The International Space Station is currently inaccessible after the recent Soyuz launch abort. We’re still looking at the better part of a year before SpaceX or Boeing have any hope of a manned launch, so investigators are anxious to figure out what happened during last week’s incident. According to an initial report from the Russian space agency, the blame lies with one of the rocket’s four first stage boosters.
On Oct. 11, Russian cosmonaut Alexey Ovchinin and NASA astronaut Nick Hague were forced to abort their trip to the International Space Station after several minutes in the air. The pair returned to Earth safely following a ballistic reentry, which can include g-forces twice what they would experience during launch. The current ISS crew can receive supplies via unmanned vehicles, and there’s a Soyuz descent module docked for emergency return trips. However, no new crew members can reach the station until the cause of last week’s incident is addressed.
According to Roscosmos head of human spaceflight Sergei Krikalev, the investigation has focused on a possible collision between part of the first stage and the second (or core) stage. The Soyuz MS-series has a reputation as a reliable vehicle in part thanks to its modular design. At launch, the four first stage boosters ignite, each one with four kerosene-fueled RD-107A engines. These four boosters are arranged radially around the main/second stage of the vehicle. When the first stage boosters finish their job, they jettison simultaneously. However, one of those boosters might not have come off cleanly.
The Soyuz first stage boosters all have propellant systems to push them clear of the main stage, but that may have failed. The problematic booster likely collided with the body of the rocket as it ejected two minutes after launch, causing damage and triggering an automatic abort.
Russian authorities are still conducting an investigation, and a full report will come out around Oct. 20. Roscosmos says it’s speeding up construction of another Soyuz so it can resume launches quickly if it gets the green light. NASA is conducting its own investigation of the incident, but it hasn’t made any statements yet. The US agency hopes to stop using Soyuz rockets to reach the ISS in the next year, but the date for SpaceX and Boeing to begin carrying passengers has been pushed back several times.
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