The American space agency and private companies are developing vehicles to take humans into low Earth orbit and even farther into space. A space vehicle system called Crew Space Transportation is a part of the effort. Boeing, the aircraft manufacturer, says its CST-100 Starliner will start flying human crews to the International Space Station by the end of next year. The United States no longer uses its reusable space shuttle to send astronauts into space. The last shuttle flight took place in 2011. Since then, the U.S. space agency has depended on Russian spacecraft to launch crews to the International Space Station. Boeing and another company, Space X, say they can fly astronauts to low orbits for about $20 million less than the current Russian spacecraft, Soyuz. Astronauts are already training for commercial spacecraft missions in flight simulators.
