Photos: News media images of Atlas 5 launch

China’s heaviest rocket has rolled to its launch pad for liftoff Thursday with the country’s first Mars landing mission, an ambitious attempt to place an orbiter around the Red Planet and a robotic rover on the Martian surface in early 2021.

In a breath-taking display at daybreak Wednesday, an Atlas rocket powered an enormous U.S. Navy satellite into space to close the last remaining gap and give global reach to the military’s new mobile communications system.

Arianespace’s third Ariane 5 launch of the year was set liftoff Friday from Kourou, French Guiana, but an issue with a sensor on the rocket’s first stage liquid hydrogen tank caused officials to scrub the launch attempt. The Ariane 5 is poised to carry three U.S.-built commercial satellites into orbit, while testing a few rocket upgrades, including a modified fairing needed for the launch of the James Webb Space Telescope next year.