Sergey Mikayev

First spaceflight, from the cosmonaut class of 2021 — the smallest intake Roscosmos has run in two decades — and a test engineer whose career before orbit was spent not flying but building and breaking the hardware that cosmonauts rely on. Sergey Mikayev represents a newer generation of Russian space professionals: less military, more technical, and deeply familiar with the structural realities of the Station.

Before spaceflight

Mikayev was born in Russia and studied engineering, eventually earning a doctorate in structural mechanics. Before his selection as a cosmonaut, he worked at TsNIIMash — the Central Research Institute of Machine Building — which is Roscosmos’s primary research and testing facility. TsNIIMash is where Russian space hardware goes to be validated: structural loads, vibration tests, thermal cycling, materials analysis. If something is going to fail, the goal is to make it fail there, not in orbit.

His role as a test engineer gave him an intimate understanding of how Station hardware behaves under stress — knowledge that translates directly to diagnosing anomalies in orbit, where you cannot simply swap out a failed component and run the test again.

He was selected for the cosmonaut corps in 2021 as part of a very small intake. The training programme that followed covered Soyuz operations, Station systems, spacewalk preparation, and extensive cross-training with NASA and ESA.

Spaceflight career

Expedition 74 is Mikayev’s first spaceflight. He launched in December 2025 aboard a Soyuz spacecraft for a planned six-month stay. As a first-time flyer he has been working through the steep learning curve of adapting to microgravity while taking on increasing responsibility for Russian-segment operations.

This expedition

Mikayev serves as flight engineer with a focus on the Station-side instrumentation for the long-running orbital-debris characterisation campaign — a research programme that uses sensors mounted on the exterior of the Station to measure the size, velocity, and frequency of micrometeorite and debris impacts. The data matters because it feeds directly into the risk models that determine how much shielding future spacecraft need.

He also supports general maintenance and experiment operations across the Russian segment, working under the guidance of Commander Sergey Kud-Sverchkov.

The person

Keeps a chess set magnetised to a bulkhead in Zvezda and plays against anyone who will sit still long enough. Colleagues describe him as curious, technically rigorous, and more talkative than the average Russian crew member — traits that make him a good bridge between the segments. His background in testing gives him a distinctive perspective: where others see a system working, he sees a system that has not yet been stressed to failure.