Iridium Communications Inc of McLean, VA, USA has completed an extensive testing program for qualification of its new solar panel design for the Iridium NEXT constellation of satellites.
The array that powers the satellites contains four solar panels and will span 9.4m when fully extended, developing more than 2kW of power over a demanding charging cycle in Iridium’s low earth orbit. The panel was developed by Boeing subsidiary Spectrolab Inc of Sylmar, CA, USA, which manufactures multi-junction space solar cells and panels, and Mitsubishi Electric Corp (MELCO), which supplies lightweight solar panel substrates. These companies are part of the Iridium NEXT Mission Team, led by Iridium’s prime contractor and European satellite manufacturer Thales Alenia Space.
The solar arrays are powered by new, larger triple-junction (XTJ) solar cells manufactured from 6-inch wafers, which yield 50% more solar cell surface area than cells used in Iridium’s existing constellation and deliver higher performance while reducing costs.
“The successful completion of qualification testing for the solar panel design marks yet another important milestone on our journey to launching Iridium NEXT,” says Iridium’s chief operating officer Scott Smith. "The innovation at the heart of the solar panels demonstrates how we are fundamentally re-thinking the design of every aspect of our constellation with improved efficiency, performance and longevity in mind.”
Working closely with Spectrolab, the new design was put through a grueling life test and qualification program to ensure that it works to specification using representative sections of the actual panels. The design verification test represented every mechanical and electrical configuration and was tested with a simulation of the rigorous low-earth-orbit charging environment into which the arrays will be deployed.
The solar array was tested to 1.5 times its planned lifespan in space to ensure it can meet and exceed the expected lifetime of the satellite. The solar cells were put through 75,000 thermal cycles, each one representing the Iridium NEXT satellite’s movements in and out of the sun’s radiating heat as it orbits the Earth.
The Iridium NEXT satellite network will consist of 66 in-orbit satellites and a number of in-orbit spares. The constellation is expected to begin launching in 2015 and will offer continued service for Iridium customers as well as greater bandwidth and data speeds when fully operational in 2017.
