Live coverage: Atlas 5 countdown and launch journal

A new generation of spacecraft with unprecedented clarity and speed to observe the weather, improve forecasting and enhance tracking of severe storms across the United States begins with the launch of an Atlas 5 rocket on Saturday.

SpaceX engineers are readying two Falcon 9 rockets for launches Oct. 7 and Oct. 9 from Florida and California, setting up another quick turnaround to first deploy a large TV broadcasting satellite for SES and EchoStar over the United States with a previously-flown booster, then add 10 more spacecraft to Iridium’s fleet of new-generation voice and data relay network.

A United Launch Alliance Atlas 5 rocket lifted off from Cape Canaveral at 1:21 p.m. EDT (1721 GMT) with a satellite to replenish the U.S. Air Force’s Global Positioning System navigation network.