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Revolutionary Ion Thruster To Be Tested On International Space Station (abc.net.au)
Three Australian researchers have developed "an ion thruster that could replace the current chemical-based rocket propulsion technology, which requires huge volumes of fuel to be loaded onto a spacecraft." Slashdot reader theweatherelectric shares this article from the ABC News:
An Australian-designed rocket propulsion system is heading to the International Space Station for a year-long experiment that ultimately could revolutionize space travel. The technology could be used to power a return trip to Mars without refuelling, and use recycled space junk for the fuel... It will be placed in a module outside the ISS, powered, as Dr Neumann describes, by an extension cord from the station. "What we'll be doing with our system is running it for as long as we can, hopefully for the entire year on the space station to measure how much force it's producing for how long."
In the early 2000s "it was basically a machine the size of a fist that spat ions from a very hot plasma ball through a magnetic nozzle at a very high velocity," and the researchers are now hoping to achieve the same effect by recycling the magnesium in space junk.
In the early 2000s "it was basically a machine the size of a fist that spat ions from a very hot plasma ball through a magnetic nozzle at a very high velocity," and the researchers are now hoping to achieve the same effect by recycling the magnesium in space junk.
No it isn't. TLDR, read atomic rockets, n00b. Or, since you won't be reading it : high specific impulse ion drives have existed in various test forms for years. They are easy to make and they all have high efficiency, albeit some designs are more reliable than others. The problem with all of them is the nasty equation KE = 1/2 m * V^2. That means the higher the exhaust velocity (and thus specific impulse which is the fuel efficiency), energy required goes up with the square of exhaust velocity.
Plenty of ion thruster designs, including VASIMR, have reasonable energy efficiency. The problem is that you still have to pay the bill even if the efficiency were 100%. You still have to supply as much electrical power as the kinetic energy of the escaping propellant.
This is a big problem. Even the most exotic nuclear power generator designs anyone has drawn up, the nuclear generator is a heavy ass piece of equipment being propelled by barely any resulting thrust from the ion drive. It means that you might have great specific impulse but trips to Mars still take months. What you need is also high thrust. That's why the best engine for space travel that currently is feasible is still plain old nuclear-thermal. You only get an ISP of about 1000 (compare to 15k for this particular thruster), but you get thousands of times more thrust. You can complete your Mars injection burn in about half an hour instead of having to run the engine for months. That in turn increases efficiency because there is always 1 optimal point to do your engine burns at.
For those interested, there is a lengthy and interesting interview with Dr Neumann about this on The Space Show. http://thespaceshow.com/show/0...
Hi,
I'm Ian Whitchurch, the CEO of Neumann Space.
First of all, if you want more technical information about the Neumann Drive, there's an article in Applied Physics Letters. It may be available here
http://scitation.aip.org/conte...
If that isnt working, then you might know someone with an APL subscription, or it might be somewhere on the internets under "A centre-triggered magnesium fuelled cathodic arc thruster uses sublimation to deliver a record high specific impulse Patrick R. C. Neumann, Marcela Bilek and David R. McKenzie".
Secondly, it's not just the Neumann Drive that's going up to the Bartolomeo platform on the ISS. We're planning on taking a bunch of other peoples small projects, which deserve to go into space, but cant by themselves get a ride into orbit, or an easy method to get power, heating, cooling and communications once they are there. If you're interested, you might want a look at this fine Airbus DS press release.
https://airbusdefenceandspace....
There is also information available about the Facility for Australian Space Tests on our website, at http://neumannspace.com/fast/
Thirdly, Im happy to answer further questions people might have.
Finally, our poor, poor website. Also, the original post lacks a poll, which itself lacks a Cmdr Taco option. What the heck am I supposed to vote for ?
The problem with space junk is less about getting to it and more about getting to it safely. Everything in orbit is travelling a minimum of 17,000 mph. Have you seen what happens when car into a wall at only a 100 mph difference? Think two flimsy satellites colliding with a 400 mph difference. There will be hypersonic shards of metal everywhere.
Anons need not reply. Questions end with a question mark.
http://descanso.jpl.nasa.gov/S... is as good a summary as any about NASA's current ion engines, while the APL paper by Neumann, Bilek and McKenzie for the http://scitation.aip.org/conte... has information about the Neumann Drive.
