Supply Ship Boosts Space Station’s Orbit
The Russian unmanned cargo ship Progress 21 is caught by a camera mounted to the exterior of the International Space Station as it prepared to dock at the outpost on April 26, 2006.
Credit: NASA TV/collectSPACE.com.

The International Space Station (ISS) reached a higher orbit Thursday after a cargo ship fired its engines during a brief, but successful, maneuver, NASA and Russian space officials said.

The Progress 21 cargo ship docked at the aft end of the station's Zvezda module fired its onboard engines for 6.5 minutes, boosting the orbital laboratory's orbit by about 1.7 miles (2.8 kilometers), NASA Johnson Space Center spokesperson James Hartsfield told SPACE.com.

NASA officials said the orbital boost prepared the ISS for the June arrival of Progress 22, a new cargo ship that will launch from the Baikonur Cosmodrome, Kazakhstan in Central Asia atop a Soyuz rocket.

Progress 22 is expected to launch on June 24 and dock at the ISS two days later, Hartsfield said, adding that an older cargo ship - Progress 20 - will be cast off prior to the new spacecraft's arrival. Progress 20 has been docked at the Russian-built Pirs docking compartment since December 23, 2005.

Thursday's ISS orbit reboost comes after an aborted test of the two ISS engines attached to the Zvezda module's aft end. Russian ISS controllers used the test to check whether the Zvezda engines, which were last used in July 2000, were still operational. The failed engine firing did not affect the docking of Progress 21.

Progress 21 arrived at the ISS on April 26 after a two-day spaceflight from Baikonur Cosmodrome. The cargo ship ferried 2.5 tons of food and supplies to ISS Expedition 13 commander Pavel Vinogradov and flight engineer Jeffrey Williams. The two astronauts are in the midst of a six-month mission aboard the ISS and arrived at the station on April 1.