LONDON — Mobile satellite services provider Globalstar on Dec. 5 said it has returned to full service a satellite that had been removed from operation in early 2011 following a defect in one of its momentum wheels.
Globalstar said the fix will permit the satellite, launched in October 2010, to function for its full 15-year life, and that the software upload is applicable to any of the other 17 second-generation Globalstar satellites in orbit.
The software patch was developed by Covington, La.-based Globalstar and its satellite prime contractor, Thales Alenia Space of France and Italy, following momentum-wheel friction issues that were one of several reasons for the delay in the launch of the full 24-satellite second-generation constellation.
Globalstar has rescheduled the launch of the last batch of six satellites for early February aboard a Russian Soyuz rocket marketed by an affiliate of Arianespace of Evry, France, and operated from Russia’s Baikonur Cosmodrome in Kazakhstan.
Each Globalstar satellite carries four momentum wheels, manufactured by Goodrich ISR Systems, a division of United Technologies Corp. The satellites need three wheels to function, with the fourth acting as a spare.
Globalstar had taken the affected satellite out of service several weeks after it was placed into operational orbit as a preventive measure to begin an investigation into the cause of the problem, and into possible work-around, before a second wheel failure occurred.
Thales Alenia Space officials have said the software repair will permit the Globalstar satellites to function in most operating modes with just two momentum wheels. The modification involves compensating for the loss of a wheel on one axis.
Globalstar Chairman Jay Monroe, in a Dec. 5 statement, said the software package “also provides a fix for similar problems that may happen across our constellation.”