Investigation finds faulty sensor the reason for Soyuz MS-10 accident
It was a faulty sensor that ultimately caused the Oct. 11, 2018, launch abort of a Soyuz-FG rocket carrying an American astronaut and Russian cosmonaut into space for a planned six-month stay aboard the International Space Station.
The investigation was completed and on Nov. 1 the Russian commission released the results in a press conference at the Central Research Institute of Machine Building in Korolyov, Russia.
“The launch ended up with a launcher failure caused by abnormal separation of one of the strap-on boosters (Block D) that hit with its nose the core stage (Block A) in the fuel tank area,” lead investigator Oleg Skorobogatov told reporters, according to Roscosmos. “It resulted in its decompression and, as consequence, the space rocket lost its attitude control.”
Roscosmos said the separation was caused by the “non-opening” of a nozzle that was intended to vent oxygen following the detachment of Block D booster to push it away from the core stage. However, the sensor pin that would have triggered this event was deformed.
According to the report, the pin was bent by nearly seven degrees during the assembly of the boosters with the core stage in Baikonur Cosmodrome, Kazakhstan. The investigators did not reveal if they knew how the sensor was bent.
Soyuz MS-10 launched at 4:40 a.m. EDT (8:40 GMT) Oct. 11 from Baikonur Cosmodrome. After about two minutes of flight, the four strap-on boosters were supposed to separate and fall away harmlessly. In a dramatic video released by Roscosmos, the Block D booster can be seen not separating as the other three had. This resulted in it pushing the core off axis. Later frames of the video show the core spinning with pieces of the lower stage hanging off, possibly indicating that there was a break up of the lower portion of the vehicle.
Following the failure, the emergency escape system pulled the Soyuz MS-10 capsule with NASA astronaut Nick Hague and Russian cosmonaut Aleksey Ovchinin away from the booster. They landed in their capsule just under 20 minutes later in Kazakhstan.
Since the accident, one Soyuz rocket—a Soyuz 2.1b variant—has launched. There were no apparent problems with this vehicle. At least three more Soyuz vehicles are expected to launch before the next crewed flight including another Soyuz-FG with the launch of Progress MS-10 on Nov. 16. According to Roscosmos, all upcoming Soyuz rocket launches will be disassembled and inspected to ensure a similar problem does not occur.
The next crewed flight is expected to be on Dec. 3—Soyuz MS-11 with Russian cosmonaut Oleg Kononenko, Canadian astronaut David Saint-Jacques and NASA astronaut Anne McClain. They will join the already aboard Expedition 57 crew—European Space Agency astronaut Alexander Gerst, Russian cosmonaut Sergey Prokopyev and NASA astronaut Serena Aunon-Chancellor.
Gerst, Prokopyev and Aunon-Chancellor arrived at the ISS in June 2018 using their Soyuz MS-09 spacecraft. They are expected to leave by Dec. 20 and return to Earth.
Video courtesy of Roscosmos
Derek Richardson has a degree in mass media, with an emphasis in contemporary journalism, from Washburn University in Topeka, Kansas. While at Washburn, he was the managing editor of the student run newspaper, the Washburn Review. He also has a blog about the International Space Station, called Orbital Velocity.