Progress 77 cargo spacecraft and Pirs docking compartment depart the ISS

NASA has confirmed that the un-piloted Russian Progress 77 cargo spacecraft has been undocked from the international space station. The biggest difference between this undocking and a large number of other undockings that have occurred at the Pirs docking compartment over its lifetime is that the docking compartment detached from the ISS along with the cargo spacecraft. The undocking happened at 6:55 AM EDT on July 26.The spacecraft will reenter the Earth's atmosphere and burn up in the sky over the South Pacific. Progress 77 launched and docked with the ISS in February, bringing more than a ton of cargo to the crewmembers aboard the orbiting space station at the time. The removal of the Pirs docking station is historic for the ISS, and unfortunately, the deorbit and reentry won't be covered on NASA TV.

The departure of the cargo spacecraft and the docking port leaves the Earth-facing side of the Russian segment of the station ready to accept the new Russian Multipurpose Laboratory Module (MLM). After years of delays, that module is scheduled to dock with the space station on Thursday, July 29. The new module is called Nauka, which is the Russian word for science.

The module launched on July 21 and will serve as a new science facility, docking port, and spacewalk airlock for future operations aboard the ISS. NASA will air coverage of the new MLM docking with the ISS beginning at 8:30 AM on Thursday, July 29, with the docking expected to occur at 9:25 AM. Pirs has been part of the space station since September 2001 and was a docking port for Russian spacecraft and an airlock for Russian spacewalks.

Pirs had to depart the station for the new laboratory module to be attached. MLM previously deployed its solar arrays and navigational antennas as planned. It spent eight days in free flight allowing Russian flight controllers to evaluate systems on the module. MLM is 43 feet long and weighs 23 tons, it will attach to the same ISS port Pirs departed.