A little while ago the Progress MS-6 spacecraft docked with the International Space Station in the mission also referred to as Progress 66. The Russian space freighter, which blasted off last Wednesday, is carrying food, water, scientific experiments, propellant and various hardware.
The Progress MS-6 cargo spacecraft regularly docked with the International Space Station’s Russian Zvezda module using the automatic system that allows Russian spacecraft a direct berthing. During the week the crew will proceed with the opening of the hatch and the procedures to make the Progress MS-6 an appendix of the Station. At that point, they can begin the unloading operations.
According to the original plans, the Progress MS-6 spacecraft was supposed to be used as a sort of space tug to remove the Russian Pirs module, but the Russian space agency Roscosmos postponed the plan due to the further delay in completing the new Nauka module. It’s a more advanced space laboratory, in fact it’s also known as Multipurpose Laboratory Module (MLM).
In essence, the Progress MS-6 spacecraft was scheduled to be used to move the Pirs module away from the International Space Station, as the Nauka module will be installed in its place. In that procedure the spacecraft was supposed to undock from the Zvezda module, dock with the Pirs module and use its thrusters to drive both of them away from the Station. At that point, the Progress MS-6 and Pirs would’ve fallen back into the Earth’s atmosphere disintegrating.
At this time, the new tentative date to launch the Nauka module is some time at the end of 2018. It’s impossible to tell if Nauka will be really ready after all the delays accumulated over the last few years. If it’s finally launched according to the new schedule, the Progress MS-9 spacecraft will be used as a tug to get rid of the Pirs module.
Because this use of the Progress MS-6 spacecraft has been canceled, its mission is substantially accomplished. In fact it can’t return to Earth so it will be filled with hardware failed or otherwise become unusable and assorted junk and will disintegrate returning into the Earth’s atmosphere. This mission epilogue will probably take place in December 2017 but the exact date depends on various factors.