penetrating the surface of the Earth. Its location changes at a rate of about 56 kilometers (35 miles) per year. Currently, it is located in the Arctic Ocean north ofRussia, hundreds of kilometers away from the geographic North Pole. ...
The azimuth (\(\gamma \)) and elevation (\(\eta \)) angles of the satellite ray path and the differential delay (\(\Delta \tau \)) between two signals are measured. The ray path crosses shells at the height \(h_{si}\) (Lo and Hi for the lower and higher shells, respectively)...