Wednesday, 27 June 2012

A flashing GPS satellite (Navstar 39, USA 128)

This blog's readers will be familiar with the Global Positioning System (GPS). These US navigational satellites provide us with navigational aid, whether you are on a boat, aircraft, in a vehicle, hiking, or just using your cellphone. Our modern world would be nowhere without them.

But have you ever seen a GPS satellite?

click image to enlarge

In the evening of June 25 I by chance captured one of the 41 operational a GPS satellite that was decommisioned last year on photograph: Navstar 39 (USA 128, GPS 2A-27, 1996-056A). It showed up as a very bright small trail  and was flashing at a rate of  2-3 flashes per 10 seconds. Above is a compilation of the photographs taken (Canon EOS 60D with Samyang 1.4/85mm lens).

GPS satellites do not usually get this bright: the satellite was evidently flaring due to a favourable sun-satellite-observer line-up. As this is a decommisioned satellite, the flashing could be due (I am not sure) to the satellite having lost attitude control and being spinning.

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