Soyuz 2-1B Fregat software design fault caused launch failure says Roscosmos

by | Dec 12, 2017 | Launches, Seradata News, Soyuz

The launch failure on 28 November of the Soyuz 2-1B Fregat, which destroyed 19 satellites including the Meteor 2M-1 weather satellite, was caused by a software design fault related to the rocket’s operation from its new launch site at Vostochny Cosmodrome, in Far Eastern Russia, according to an accident investigation report by Roscosmos.

The Russian space agency/industrial conglomerate makes it clear that the main cause was the failure of the software designers to appreciate that the alignment relative to launch azimuth at the new Vostochny site was different from previous launch sites, and the way the extra rotation angle needed would affect the Fregat upper stage’s gyro-based guidance system.

While this launch was the second Soyuz flight from Vostochny (the first occurred in April 2016), importantly, this flight was the first to use the Soyuz-Fregat combination from this launch site.

Anatoly Zac of Russiaspaceweb.com has reported more detail about the failure, which can be summarised as follows:

The angle of a roll needed to achieve correct azimuth (direction relative to North) of ascent from the previous Soyuz launch sites was between the ranges of positive 140 to negative 140 degrees. However, to achieve the correct azimuth from Vostochny, the ill-fated launch would need a roll of 174 degrees (with possibly a few extra degrees to compensate for guidance error), with 10 degrees added during the Fregat stage operation to compensate for the different reference axis in the Fregat. While this was fine for the Soyuz rocket stages, it meant that the Fregat gyro platform had to turn at least 184 degrees in order to reach the required “zero” position if flown from Vostochny.

The problem was that the 184-degree rotation to zero via the expected shortest route was “backwards” 176 degrees. This backwards move to zero had not been expected by the guidance software on Fregat, which thought that the stage was still off target by 360 degrees and started a compensatory rotation using its thrusters at one degree per second.

Unfortunately, about 60 seconds into this roll the main engine started its pre-planned firing to achieve orbit, but was pointing in the wrong direction as the roll had not been completed. The result was that orbital velocity for the planned parking orbit was not achieved and the Fregat stage and its 19-satellite payload fell back to Earth and into the Atlantic Ocean.

While the investigation is confident about the above being cause of the failure, the underlying cause is still being investigated.

Soyuz 2-1B Fregat launch from Vostochny took off successfully but went wrong later. Courtesy: Roscosmos

 

 

About Seradata

Seradata produce the renowned SpaceTrak Launch & Satellite Database. Trusted by 100 of the world’s leading Space organisations, SpaceTrak is a fully queryable database used for market analysis, failure/risk assessment, spectrum analysis and space situational awareness (SSA).

For more information go to www.seradata.com/spacetrak

Related Articles

Third OneWeb launch of the year takes constellation count to over 200

Following a brief one-day delay a Soyuz 2-1B (with Fregat upper-stage) rocket lifted-off from Vostochny Cosmodrome, Russia, at 1738 GMT, Read more

Another 36 OneWeb satellites are sent into orbit via a Soyuz 2-1b/Fregat

A Soyuz 2-1b/Fregat rocket was launched into orbit from the launched from the Vostochny Cosmodrome in the far east of Read more

First OneWeb launch of 2021 carried out as planned to make up for lost time

Arianespace, through its Russian joint venture Starsem, has launched a Soyuz 2-1b/Fregat vehicle carrying 36 OneWeb satellites into low Earth Read more

Soyuz 2.1b/Fregat launches 36 OneWeb satellites from Vostochny

A Soyuz 2-1b/Fregat was launch from Vostochny in Eastern Russia at 1226 GMT on 18 December carrying 36 OneWeb communications Read more

Three Gonets-M satellites are launched on a Soyuz – plus a small nanosat

At 0114 GMT on 3 December 2020 a Russian Soyuz 2-1b/Fregat launch vehicle was launched from the Plesetsk launch site Read more

Soyuz rocket launches from Plesetsk carrying three Gonets-M satellites and 19 rideshare passengers

Lifting-off at 1120 GMT on 28 September from the Plesetsk Cosmodrome, Northern Russia, a Soyuz 2-1B mission has carried 22 Read more

Space tourism to involve spacewalks as Roscosmos plans trip…as NASA astronauts do their own spacewalk in June

Roscosmos, the Russian space agency/industrial complex, has announced that it plans to allow two tourists to ride aboard a Soyuz Read more

NASA plays safe and orders another “ride” on Soyuz for its astronauts in case commercial crew ops have issues

While the first manned Commercial Crew programme test flight of SpaceX Crew Dragon is due later this month, NASA is Read more

Cookies & Privacy

Click here to read about use of cookies on the website

Categories

Archives