Question

why is geostationary satellites not useful for studies in polar region?

Answer 1

There cannot be geostationary satellite at the poles, because, it would have to be at rest, which cannot happen as it would get pulled by the earth's gravity and eventually crash to the earth's surface. In fact, there can not be geo stationary satellite anywhere else, except above the equator.

Answer 2

geostationary satellites moves over a specific region not on the polar axis that is my they cannot be used for study of polar regions

A geostationary satellite, is a satellite that revolves in the same direction the earth rotates. There cannot be geostationary satellite at the poles, because, it would have to be at rest, which cannot happen as it would get pulled by the earth's gravity and eventually crash to the earth's surface. that's why geostationary satellite is not use for study of polar region