For most spacecraft, this means turning on the engines briefly at the beginning to get off earth and up to speed, and then only turning them on again at the end to decelerate.

How do spaceships slow down in space?

To slow down, you fire a forward-facing thruster. To alter your course, you fire a thruster in a sideward direction. To rotate your spacecraft, you fire a pair of sideward-pointed thrusters located near opposite sides of the spacecraft. To stop rotating, you fire thrusters aimed in the opposite direction.

How fast do you decelerate in space?

Out into space

Once at a steady cruising speed of about 16,150mph (26,000kph) in orbit, astronauts no more feel their speed than do passengers on a commercial airplane.