MOSCOW, April 23. /ITAR-TASS/. Russia's resupply spacecraft Progress M-21M is due to undock from the Interntaional Space Station (ISS) on Wednesday for the third testing of the new approach system Kurs-NA, which is installed on board the spacecraft, an official at the Flight Conrol Center (FCC) outside Moscow told ITAR-TASS.
"At 12:57, Moscow time, in line with the programm for the flight of the cargo supply transport spacecraft Progress M-21M, it is planned to undock it from the orbital station. The spacecraft will be on an autonomous flight until April 25, 2914, after which it will again approach the space station in order to carry out an operation for a rendezvous and re-docking with the ISS to test the new system Kurs-NA," the FCC official pointed out.
The new approach sysyem was first tested in space on July 24, 2012. The resupply spacecraft Progress M-15M, fitted out with the Kurs-NA, was undocked from the ISS but was not able to return to the orbital complex and re-redock. A re-docking operation was aborted. During the rendez-vous with the station, the spacecraft instrumentation sent out a warning signal about a possible abort. The docking system steered the spacecraft away to a safe distance. The spacecraft returned to the orbital station several days later, on July 29. At a second attempt, the Kurs-NA system operated in a nominal mode. A sensor instrumentation malfunction was referred to as the cause of the setback during the first attempt.
The second flight test of the Kurs-NA was carried out by means of the resupply spacecraft Progress M-21M during a flight to the ISS. The spacecraft had been launched from the Baikonur spaceport on November 26, 2013.
The Progress M-21M docked with the orbital station on November 30. The docking operation was being carried out by means of the new approach system in an automatic mode. However, ISS crew commander Oleg Kotov switched over to a manual docking operation when the spacecraft was 50 metres away.
Vitaly Lopota, president of the space rocket corporation Energia, mentioned discrepancy between the predicted and measured parameters of rendez-vous, due to which the system aborted rendez-vousand the teleoperator mode of control had to be resorted to.
The Kurs system which has been installed on board the spacecraft since the 1990s is currently the main approach system for Soyuz spaceships and Progress spacecraft.
The Kurs-NA new modification system is notable for substanial changes: weight, dimensions, and power consumption have been reduced while automationing and accuracy have been augmented.