STS-135: The final shuttle launch

Relativity Space, a small launch startup aiming to fly its orbital rocket from Cape Canaveral for the first time next year, announced Wednesday it has signed a contract with Iridium for up to six launches of the company’s spare communications satellites. Relativity also announced it plans to develop a second launch pad at Vandenberg Air Force Base in California to allow for missions to polar orbits.

Gearing up for the third Falcon 9 launch in less than two-and-a-half weeks, SpaceX fired up a rocket booster at Cape Canaveral on Thursday ahead of an early morning launch Tuesday with an Indonesian communications satellite.

If all goes according to plan, engineers in southern Mississippi later this month will load cryogenic propellants into the core stage of a rocket NASA says will launch astronauts back to the moon, exposing its tankage and internal plumbing to extreme operating conditions hundreds of degrees below zero for the first time. The fueling test — a major milestone in its own right — is a precursor to a high-stakes eight-minute test-firing of the Space Launch System’s four shuttle-era main engines planned as soon as November.