Photos: Tuesday’s Atlas 5 rollout

For the fourth time this week, a rocket launch from Cape Canaveral was stopped with seconds remaining in the countdown Friday night, when a SpaceX Falcon 9 rocket automatically aborted its liftoff with a new GPS navigation satellite during the engine startup sequence.

NASA’s Perseverance rover, set for liftoff Thursday on a journey to Mars, posed some unusual challenges for launch crews working with the robot’s plutonium-fueled power generator, but United Launch Alliance’s Atlas 5 rocket is uniquely suited for the job, the company’s CEO says.

The International Space Station is likely to continue operating for another decade, but without more government support, a privately-owned outpost may not be ready in time to replace it, NASA Administrator Jim Bridenstine said.