A couple of weeks ago, ground teams at NASA's Kennedy Space Center in Florida removed one of the four main engines from the Space Launch System rocket slated to send four astronauts on a voyage around the Moon next year.

NASA officials ordered the removal of one of the massive rocket's RS-25 main engines after discovering a hydraulic leak on the engine's main oxidizer valve actuator, which controls the flow of super-cold liquid oxygen propellant into the engine's main combustion chamber, an agency spokesperson told Ars.