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Progress Docks with Space Station
Progress 31

The ISS Progress 31 cargo craft approaches the International Space Station for docking. Photo Credit: NASA TV

An unpiloted Progress cargo carrier arrived at the International Space Station’s Pirs Docking Compartment at 7:28 a.m. EST Sunday after a four day flight from the Baikonur Cosmodrome in Kazakhstan.

The Progress docked using the backup TORU manual system. Shortly after launch, one of two proximity antennas of the Kurs automated docking system failed to deploy. Mission Control Moscow successfully commanded deployment of the antenna about three hours later, but Flight Engineer Yury Lonchakov used the TORU system to bring the Progress to its docking port.

The station's 31st Progress unpiloted spacecraft brings to the orbiting laboratory more than 1,800 pounds of propellant, more than 100 pounds of oxygen and air, more than 450 pounds of water and nearly 3,000 pounds of dry cargo. Total cargo weight is 5,342 pounds.

P31 replaces the trash-filled P30 which undocked from the aft port of the Zvezda service module Nov. 14 and will deorbit Dec. 7 after for destruction in the Earth's atmosphere after geophysical experiments.

Mike Fincke and Yury Lonchakov

Flight Engineer Yury Lonchakov, seated at the controls of the TORU manual docking system, and Commander Mike Fincke give a thumbs up after the successful docking of the ISS Progress 31 cargo craft. Photo Credit: NASA TV

P31 spent two extra days in orbit for testing its avionics upgrades, including a new main computer, accelerometers, telemetry downlink system, additional interfaces to the docking system and display overlays.

Once the cargo is unloaded, P31 will be filled with trash and station discards. It will be undocked from the station and before deorbit, it may freefly to test new Soyuz navigation software. Then, like its predecessors, it will be commanded to re-enter and burn in the Earth's atmosphere.

The Progress is similar in appearance and some design elements to the Soyuz spacecraft, which brings crew members to the station, serves as a lifeboat while they are there and returns them to Earth. The aft module, the instrumentation and propulsion module, is nearly identical.

But the second of the three Progress sections is a refueling module, and the third, uppermost as the Progress sits on the launch pad, is a cargo module. On the Soyuz, the descent module, where the crew is seated on launch and which returns them to Earth, is the middle module and the third is called the orbital module.