Spaceflight history has had close calls with challenging ascents to orbit and re-entries. Thankfully, no mission has ended tragically with a crew stranded in-orbit, although one Russian mission came awfully close.

After a 91 day mission aboard the space station Mir, Russian cosmonauts Vladimir Lyakhov and Abdul Ahad Mohmand undocked their Soyuz TM-5 spacecraft from the station on September 5, 1988, in preparation for returning to Earth.

The Soyuz spacecraft is the oldest manned spacecraft in use by any nation, first launched in 1967.

Its first mission was a collection of tremendous miscalculations and malfunctions (paralleling unrelated issues with the Apollo command module design at the  time) that led to the death of Vladimir Komorov.

Since that tragedy, the Soyuz has (and continues) to evolve or adapt to new tasks and destinations to low Earth orbit.

In 1988, the Mir station was still an infant but rapidly growing. Based with years of research on Soviet space station use, Mir’s construction would eventually dwarf, in both size and mission time, the 120-odd days of American space station experience aboard Skylab in 1973-1974. Mir herself would be small in comparison to her successor…but that is a different tale.

1987 mir kvant soyouz
Mir, in 1988.

But 1988, there was only the Core and the Kvant-1 modules.

The Soyuz, compared to its American counterpart spacecraft in the early 1970s, was a curious mix of not two, but three modules.

The habitable Orbital Module contains the docking mechanism, storage and other facilities for comfort while en route to or from an orbital destination.

The middle compartment is the Descent Module, the habitable central command element and the re-entry module for a crew.

The last module is the Instrumentation & Service Module, an unmanned section that holds propulsion, power and life support equipment. On launch, all three modules are shrouded on liftoff.

The normal procedure at the time, prior to re-entry, was to jettison the Orbital Module before retrorocket burn by the Service Module. Then the Descent Module separates and re-orients itself for a proper entry angle into the atmosphere. Jettisoning the Orbital Module was a fuel saving measure with the newer Soyuz-T spacecraft.

The TM-5 crew jettisoned the Orbital Module, reoriented for retrofire, and…nothing happened. A sensor glitch persisted for seven long minutes.

When the retrorockets finally began to fire, the commander shut them down after a few seconds.

The crew waited for another automated firing, three hours later, but this burn quit prematurely after just six seconds.

Commander Lyakhov tried the make a manual burn but then the computer intervened and cut off the burn after 60 seconds.

To make matters much much worse, the computer also began a command sequence that would’ve activated the pyrotechnics that would separate the Descent Module from the Service Module. The crew halted this sequence in time. Else, their Descent Module, powerless to reenter on its own without the Service Module retrorockets, would become their tomb, floating alone in orbit until the batteries died, the oxygen used up and the lifeless module returned to earth.

Russian flight controllers were confused as well. With no immediate answers, they tell the crew to waive off another retrofire attempt. Both crew and ground controllers are painfully aware of two critical points. (1) Without the jettisoned Orbital Module, returning to Mir is impossible. What few creature comforts were aboard, such as a toilet, also disappeared with the Orbital Module.

Outside of the retrorockets and their fuel quantity (2) the computer glitch was the greater problem.

Eventually the ground controllers discovered that the spacecraft computer still had its ascent and rendezvous programming active, which would have different information for orientation of the spacecraft than the reentry programming. As such, the sensors that controlled re-entry were trying to orient the spacecraft to go to the station, not Earth.

It took a full day before controllers resolved the software issue and felt it safe to try retrofire once more. This time, the burn was successful, and the crew landed safely.

The Russians returned to a fail-safe procedure on later missions to keep the Orbital Module until a successful retrofire.

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