WASHINGTON — The U.S. government’s announcement Feb. 14 that it plans to shoot down a dead satellite rather than allow its toxic hydrazine fuel to come down and possibly cause harm touched off a flurry of speculation about possible ulterior motives, but NASA Administrator Mike Griffin was adamant that the hazard is real and unique.
“The hydrazine tank will survive entry and will, absent a very lucky break, land with enough hydrazine onboard to pose the hazard cited in the briefing,” Griffin told Space News via e-mail Feb. 14. Earlier in the day, Griffin, U.S. Marine Corps Gen. James Cartwright, vice chairman of the Joint Chiefs of Staff, and Ambassador James Jeffrey, deputy national security advisor to U.S. President George W. Bush, held a Pentagon press conference to announce and explain the decision to go ahead with the unprecedented operation.
The satellite in question is a classified U.S. National Reconnaissance Office (NRO) spacecraft that died shortly after being launched in December 2006. In January, U.S. government officials acknowledged that the 2,275-kilogram experimental satellite was hurtling out-of-control toward Earth and likely would re-enter the atmosphere sometime during March.
At the time White House officials downplayed the danger. But an intelligence source said the NRO determined more than a month ago that there was a risk and consulted with NASA, U.S. Air Force Space Command and other government agencies on the matter.
After evaluating the risk, these organizations made recommendations to the White House National Security Council. The council then recommended to the president that the satellite be shot down, if possible.
During the press conference, Griffin said it is impossible to predict today where the satellite might come down if left to re-enter the atmosphere on its own.
Although numerous bus-sized spacecraft have come crashing back to Earth harmlessly over the years, the NRO craft is unique in that it has a full load of frozen hydrazine aboard, Griffin said in his e-mail. “No other case is known … wherein a tank full of hydrazine impacted land in an uncontrolled re-entry,” Griffin said.
A similar tank aboard NASA’s doomed Space Shuttle Columbia, which broke up upon re-entry in February 2003, came down intact in a wooded area in Texas. But Griffin noted that the shuttle tank was nearly empty upon landing.
“We have no experience with the entry of a frozen tank of hydrazine,” Griffin said. “We know that the entry heat loads are insufficient to melt the hydrazine completely, much less vaporize it completely.”
During the press conference, Griffin said the tank will be breached because its feed lines will be severed during re-entry and that the hydrazine eventually would evaporate. As a result, officials said, an area roughly the size of two football fields would be affected.
While the chances of the tank coming down in a populated area are small, the danger was deemed sufficient to justify the shootdown, Jeffrey said. “Specifically, there was enough of a risk for the president to be quite concerned about human life,” he said.
Several experts suggested other factors might have played into the decision to move ahead with the intercept attempt, which will utilize U.S. Navy ships equipped with the Aegis Ballistic Missile Defense System and will take place during a several day window that opens after NASA’s Space Shuttle Atlantis returns from its assembly mission at the international space station. At press time, the shuttle was slated to land Feb. 20.
Some saw as a potential motivating factor – or at least a side benefit – the opportunity to demonstrate the Aegis Ballistic Missile Defense (BMD) system in a real-world scenario. Although the Aegis BMD system has been largely successful in demonstrations to date, the U.S. missile defense program in general has come under criticism over the years for choreographing its tests.
“It’s closer to an operational type condition than you would get on an instrumented range,” said one former congressional staffer.
Others saw it as a demonstration of an anti-satellite capability, noting that it comes roughly one year after China deliberately destroyed one of its own satellites with a ground-based missile. “The stated rationale for the test of dealing with a fuel problem is disingenuous,” said Michael Krepon, cofounder of the Stimson Center, a think tank here. “This is a thinly disguised,
Cartwright said software modifications are being made to the interceptor, known as the Standard Missile 3, and to the Aegis targeting system, for the shoot-down attempt. He
characterized the changes as a “one time deal,” and said the Standard Missile 3 was chosen because of its proven hit-to-kill capabilities.
“This is an extreme measure for this problem,” Cartwright said. “It would not be transferable to a fleet configuration.”
The Chinese anti-satellite test was widely criticized around the world
as an unnecessary act
that created a tremendous amount of hazardous debris in a heavily utilized area of Earth orbit. It was the first destructive anti-satellite test since 1985, when the United States destroyed one of its own spent satellites with an air-launched missile.
Cartwright and Griffin said the planned intercept of the U.S. spy satellite will take place at a low enough altitude – about 240 kilometers – that orbital debris will not be a lasting problem. They said more than 50 percent of the remains of the destroyed satellite would re-enter and burn up after less than two orbits – in other words, within hours – and the remainder would come down within a month.
The Chinese test, by contrast, occurred at an altitude of some 850 kilometers, Griffin said. Cartwright said debris from that test likely will remain aloft for 20 years or more.
Cartwright also dismissed speculation that the satellite’s destruction was ordered
to prevent its sensitive and highly classified onboard technology from falling into the wrong hands. “That is really not an issue,” he said. ”Once you go through the atmosphere and the heating and the burning, that would not be an issue in this case. It would not justify using a missile to take it and break it up further.”
Asked whether the planned shootdown was in any way a response to China’s test, Cartwright said: “This is all about trying to reduce the danger to human beings. That was a decision that was taken by the president after listening to all the technical arguments you’ve heard today. That was the calculation: hydrazine equals hazard to human beings, and we tried to do what we could to mitigate it.”
The former congressional staffer also was skeptical that sending a message to China was part of the administration’s calculus. “There are probably as many reasons not to do anything as to do anything if the issue is sending signals, which is why I expect that’s not their intention,” the former staffer said. But the former staffer added that now that this “target of opportunity” has presented itself, it is hard to avoid coming to the conclusion that it serves multiple ends, both diplomatic and technical.
“The politics of proving that U.S. missile defenses have offensive capabilities are not good,” said Theresa Hitchens, director of the Center for Defense Information, a think tank here. “There have always been suspicions abroad that missile defense was just a cover story for offensive [anti-satellite weapons]. I don’t believe that, but this doesn’t help the perception.”
Retired Air Force Maj. Gen. Robert Dickman, now executive director of the American Association of Aeronautics and Astronautics, said the White House may have been swayed by the potential consequences of not acting. “There is a safety risk,” Dickman said. “If we had the opportunity to mitigate that risk and chose not to and we got unlucky enough that it landed in a densely populated area I’m not sure how we would defend ourselves.”
Jeffrey noted that another key difference between the Chinese anti-satellite test and the Pentagon’s plan is that the White House has been up front about informing the international community – along with other branches of the U.S. government. “We let many countries know at the end of January that the satellite was descending, that it would likely have hydrazine, and talked a bit about the consequences of that,” he said. “Today, we’re reaching out to all countries and various organizations – the U.N., some of its subordinate agencies, the European Space Agency and NATO – to inform them of the actions that we’re describing to you today.”
Joan Johnson-Freese, a professor at the U.S. Naval War College and an expert on space policy issues, said the U.S. diplomatic initiative could set a standard for other countries planning similarly controversial actions. “We have set up a new model for a regime when you have to do these sorts of things… The model has been set, to our credit,” she said.