Tech Talk

The plan announced by the military involves using a single Standard Missile 3 from the Aegis Ballistic Missile Defense System arsenal aboard a U.S. destroyer in the Pacific to hit the approximately 2500-kg satellite as it begins to plummet into the planet's atmosphere and, thereby, burn or dissipate its fuel complement, while also breaking it into pieces more likely to disintegrate on re-entry.

Gen. Cartwright told the media that if the first missile fails, the White House would advise the Navy as to whether it should take a second or third shot from another destroyer. He said that, once the satellite enters the atmosphere, it will be "next to impossible" to strike it with Aegis technology, due to the fluctuations of re-entry. Still, the general said that this approach offered the best chance possible of reducing the potential for harm in this situation. "We are better off taking the attempt than not," he noted.

The controversial nature of such an attempted shoot-down in very low orbit comes by way of comparing today's plan to an incident from last year in which the Chinese military used an anti-satellite (ASAT) system to destroy one of its own aging weather satellites. Thirteen months ago, the incident touched off a roaring debate in the media over the unannounced move as a hostile demonstration of China's newfound capabilities in space. At the time, representatives of the U.S. government denounced the action as being deliberately provocative. Since then, the dispute has largely died down as cooler heads in the public sector prevailed. One of the cooler heads was our own longtime contributor on space technology, James Oberg.

In a blog entry in this space from January 2007, Is China's Satellite Killer a Threat?, Oberg wrote: "The question now is whether China's ASAT missile is a serious weapon or merely a symbol, meant to put pressure on other countries, particularly the United States. To answer it, we must examine the gap separating the satellite-killing demonstration and the needs of a real weapon--one that would be a genuine threat to other countries' satellites."

He reasoned: "The Chinese weapons system has so far demonstrated only that it can pose a threat to low-orbiting objects, of which the most important are reconnaissance satellites. But these satellites have backup." In a masterful analysis, he cautioned policymakers to look beyond the primitive technical merits of the Chinese demonstration and concentrate on its political implications.

(Please visit the James Oberg website for more insight into this topic and related matters involving space warfare technology.)

After the flurry of news today reached one of my bosses at IEEE Spectrum, he sent me a note wondering whether the U.S. plan to kill one of its own satellites wasn't overly similar to last year's demonstration by China, and he pointed to a report in today's New York Times online edition, U.S. Officials Say Broken Satellite Will Be Shot Down, which contained the following language: "The United States has opposed calls for a treaty limiting anti-satellite or other weapons in space. On Thursday, officials pledged that the United States will remain wholly within compliance of treaties requiring the notification of other nations before it launches a missile at the disabled satellite."

So I thought I understood what the implications of the inquiry by this senior Spectrum editor were.

In my reply to him, I noted that I thought the argument put forth in the press conference by Gen. Cartwright was correct, where he said there was no intended parallel between the Chinese action and the U.S plan, because the former was a vehicle orbiting at a much higher altitude, 850 km, than that of the latter, which will be targeted as its decaying orbit descends to about 240 km. The American plan will likely leave some debris intact at the edge of space for a period of time (before it also burns up on re-entry)--if the interception even works. But the Chinese ASAT test left the largest known debris field ever in a prime orbital altitude, where it will pose a constant hazard to future spacecraft.

My conclusion is that the two ASAT scenarios are apples and oranges. The Chinese test was unnecessary and intended. The planned U.S. attempt is necessary and unintended.

Today's Pentagon briefing sounds like the first signal to the rest of the world that the U.S. will respond with its ASAT technology to accidental situations such as this when they threaten populated areas. Beyond that, the plan looks like a response to what Gen. Cartwright said today is "a little bit different" case.