US-A

RORSAT ( Radar Ocean Reconnaissance SATellite; German radar -based satellite to monitor the oceans ) is the western name that the Soviet satellite series Uprawljajemij Sputnik Aktiwnij (US- A or U.S. AM, GRAY index of the complex: 17K114 that the satellite 17F16 ) was given. These satellites were launched 1967-1988 to monitor NATO and merchant vessels using active radar. RORSATs were, like the other military satellites, under the Cosmos designation. They were taken with cyclone 2 rockets into orbit.

Thus, the search radar operates effectively, had to be chosen for the RORSATs a low orbit. Due to the high energy requirements of the radar no solar cell could be used to power the satellite, this would have led by their size to large frictional losses in the atmosphere, the resistance of which plays a role in this relatively low height. Thus, the height of the orbit would have reduced quickly. Consequently, all wore operational RORSATs nuclear reactors of the type BES -5, which were operated with 235U. Normally the reactor cores were taken at the end of its life on a high orbit (called a "disposal path "). However, there were a number of incidents in which radioactive materials are passed into the atmosphere. The first prototypes of RORSAT series did not include a reactor, but were powered by batteries, but only had a lifespan of a few days.

Specifications

The satellites have a mass of about 3.8 t ( off mass 4.3 t), a diameter of 1.3 m and a length of about 10 m. Two large elongate antennas are mounted on each side of the satellite. The fuel for the reactor section ( mass 53 kg and 0.6 m length and 0.2 m in diameter ) consists of 37 cylindrical fuel elements with a total of 31.1 kg of uranium fuel enriched to 90 % 235U.

Accidents

The launch failed and the reactor crashed north of Japan in the Pacific Ocean. The radiation was detected by a U.S. research aircraft.

The reactor core could not be shot in a high orbit at the end of its life. Radioactive material occurred on January 24, 1978 back into the atmosphere and left a trail according to the contaminated an area of ​​124,000 square kilometers of Canada's Northwest Territories with radioactive material.

The end of 1982 could not be reached the final orbit. The reactor core was separated from the rest of the satellite and was the last piece of the satellite that returned to Earth. It crashed on February 7, 1983 in the South Atlantic.

The also with " plasma -A" designated satellite served (as well as Cosmos 1867) to test the new type of reactor Topaz 1, the charges 5-10 kW of electrical power at 320 kg mass and contained 12 kg 235U. It was launched on February 2, 1987, but turned off again after 142 days. Since July 2008, the satellite is divided into parts ( ex 30), which slowly spread across the web.

The primary system failed while trying to shoot the reactor core into its final orbit. However, the reserve system, the core shot into orbit, which was 80 kilometers below the planned.

Other concerns

Although most of the reactor cores were successfully shot on high orbits, these orbits are not final. If no further measures are taken, the highly radioactive objects return after a few hundred years back into Earth's atmosphere back, but until then, the radioactivity should be planned as far fallen. The RORSATs considered as the main source of space debris at an altitude of about 950 kilometers above the earth. By design, the satellite emitted their coolant, a eutectic sodium - potassium alloy ( NaK ), when separating the reactor core into orbit. It is estimated that there are 110,000 to 115,000 (perhaps frozen ) drops, which have a diameter of 50-70 millimeters. Since the metal coolant is irradiated with neutrons from a nuclear reactor, it contains small amounts of radioactive argon 39, which has a half life of 269 years.

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