Mir's close calls
No matter what was said and written about Mir during its trouble years at the end of the 1990s, this space station will enter history books as a resounding success. Yet, 15 years of Mir operation testify that despite the fact that humans learned to survive in orbit for months and years, space remains a very dangerous place. Here is the log of the most perilous situations, which Mir inhabitants had to go through and important lessons they gave to cosmonauts and designers of future spacecraft.
September 6, 1988: The Soyuz TM-5 landing
After rather uneventful seven-day visit to Mir, a guest cosmonaut from Afghanistan Abdul Akhad Momand boarded the Soyuz TM-5 spacecraft for a trip home, accompanied by an experienced commander Vladimir Lyakhov, returning home after a long-duration mission to Mir. Immediately after undocking, a combination of human errors caused the Soyuz to spin around, while still in proximity of the station. Fortunately, the commander was able to stabilize the ship quickly and safely depart the station. Sometime later, as planned, the Soyuz jettisoned its habitation module in preparation for the deorbiting maneuver. (Separating the module would allow to save fuel for deorbiting maneuver).
However, 30 seconds before scheduled braking maneuver, the orientation system onboard the spacecraft failed causing a seven-minute delay in the engine firing. When the engine did fire automatically, Lyakhov immediately shot it down, since he had no idea where the new reentry trajectory would take the craft.
One orbit later, the crew made a second attempt to deorbit their Soyuz. However, this time, the automatic system confused by previous emergency instructions from the ground, not only shot down the engines, but also launched a countdown for the separation of the propulsion module with all its vital systems including braking engine itself. If Laykhov did not manage to suppress the countdown, the automatic system would separate the reentry capsule from the propulsion module and most certainly doom the crew.
After the ordeal, the Soyuz TM-5 and its crew circled the Earth for 24 hours, without toilet and water left in the jettisoned habitation module. Another deorbiting attempt was made on September 7, 1988, when everything worked perfectly and the crew landed safely.
The Soviet designers learned from the lesson: never again the habitation module, with all its vital systems, would be separated from the Soyuz until deorbiting maneuver had been successfully completed.
1990: Soyuz TM-9 insulation problems
Soon after the launch toward Mir on February 11, 1990, the cosmonauts Anatoly Soloviev and Alexander Balandin discovered that thermal protection sheets on the reentry capsule of their Soyuz spacecraft came loose. Fearing resulting failures in the spacecraft sensors, ground control devised a plan to fix the insulation back in place during an emergency EVA, once the crew gets to Mir. The possibility of sending a one-man rescue ship to pick Soloviev and Balandin was also under consideration.
After watching instructional tapes on insulation repairs, Soloviev and Balandin ventured outside the station through the hatch of the Kvant-2 module on July 17, 1990. After an exhaustive spacewalk and their supply of oxygen running out the repair job was mostly accomplished. However, when the cosmonauts returned to the Kvant-2 they discovered that the module's airlock hatch would not close. Thanks to the module's ingenious design, the crew was able to unpressurize the middle compartment of the Kvant-2 and used it as an airlock to return into the station.
During the next spacewalk on July 25, 1990, the crew resumed its struggle with the hatch on Kvant-2 and eventually succeeded with closing it properly and repressurizing all compartments on the module.
In August 1990, the Soyuz TM-9 landed flawlessly, while the damaged hatch of the Kvant-2 module was eventually repaired as well. This experience gave another lesson to designers: build your airlocks with hatches opening inside the craft, so that internal pressure would help to keep it tightly closed. One wondering how this lesson was learned should look at the docking compartment of the International Space Station, which also serves as the airlock for the Russian segment of the station. Its EVA hatch opens inside.
March 21, 1991: Progress M-7 near miss
Following a first aborted attempt to dock, the Progress M-7 cargo ship controlled from the ground, tried again only to zoom within meters from the station, narrowly avoiding the collision.
The rendezvous problems reoccur as Mir crew redocks its Soyuz TM-11 spacecraft to the rear docking port on Mir's Kvant-1 module. The problem is finally traced to the Kurs rendezvous system onboard Mir, which has one of its antennas missing.
January 14, 1994: Soyuz TM-17 collides with Mir
As the departing Russo-French crew conducts overflight inspection of the station, their Soyuz TM-17 spacecraft hits the Kristall module on Mir at least twice.
Following the successful landing of the crew, the ground processing teams discover a number of "souvenirs" taken by the crew from the station, which exceed the weight limit allowed onboard the Soyuz during landing. The Russian investigation team suggests that excessive weight onboard the craft not only endangered the crew during landing, but it could also contribute to the problems with the attitude control system during the overflight of the station and therefore make the collision with the station more likely.
The moral of the story: the strict "packing up" guidelines for the future station crews.
February 23, 1997: Fire onboard!
During a routine ignition of an oxygen-generating canister, cosmonaut Alexander Lazutkin suddenly faces a flame going out of control. Before the crew puts on gas masks and extinguishes the fire, a multi-module complex, including the Soyuz spacecraft, their only "lifeboat" is filled with smoke. Fortunately, the station's life-support system eventually "clears the air."
June 25, 1997: The collision!
The same Russian crew including Vasiliy Tsibliev and Alexander Lazutkin, which just several months ago was battling flames on Mir, plus NASA astronaut Michael Foale, found themselves in the middle of the worst collision in space history. During a docking test with the use of remote control onboard the station, Tsibliev lost control of a tumbling cargo ship. The vehicle collides with the station and seconds later, the crew onboard Mir hears a hissing sound of air escaping their vessel. Miraculously, almost instantly, the crewmembers were able to locate the air leak to Spektr module. After short struggle to find cutting tools, they severed the cables leading into the Spektr and safely sealed the hatches.
The solar panel battered in the 1997 collision with the cargo ship is clearly visible on the photo taken from the US Space Shuttle during visit to Mir. Click to enlarge: 350x310 pixels, 52K. Credit: NASA