last one to avoid taking a straight line and running into the sun).
If you're not in a hurry, or are on tight power rations, accelerating/decelerating @ 0.01G would get you to your destination in 17 and 47 days respectively.
The beauty of constant acceleration, of course, is that -- just like keeping your money in the bank and letting the interest repeatedly compound -- constant acceleration quickly builds on itself to your advantage. So while our 0.1G drive could get us to Mars in between 5 and 15 days, it would get us out to the Jovian moons in something like 20 days, or to Pluto in less than 60. (These are all really quick and dirty averages but I'm really rather abusing the privilege with Pluto, since its orbit is so screwy, but the average should be in there, somewhere.)
Rockets to Mars, blah blah blah... Who cares?
The Laws of Physics as we know them would have to be wrong, fundamentally wrong. That's the important bit... Or there's a glitch in the (obviously-flawed*) experiment. Place your bets.
(* They left the door open to their vacuum chamber because their RF amp wasn't vacuum compatible. Sounds last-minute to me, otherwise why would they being using a vacuum chamber with the door open?)
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