Department of Defense and U.S. Navy officials were cheering after a modified Standard SM-3 missile from the Aegis cruiser Lake Erie (CG-70) shot down a disabled American spy satellite. The published reason for the feat-believed to be the second time that a missile launched from the surface of the earth has shot down a space object-was to destroy the satellite's dangerous hydrazine fuel tank.
The first such event probably occurred in January 2007, when the Chinese employed an SC-19 ballistic missile to fire directly at and destroy an outdated Feng-Yun-1C weather satellite 527 miles above the earth. Two previous anti-satellite (ASAT) attempts by China may have been intentional misses for test purposes. At the time of those earlier missile launches the U.S. intelligence community reportedly believed that China was close to proving the ability to hit an orbiting satellite; still, some U.S. officials were taken by surprise when the ASAT capability was demonstrated, creating a massive field of space debris.
But almost immediately after the 21 February satellite shootdown by the Lake Erie, theories erupted about the intercept's real purpose. One, that it was to send a message to China that the United States could also shoot down a satellite, albeit one falling out of orbit. Other theories include a message to Iran, North Korea, and other countries that the United States has a viable ballisticmissile defense capability; a demonstration test to prove to U.S. engineers and military leaders-and the public-that the system really works; and to prevent components of the spy satellite from falling into areas where they might be compromised.
All are probably true. Indeed, the least likely reason-some would say the least valid-was to destroy the fuel tank. The classified spy satellite malfunctioned soon after launch. On board was a tank containing approximately 1,000 pounds of hydrazine, which was intended to power the satellite's maneuvering system. Hydrazine is highly toxic and, according to the Department of Defense, the fuel tank might have survived the satellite's reentry into the earth's atmosphere. But several scientists and engineers speaking publicly have said that the probability of the spherical fuel tank surviving the reentry and endangering people was virtually nil.
While most of the smaller components of the satellite would have burned up as they passed through the earth's atmosphere, large sections, including those containing the hydrazine fuel, may have survived. This was not the first time a satellite passed through the atmosphere containing dangerous materials. Small nuclear reactors with their radioactive fuel of three Soviet radar ocean reconnaissance satellites (RORSAT) have plunged into the earth's atmosphere: Kosmos 954 in January 1978, with portions of that craft landing in Canada; Kosmos 1402 in February 1983, which fell into the Indian Ocean; and Kosmos 1990 in February 1989. Apparently no significant pieces of the last survived reentry. (The U.S. Skylab-sans dangerous materials-reentered the earth's atmosphere in 1979, spewing debris onto buildings in the town of Esperance, south of Perth, on the western coast of Australia. The U.S. government was fined for littering!)
No attempt was made to intercept the RORSAT reactor sections when they plunged to earth-there was little realistic capability to do so at those times.
In February 2008, six days after the destruction of the U.S. spy satellite, secretary of Defense Robert M. Gates said that the mission's success shows that U.S. plans for a missile-defense system are realistic. However, he added that the three U.S. Aegis ships assigned to the operation would not retain their anti-satellite capability, but would continue to be capable of intercepting tactical/ theater ballistic missiles.
There is a major difference between intercepting a rapidly decaying satellite about 150 miles above the earth and a satellite in low-earth orbit, at least 200 miles above the earth or, as the Chinese intercept just over a year ago, more than 500 miles above the earth. Still, to score a direct hit at an altitude of some 150 miles against an object traveling at almost 18,000 miles per hour was a remarkable feat. The satellite's larger remnants were expected to mostly burn up in the earth's atmosphere with the surviving chunks coming down at sea; the smaller pieces would burn up in the atmosphere over the next 40 days.
The Lake Erie was the first of several U.S. Aegis cruisers and destroyers to be fitted with a ballistic-missile intercept system. In July 2006, when the North Koreans launched several ballistic missiles, the Lake Erie and two Aegis destroyers were sent to the area. They tracked and monitored those missile tests.
For the February 2008 intercept the Lake Erie was accompanied by the Aegis destroyers Decatur (DDG-73) and Russell (DDG-59). They deployed west of Hawaii and were fitted with upgraded computer/ fire-control programs and the modified Standard SM-3 missile.
Other versions of the Standard missile arm all U.S. CG/DDG warships as well as those of some other nations, including several Japanese Aegis destroyers that are also configured for ballistic-missile defense. The SM-3 missile employed in the ASAT role is 21-feet long and has a small fourth stage for the "hard kill" role. The weapon generates 130 megajoules of kinetic energy at the point of impact.
Details of its target are largely classified. The spy satellite-given the tracking number USA 193-weighed an estimated 5,000 pounds and reportedly was some 15 feet long and 8 feet in diameter; with its radar antennas extended the satellite was about the size of a basketball court. It was launched from Vandenberg Air Force Base, California, on 14 December 2006, atop a Delta II rocket. It failed to function immediately after launch.
The Lake Erie shoot-down stands as a milestone in the development of the Aegis Fleet air/missile defense system, showing the flexibility of that shipborne weapon system. While the Aegis could still face even more difficult challenges, such as intercepting antiship missiles in coastal or littoral areas, it has now demonstrated another aspect of the system's ballistic-missile defense capabilities.
Proceedings columnist and author Norman Polmar has been named chairman of the Science and Technology Advisory Committee of the Department of Homeland security. The committee makes recommendations to the Under secretary, including identifying research areas of potential importance to national security. By legislation, it consists of 20 members who are eminent in such fields as emergency response, research, engineering, new product development, business, and management consulting. They are appointed on the basis of distinguished service and selected to provide a cross-section of the research, development, demonstration, and implementation expertise. The committee met from 2002 to 2004 under the chairmanship of retired Air Force General Larry Welch, after which it ceased functioning. It was reestablished in 2007.