Short version is that xenon drives vary in specific impulse and power efficiency depending on the power levels, while Neumann Drives vary in specific impulse and power efficiency depending on the fuel used, while the power level affects how many pulses per seconds. Higher power levels appear to cause faster wear of the grid in Gridded Ion Thrusters, or the chamber in the case of Hall Effect Thrusters, as well as needing more investment in Power Processing Units and so on. Additionally, there is the issue of tankage, regulators and so on for dealing with the xenon itself, which means it's not a straight 1:1 comparison. That said ...
TLDR : Magnesium in a Neumann Drive runs about 9 uN/watt and 11 000s specific impulse. A NSTAR running at ~1000 watts input has about 32 uN/watt and 2850s of specific impulse.
Then simply 3D print ion thrusters on Mars and bring Mars closer to the Earth.
Do I have to do *all* the thinking around here?
The Neumann thruster is all about saving launch capacity. Most of the ion thrusters we have now work with e.g. Xenon gas; you have to loft their fuel, and your engine mass budget has to include the material handling for the propellant; tanks, valves, etc.
The idea of the neumann thruster is that your reaction mass comes from a simple sold puck which is gradually ionized; so you immediately win on a bunch of hardware you don't have to lift.
And then, you can use as reaction mass the sorts of stuff which is already up there in orbit. Got some excess second stage, which you've lofted to orbit at ruinous cost? Instead of dropping it back into the atmosphere to burn up, melt it into a puck at the focus of some mirrors, and then use it as reaction mass for a few years.
Space junk turned into valuable fuel. Big win. .... IF it works.
I'd like to see an EM Drive put into testing up there too (yes, yes, yes - I know it's defying the [known] laws of science. No reason not to test it in space since it seems to pass all tests on earth)
Hey maybe we could strap the ION Drive face-to-face with an EM Drive, throw them out the hatch and see who pushes who around!
Nahh, he's saying he's a fan of atomic rocket and he doesnt think anything else has the thrust to do what he wants, and so he does the circular firing squad thing that the space sector has been doing for the last fifty years.
Even if he is right, there is still a need for non time sensitive cargos of canned goods, metal powders for your advanced manufacturing printers, copper wire and all the other crap colonists will need, and thats where being able to go 'it'll take 500 days and we dont care' becomes important, even if it isnt the ion drives that are taking the humans to Mars they are still helping.
We know how Zubrin feels about VASIMR. There's also good reason to disagree with him. For example, his nuclear reactor criticism? He himself proposes building a powerful nuclear reactor to power colonies on Mars, so he's not self-consistent. His power density figures aren't anywhere close to realistic. He talks like 50W/kg is some sort of unachievably optimistic goal, when in reality ATK Ultraflex solar arrays already get 150W/kg (and MegaFlex 200W/kg), figures that have been going up significantly with time; high power nuclear designs for future space missions are measured in kilowatts per kilogram. His complaints about the funding that's gone to VASIMR versus other things are unfair, as VASIMR hasn't received all that much funding - certainly not enough to develop a nuclear reactor as he mentions. And nobody is going to develop a power system for VASIMR without having first validated the propulsion system (something Zubrin apparently doesn't want them to do). He tries to portray its various ion drive competitors as better, without mentioning that the primary reason for choosing VASIMR is its high peak thrust levels. Lastly, Zubrin's dismissal of the dangers of in-transit radiation is not shared by most researchers.
Everybody point at the libertarian and laugh.
It's a stupid comparison that's not to Zubrin's credit. The reason that no powerful space nuclear reactors have been developed is because there hasn't been any demand for them. Nuclear reactor power to weight ratios don't scale up linearly, they scale up vastly higher than linearly. Figures of 1000W/kg aren't just some sort of out-of-a-hat fantasy numbers, they're based on the very real work in the field. More to the point, even solar is already in the low hundreds of watts per kilogram, so again, Zubrin's acting like 10W/kg is the state of the art and 50W/kg overoptimistic is beyond absurd.
Everybody point at the libertarian and laugh.
It's a cylinder. Inside it are rods. The rods have channels in between. There is HEU fuel inside the rods and they are made of high temperature alloys.
For a practical Mars mission, your spacecraft would have 2-4 NERVA engines, each a little smaller than the last. On earth departure, you eject the rods that block the fuel channels and dampen the reaction. Engine is cold and has never been run at that point. You run the engine until the burn is complete. Then separate the hot radioactive mess of an engine that is melting down because when the propellant flow stops, so does the cooling.
That's the simplest way to do it. No nuclear power reactor, it's 1 time use. The pumps, radiation shield, and so forth you don't stage separate, you just eject the core and pressure vessel cannister it is. (so it can be extremely light, under a metric ton)