October 31, 2006:
The increasing number of incidents of space satellites being "hacked", is actually just an increase in the number of satellites up there, and the number of ground stations broadcasting information up into the sky. Most of these "hacks" are just satellite signals interfering with one another. Same with cases where people believe their GPS or satellite communications signals are being jammed. On further investigation, the real reasons tend to be less interesting, and a lot more technical. All this usually has a large element of human error mixed in.
But all of this accidental jamming, only demonstrates how easy it would be to do it on purpose, and there have been a few examples of that. In response, the U.S. Air Force, which has taken the lead in developing electronic tools for attacking, and defending, satellite communications, and the satellites themselves, has been training people to attack, and defend, space satellites. This effort involves figuring out new, or improved, ways to jam satellites. Then you keep that stuff secret, in case potential enemies have not figured this out themselves. Next, you work on ways to defeat the weapons developed. Most of this is playing around with the signals themselves. You can unjam a jamming signal with another signal. However, a lot of trial and error is required, and you want to get that done way in advance of any actual war. When you do have to use this stuff for real, you have to expect that the enemy may well have come up with some angle you missed. Thus there will be some rapid improvisation, and you will have more time and resources for this if you have worked out, ahead of time, the details of disasters you have already anticipated. No one is releasing much information about this, for obvious reasons. There won't be much discussion from any government, unless there is a terrorist attack using these techniques. That's yet another thing to worry about. There have already been such attacks in China, by a banned religious group, and elsewhere. It can be done, it just isn't easy, and it's not getting an easier.