A Russian Progress cargo ship disembarked from the International Space Station early Monday, taking with it the airlock and the two-decade-old Pirs docking compartment to clear the way for the arrival of Russia’s new multipurpose Nauka laboratory module on Thursday.
With the Progress MS-16/77P supply ship tightly closed at Pirs, the hooks and latches holding the mooring compartment in the ground-facing port of the Zvezda service unit opened, and the advance slipped back at 6:55 AM EDT.
The flight plan called The Progress to fire its engines at 10:01 a.m., resulting in a devastating plunge into the atmosphere 41 minutes later. The throttle burn was planned to ensure that any debris that might survive the return heating would fall harmlessly into the South Pacific.
Docking was planned to be canceled last Friday, two days laterFrom the Baikonur Cosmodrome in Kazakhstan, but problems with the navigation and propulsion systems in the laboratory prompted Russian flight controllers to delay Peres’ departure.
Finally, after several anxious days of troubleshooting, the Nauka’s propulsion system was restored to normal operation, and two successful KURS navigation and rendezvous system tests were conducted. While few details were provided, the directors of the Russian missions subsequently agreed to Pirs and Progress to leave.
Pirs was launched on September 14, 2001, three days after the September 11 attacks. It served as a docking port for visiting Soyuz crew ships and Progress trucks for nearly 20 years and as an airlock for Russian spacewalks.
The larger, 44,000-pound Nauka unit features an air pressure equalization base and docking port, expanded crew spaces, research space, an additional toilet, an oxygen generator, solar arrays and an ESA-made robotic arm. The Nauka’s engines will also help provide roll control to keep the station oriented properly.
With Pearce gone, NASA flight controllers planned to reposition the station’s Canadian robot arm on Russia’s Zarya module so it could perform a seven-hour inspection of the now vacant Earth-facing port of Zvezda. Russian engineers want to make sure there are no debris or other problems that could prevent the mooring mechanism from working properly when Nauka arrives.
Assuming no problems are found, the lab module will complete its appointment with the space station on Thursday, and will move to dock at the Earth-facing port of Zvezda at 9:24 a.m. It will take up to 11 Russian spacewalks over the course of about seven months to electrically connect and equip the new lab unit.
The docking at Nauka will come a day before a United Launch Alliance Atlas 5 rocket launches the Boeing CST-100 Starliner crew capsule to the station for an unmanned test flight. Atlas 5 is expected to launch on Board 41 at Cape Canaveral Space Force Station on Wednesday, where it will launch at 2:53 p.m. Friday.
The Starliner, like SpaceX’s Crew Dragon spacecraft already in operation, is designed to transport American astronauts and partner agencies to and from the space station on a commercial basis, helping to end NASA’s post-shuttle reliance on Russia’s Soyuz spacecraft for crew transportation.
A Starliner’s initial test flight in December 2019 ran into major software problems, prompting Boeing to launch a second uncrewed test flight ahead of the ship’s first planned launch with crew on board late this year or early next.
For the test flight, the Starliner will dock at the front end of the station’s forward harmony module, return to White Sands, New Mexico, and land on August 5.