Two astronauts marooned in space may sound like the plot of a Hollywood blockbuster, but for two Nasa crew members, it is now a reality. Commander Barry Wilmore and pilot Sunita Williams are currently in limbo on the International Space Station (ISS). They arrived in the Boeing Starliner spacecraft – the first test of the spaceship with astronauts. Wilmore and Williams were supposed to stay on the ISS for around eight days and return on the same spacecraft. But there is now debate about the safety of Starliner after it experienced helium leaks and thruster problems on its way to…