Progress M-21M cargo vehicle was undocked from the ISS  up to April 25 to check Kurs-NA modernized docking and approaching system, – Mission Control Centre representative stated.

“Cargo vehicle was undocked from the ISS in automatic mode involving Kurs-NA system. On Friday at 16.16, Moscow time in accordance with the plan Progress M-21M will be docked with the station again to test Kurs-NA system operation”, – the spokesman reported.

Kurs-NA system peculiarity lies in the fact that it does not use analog signal processing forwarding this function to microprocessors. Kurs-NA system is more accurate in comparison with the previous Kurs system.

Kurs-NA system was first tested during the undocking and the following docking attempt of Progress M-15M cargo vehicle with the ISS on July 24, 2014. That time the tests were a failure. When progress vehicle was 161 km from the station new system commanded to cancel all the following operations and the docking was stopped. MCC specialists analyzed the situation, rebooted the system and the vehicle successfully docked with the station in a couple of days.

Second flight tests took place on November 30, 2013 and were also a failure. ISS crew had to switch to manual control and dock the station with cargo vehicle in the manual mode.