Spektr-UF (Spektr-UV, SUV, World Space Observatory Ultraviolet, WSO-UV)

Spektr-UF (also known as Spektr-UV or SUV) is a UV space observatory mission. The mission is led by Russia, but involves multiple international partners. The mission is also known as World Space Observatory Ultraviolet (WSO-UV).

The Spektr-UF project is led by Russia (Roskosmos) with international cooperation including three basic participants: Russia (provides the telescope, spacecraft, launch facilities, ground segment), Spain (ISSIS, ground segment) and Germany (spectrographs).

Originally the satellite was to be built on the Spektr bus, a derivative of the Prognoz-EW-Bus and to be launched on a Proton-K Blok-DM-2 booster, but budget problems have forced a redesign. Now it will be based on the smaller Navigator bus and will be launched on a Zenit-3F combination.

The main instrument is the T-170M 1.7-meter Ritchey-Chretien telescope, a lighter version of the originally planned T-170 telescope. It is equipped with three instruments:

• HIRDES (High-Resolution Double Echelle Spectrograph): R~55000 spectroscopy of point sources in the 102-320 nm range (Germany)
• LSS: Long-slit low-resolution (R~2500) spectroscopy in the 102-320 nm range
• ISSIS (Imaging and Slitless Spectroscopy Instrument for Surveys) being developed to carry out UV and optical diffraction limited imaging of astronomical objects. The ISSIS incorporates three channels:High Sensitivity Far-UV Channel: 120-200 nm; Channel for Surveys (FUV): 120-600 nm, optimized for 120-270 nm; Channel for Surveys (UVO): 120-600 nm, optimized for 270-600 nm. (Spain)

The future of this project is uncertain. Originally a launch in May 2021 is planned. A switch to a Proton-M Blok-DM-03 launch vehicle is likely, as the Zenit-3F will be most probably phased out long before the planned launch date. It will be placed into a geosynchronous orbit with an inclination of 51.6°. In May 2019, a launch date in October 2025 was announced.