This encyclopaedia contains lots of spoilers - you should play through the campaigns first before reading too much here!cam22fmv.ogg: Construction of a satellite defence system began in 2081 and was completed in 2082.
In 2085, the NASDA satellites fired their nukes at earth.
There were also ground based sites. Many of these were destroyed in the nuclear counter-strikes, but there's bound to be some out there.
The NASDA satellites also contained pulse lasers designed to shoot down missiles approaching North America.
We know that NEXUS is searching for NASDA Central in the Eastern Sector. This was one of the land-based control centres for the satellites.