Soyuz 7K-ST No. 16L

Soyuz 7K-ST No.16L, sometimes known as Soyuz T-10a or T-10-1, was an unsuccessful Soyuz mission intended to visit the Salyut 7 space station, which was occupied by the Soyuz T-9 crew. However, it never finished its launch countdown; the launch vehicle was destroyed on the launch pad by fire on September 26, 1983. The launch escape system of the Soyuz spacecraft fired two seconds before the launch vehicle exploded, saving the crew. It is so far the only case in which a launch escape system has been fired with a crew aboard.^[1]

Crew

Mission parameters

• Mass: 6850 kg
• Perigee: N/A
• Apogee: N/A
• Inclination: N/A
• Period: N/A

Mission highlights

The Soyuz spacecraft narrowly escapes disaster.

The crew were sitting on the pad awaiting fueling of the Soyuz-U booster to complete prior to liftoff. Approximately 90 seconds before the intended launch, a bad valve caused nitrogen pressurization gas to enter the RP-1 turbopump of the Blok B strap-on. The pump began spinning up, but with no propellant in it, the speed of rotation quickly exceeded its design limits which caused it to rupture and allow RP-1 to leak out and start a fire which quickly engulfed the base of the launch vehicle. Titov and Strekalov could not see what was happening outside, but they felt unusual vibrations and realized that something was amiss.^[2] The launch control team activated the escape system but the control cables had already burned through, and the Soyuz crew could not activate or control the escape system themselves. The LES could be activated by radio command, but it required two launch personnel in a building some distance away to press two buttons within 5 seconds of each other after receiving a code word. This procedure took 20 seconds to perform, by which time the entire booster and pad were in flames.^[3] Explosive bolts fired to separate the descent module from the service module and the upper launch payload shroud from the lower. Then the escape system motor fired, dragging the orbital module and descent module, encased within the upper shroud, free of the booster with an acceleration of 14 to 17g (137 to 167 m/s²) for five seconds. According to Titov, "We could feel the booster swaying from side to side. Then there was a sudden vibration and a jerking sensation as the LES activated."

Just after the escape tower pulled the descent module away, the booster exploded. Its remains burned on the pad for nearly 20 hours. Four grid fins on the outside of the shroud opened and the descent module separated from the orbital module at an altitude of 650 meters (2132 feet), dropping free of the shroud. The descent module discarded its heat shield, exposing the solid-fuel landing rockets, and deployed a fast-opening emergency parachute. Touchdown occurred about four kilometers (2.4 miles) from the launch pad. The two crew members were badly bruised after the high acceleration, but were otherwise in good health and did not require any medical attention.^[1] Upon being greeted by recovery crews, they immediately asked for cigarettes to steady their nerves. The cosmonauts were then given shots of vodka to help them relax.^[4]

The explosion and fires severely damaged LC-1 (the same pad used by Sputnik 1 and Vostok 1), which cost an estimated 300 million USD to repair. Official records claim that the LES activated a mere six seconds before the booster exploded, but some estimates put the time as low as two seconds.

US KH-11 reconnaissance satellites returned photos of the damaged LC-1 in several runs during late 1983-early 1984.

The descent module was refurbished and later used on Soyuz T-15.

The failure's immediate result was the inability to replace the aging Soyuz T-9 return capsule attached to the Salyut 7 space station. This led to dire reports in the Western media about the cosmonauts remaining aboard Salyut 7 (which had arrived several months before in the T-9) being 'stranded' in space, with no ability to return.

Official reports by the Soviet news agency TASS gave few details, merely saying that there had been a pad accident and the cosmonauts were rescued by the LES. It was not until several years later during glasnost that the full story of the accident was revealed to the outside world.

Years later, in an interview with the American History Channel regarding the flight, Titov claimed that the crew's first action after the escape rocket fired was to deactivate the spacecraft's cockpit voice recorder because, as he put it, "We were swearing".^[4]

In a 2001 ceremony at the Houston Manned Space Flight Center commemorating 40 years of manned spaceflight, which was attended by various representatives of the Russian and US space programs, Titov and Strekalov thanked Mercury spacecraft designer Maxime Faget for coming up with the LES which saved their lives.

See also

• Soyuz 7K-T No.39 - a 1975 Soyuz launch failure
• Space accidents and incidents

References

External links

• "History of Soyuz Escape System", Russian Spaceweb website