Scheduled to dock at the International Space Station Saturday, the unmanned Progress spaceship is loaded with 2.6 tons of food, fuel, oxygen, propellant and supplies for the Expedition 23 crew.
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.
The ISS Progress 35 that undocked from the station’s Pirs docking compartment April 22 was deorbited Tuesday as its engines fired for a final time at 2:05 p.m., sending the craft to a destructive re-entry over the Pacific Ocean.