Almaz

While the first SARs have yet to fly on Resurs-02, the Russian experts have already gained experience with this advanced technology under the Almaz program. The basic Almaz spacecraft was first designed in the 1960's under Chief Designer Vladimir Chelomei as a military manned space station. Almaz was flown three times during the 1970's (Salyut 2 in 1973, Salyut 3 in 1974, and Salyut 5 in 1976) and its civilian derivative was used for the remaining Salyut missions. The fourth Almaz vehicle was the first to be equipped with a large, high resolution SAR and was scheduled for launch in 1981. However, a dispute between Chelomei and Minister of Defense Ustinov led to a grounding of the spacecraft until 1986 when it was finally launched but failed to reach orbit due to a failure of its Proton booster. A duplicate satellite was later flown during 1987-1989 as Kosmos 1870 (Reference 688).

An improved Almaz, officially designated Almaz 1, was launched on 31 March 1991 (eight months after its target date) into an initial operational orbit of approximately 270 km with an inclination of 72.7 degrees, slightly higher than the 71.9 degree inclination of Kosmos 1870. The primary manufacturer and integrator of Almaz 1 was the Machine Building NPO using the former Chelomei facilities in the Moscow suburb of Reutov. The principal radar payload was contributed by the Vega NPO. The observation program was prepared with the assistance of the State Committee on Hydrometeorology, the State Geodesy Committee, the Ministry of Nature Management, and the USSR Academy of Sciences.

The initial on-orbit mass of Almaz 1 was 18,500 kg with sufficient propellants to maintain the vehicle at a low altitude for up to two years and to provide for a controlled reentry over abroad ocean area at the end of mission. The spacecraft core consisted of two joined cylinders with a length of 12 m and a maximum diameter of the larger cylinder of 4.2 m. This basic space station structure (similar to Salyut and Mir) has an interior volume of 90 m³ which is maintained at standard temperatures and pressures.

Attached to the spacecraft bus were two solar panels capable of generating a meanpower of 2.4 kW and a peak power of 7.5-10 kW and two 3-piece SAR antennas (1.5 m by 15 m) along either side of the spacecraft. At the forward end of Almaz 1 between the two SAR antennas were two phased-array antennas to permit real time data transfers via a geosynchronous relay satellite. Two small dish command and control and data transmission antennas were located at the aft end of Almaz 1, and a separate data transmission antenna extended upward from the spacecraft's midsection (Figure 4.86).

Almaz spacecraft can carry a payload of 46.5 metric tons. On Almaz 1 this was divided Between the SAR and a multi-channel microwave radiometer operating at 6-37.5 GHz with a swath of 600 km and a resolution of 10-30 km. the SAR transmitted at a frequency of 3 GHz with an average power of 80 W and a peakpower of 190 kW. A typical radar image covered a region 20-45 km wide and 20-240 km long with a resolution of 15-30 m. However, Almaz 1 could aim its coverage over a swath at least 350km wide. Unfortunately, the failure of one of the SAR antennas to deploy fully rendered that side inoperable. The main data reception center was located in Moscow region, although designs for data processing stations outside the USSR/CIS with a VAX-11/785, two Micro VAX lI's, and four IBM PS/2-80's have been created (References 689-692).

Originally, a second Almaz 1-type spacecraft, with some payload modifications, was to be launched in 1993 on a two-year mission. In particular, Almaz-1 B would carry three synthetic aperture radars: SAR-10 (9.6 cm wavelength, 540 m resolution, 25-300 km swath), SAR-70 (70 cm wavelength, 15-60 m resolution, 100-150 km swath), and a 3.6-cm wavelength SAR. Multi-spectral scanners, including MSU-E and MSU-SK, would also be carried as well as a Balkan-2 lidar. However, a lack of funding has postponed the flight of Almaz-1 B to late 1997 at the earliest.

Likewise, plans for even more sophisticated and capable Almaz 2 spacecraft have been delayed until near the turn of the century. Almaz 2's payload mass of 6.5 metric tons would be powered by solar arrays with a maximum beginning-of-life average power rating of 3.8 kW. More than three metric tons of propellants would be available for a mission duration of up to five years at an altitude of 600 km (References 693-703).