This volume contains the results of research and development connected with the creation oftelescopes intended for the new regions of the spectrum mastered by astronomy: the x-ray, submillimeter (far infrared), and radio regions. The creation of x-ray, submillimeter, and radio telescopes and the receiver apparatus connected with them is a complicated and, in many respects, unusual problem. Therefore, the experience accumulated at the Institute of Physics can prove useful to specialists working in this field, This volume is intended for scientists, engineers, and builders occupied in research and development in the fields of x-ray, submillimeter, and radio astronomy as well as for students of advanced courses in these specialties, V CONTENTS A Reflecting X-Ray Telescope for an Orbital Astrophysical Station. * * * * * * * * * 1 I. L, Beigman. L. A. Vainshtein, Yu. P. Voinov, D. A. Goganov, N. I. Komyak, S. L. Mandel'shtam, I. P, Tindo, N, A, Shatskii, and A. I. Shurygin Mirror Systems for X-Ray Telescopes. * * * * * * * * * * * * * * * * * * * * * * * * * * * * 13 I. L. Beigman, L, A. Vainshtein, Yu. P. Voinov, and V. P, Shevel'ko Extra-Atmospheric studies in the Submillimeter Range Using On-Board Telescopes . . * . . * * * * * . . . * . . . * . * . . . * . . * . * * . . . * * . . . * . . * * . 35 A. E. Salomonovich and A. s.