MIAMI, United States (AFP) — NASA on Tuesday performed its second and last test-fire of a rocket booster for the Space Launch System (SLS), a powerful engine that may one day launch astronauts to Mars, the US space agency said. Fire and gray smoke billowed from the booster, which lay on the ground during the two-minute test fire in the remote hills of Utah at 11:05 am (1605 GMT). NASA has described the SLS as […]