Yep. Could be GaAs.
<<ouch, that was soo bad>
The article said that similar arrays have been used recently in other space satellite systems.
Interesting bit of history towards the end of this article too: <a href="http://www.hughespace.com/hsc_pressreleases/99_10_22_spectrolab.html>http://www.hughespace.com/hsc_pressreleases/99_10_22_spectrolab.html
Marcia
