Russian Cargo Ship Departs ISS

A trash-laden Russian cargo ship cast off from the International Space Station (ISS) Wednesday and plunged back to Earth, making room for a new resupply spacecraft set to launch Thursday.

Russian ISS flight controllers remotely undocked the unmanned Progress 18 spacecraft from its berth at the aft end of the station's Zvezda service module at 6:26 a.m. EDT (1026 GMT), NASA spokesperson Kylie Clem told SPACE.com. Separation of the two spacecraft went smoothly, while ISS Expedition 11 commander Sergei Krikalev and flight engineer John Phillips observed the undocking, she added.

The undocking makes room for Progress 19, an unmanned spacecraft set to launch Thursday atop a Soyuz rocket at 9:08 a.m. EDT (1308 GMT). The space shot will be staged from Baikonur Cosmodrome in Kazakhstan.

Progress 19 will deliver more than 2.6 tons of fresh oxygen, propellant and food, as well as vital spare parts and other equipment.

Among the major items packed aboard the spacecraft is a replacement liquid unit for the station's Elektron oxygen generator - the primary oxygen generator for the ISS - which failed earlier this year. ISS astronauts have relied on secondary oxygen supplies stored in Progress tanks, as well as oxygen-generating candles to maintain their cabin atmosphere.

Russian-built Progress spacecraft provide steady supply shipments to ISS crews, and made the only cargo shipments during the more than two years between the 2003 Columbia accident and the July 28 arrival of NASA's space shuttle Discovery. Another Russian cargo ship, Progress 20, is slated to launch toward the ISS in December. The next shuttle delivery, Discovery's STS-121 flight, is expected no earlier than March 2006.

Progress 18 arrived at the ISS on June 18, delivering more than two tons of supplies, spare parts and other equipment for the Expedition 11 crew. Krikalev and Phillips spent the last week packing Progress 18 with waste, trash and other unneeded items before closing the spacecraft's hatch Tuesday morning.

Russian space station officials expected much of Progress 18 to burn up during reentry, with remains to crash into the Pacific Ocean at about 10:13 a.m. EDT (1413 GMT), according to Russia's Interfax News Agency. The spacecraft's remnants were expected to splashdown about 1,864 miles (3,000 kilometers) east of Wellington, New Zealand, Interfax reported.

• Complete Coverage: ISS Expedition 11