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Hypersonic Radio Black-Out Problem Solved
KentuckyFC writes "Russian physicists have come up with a new way to communicate with hypersonic vehicles surrounded by a sheath of plasma. Ordinarily, this plasma absorbs and reflects radio waves at communications frequencies, leading to a few tense minutes during the re-entry of manned vehicles such as the shuttle. However, the problem is even more acute for military vehicles such as ballistic missiles and hypersonic planes. Radio blackout prevents these vehicles from accessing GPS signals for navigation and does not allow them to be re-targeted or disarmed at the last minute. But a group of Russian physicists say they can get around this problem by turning the entire plasma sheath into a radio antenna. They point out that any incoming signal is both reflected and absorbed by the plasma. The reflected signal is lost but the absorbed energy sets up a resonating electric field at a certain depth within the plasma. In effect, this layer within the plasma acts like a radio antenna, receiving the signal. However, the signal cannot travel further through the plasma to the spacecraft."
Until the creation of the Tracking and Data Relay Satellite System, the Space Shuttle would, like Gemini, Mercury, Apollo, and others, endure a 30 minute long communications blackout before landing. However, the Shuttle can communicate with a Tracking and Data Relay Satellite during re-entry. This is because the shape of the Shuttle creates a "hole" in the ionized air envelope, at the tail end of the craft, through which it can communicate upwards to a satellite in orbit and thence to a ground station.
Damn Obama, wasting our taxe... oh? Whats that? Russian Scientists you say?
The space program has been used for military research and military purposes. There's quite a bit of overlap between sending a man to orbit and sending a missile to orbit. That GPS satellite can be used to get you from point A to B or that ballistic missile to Moscow. Satellite cameras to search the stars aren't altogether different from spy satellites to search the ground. Maybe some of the experience they've gotten from, say, the Mars rovers was useful in building the various military drones they have now.
I think it's fair to say that the military would find ways to use civilian technology in relevant fields, and space exploration has some pretty big overlaps.
SSC
I read the full summary. The last sentence that the signal cannot travel into the craft from the plasma. How is that solved?
FTFA:
Considering we can communicate with interplanetary (and now some technically interstellar) probes with received signal strengths on the order of -200 dBm, and we can build arbitrarily large transmitters/receivers on the ground, and health and status telemetry doesn't require huge bandwidths (on the order of 10^2 bps), I'd say he's right.
I can see the fnords!
You're really limit in your thinking.
Technology is constantly developed to make killing more precise; which means LESS killing.
And there are a hell of a lot of spin-offs that are used in civilian markets. I don't see why you have created some sort of demarcation between killing tech and non killing tech. there is just tech that is used. The same tech is often used for killing as it used for non killing.
The Kruger Dunning explains most post on
I'm pretty sure it would all work out if they just reversed the polarity of the tachyon emitter.
Well, I read the full introduction of the paper, and the conclusion, skipping only the detailed plasma physics models & calculations. They do mention the strategy of putting an antenna through the plasma which can last as long as one fuel tank before it ablates, but they instead propose that (more elegantly) a small commercially-available 3 kW high frequency klystron amplifier (a lot less power than the radar) be placed at the surface of the aircraft, where it will disrupt a very small region of the plasma in a manner that will scatter ~.7 - 2% of the original incoming signal (which will resonates in a layer of the plasma) back to the aircraft; that is enough power for a 5 m. antenna and a commercially-available high sensitivity GPS receiver to pick it up. There is an analogous explanation for outgoing signals. They account for quite a few confounding plasma effects, acknowledge that there are some others that can't be modeled so clearly (or maybe they didn't think of), but predict that getting the system to work would be a not-so-difficult engineering challenge.
My first thought was, "Boy, I hope all the space opera authors read this preprint: no more signal attenuation from the plasma engines in the atmosphere!" Now there is one more area in which reality is exceeding a certain segment of--rather soft--science fiction (that I am only familiar with--AHEM--because of Baen's visionary no-DRM any-format ebook policy).
That's actually exactly what they're doing, but slightly different approaches.
Patent:
Uses adaptive impedance matching to allow signal propagation through the plasma.
This project:
Uses adaptive frequency matching to allow signal re-transmission through the plasma.
Same net effect, exploiting the same properties (The patent changes the impedance of the transmission circuit to match the plasma, while TFA describes varying the frequency until we hit an impedance match with the plasma (changing the frequency changes the effective impedance of the plasma).
The A-135 can only really defend Moscow against a single warhead, or just a handful at the most. The radar system itself is susceptible to suppression, seeing as how there's only one pillbox providing support for the interceptors. Only the first wave defense is likely to be effective, and there's only 32 of those missiles, which would hardly put much of a dent into a serious ballistic missile attack, considering the number of decoys and warheads implemented in modern missile systems. The second wave defenses, while more numerous, are non-nuclear now and probably wouldn't intercept much of anything. They were designed for nuclear warheads originally, something which of course would irradiate much of Moscow anyway. There may still be some nuclear warheads in the second wave, but stopping the enemy missiles from striking your city isn't all that great if your own missiles kill you anyway.
This is all, of course, predicated on the idea that the A-135 is still operational. There's some evidence that it's not, really, and only used for "tests" whenever the US starts thinking about upgrading their own ABM systems.
-mrxak
Onions Will Kill You