Okean (Ocean) is a USSR/Ukrainian (prior/after 1992) Earth observation satellite program for the operational monitoring of ocean surfaces (sea surface temperatures, wind speed, sea color, status of ice coverage, cloud coverage and precipitation). In particular, the Okean-O1 spacecraft with their polar orbits provide valuable complementary data on the ice status in the Arctic and Antarctic regions (support of navigation information for ships in the northern latitudes), which are not visible from geostationary meteorological satellites.
Launches of the series were conducted from the Plesetsk Cosmodrome using the Tsyklon-3 launch vehicle.
Orbit: polar near-circular orbit, altitude range of 500-660 km, inclination 82.5º, period = 98 minutes.
Background: The Okean program was initiated in 1976 by the former USSR (Union of Soviet Socialist Republics). In particular, the Yuzhnoye State Design Office of the Ukraine was instrumental in this effort. Launches started in 1979 within the experimental Okean (Cosmos) series. Mission objective: a major interest was in the operation of active and passive microwave sensors. Both MW (microwave) sensor types provide an all-weather observation capability.
Early Experimental Cosmos Program
The predecessor series of the Okean series was the experimental Cosmos series.
• Cosmos 1076 (also referred to Okean-E); launch from Plesetsk on a Tsyklon vehicle on Feb. 12, 1979; orbit: altitude = 514 km x 530 km; inclination = 82.6º; S/C mass = 1950 kg. A test mission of the Okean satellite without the radar. Objective: Development of methods for obtaining operational information on the Pacific Ocean. Operations were terminated on March 13, 1980. The S/C reentered the atmosphere on Aug. 10, 2001.
• Cosmos 1151 (Okean-E); launch from Plesetsk on a Tsyklon vehicle on Jan. 23, 1980; orbit: altitude = 566 km x 589 km; inclination = 82.6º; S/C mass = 1950 kg. The second test mission of the Okean satellite without the radar. Operations were completed on Oct. 13, 1981.
• Cosmos 1500 (also referred to as Okean-OE the first prototype S/C); launch from Plesetsk on a Tsyklon vehicle on Sept. 28, 1983; orbit: 649 x 679 km, inclination = 82.6º; S/C mass = 1950 kg. The S/C was operational until July 16, 1986. 1)
• Cosmos 1602 (also referred to as Okean-OE); launch from Plesetsk on a Tsyklon vehicle on Sept. 28, 1984; orbit: 629 x 664 km, inclination = 82.5º; S/C mass = 1950 kg. The S/C was operational until Dec. 5,1986.
• Cosmos 1766 (also referred to as Okean-O1-N1); launch from Plesetsk on a Tsyklon vehicle on July 29, 1986; orbit: 601 km x 631 km, inclination = 82.5º; S/C mass = 1950 kg. The S/C was operational until Oct. 24, 1988.
• COSMOS 1869 (also referred to as Okean-O1-N2); launch from Plesetsk on a Tsyklon launcher on July 16, 1987; orbit: 602 km x 632 km, inclination = 82.5º; S/C mass = 1950 kg. The S/C was operational until May 30, 1989. 2) 3)
Sensor complement of the Cosmos satellites 1076 and 1151:
The simultaneous spectral measurements in several wavelengths provide a means of evaluating the hydro-physical parameters of the sea surface, the meteorological parameters of the atmosphere as well as of the sea surface. The parameters are: sea surface temperature, wind speed at the sea surface boundary, liquid vapor content in clouds, integrated water vapor, etc. 4)
Device Νu (Passive MW Radiometer), a nadir-pointing instrument developed by NPO Vega, measuring the emission radiation of the atmosphere/ocean system at the following (micro) wavelengths/frequencies: 0.8 cm (37.5 GHz), 1.35 cm (22.22 GHz), 3.2 cm (9.37 GHz), and 8.5 cm (3.53 GHz).
Device Pi (Non-scanning Polarimeter) measuring radiation at wavelength 3.2 cm (with two orthogonal polarizations at a look angle of 53º relative to nadir, and with one polarization at nadir). Along-track footprints of 12 m distance and 6 m normal to the orbital track are generated.
Device 174 K (IR Spectrometer).
MSU-M. A four-band (VIS) multispectral scanner for monitoring ocean color. Swath width = 1900 km, resolution = 1.8 km.
The Cosmos satellite series 1500 - 1869 was equipped with a subset of instruments of the first series, i.e. one or two passive MW radiometers per satellite measuring the emission radiation of the atmosphere/ocean system. - Cosmos 1500 was the first USSR satellite equipped with a side-looking, all-weather radar, namely RLSBO (or SLAR), a real-aperture radar instrument.
Table 1: Overview of Okean series satellites
Note: Sich is the Ukrainian name for `Owl'. Sich-1 has the same orbit and sensor complement as the Okean-O1 spacecraft series. NKAU (National Space Agency of Ukraine) was founded in 1992.
1) A. I. Kalmykov, et al, “Determination of Oceanic Surface Structure with `Cosmos-1500' Satellite Side Looking Radar,” Intercosmos Council, 1984
4) Information provided by B. Kutuza of IRE-RAS (Institute of Radioengineering and Electronics-Russian Academy of Sciences), Moscow
The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: ”Observation of the Earth and Its Environment: Survey of Missions and Sensors” (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates.