Cosmonauts complete VKD-64 spacewalk

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Cosmonauts complete VKD-64 spacewalk

On Oct. 16, 2025, members of Expedition 73 Sergei Ryzhikov and Aleksei Zubritsky ventured on the exterior of the Russian ISS Segment for more than six hours, installing the Ekran-M experiment for the production of semi-conductors in the vacuum of space.

Previous spacewalk: VKD-63

mle

Cosmonaut Aleksei Zubritsky demonstrates the KNA MLE unit inside the Nauka module in October 2025.

VKD-64 spacewalk at a glance:

Spacewalker 1	Sergei Ryzhikov, Orlan-MKS No. 7 suit with red stripes
Spacewalker 2	Aleksei Zubritsky, Orlan-MKS No. 6 suit with blue stripes
Duration	5 hours 38 minutes (planned); 6 hours 9 minutes (actual)
Hatch opening	2025 Oct. 16, 20:08:17 Moscow Time (actual); 19:50 Moscow Time (planned)
Hatch closure	2025 Oct. 17, 02:19 Moscow Time (actual); 01:28 Moscow Time (planned)
Airlock	MIM2 Poisk
ISS expedition	73

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The VKD-64 spacewalk, staged from the Poisk module, MIM2, had the main objective of deploying an experimental hardware for the so-called Molecular Beam Epitaxy, or MBE, which is an exotic technique for forming high precision and super-thin layers of material (first of all semi-conductors) by directing beams of atoms or molecules on a special surface. To be effective, the method requires very high vacuum, which is hard to achieve on the ground, and, therefore, spurred the development of space-based systems, including the large disk-shaped MBE platform deployed from the cargo bay of a Space Shuttle in the 1990s. From around the same period, the Russian industry sought to develop the Oka-T free-flying station module, focused on the same technology, but the project never went beyond the drawing board.

The MBE is abbreviated as MLE in Russian (for Molekulyarno-Luchevaya Epitaksiya), giving its name to the experimental unit developed at the Rzhanov Semiconductor Physics Institute in the 2020s. Known also as Ekran-M, the more-than-100-kilogram drum-shaped aggregate was delivered to the ISS in September 2025 by the Progress MS-32 cargo ship. Like its predecessors, the experiment was to attempt to produce gallium arsenide, which is critical for high-end electronics, optics, lasers, solar elements and other technologies. The MLE equipment was to be installed on the exterior of the Nauka module, MLM, a part of the Russian ISS Segment, via a special adapter. The spacewalker carrying the unit was expected to be delivered to the installation site with the help of the European Robotic Arm, ERA, (INSIDER CONTENT). The cosmonauts were trained to connect power cables to the MLE unit, which was to operate under remote control. Its material-processing cassette was designed for periodic re-loading by spacewalking cosmonauts, with the first such operation scheduled within around two weeks after the VKD-64 spacewalk, which would install the system.

If time allowed after the installation of the Ekran-M equipment, the VKD-64 cosmonauts were also expected to move to the Zvezda Service Module, SM, where they were to remove and discard into orbit the High Resolution Camera, HRC, of the Canadian company UrtheCast, which was installed in 2014. They also had an assignment to clean Widnow No. 1 on the service module. On their way back to the airlock, the spacewalkers were also expected to remove the SKK No. 3-M2 container, that exposed material samples to space conditions, from the exterior of the Poisk module.

Naturally, Russian scientists hoped that the MLE experiment would eventually lead to semi-industrial or even commercial production in space, but no previous attempts to industrialize this technology in orbit had materialized. Perhaps, latest push to reduce cost of space transportation and the emergence of new-generation space stations, including the ROS project, could provide another impetus for jump-starting effort in the field.

Just ahead of the spacewalk, mission control displayed the following timeline for VKD-64 on the night from October 16 to October 17, 2025:

17:00 - 18:15 Moscow Time: Equipment setup, entering space suits;
18:15 – 19:44 Moscow Time: The (internal) hatch closure (between MIM2 and SM), airlock operations;
19:44 – 19:50 Moscow Time: MIM2 Egress hatch opening;
19:50 – 01:30 Moscow Time: VKD-64 spacewalk operations;
01:27 – 01:30 Moscow Time: Closure of the MIM2 ingress hatch;
01:30 – 02:30 Moscow Time: Airlock re-pressurization.

