Introduction to the issue on Signal Processing for Space Research and Astronomy

SPACE research in general, and astronomy in particular, are some of the most challenging application areas for signal processing. Digital signal and image processing techniques have been widely used for optical astronomy and radio astronomy as well as in deep-space communication. Several new instruments are being designed for radio, optical, and other frequencies. These instruments will push our understanding of the universe even further and ambitious design goals for these instruments will rely on advanced signal processing techniques. Traditionally, radio telescope design was in the forefront of electrical engineering technology. Technological advances in the last decade have created possibilities for large distributed interferometric radio and optical telescopes with very large receiving areas, extremely large aperture, and a sensitivity which is one to two orders of magnitude better than the current generation. Increased sensitivity implies receiving more interfering signals; therefore, RFI detection and removal is now an important topic in radio astronomy. Fortunately, massive digital phased-array technology has also greatly advanced during this period and can provide increased flexibility to filter out interference as well as the possibility of directing multiple beams simultaneously. Several major, international research groups are working on next generations of phased-array instruments. The most ambitious one falls under the framework of the Square Kilometer Array programm (SKA), with a target commissioning date of 2020. A second instrument, which is a distributed phasedarray radio telescope is the Low Frequency Array (LOFAR) currently under construction in The Netherlands, and slated for 2009. The LOFAR design calls for an instrument consisting of about 13 000