Monitoring of space objects in medium Earth orbit with early-warning radar

Abstract

The early-warning radar opportunity in an artificial satellite in medium Earth orbit surveillance is observed. The nowadays Russian early-warning radars provide long distance monitoring in purpose to track space apparatuses. In comparison with telescope observations, radar observations are not limited by weather conditions and the daylight resence, so advantages are obvious. More over it, radars allow to get not only angular coordinate measurings, but also distance and radial velocity measurings. However, the radar operating distance is usually limited by several thousands kilometers, so it is possible to track only satellites in low Earth orbit. But by means of some additional measures it could be achieved to track satellite in medium Earth orbit. The amount of those measures, defined as special operating mode, is represented. The main difficulty, that is discussed, is in large distance between satellite and radar. The value of the semiaxis of the objects under consideration can be up to 40,000 kilometers. The radiated electromagnetic field energy decreases as the square of distance that radiowave overcomes. So when the transmitted radar signal is reflected from sattelite, the received echo signal level is deep under receiver noise. The most common way to increase signal-to-noise ratio is in transmitted signal duration increasing.