Giving every opportunity for the storm clouds to blow clear after a four-hour hold, the United Launch Alliance Delta 4-Heavy rocket counts down Thursday afternoon at Cape Canaveral until the clocks had to be halted for the day.

A United Launch Alliance Atlas 5 rocket lifted off at 7:50 a.m. EDT (1150 GMT) Thursday from pad 41 at Cape Canaveral Air Force Station with NASA’s Mars 2020 Perseverance rover.

Crew members aboard the International Space Station are investigating a tiny pressure leak on the Russian side of the orbiting outpost. The crew traced the leak to a small hole on the Soyuz MS-09 spacecraft, which ferried a three-person crew to the station in June. Mission control is examining options to repair the damage, and NASA says the crew is not in danger.