The two astronauts stranded at the International Space Station since December are a step closer to home with the arrival of a SpaceX capsule. SpaceX launched the rescue mission on Saturday afternoon with a downsized crew of two astronauts and two empty seats reserved for Butch Wilmore and Suni Williams who will return to Earth in February. NASA switched Wilmore and Williams to SpaceX following concerns over the safety of the Boeing Starliner capsule they used to travel to the ISS. It was the first Starliner test flight with a crew but NASA decided the thruster failures and helium leaks that ha…