www.radartutorial.eu www.radartutorial.eu Radar Basics

Space Detection and Tracking System

Space Detection and Tracking radar is a very accurate system with an extreme range. It is used to catalog the orbit of satellites and space debris in near-Earth space (up to 3,000 km in altitude).

Space debris is a persistent and growing threat to satellites and space travel. Due to its extremely high velocity, it has the potential to penetrate satellites and spacecraft as projectiles with high destructive potential. To avoid the risk of collisions, it is essential to locate, track, identify and document the orbit of these particles.

Figure 1: With two radars, the exact position can be calculated despite poor angular resolution.

Figure 1: With two radars, the exact position can be calculated despite poor angular resolution.

Range resolution is an unimportant problem for modern radars that operate with broadband signals. However, the angular resolution depends on the size of the antenna, which is not so easy to increase because it affects its motricity. For example, with an antenna with a half-power beam width of 4 degrees, the beam width is 200 km at a distance of 3,000 km, while using a bandwidth of 100 MHz the range resolution is less than 1.5 m.

The wider the antenna is, the less it can be directed quickly towards the target due to its large mass. To avoid huge antenna dimensions to decrease the beam width, two radar sets can be used, installed at a distance of about 300 km. Both radars simultaneously measure the range of the target from different angles. Precise angular determination can be made from the two accurately measured distances using multilateration. This functionality is carried out with GESTRA radars installed at several locations.

The conventional method for achieving the required angular resolution in space radar systems is to magnify the antenna. For example, the TIRA radar of the Fraunhofer Institute for High Frequency Physics and Radar Techniques (Wachtberg, Germany) has a parabolic antenna with a diameter of 34 meters.