Chinese Laser vs. U.S. Sats?
"China has fired high-power lasers at U.S. spy satellites flying over its territory in... a test of Chinese ability to blind the spacecraft," Defense News is reporting. And, at least in theory, those lasers might be able temporarily take offline America's most powerful orbiting spies, like the giant electro-optical Keyhole spacecraft or radar-based satellites like the Lacrosse.
Now, the article is a little short on details. "It remains unclear how many times the ground-based laser was tested against U.S. spacecraft or whether it was successful," the story says.
And there's a touch of hyperbole in the piece. According to the article, a recent Pentagon report "acknowledge[d] China has the ability to blind U.S. satellites, thanks to a powerful ground-based laser." That's not exactly right. What the report actually says isn't quite so definitive:
Evidence exists that China is improving its situational awareness in space, which will give it the ability to track and identify most satellites. Such capability will allow for the deconfliction of Chinese satellites, and would also be required for offensive actions. At least one of the satellite attack systems appears to be a groundbased laser designed to damage or blind imaging satellites.
Nevertheless, citing unnamed "top officials," the trade journal asserts that "China not only has the [anti-satellite] capability, but has exercised it. It is not clear when China first used lasers to attack American satellites. Sources would only say that there have been several tests over the past several years."
Within the U.S. military, there's a contingent that's been worried for years about China arming up like this. The other day, I was talking to an Air Force colonel, about the Pentagon's plans for "prompt global strike" -- the ability to launch, in a matter of hours, a bolt-from-the-blue attack against an enemy thousands and thousands of miles away. Some in the armed forces talk about the strikes as a way to take out an Iranian nuclear facility, a terrorist chieftain, or a North Korean missile on the launchpad. But this colonel had a different target in mind for the instant attack: a Chinese "anti-satellite, ground-based laser wreak[ing] havoc with our constellation."
If China really is pursuing such a weapon, it wouldn't be the only country looking at lasers to interfere with enemy eyes above the sky. In a 1997 test, the U.S. fired a chemical laser at a satellite orbiting 420 kilometers above the Earth. The "laser apparently had technical difficulties," according to the Union of Concerned Scientists, "but the results of the test were startling."
A lower-power (30-watt) laser intended for alignment of the system and tracking of the satellite was the primary laser source used during the test, and it appeared that this lower-power laser was sufficiently powerful itself to blind the satellite temporarily, although it could not destroy the sensor.
These days, the Air Force's Starfire Optical Range is shooting lasers in the sky, trying to figure out how best to correct for atmospheric interference. Astronomers looking into the heavens will be the most immediate beneficiaries. But Starfire could help out anti-satellite weaponeers, too. These days, ground-based lasers aren't powerful enough -- or good enough at traveling through the air -- to permanently take out a satellite; the best the beams might be able to do is blind the thing, temporarily. That could change, if Starfire (or its Chinese equivalent) does its job right.
UPDATE 10:12 AM: Color Theresea Hitchens, the Center for Defense Information's resident spacewar guru, "not convinced – nor impressed."
The folks quoted in this story are neither space nor China experts -- and those folks are easy to find. And there is the odd timing: just as Griffin goes to China, over the earlier objections of Rummy and the P-gon. Statements like "China's burgeoning antisatellite capabilities..." -- who SAYS? Even the P-gon hasn't gone that far in its reports on Chinese Military Power.
All that said, I would NOT be surprised if the Chinese were testing a Ground-Based Laser. So are we, at Starfire Optical Range. If they lased U.S. satellites though, how do we know they were trying to blind them rather than TRACK them -- since we say Starfire is using lasers only to track sats? China doesn't have all that great tracking ability, and it needs it, not just to track our stuff but their own. There isn't any real way to tell, I don't think, what the INTENT behind such lasing would be.
NOT that it is a good thing -- lasing other people's sats without their consent, or at least specific statements of your intent to do only tracking, in peacetime ought to be off the playing field, hence the need for a code of conduct of some sort in space operations.
Finally, with regard to laser blinding -- it is not as easy as it sounds to "blind" an optical satellite with a laser. I'm no physicist, but as I understand it, imaging satellites usually work in several wavelengths, meaning first of all you'd have to have lasers in all the colors that match those wavelengths to blind the sat, not just one single wavelength laser beam. Secondly, because of the way imaging sats work, taking pictures of strips of the Earth using strips of pixels, you'd have to figure out how to blind all the pixels -- which apparently is so hard as to be well nigh impossible. And I note that as far as I know, we haven't gotten that far with Starfire, so what makes us so sure the Chinese are ahead of us there?
If you ask me, the story raises more questions than answers.
One reason that the US may oppose banning weapons in space is because we already *have* nuclear weapons in space, in the form of the Ajax Project: http://www.WebFeats.com/EOD/
Posted by: Hank Mishkoff at January 23, 2007 2:37 PM