HELP!me plz rev. 1?

In orbit no gravity detector is possible because everything is weightless. All the gravity sources result in the orbiting body accelerating in some direction, but the result of that acceleration is weightlessness, so no instrument could detect the force of gravity in that case. The best you can do is use radar or optical surveying methods to measure how fast you are going with respect to some planet every second, and calculate from the changing speed and direction what the gravity must be that is causing the changes. An orbit is not a delicate balance between the pull of gravity and the centrifugal force of the orbital motion. If it were, planets, asteroids and all artificial satellites would quickly fall out of orbit for lack of correct control. Instead, orbiting things will speed up under the influence of gravity if they get too close to a gravity source and slow down if they get too far from a gravity source. This results in an elliptical orbit.