RORSAT
RORSAT ( R adar O cean R econnaissance SAT ELLITE ; German radar-based satellite to monitor the oceans ) is the western name of the Soviet satellite series Uprawljajemij Sputnik Aktiwnij (US-A or US-AM, GRAU index of the complex: 17K114, the of the satellite 17F16). These satellites were launched between 1967 and 1988 to monitor NATO and merchant ships with active radar. RORSATs were - like the other military satellites - carried under the name Kosmos . They were brought into orbit with Zyklon 2 rockets.
Nuclear reactors for power supply
For the search radar to work effectively, a low orbit had to be chosen for the RORSATs . Due to the high energy requirements of the radar, solar cells could not be used to power the satellite. Due to their size, they would have led to great friction losses in the atmosphere , the resistance of which still plays a role at this relatively low altitude. Thus the altitude of the orbit would have decreased rapidly. Hence, all operational RORSATs contributed nuclear reactors of the type BES-5 , with 235 U were operated. Normally, the satellite reactor modules were detached at the end of their life and flew into a higher orbit (a so-called "elimination orbit") on their own. However, there have been a few incidents where radioactive material was released into the atmosphere. The first prototypes of the RORSAT series did not contain a reactor, but were operated with batteries, which however only had a service life of a few days.
Although most of the reactor cores successfully reached high orbits, these orbits are not final. If no further measures are taken, the highly radioactive objects will return to the earth's atmosphere after a few hundred years; by then, however, the radioactivity will have dropped.
The RORSATs are considered to be the main source of space debris at an altitude of around 950 kilometers above the earth. By design, the satellite emitted her coolant, a eutectic sodium - potassium - alloy ( NaK ), during the separation of the reactor core into orbit. It is estimated that there will continue to be on the order of 10,000 drops (about 5 mm to a maximum of 55 mm in diameter) over the next few decades.
Since the metal coolant was irradiated with neutrons from the nuclear reactor, it contains small amounts of the radioactive argon -39, which has a half-life of 269 years.
Technical specifications
The satellites have a mass of around 3.8 t (launch mass 4.3 t), a diameter of 1.3 m and a length of around 10 m. Two large elongated antennas are attached to each side of the satellite. The fuel section for the reactor (mass 53 kg, 0.6 m length and 0.2 m diameter) consists of 37 cylindrical fuel elements with a total of 31.1 kg uranium fuel, which is enriched to 90% 235 U.
Accidents
RORSAT false start, April 25, 1973
The start failed and the reactor crashed into the Pacific Ocean north of Japan. The radiation was detected by a US measuring aircraft.
Cosmos 954
The reactor core could not be launched into high orbit at the end of its life. Radioactive material re-entered the atmosphere on January 24, 1978, leaving a trail that contaminated an area of 124,000 square kilometers of Canada's Northwest Territories with radioactive material.
Cosmos 1402
The end of 1982 could not be reached. The reactor core was separated from the rest of the satellite and was the last piece of the satellite to return to Earth. It crashed into the South Atlantic on February 7, 1983.
Cosmos 1818
The satellite, also called “Plasma-A”, was used (like Kosmos 1867) to test the new Topas-1 reactor type, which with a mass of 320 kg delivered 5-10 kW electrical power and contained 12 kg of 235 U. It was started on February 2, 1987, but switched off again after 142 days. Since July 2008 the satellite has been disintegrating into parts (30 so far) that are slowly spreading along the orbit.
Cosmos 1900
The primary system failed while attempting to shoot the reactor core into its final orbit. However, the reserve system shot the core into an orbit 80 kilometers below the planned one.
Start list
Start date | Surname | Remarks |
---|---|---|
December 28, 1965 | Cosmos 102 | Test satellite |
July 20, 1966 | Cosmos 125 | Test satellite |
December 27, 1967 | Cosmos 198 | |
March 22, 1968 | Cosmos 209 | |
3rd October 1970 | Cosmos 367 | |
April 1, 1971 | Cosmos 402 | |
December 25, 1971 | Cosmos 469 | |
August 21, 1972 | Cosmos 516 | |
April 25, 1973 | False start | |
December 24th 1973 | Cosmos 626 | |
May 15, 1974 | Cosmos 651 | |
17th May 1974 | Cosmos 654 | |
April 2nd, 1975 | Cosmos 723 | |
April 7th 1975 | Cosmos 724 | |
December 12th 1975 | Cosmos 785 | |
2nd July 1976 | Cosmos 838 | |
17th October 1976 | Cosmos 860 | |
October 21, 1976 | Cosmos 861 | |
November 26, 1976 | Cosmos 868 | |
September 16, 1977 | Cosmos 952 | |
18th September 1977 | Cosmos 954 | |
April 29, 1980 | Cosmos 1176 | |
March 5th 1981 | Cosmos 1249 | |
April 21, 1981 | Cosmos 1266 | |
August 24, 1981 | Cosmos 1299 | |
May 14, 1982 | Cosmos 1365 | |
June 1, 1982 | Cosmos 1372 | |
August 30, 1982 | Cosmos 1402 | |
2nd October 1982 | Cosmos 1412 | |
June 29, 1984 | Cosmos 1579 | |
October 31, 1984 | Cosmos 1607 | |
August 1, 1985 | Cosmos 1670 | |
August 24, 1985 | Cosmos 1677 | |
March 21, 1986 | Cosmos 1736 | |
August 20, 1986 | Cosmos 1771 | |
2nd February 1987 | Cosmos 1818 | Test satellite with Topas reactor |
June 19, 1987 | Cosmos 1860 | |
July 10, 1987 | Cosmos 1867 | Test satellite with Topas reactor |
December 12, 1987 | Cosmos 1900 | |
March 14, 1988 | Cosmos 1932 |
Web links
- Sven Grahn: The US-A program (Radar Ocean Reconnaissance Satellites - RORSAT) and radio observations thereof (English)
- IPPE: High-Temperature Nuclear Reactors for Space Applications ( Memento from November 1, 2007 in the Internet Archive )
- Images from the US-A RORSAT satellites ( Memento from September 28, 2016 in the Internet Archive ) with French explanations
Individual evidence
- ↑ US-A on Gunter's Space Page, accessed December 18, 2010
- ↑ Carsten Wiedemann, Eduard Gamper, Andre Horstmann, Vitali Braun, Enrico Stoll: The Contribution of NaK Droplets to the Space Debris Environment , accessed on November 11, 2018
- ^ Globalsecurity.org: RORSAT
- ↑ US-A in the Encyclopedia Astronautica (English)
- ↑ Russian atomic satellite crumbles in space . Russia News, January 2009