Russia will try to test a new spacecraft docking system again Saturday with an unmanned cargo ship at the International Space Station, after a first attempt earlier this week failed and was prematurely aborted.

A robotic Russian Progress 47 cargo ship undocked from the space station on July 22 for the test, and will attempt to automatically link up to the orbiting outpost tomorrow at 9 p.m. EDT. The Progress 47 arrived at the space station in April, and had been attached to the Pirs docking compartment on the Russian segment of the orbiting laboratory.

Russian flight controllers tried to test the new Kurs-NA docking system on Monday, but a technical glitch stopped the spacecraft from arriving at the space station. The spacecraft’s onboard computers kept it a safe distance away from the orbiting laboratory while Russian engineers on the ground tried to diagnose the problem.

“The Progress has been experiencing some issues with the new Kurs-NA system,” Dan Harman, NASA’s International Space Station manager of operations and integration, told reporters in a news briefing Thursday. “Right now they’re continuing to work through those.”

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The Kurs-NA docking system is an upgraded version of the Kurs system that has been used for years on Russian spacecraft. The Kurs-NA system features updated electronics, and is expected to use less power and improve safety. Russia intends to eventually use the newer automated system on future robotic and manned missions to the International Space Station.

During Saturday’s docking test, the Progress 47 spacecraft will approach the station to within roughly 29 miles (46 kilometers). At this point, the Kurs-NA system will be activated, and if the spacecraft appears to be performing well, Russian flight controllers will proceed with the automatic docking.

NASA Television will broadcast live coverage of the attempted redocking beginning at 5 p.m. EDT on Saturday. NASA TV can be viewed here: http://www.nasa.gov/ntv.

The docking attempt will come just a day after Japan safely docked its own unmanned cargo spaceship, HTV-3, at the space station. The robotic freighter arrived Friday morning to deliver a new batch of food, supplies and science experiments.

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