The US space agency is asking commercial partners to develop crew transportation systems. Commercial companies have already proven that they can get supplies to the International Space Station but NASA’s asking them to up their game. But they warn such systems need to be safe and efficient and also cost-effective for American taxpayers. Systems will include rockets, spacecraft, and ground transportations. Commercial companies has already made a lot of progress designing and developing the next generation of U.S.crew transportation systems for low-Earth orbit but NASA says the next phase of development will ensure a strong emphasis on crew safety. They said the request for proposals begins the journey for a new era in U.S. human spaceflight. And the goal is to launch by the end of 2017.