ORION-3,4,5: space observatories

After the successful completion of the SOYUZ-13 – ORION-2 flight, a decision was made to create space observatories ORION-3, 4, 5 with increased stabilization accuracy and several other tasks. So ORION-4 should have installed a telescope with LiF optics instead of quartz, which would allow expanding the UV range towards deeper ultraviolet. ORION-5 was intended to obtain not spectral, but direct images of the starry sky, which causes tightening requirements for the accuracy of observatory stabilization.

ORION-3 Observatory, front heat shield removed
Observatory control unit	Block of X-ray instruments of the solar site of the observatory

A technological prototype of the ORION-3 observatory was manufactured with a change in the layout of the platform and the design of individual components and with modification of the stabilization system. This sample passed all tests, including the real sky test. 

Checking the accuracy of stabilization of the ORION-3 observatory against the natural sky. The observatory was installed on a biaxial dynamic stand. The stabilization accuracy was within 1-2 arc. sec. The recording was made at a standard telemetry station at SKB Granit in 1977 – 1978.

After the change of the chief designer at NPO Energia and the suspension of joint work as a result, as well as for a number of other reasons, it did not come to a real launch and the work was eventually closed.