A satellite orbits earth in a circular orbit. Does Earth's gravity do work on the satellite? Explain.

No. Work done is equal to the product of the force and the distance travelled in a direction parallel to the force. (W = F • d)

In the circular motion of the satellite, Earth's gravity acts as the centripetal force and the motion of the satellite is constantly perpendicular to the direction of the force.

So, work done = gravitational force • 0 = 0J

Yes it does.

The gravity of the earth and moon contribute.