Star gazers across North America were out in force on the second weekend of August to watch the annual Perseid meteor shower. With all those eyes aimed skyward, not much goes unobserved. But this year the throngs of enthusiasts were surprised and puzzled by a strange sighting.
On three consecutive nights, August 8, 9 and 10, a formation of three unblinking starlike objects in a flattened triangular configuration cruised across the star fields. Veteran stargazers had never seen anything like it.
Individually, they were unremarkable objects -- fourth magnitude (fainter than the Big Dipper stars) and moving like typical Earth-orbiting satellites, dozens of which are visible nightly. But three satellites travelling in formation? Bizarre.
The sightings became a hot topic among the 800 amateur astronomers at Starfest, Canada's largest astronomy convention held each summer at a dark-sky campground near Owen Sound. This year, Starfest coincided with the Perseid weekend and the strange trio of moving lights was tracked by scores of observers.
Immediately following Starfest, Ted Molczan, a Toronto-based satellite orbit expert, solved the mystery. Not only is there a set of three satellites traveling in formation, Molczan said, there are three sets -- and we saw two of them.
Molczan explained that the satellites are part of the U.S. navy's spaceborne electronic intelligence system, code-named Parcae after the three daughters of Zeus that spin, measure and cut thethread of fate. Before the code name became known, non-military satellite specialists named the satellites NOSS, for Naval Ocean Surveillance System.
Officially, the U.S. navy does not acknowledge the existence of NOSS and, until the Perseid weekend, most astronomers had never seen or heard of them.
Each group of three NOSS satellites flies at an altitude of 1,100 kilometers in a formation about 100 kilometers across. The satellites track the position, speed, and direction of travel of all military ships at sea. They do this by detecting communication, navigation and weapons control signals that are emitted almost continuously by naval ships. Three satellites in a group can pinpoint these ships much better than one by measuring the time difference of signal receipt.
Various versions of the NOSS satellite trio system have flown since the first test of the concept in 1971. The three sets now in use were launched in 1990, 1991 and 1996 and are about three meters across, much bigger than previous generations. But even so, Molczan says, these satellites are normally fainter than the sighting reports on the Perseid weekend. He notes that conditions were exceptionally favourable, with the satellites well positioned to reflect sunlight and seem brighter than normal.
Original file name: .CNI - Triangle of Stars??
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