Russia Blames Software Error For Nauka Misfire That Changed ISS Attitude by 540 Degrees

Russia Blames Software Error For Nauka Misfire That Changed ISS Attitude by 540 Degrees

Russia finally issued a statement on July 30 about what happened the previous day when the Nauka module suddenly fired its engines after docking with the International Space Station (ISS). Blaming it on a software error, the statement downplayed the incident, just as NASA officials did during a teleconference the day the incident occurred. But a NASA flight director was more blunt saying the space station brought “a knife to a gun fight” during the ordeal. Days later NASA updated its report on how much the ISS’s attitude was disrupted — 540 degrees, not 45.

The 13 meter long, 20.2 Metric Ton Nauka (Science) module docked with the ISS at 9:29 am EDT on July 29 after years of delay and a sporty 8-day rendezvous.

Also known as the Multi-purpose Laboratory Module (MLM) or FGB-2, Nauka is as large as Russia’s other two major ISS modules, Zarya and Zvezda (also called the Service Module–SM). Nauka adds more living accommodations and oxygen generating capacity as well as scientific research facilities and a European Robotic Arm.

All is well now, but it was tense the day of the docking. Just as everything appeared to settle down, Nauka’s engines suddenly and inadvertently sprang to life, changing the space station’s orientation in space, or attitude. During a media teleconference that afternoon, NASA officials said the attitude was off by 45 degrees before engines on Russia’s Zvezda module and Progress MS-17 cargo spacecraft could compensate.

Russia’s space state corporation Roscosmos and the Russian media were silent throughout the episode. What the world knew was thanks to NASA and its live coverage of ISS communications plus the media teleconference.

The next day, Roscosmos issued a statement from former cosmonaut Vladimir Solovyov, who is now Designer General of Russia’s RSC Energia, which built Nauka and is part of Roscosmos.

Due to a short-term software failure, a direct command was mistakenly implemented to turn on the module’s engines for withdrawal, which led to some modification of the orientation of the complex as a whole.

This situation was quickly countered by the propulsion system of the Zvezda module. At the moment, the station is in its normal orientation, all the ISS and the multipurpose laboratory module systems are operating normally. A reliable internal power and command interface was created, as well as a power supply interface that connected the module to the station.

Like the NASA officials at the teleconference yesterday, Russia’s statement downplayed the significance of Nauka’s engines unintentionally firing. But NASA flight director Zebulon Scoville, who was on console at Mission Control Center (MCC)-Houston, gave a more blunt assessment via Twitter.

Scoville said the estimate that the space station’s attitude was off by “only” 45 degrees was “premature” and “we proceeded to do headstands and cartwheels” of which “Olympic judges would be proud.”  It was a “force fight” between the misfiring thrusters on Nauka/MLM and those trying to correct the situation on the Zvezda/Service Module (SM) –“the ISS brought a knife to a gun fight.”

NASA officials stressed the ISS crew was never in any danger due to the misfiring, but decided to delay launch of Boeing’s Starliner’s uncrewed Orbital Flight Test-2 (OFT-2), that had been scheduled for July 30.

On August 2, Kenneth Chang of the New York Times published an article detailing more of Scoville’s story and characterizing what happened to the ISS as a “back flip.”

“In an interview, Mr. Scoville described how the International Space Station spun one-and-a-half revolutions — about 540 degrees — before coming to a stop upside down. The space station then did a 180-degree forward flip to get back to its original orientation.”

The next day, NASA made it official, acknowleding in an update to its earlier tweet that the ISS attitude did in fact change by about 540 degrees.

The bottom line is that the crew was not in danger and the ISS appears to have withstood the gyrations, but as Scoville said, “Yeehaw! That. was. a. day.”


This article was updated.

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