SpaceX launched a Falcon 9 rocket at 7:29 a.m. PDT (10:29 a.m. EDT; 1429 UTC) Sunday from Vandenberg Space Force Base, California with 10 missile tracking and data relay satellites for the U.S. military’s Space Development Agency. The launch occurred three days after SpaceX aborted the first launch attempt at T-minus 3 seconds to examine data from one of the Falcon 9’s main engines.

SpaceX is preparing this week for the second flight of the upgraded “Block 5” version of the company’s Falcon 9 rocket, and a hold-down firing of the booster was accomplished Wednesday at Cape Canaveral ahead of a middle-of-the-night launch this weekend with a Canadian-owned commercial communications satellite. The static fire test occurred at 5 p.m. EDT (2100 GMT) Wednesday.

Speaking publicly for the first time since a Falcon 9 rocket failure that destroyed a Dragon cargo capsule for the International Space Station, SpaceX founder Elon Musk said Tuesday that engineers are still piecing together what happened during the June 28 accident in hopes of announcing more details within a few days.