| A | B |
|---|
| NASA | National Aeronautics and Space Administration |
| thrust | the force that accelerates a rocket |
| orbital velocity | the speed and direction a rocket must have in order to orbit the Earth |
| escape velocity | the speed and direction a rocket must travel in order to completely break away from a planet's gravitational pull |
| artificial satellite | any human-made object placed in orbit around a body in space |
| space station | a long-term orbiting platform from which other vehicles can be launched or scientific research can be carried out |
| geosynchronous orbit | an orbit in wich a satellite travels at a speed that matches the rotational speed of the Earth exactly |
| space probe | a vehicle that carries scientific insturments to planets or other bodies in space |
| space shuttle | a reusable vehicle that takes off like a rocket and lands like an airplane |
| rocket | a machine that uses escaping gas to move |
| low Earth orbit | an orbit located a few hundred kilometers above the Earth's surface |
