Russian Progress 77 cargo spacecraft arrives at the ISS marking the end for Pirs

Earlier this week, we mentioned that Russia had launched a resupply spacecraft to the ISS filled with supplies for the space station crew. The mission was Progress 77, and it has arrived at the ISS Pirs docking station on the Russian segment of the spacecraft as of 1:27 AM EST today. Progress 77 arrived at the ISS two days after launching from Baikonur Cosmodrome in Kazakhstan on Sunday.

The ISS and Progress 77 were flying over Argentina when they docked. Aboard the cargo ship was over one ton of nitrogen, water, and propellant for the space station, along with new scientific experiments and supplies. Progress 77 will remain docked with the space station until later in the year.

This mission marks the last time the Pirs docking module will be used. Progress will stay connected to the module and detach Pirs from the Earth-facing side of the ISS Russian segment when it leaves. That docking segment has spent nearly two decades in service, acting as a docking port and spacewalk airlock.

When Progress 77 and Pirs depart, it will have been days after the launch of the "Nauka" Multipurpose Laboratory Module aboard a Proton rocket from Russia. Nakua is a multifunction docking port and research facility that will be docked to the port Pirs previously occupied.

Progress will fire its engines to push it and Pirs into Earth's atmosphere, where both will burn up during reentry. The new Russian module marks the first addition to the space station's Russian segment in a decade. The module has been in development for nearly 25 years and weighs in at 20 tons. Nauka will be the largest spacecraft Russia has launched since it sent the Zvezda Service Module to the ISS in 2000.