Spektr module for the Mir space station

The Spektr (spectrum) module became the fifth major component comprising the Mir space station. Launched in 1995, the nearly 20-ton spacecraft remained fully functional until 1997, when it became the victim of an unintentional collision with a wayward cargo ship.


Original layout of the Spektr module. Credit: TsPK

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Spektr module (77KSO) at a glance:

Launch date
May 20, 1995
Docking date June 1, 1995
Launch vehicle UR-500K Proton
Mass within Mir complex 20 tons (original)
Length 9.1 meters (original)
Diameter 4.35 meters
Payload mass 7 tons

The end of the Cold War literally transformed the purpose and shape of the Spektr module. The spacecraft was developed for a top-secret military program code-named "Oktant." Within "Oktant," the Soviet Ministry of Defense planned a series of experiments in surveillance from space and tests of technology for antimissile defense.

The experiments would continue the research in the field started aboard the top-secret TKS-M module, which docked to Salyut-7 in 1985 under the official "cover-up" name Kosmos-1686.

A set of surveillance instruments and launch containers for artificial targets were mounted on the exterior of the module, while a control station was set up in its interior for a specially trained researcher. An experimental optical telescope code-named "Pion" was the heart of the Spektr's payload.

However, with the end of the arm race and the shrinking of Russia's space budget at the end of the 1980s, the Spektr module was stuck on the ground for an indefinite period of time. Russian officials reportedly considered launching Spektr and its sister-ship - the Priroda module - to the International Space Station.

The rescue came in the mid-1990s with the resurgence of US-Russian cooperation in space. The Spektr was quickly refurbished for a new mission: to house experiments for the cooperative program. The module's military payload was replaced with a new conical-shaped section housing a second pair of solar panels, which would improve Mir's ever-diminishing power-supply capabilities provided by its aging solar arrays.

The propulsion system onboard Spektr featured small 11D458 and 17D58E thrusters developed at NIIMash.

A Phaza spectrometer was the only leftover from the Spektr's military past, when the module made it into orbit in May 1995.

Although it docked successfully with Mir on June 1, 1995, the Spektr turned out to be the unluckiest component of Mir. In June 1997, a Progress M-34 cargo ship, which went astray during a remote-controlled docking experiment, hit the Spektr and its solar panels. The collision caused depressurization of the spacecraft and almost cost the lives of the station's crew. Fortunately, the cosmonauts were able to severe the cables leading to the module and close the hatch connecting it with the rest of the station.

Later, the hatch leading into Spektr was replaced with a special sealed plate carrying airtight interfaces for the power cables. In the course of the so-called "internal" spacewalk into the depressurized module, the cosmonauts ran power cables from Spektr's undamaged solar panels to the hatch. As a result, the space station was able to reclaim the electricity generated onboard the damaged and sealed-off module.

All attempts to pinpoint the exact location of the air leak onboard Spektr and to repair it proved fruitless, leaving the Spektr off limits for the rest of the station's life span.

During the last expedition to Mir in the Spring and Summer of 2000, cosmonauts discovered that a small leak, which had bothered mission control since the Summer of 1999, was caused by a small test valve in the plate which sealed off the Spektr. The leak was reportedly isolated in a matter of seconds.

Next chapter: Priroda module


Page author: Anatoly Zak; Last update: January 3, 2023

Page editor: Alain Chabot: Last edit: May 20, 2020

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An isolated view of the Spektr module in its original configuration. Credit: TsPK


The Spektr module during pre-launch processing at the spacecraft assembly building at Site 254 in Baikonur.

A training version of the Spektr module minus its thermal protective insulation and the military payload which was attached to the spacecraft from the left. Copyright © 2001 Anatoly Zak

The "new" tail section of the Spektr module with two additional solar arrays, which replaced its military payload, after the spacecraft was "demilitarized" in the mid-1990s. Copyright © 2001 Anatoly Zak

A solar panel battered in the 1997 collision with the cargo ship (bottom left) is clearly visible on the photo taken from the US Space Shuttle. Credit: NASA