According to BusinessWeek, a congressional commission has concluded that hackers—probably affiliated with the Chinese military—"interfered" with two U.S. satellites in in 2007 and 2008. So apparently satellites are things you can hack into.
The satellites were earth observation satellites, and the periods of interference only lasted minutes at a time. The commission found that whoever was hacking into them "achieved all steps required to command the satellite"—though they never actually exercised that control. The incursion took place through a commercial satellite station based in Norway.
That makes defacing web sites and scooping up emails seem a little...junior varsity? Anonymous needs to up its game, and start send flaming balls of wreckage careening toward its enemies from the sky.