how hot is plasma
Just wondered how hot the friction / air has to get to become plasma and thus conductive for the EM shield to work ?
I guess up till that temperature, then normal heat shielding has to be employed .
Space boffins have hatched a plan to test their radical new superconductor magnet forcefield re-entry heatshield technology by firing it into space from a Russian submarine. Flight International reported on the scheme yesterday, describing cooperative efforts by German space agency DLR (Deutschen Zentrums für Luft- und …
So at what temperature do these superconducting magnets work?
Isn't liquid nitrogen normally involved...? If the shield starts failing a little bit and temperatures rise, won't it fail catastrophically?
So all this is supposed to be lighter and less troublesome than pesky passive heat shields?
I'll keep my gold foil pants on if it's all the same to you...
Wouldn't be cheaper and easier to call NASA and to pull one of their SR-71 Blackbirds out of mothballs and put back in to service?
While its not a re-entry vehicle, wouldn't is also suffer from some of the same problems flying at Mach 3?? (I don't know the top speed or altitude)
Or borrow an F16 or one of the other 'super jet fighters' to fly really high in to the atmosphere and then launch a smaller rocket in to a shallow orbit for testing?
Yeah I know, I'm a US guy, but surely the EU and or Israel and other countries have similar capabilities without going all Polaris on us.
Ballistic missiles go high, very very high - far higher than even the magnificent SR71 Blackbird. Also, the size of the test object is far larger than any fighter can carry - a big plane like a B52 might manage the weight, but it would be aerodynamically hell.
No, it has to be tested by a ballistic missile - and why not go to a country with many spare ballistic missiles? Russia is probably cheaper than the US, too.
Ballistic missiles are totally the way to go.
The Russian Navy offers ballistic missile launches at a cut rate subsidized by their training budget. Payloads can be launched for as little as $500 a kilo! Or pound, I can't remember. Regardless, its cheap.
Using ballistic missiles for space launch is an old idea. American Gemini astronauts used to ride on Titan II ICBMs -- the same missile they used in Star Trek First Contact.
American ballistic missiles are regularly sold surpluss to companies who convert them into launch vehicles. Orbital Sciences does this.
For the record, the ceramic heat shields on the US Space Shuttle are designed to handle temperatures approaching 2000 degrees Celsius. Now, communication between earth and the ship gets squelched during the initial re-entry due to a phenomenon they call "ionization blackout." As I recall, when a gas ionizes due to heat, it is essentially becoming a plasma, so this sounds to me like they're hitting the butter zone, and the gas is sufficiently ionized for an EM shield to start working. I give credit to these boffins for at least saying essentially, "It sounds promising, but to know better, it's time for an experiment." A test flight and some hard data will at least tell us if this plan is more than just a load of hot air.
I think the idea is not to create different heat shieleding but in addition to conventional shielding - afterall you still need shielding up until plasma point. At which you could pretty much change your angle of descent to something more favourable.
If this shielding works then the possibilities of better windows of re-entry would exists.
@Ian Michael Gumby and other "why doesn't NASA..."
The article clearly states that it's the EU Space Agency, not NASA, that wants to test their tech. Hence the Russian missile and not a US aircraft (BB or F16, etc).
It, of course, would make no nationalistic sense to have a global space agency working in cohorts with each other for the betterment of space exploration...
Mine's the one with the "Federation" communicator on the left breast.
Anyone at all?
I'm such a child.
On a more serious note if the only (I say only like it's not significant) technical problems they've got is how to fit the kit into the testbed then they've already done a vast amount.
I am assuming the forcefield tech itself actually works of course. I look forward to the launch.
Well done, scf-fi realising, force field creating type science bods!
Oh, yeah. You could have the scene where the crewmember shouts "SHIELDS ARE FAILING!" and then everything explodes. Perhaps not good for the crew, but it gets points for being dramatically appropriate.
On a more serious note, this is interesting research. I guess a working magnetic shield would also be quite useful to keep charged particles away during long space trips, helping protect the crew from long-term exposure to radiation.
Temperature is a measure of kinetic energy. Researchers talk the enthalpy of the flow or the energy involved (WM^-2 or BTU/ft^2/Sec depending on what side of the Atlantic you happen to be on).
At high altitude pressure is literatly in molecules per ^m-3 rather than any conventional pressure unit. You get a "temperature" for dissocated air molecules and another for electrons. A typical model requires 11 seperate species to describe the airflow. Atoms can have temepartures of 10000K, while electrons have 15000k. Note leV=11605.4 K so that's less than 1eV of kinetic energy for electrons. It's like a match dropped on your hand. Lots of tempearture but little actual energy.
The question is how much energy gets dumped into the capsule *before* the flow is ionised enough for the magnets to deflect it. Should be interesting to find out.
"As it Says .... Anything can happen in the next half hour" ... Anonymous Coward Posted Wednesday 25th November 2009 13:28 GMT
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The reason they use russian missiles is that the Russians have huge stockpiles which there still trying to get rid of to meet decommisioning targets and so there cheap as chips to launch with and because the russians build good rockets they have great reliability.
Cheap, reliable, reducing the worlds stock of surplus military rockets, and performing great science... what more can you ask for?