Photos: Atlas 5 rocket aims for International Space Station

Delays have set up the possibility of up to three rocket launches this weekend from different pads along Florida’s Space Coast, including two SpaceX missions on Sunday that could set a company record for the shortest span between two Falcon 9 rocket launches. But in the world of ever-changing launch schedules, numerous factors such as weather and technical issues could thwart launch plans this weekend. 

Departing Cape Canaveral at 8:37 a.m. EDT Thursday, the United Launch Alliance Atlas 5 rocket lifted a classified national security satellite into orbit for deployment.

A balky interplanetary seismic instrument that ran into technical problems in 2015, forcing a two-year delay in the launch of NASA’s InSight lander to Mars, cleared a major test last week after engineers redesigned part of the sensor package, boosting confidence that the mission will be ready to blast off in May 2018.