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. Vehicle designs and controls have changed since the early days of spaceflight. In the future, astronauts will fly with the help of computer screens that are sensitive to touch.

Eric Boe is an astronaut with NASA.

"You know, it is like learning how to drive a car, except for now you are learning how to drive a spaceship."

The space agency is using a number of flight simulators. The machinery was developed to help astronauts understand the design of a spacecraft's cockpit.

The agency, better known as NASA, is developing its new Orion spacecraft and a more powerful rocket, called Space Launch System.

In the future, NASA officials want to let private companies take the lead in low orbit flights. By doing so, they want the space agency to direct its attention on deep space flights, such as the first manned flight to Mars.

I'm Anne Ball.

George Putic produced this story for VOANews. Jim Dresbach adapted this story for Learning English. George Grow was the editor.