The old pier had made way for the new.
After twenty years of quiet service as laboratory, airlock, and harbor for visiting spacecraft, Russia's Pirs module departed the International Space Station on Monday, July 26, 2021, carried away by a cargo vessel and dissolved into the Pacific. Its retirement was not merely a decommissioning but a deliberate act of making room — a recognition that the future sometimes requires releasing the past before it can arrive.
- Technical failures aboard the incoming Nauka module — a stalled engine burn and a faulty antenna — created cascading uncertainty and pushed the entire handoff back three critical days.
- Cosmonauts methodically sealed and pressure-tested the hatches separating Pirs from the station, a ritual of farewell that transformed a working module into an object ready to be surrendered to gravity.
- At 10:01 a.m. Eastern time, the deorbit burn committed both Progress MS-16 and Pirs to reentry, their decades of orbital life ending in atmospheric fire above a remote stretch of the Pacific.
- With the docking port now vacant, the Russian segment of the ISS waits in readiness — Nauka, carrying Europe's robotic arm and expanded laboratory capacity, is scheduled to fill that silence on Thursday.
On the morning of July 26, 2021, the Progress MS-16 cargo spacecraft and the Pirs docking module undocked from the International Space Station and began their final descent. Pirs — Russian for "pier" — had been a fixture of the station since September 2001, spending two decades functioning simultaneously as science lab, docking port, and spacewalk airlock. Small but indispensable, it was now being retired to clear the way for Nauka, a larger multipurpose laboratory that had launched just five days earlier and was bound for the same berth.
The transition had not been smooth. Nauka's journey to orbit was troubled from the start: its main engine failed to complete the first orbit-raising burn, forcing controllers to rely on backup thrusters, and an antenna malfunction added further concern. The undocking of Pirs, originally planned for July 23, was delayed three days while engineers worked through the problems and confirmed Nauka would successfully reach the station.
Once that confidence was established, cosmonauts Oleg Novitskiy and Pyotr Dubrov sealed the hatches between Pirs and the Russian segment, pressure-tested them, and prepared the module for departure. When the moment came Monday morning, Progress fired its thrusters to pull the pair away. The deorbit burn followed, sending both objects back through the atmosphere. Most burned away on reentry; the remaining debris fell harmlessly into a remote area of the Pacific. Roscosmos marked the moment on Twitter with a simple farewell.
With the port now open, the station awaits Nauka's arrival on Thursday — bringing not only new laboratory space but also a European-built robotic arm designed to service the Russian segment for years ahead. One pier retired; another, larger one on its way.
On Monday morning, July 26, 2021, at 6:55 a.m., a Russian cargo ship and the docking station it was tethered to slipped away from the International Space Station and began their final descent toward Earth. The Progress MS-16 spacecraft and the Pirs module—which had been bolted to the station for two decades—undocked without incident, their separation marking the end of an era and the clearing of a crucial berth for what comes next.
Pirs, whose name means "pier" in Russian, had been working since September 2001, when it first launched to the station. For twenty years it served triple duty: a science laboratory, a docking port for visiting spacecraft, and an airlock through which cosmonauts could venture into the vacuum for spacewalks. The module measured just under five meters long and two and a half meters wide, weighing roughly 3,838 kilograms. It was time to go. The Russian space agency Roscosmos had decided to retire it to make room for something larger and more capable—the Nauka multipurpose laboratory module, which had launched just five days earlier and was scheduled to dock on Thursday, July 29.
The undocking had originally been planned for Friday, July 23, but delays in the Nauka mission pushed it back three days. Nauka's journey to orbit had been rocky. Its main engine failed to complete the first burn needed to raise its orbit, forcing mission controllers to rely on backup thrusters instead. An antenna problem emerged. And there were concerns about the docking target itself—the very port where Pirs now sat. The decision was made to wait, to give engineers time to troubleshoot, and to ensure Pirs would be clear and ready when Nauka finally arrived.
On Saturday, once it became certain that Nauka would reach the station, cosmonauts Oleg Novitskiy and Pyotr Dubrov began the careful work of preparing for separation. They closed the hatches between Pirs and the rest of the Russian segment, then tested them to confirm they held pressure. The module was being sealed off, isolated, prepared for departure.
When the moment came on Monday morning, the Progress spacecraft's thrusters fired to slow the pair down and move them to a safe distance. At 10:01 a.m. Eastern time, controllers initiated the deorbit burn—the final push that would send both objects plummeting back through the atmosphere. Most of what they were made of would burn away during reentry. What remained, the non-combustible structural elements, splashed down in a remote stretch of the Pacific Ocean, far from any shipping lanes or populated areas. Roscosmos posted a farewell on Twitter: "Thank you for your work, Progress and Pirs."
With the port now empty, the Russian segment of the station stood ready. Nauka would arrive in three days, bringing with it not just additional laboratory space but also a new robotic arm built by the European Space Agency—a tool that would service and maintain the Russian side of the station for years to come. The old pier had made way for the new. The handoff was underway.
Citações Notáveis
The non-combustible structural elements fell in a non-navigable area of the Pacific Ocean.— Roscosmos
A Conversa do Hearth Outra perspectiva sobre a história
Why retire a module that's been working for two decades? Couldn't they have kept Pirs and docked Nauka somewhere else?
The station's architecture doesn't work that way. Each docking port is specific, and the Russian segment only had so much real estate. Pirs was aging, and Nauka was designed to be its replacement—bigger, more capable, with better science facilities. You don't keep the old thing just because it still works.
But the timing seems tight. Nauka had all these problems—engine failures, antenna issues. What if it couldn't dock?
That's exactly why they delayed the Pirs undocking. They weren't going to detach the old module until they were confident the new one would actually make it. If Nauka had failed completely, they would have had to figure out a different plan. But the engineers believed it would get there, so they moved forward.
What happens to all the equipment and experiments that were in Pirs?
They would have been moved out beforehand—transferred to other modules, or packed into the Progress cargo ship before it undocked. You don't just abandon things. Everything of value gets relocated or brought back to Earth.
And the robotic arm that Nauka is bringing—that's a big deal?
It changes what the Russian segment can do. For twenty years, spacewalks were the only way to service and maintain things on that side of the station. Now they'll have a mechanical arm that can do some of that work remotely. It's an upgrade in capability and safety.
So this is really about modernization, not just making space?
Exactly. The station is a living thing. Modules age, technology improves, and you refresh the system. Pirs did its job. Now it's Nauka's turn.