Thursday’s dramatic launch abort that returned the crew of Soyuz MS-10 safely to Earth after a still-unidentified booster anomaly was the first time a crewed spacecraft bound for the International Space Station has suffered a mission critical failure. But it was not the first time that a manned Soyuz rocket has been forced to activate its launch abort system.
The current iteration of the manned Soyuz booster, the Soyuz-FG, had until today boasted a 100 percent success rate. The derivative has been transporting crews to the space station since coming into service in 2001, conducting 55 successful flights in 17 years. But previous versions of the manned Soyuz launch vehicle have twice seen their launch abort systems activated.
The first recorded instance of a launch escape maneuver came in 1975, when Soyuz 18-1 took off for the Salyut 4 space station. The situation looked quite similar to what Russian cosmonaut Alexey Ovchinin and American astronaut Nick Hague experienced Thursday. Both flights experienced an abort midflight, forcing the capsule to separate from the rocket.
Details of Thursday’s launch abort were not immediately clear. According to NASA TV footage of the launch, Russian flight controllers first announced a booster failure about 165 seconds into flight. However, other reports in the Russian press have placed the abort time as early as 119 seconds.
The 1975 Soyuz-18-1 mission was much further along in its flight when the abort occurred: just under five minutes, amid the rocket’s second and third stage separation. The capsule had jettisoned its launch escape tower earlier in the launch, and had to ignite its engines to pull away. The crew experienced an intense re-entry, and landed in the wilderness close to the Chinese border.
According to the TASS news agency, the crew of Soyuz 18-1 experienced anywhere from 20 to 26 Gs on their descent. This is far in excess of what some sources in the Russian press have estimated the crew of Soyuz MS-10 experienced Thursday: anywhere from 5 to 7 Gs. It is not yet clear whether they escaped using the launch escape tower or their capsule’s engines.
This leaves Soyuz 10-1, a 1983 mission to the Salyut 7 space station, able to retain its title as the only manned mission to use the launch escape tower — a funnel-like cap or tower that sits atop the stack ready to whisk the crew capsule away from an exploding rocket on the launch pad or during early phases of flight. NASA is using a similar design for Orion.
Forty-eight seconds before Soyuz 10-1 launched, a fire broke out on the launch pad. The launch escape tower activated two seconds before the rocket below the crew exploded, ripping the Soyuz spacecraft away from the inferno as it engulfed the launch pad. The escape tower then angled the capsule off to the side, ejected, and the capsule opened parachutes for landing.
All things considered, the Soyuz has proven itself reliable historically and its launch escape system — at various stages of flight — has proven effective three times now. Which is good news for NASA and companies like SpaceX and Boeing that are developing similar systems for their manned spacecraft — but have never had to test them under live conditions.