By now, if you're even the least technically inclined person, you've heard that a large U.S. satellite in orbit above us has lost the ability to control its position and is slowly drifting back to earth. U.S. officials conveyed the information to major news outlets, such as the New York Times and the Associated Press, on Saturday under anonymous conditions. Though the officials were cautious to categorize the nature of the machine, independent space experts quickly pegged it as a crippled spy satellite.
"Appropriate government agencies are monitoring the situation," Gordon Johndroe, a spokesman for the National Security Council, replied when asked about the matter after the news was leaked. "Numerous satellites over the years have come out of orbit and fallen harmlessly. We are looking at potential options to mitigate any possible damage this satellite may cause."
Beyond that, he would not comment on the status of the satellite or what measures might be employed to control its descent.
However, one intelligence expert who would go on the record, John Pike, told an AP reporter that spy satellites typically are disposed of through a controlled re-entry into the ocean to render the spacecraft inaccessible and he discounted any notion that the U.S. would try to destroy the object in orbit with a missile, as that would create an even more uncertain outcome for it.
Pike, the director of the defense research group globalsecurity.org said the vehicle in question is most likely an NROL-21 earth imaging satellite, which failed in its mission shortly after lift-off a year ago. For purposes of comparison, he told the AP that the slowly descending object is about the size of a small bus.
On its Web site, globalsecurity.org described the situation in these words:
A Delta II lifted off from Vandenberg Air Force Base on 14 December 2006, carrying the NROL-21 USA-193 satellite. The NROL-21 spacecraft failed within hours of its launch. By January 2008 the satellite was expected to reenter the Earth's atmosphere in late February or March. Although some of the spacecraft would burn up on reenty, the uncontrolled reentry could result in some heavier pieces of debris reaching the Earth's surface. The odds were about three in four that the debris would hit an ocean area. Although the safety hazard of the impacting debris was small, there was some concern that secrets of the spacecraft could be compromised if the debris were recovered by a hostile intelligence agency.
As to why the satellite failed in the first place, another expert told the New York Times it was essentially a matter of communications. "It''s not necessarily dead, but deaf," said Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics.
In light of the toxic substances spy satellites use in their missions, he added: "For the most part, re-entering space hardware isn''t a threat because so much of the Earth is empty. But one could say we''ve been lucky so far."
With a timeline of a month or so before the orbit of the NROL-21 decays to a point where it plummets through the atmosphere, there will be plenty of opportunitiy for scientists to calculate its probable crash site. The odds are good, though, that it will not be situated near your neighborhood or anyone else's.