Actually, while the Earth's Gravity is what is pulling on it, the reason it is coming down is because in the low earth orbit it was placed in, there is still enough atmosphere to exert a slight drag on it, slowing it down little by little, thus lowering its orbit, until it reaches the upper levels of the "real" atmosphere, where the friction and drag will go up by several orders of magnitude. Then the FUN begins!
Those whacky scientists! It’s not being pulled by gravity. It’s being PUSHED by gravity.