Russia's Progress M-15M resupply freighter failed to re-dock with the International Space Station (ISS) due to certain problems in the freighter's new Kurs-NA rendezvous system, Russia's Mission Control Center (MCC) said Tuesday.
The unmanned Progress M-15M, which arrived at the ISS in April, undocked from the station early Monday morning to conduct a series tests of the upgraded Kurs-NA rendezvous system.
According to a spokesman of the MCC, the Kurs-NA system warned of a possible emergency situation and called off the re-docking when the Progress M-15M was approaching to the ISS.
The MCC didn't provide more details about the operation, only confirming that the Progress M-15M was now at a safe distance to the ISS.
The MCC also revealed the Progress freighter would be maneuvered to a distance of 500 km to the ISS later Tuesday and the next re-docking was scheduled on Sunday.
"We are considering to carry out the re-docking again on July 29, after Japan's cargo spacecraft HTV's docking with the ISS," the spokesman said.
The cause of the failed re-docking has been investigated, he said, stressing that the Progress freighter was still controllable and has not posed any threat to the ISS and its six crew members.
Russia's federal space agency Roscosmos said Tuesday that the Progress M-15M was now at an average altitude of 408.1 km and at a distance of 484 km to the ISS.
According to Roscosmos, the test of the Kurs-NA rendezvous system went smoothly at the beginning, but the system issued a command to stop further operations at 4:22 a.m. Moscow time (0022 GMT) when the freighter was at a distance of 161 kilometers to the ISS.
"Experts of an emergencies group are analyzing the situation and they will provide recommendations on what should be done next," Roscosmos said.
The space agency also promised the incident would not lead to a delay of the Japanese spacecraft HTV-3's docking with the ISS on July 27.
The U.S. space agency NASA said in a statement the re-docking of the Progress freighter to the ISS has been postponed "due to an apparent failure in the new Kurs-NA rendezvous system."
"Progress 47 (classified as Progress M-15M in Russia) flew approximately 1.8 miles below the station to a safe distance away from the orbiting outpost, where it will remain until another attempt is made to re-rendezvous with the space station," NASA said.
The updated Kurs-NA uses less power than the current Kurs-A system installed on Russian space ships of Progress and Soyuz. It also replaces five existing rendezvous antennas with just one thus saving mass on launch.
Progress freighters have been the backbone of the Russian space cargo fleet for decades. Russia lost a Progress cargo ship in 2011 for the first time in 30 years.
Besides, after the retirement of the U.S. shuttle fleet, Russia's Soyuz spacecraft have become the only way for astronauts to reach the ISS at least until the middle of the decade.