Cosmonauts begin VKD-64 spacewalk

After nearly two hours of airlock operations, Sergei Ryzhikov and Aleksei Zubritsky were reported starting hatch opening operations inside the Poisk module at around 20:00 Moscow Time on Oct. 16, 2025. Zubritsky was first out of the airlock, while Ryzhikov remained inside, preparing the extraction of the equipment. Both cosmonauts were reported to be nearly ready for the transfer to the Nauka module around 20:30 Moscow Time, but had to wait until the completion of the attitude control thruster firings aboard the Russian Segment. Once cleared for the transfer, the cosmonauts moved to the transfer section of the service module, where the European Robotic Arm, ERA, could reach them, while controlled by the Russian cosmonaut Oleg Platonov from the inside the station.

ERA extended to the cosmonauts' staging point on the SM transfer compartment around 20:45 Moscow Time. At that time, Ryzhikov got approval from mission control to fix himself to the portable work site on the ERA arm, while Zubritsky was holding the Ekran-M unit. One Ryzhikov attached his feet to the robotic arm, Zubritsky transferred him the Ekran-M unit. ERA was ready for moving Ryzhikov with his cargo at around 20:50 Moscow Time. In the meantime, Zubritsky started moving to the site on his own, along the surface of the station with a package of tools.

At around 21:00 Moscow Time, the cosmonauts were asked to take a six-minute break, while ERA was switching to a different mode.

As the sun was setting over the station at around 21:20 Moscow Time, Ryzhikov disembarked ERA at the Ekran-M's installation site on Nauka. Zubritsky was already waiting for him there. The cosmonauts then unwound the cable for powering Ekran-M and routed it to the instrument.

The data, power and thermal connections with the Ekran-M instrument were reported to be in place just before 22:00 Moscow Time. Few minutes later, mission control confirmed that all the interfaces worked as planned, clearing the way to the installation of the exchangeable cassette into the instrument.

Zubritsky then removed screws which held the unit in the transport position. One of the fasteners resisted, forcing Zubritsky to use a pair of pliers. The cosmonauts also had to open the top cover of the instrument, exposing it to the vacuum of space. The operation was finally completed at around 22:40 Moscow Time. A few minutes later, the cosmonauts were cleared to install the cassette. The cassette was reported to be in place soon after 23:00 Moscow Time, when mission control instructed spacewalkers to install necessary plugs on the instrument. The cosmonauts then had to complete a detailed photo documentation of the newly installed equipment.

Zubritsky then attached himself to the ERA arm, which moved him back toward the Service Module at around 23:30 Moscow Time. In the process, Zubritsky was conducting photography of the module, as he was riding the arm.

Zubritsky's first task on the Service Module was the removal of the HRC camera. In the meantime, Ryzhikov was transferring to the same location on his own. To discard the HRC camera, Zubritsky had to disconnect some cables and open a mechanical lock, before throwing the device into space. The cosmonauts got a go from mission control for disconnecting the camera soon after midnight Moscow Time on Oct. 17, 2025. Prior to the mechanical disconnect, the defunct instrument was secured with a flexible tether.

Once the HRC was secured, the robotic arm moved Zubritsky away from the station into a safe position for discarding the device, as the station plunged into darkness again. Zubritsky discarded HRC at 00:39 Moscow Time in the nighttime conditions around 4.5 hours into the spacewalk.

Around half an hour later, the cosmonauts positioned themselves at window No. 1 of the Service Module. Zubritsky completed the cleaning of the window's surface at around 01:20 Moscow Time. Two different brushes were used in the operation. The cosmonauts then headed to the Poisk module, where they removed the container with material samples, before returning to the airlock and closing the hatch at 02:19 Moscow Time on Oct. 17, 2025, after a 6-hour 9-minute spacewalk.

To be updated

This page is maintained by Anatoly Zak; last update: October 17, 2025

Page editor: Alain Chabot; last edit: October 16, 2025

The Ekran-M KNA MLE experimental unit. Click to enlarge. Credit: Roskosmos

ERA carries Ryzhikov with the MLE experiment toward the installation site on the Nauka module during the VKD-64 spacewalk. Click to enlarge. Credit: Roskosmos

Zubritsky is removing screws holding the MLE experiment in transport position. Click to enlarge. Credit: Roskosmos

Zubritsky ejects the HRC instrument from the ISS during the VKD-64 spacewalk. Click to enlarge. Credit: Roskosmos

Zubritsky cleans window No. 1 on the Zvezda Service Module during the VKD-64 spacewalk. Click to enlarge. Credit: Roskosmos