How space crafts accelerate in space and how they r changing directions?

Question

since space is a empty place without any resistance

Answer 1

Space doesn't have any resistance. But, a spacecraft doesn't run on a track, does it? Spacecrafts have propellants which are identical to petrol, diesel used by automobiles. It accelerates due to the energy gained by burning of propellant.

Answer 2

Good question. They take advantage of Isaac Newton's third law: "For every action, there is an equal and opposite reaction." When the rocket fuel is ignited and directed out of jets at the rear of the ship, it is ejected under high pressure. The ship experiences an EQUAL force in the OPPOSITE direction (that is, upwards, if the ship is sitting on the launch pad, or in whatever direction the ship is pointing).

Even when sitting on the ground, the ship does not require the ground to "push off" against. (The gases from the spent rocket fuel move off to the sides; there is no appreciable buildup of pressure under the rocket that would push it upward.)

Turning while in space is accomplished with small jets (thruster rockets) positioned at helpful places around the ship, and by adjusting the position and direction of the main rockets.

While airplanes require air pressure to provide lift (under their wings), rocket propulsion "works" whether or not there is atmosphere. In fact, friction from the atmosphere will actually slow a rocket on takeoff--that's why they typically have an pointed nose cone, to lessen air resistance.

Answer 3

Thrusters that expel matter to impart a momentum change on the remaining spacecraft. Gyroscopes or flywheel systems are generally used to change the attitude of a craft. For making fast attitude adjustments of HUGE spacecraft (like the Shuttle during reentry) thrusters would be used.

Control Moment Gyroscopes: http://en.wikipedia.org/wiki/Control_Moment_Gyroscope

Reaction Wheels: http://en.wikipedia.org/wiki/Reaction_wheels

Answer 4

Space is not empty. You can never achieve perfect vacuum.
The way space crafts and satellites move around is that they have propulsion systems which emit gases in a controlled manner. Satellite's change their course using gyro's. Gyros are huge circular disc's which can be rotated to change the orientation of the satellite.