MOSCOW - The Russian cargo ship Progress has successfully re-docked with the International Space Station early Sunday, after the failed attempt five days ago.

The unmanned Progress M-15M, which arrived at the ISS in April, undocked from the station early Monday morning to conduct engineering tests and try out the upgraded Kurs-NA rendezvous system.

But the first re-docking attempt failed due to certain problems in the freighter's new Kurs-NA rendezvous system, said Russia's Mission Control Center on Tuesday.

No problems were reported about Sunday's second attempt in the video streamed from Russian mission control.

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.