Sfera (satellite)

Sfera
Type:	Earth surveying satellite
Country:	Soviet Union
Mission dates
Dimensions:	600-880 kg
Size:	3.0 m × 2.04 m
Begin:	First launch: February 20, 1968
Starting place:	Plesetsk Cosmodrome
Launcher:	Cosmos-3M
Orbit data
Track height:	1200-1400 km
Orbit inclination :	74 ° or 83 °

Serfa on a Russian postal stationery postcard

Sfera ( Russian Сфера , for sphere , GRAY index : 11F621) is the name for Soviet earth surveying satellites .

history

When planning global nuclear strikes during the Cold War , the Soviet military needed very accurate maps and precise navigational data. Factors that affected geographic accuracy included tiny variations in the shape of the earth and its gravitational field. In 1965, the design office NPO Prikladnoj Mechaniki began developing a specialized satellite based on the KAUR-1 satellite bus for this task, which was named Geoid-Sfera. The payload of the cylindrical satellite consisted of a flashlight that emitted a series of strong flashes of light. By taking photographs of these flashes of light from several points of view and comparing the position of the satellite relative to the stars, its position could be determined with an accuracy of about 3 to 6 arc seconds . Thanks to this data, the positions of points could be determined even at great distances with an accuracy of 25 to 30 meters. In addition, the satellites were also equipped with a special radio transmitter to determine the speed of the satellite with an accuracy of 0.1 meters per second by evaluating the Doppler shift of the signal. The Sfera system significantly improved the positioning of objects on land and sea and contributed to updating the standard model of the earth's geometry and developing a new coordinate system based on it.

The satellites were usually placed in a circular orbit with an inclination of 74 °, initially 1200 kilometers later up to 1400 km high. The orbit height reduced the influence of the atmosphere on the satellite, so that only deviations from the orbit caused by the earth's gravitational field had to be taken into account. The Kosmos 3M rocket , which brought the satellites into orbit from the Plesetsk Cosmodrome , was always used for the launch .

The first satellite was launched on February 20, 1968 under the official name Kosmos-203. Although the first satellite worked for 19 months, significantly longer than the expected six months, the system suffered from significant technical problems until 1972. In 1973 the system was finally declared ready for use and serial production started. A total of 18 Sfera satellites were launched, the last of which was launched on December 26, 1978 and was in operation until May 1, 1980. Of the 18 satellites launched, 17 reached Earth orbit.

Satellites

A total of 18 satellites were launched before the series was replaced by Geo-IK satellites .

number	Surname	Start date	Launch complex	Takeoff weight kg	COSPAR name	NORAD ID	Orbit inclination	Apogee km	Perigee km
1	Cosmos-203	20th February 1968	LC132	600 kg	1968-011A	3129	74.1 °	1201	1183
-	-	4th June 1968	LC132 / 2	Startup failure
2	Cosmos-256	November 30, 1968	LC132 / 1	600 kg	1968-106A	3576	74.1 °	1223	1172
3	Cosmos-272	17th March 1969	LC132 / 1	600 kg	1969-024A	3818	74.0 °	1208	1178
4th	Cosmos-312	November 24, 1969	LC132 / 1	600 kg	1969-103A	4254	74.0 °	1175	1141
5	Cosmos-409	April 28, 1971	LC132 / 1	600 kg	1971-038A	5180	74.0 °	1218	1183
6th	Cosmos-457	20th November 1971	LC132 / 2	600 kg	1971-099A	5614	74.0 °	1211	1176
7th	Cosmos-480	March 25, 1972	LC132 / 1	600 kg	1972-019A	5905	83.0 °	1199	1173
8th	Cosmos-539	December 21, 1972	LC132 / 2	600 kg	1972-102A	6319	74.0 °	1379	1342
9	Cosmos-585	September 8, 1973	LC132 / 2	600 kg	1973-064A	6825	74.0 °	1424	1364
10	Cosmos-650	April 29, 1974	LC132 / 2	600 kg	1974-028A	7281	74.0 °	1401	1368
11	Cosmos-675	29th August 1974	LC132 / 2	600 kg	1974-069A	7424	74.1 °	1424	1364
12	Cosmos-708	February 12, 1975	LC132 / 1	600 kg	1975-012A	7663	69.2 °	1410	1368
13	Cosmos-770	September 24, 1975	LC132 / 1	650 kg	1975-089A	8325	83.0 °	1208	1165
14th	Cosmos-842	July 21, 1976	LC132 / 1	650 kg	1976-070A	9025	83.0 °	1006	966
15th	Cosmos 911	May 25, 1977	LC132 / 2	700 kg	1977-039A	10019	83.0 °	999	965
16	Cosmos-963	November 24, 1977	LC132 / 1	650 kg	1977-109A	10491	82.9 °	1206	1179
17th	Cosmos-1067	December 26, 1978	LC132 / 2	880 kg	1978-122A	11168	83.0 °	1213	1156

Web links

• Gunter's Spage Page: Sfera (English)

Individual evidence

1. ↑ Sfera on the Russian Space Web (English)
2. ↑ Sfera in the Encyclopedia Astronautica (English)
3. ↑ Cosmos 1067 in the NSSDCA Master Catalog (English)