22.1 INTRODUCTION

Significant developments have been made in space-based radar (SBR) systems and technology since the 1970 edition of the Radar Handbook was published. A new rendezvous radar was developed for the space shuttle and has become operational. The unmanned orbital maneuvering vehicle (OMV) will use a new low-cost rendezvous radar that is expected to be operational during the early 1990 time period. Synthetic aperture radar (SAR) types of SBR have been used for earth and planetary exploration. Altimeters have been used on many satellites. The technology of SBR subsystems has been developed in the areas of antennas, transmitters, receivers, solid-state transmit-receive (T/R) modules, signal processors, and prime power. This chapter will review SBR systems and technology with the intent to provide a description that is not too sketchy to be substantive. Therefore, selected systems and technology will be discussed. Several SBR systems for rendezvous, earth exploration, and planetary exploration missions will be described. Systems considerations such as the space environment, orbit selection, radar tradeoffs, advantages and disadvantages, and critical issues will be discussed. Many topics, such as electronic countermeasures, will have to be omitted. This chapter should be considered a status report on the new frontier for radar systems. A more comprehensive treatment of SBR can be found in "Spacebased Radar Handbook," written and edited by the author and published by Artech House.

22.2 SBR SYSTEMS CONSIDERATIONS