WATCH LIVE FRIDAY: Air Force Launching Missile-Detecting Satellite @ 7:42 pm ET

The U.S. Air Force's SBIRS Geo-3 satellite is scheduled to launch atop a United Launch Alliance (ULA) Atlas V rocket Friday (Jan. 20) at 7:42 p.m. EST (0042 GMT on Jan. 21). Watch the liftoff live here at Space.com, courtesy of ULA.