New US missile warning satellite fails

Washington: A Northrop Grumman Corp US military satellite designed to track enemy missiles stopped working in mid-September this year posing a potential problem for America's defence satellite constellation in the years ahead.

Defence analysts said though there was no gap in the US missile warning system, the apparent loss of a satellite, part of the Defense Support Program (DSP), could potentially expose a gap in the years to come because the redundancy of the existing constellation had been diminished.

Analysts also said that several amateur astronomers had reported that DSP 23, the last of the US missile-warning satellites built by Northrop, and launched in November 2007, had stopped transmitting in mid-September.

The fact that most of the satellites in the constellation have lasted longer than their designed operational life makes it all the more puzzling for analysts and experts that the latest in the series should have developed trouble within a year of its launch.

Defence department officials said it was unclear what had caused the failure. Explanations could range from defective parts to natural phenomenon, and though unlikely, also an intentional attack. It was also likely that the problem stemmed from the satellite being hit by space debris.

The US government has so far launched 23 DSP missile-warning satellites into space since 1970. Estimates by experts would suggest that of this number about six to 10 are still working, which would be about double the number needed to watch the entire Earth at the same time.

The inexplicable failure of DSP 23 has thrown the spotlight on the new Space Based Infrared Satellite (SBIRS) system being developed by Lockheed Martin Corp. The SBIRS programme too has been beset by problems, including delays due to technology challenges. The US government shot down a satellite last February, saying its toxic fuel tank posed a potential threat.

Though the first SBIRS sensor is already in space on board a classified satellite the first dedicated satellites of the class are not due to be launched until 2010. The SBIRS programme was launched in 1996 with the target of putting the first satellites in orbit by 2004, at a cost of $4.2 billion.

The programme has been restructured several times by now, and the budget has nearly tripled to over $11 billion.

Meanwhile, some amateur astronomers, who use optical and radio telescopes to track objects in space, have suggested that the DSP satellite may well be adrift in geosynchronous orbit. If so this could pose a danger to other satellites operating in that orbit. This possibility has been downplayed by defence officials.