Progress cargo ship fails to dock to ISS

MOSCOW - Russia's Progress M-15M resupply freighter failed to re-dock with the International Space Station (ISS) due to certain emergency situations in the station'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 at a distance of 15 km 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.

The US 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.

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 US 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.