The first-stage booster supporting the mission has been used six previous times, including on four Starlink missions. UPDATE (6:57 a.m. Saturday): The countdown for Saturday's launch was paused a little more than an hour before liftoff, according to SpaceX's website. Crews are now targeting Sunday between 3:58 a.m. and 7:58 a.m. for the launch. — ORIGINAL STORY: Spa... [718 chars]