NASA's flight director has given new details on last week's terrifying incident in orbit. A newly docked Russian module accidentally fired its thrusters, which caused the International Space Station (ISS) to roll backwards.AdvertisementIt occurred on Thursday, July 29, three hours after Russia's Nauka module docked with the space station. Russian crew members were attempting to integrate the new section. However, Naukas thrusters started to fire, causing ISS to re-roll. Russian flight controllers eventually regained control but the situation was tense for 47 minutes.NASA stated that the orbiter had shifted approximately 45 degrees during a press conference later that day. According to Zebulon Scoville (the NASA flight director at the time), that report was a bit inaccurate. He said that the actual figure was closer to 540 degrees. This means that 1.5 backflips were performed by the ISS in an impromptu display that would make any Olympic athlete jealous. According to the New York Times, the ISS was upside-down when it stopped spinning. This required a 180-degree forward turn in order to regain its original position.Concerned, I contacted NASA to inquire about the discrepancy and confirm the figures provided me by Scoville.A NASA spokesperson stated in an email that the initial value reported by flight control was 45 degrees. This was reported while the event was still unfolding. Scoville540 degrees' value was confirmed after the event analysis was completed, explained the spokesperson.NASA claims that seven crew members were never in danger. However, Jonathan McDowell, Harvard-Smithsonian Astrophysicist, told me last week that this incident was among the most serious in the ISS's 24-year history. He said that losing attitude control could lead to the collapse of the entire structure.AdvertisementScoville was not scheduled to work on Thursday. However, after the docking of Nauka, Scoville was asked to replace Gregory Whitney, flight director, who was unable to attend a meeting. Scoville saw an error message at 12:34 p.m. ET. It was related to the ISS' four gyroscopes that maintain the station's attitude control. As NYTs Kenneth Chang reports:So I thought at first, "Oh, is this a false indicator?" Mr. Scoville replied. Then I saw the thruster firings and ice on the monitors. This is not a joke. It is a real event. Let's get to the point. After about half an exhale of "Oh, geez! What now?" you can push the problem down and work it out. Even worse, there was no way for them to be turned off. According to his Russian counterparts, Nauka had been set up so it could only receive commands from Russia's ground stations. The next flight over Russia was scheduled for 70 minutes.AdvertisementNauka, an attachment to the ISS bottombelly, started to pull down the aft section, causing it a backflip of 0.56 degrees per seconds. Although the crew didn't notice the spin, it was enough to cause structural damage to the antennas and point them away from their targets. According to the NYT, ground controllers lost communication in two instances. One for four minutes and one for seven minutes. To prevent any damage, the stations' solar arrays and radiators were kept locked.Russian controllers were unable to disable Naukas thrusters so they fired thrusters attached at the Zvezda Services Module. They also fired thrusters at a Progress cargo ship that was docked at the station, fearing it might not be enough. The tug-of-war lasted 15 minutes and was finally ended when Naukas thrusters stopped working for unknown reasons (probably because it ran out of fuel). After regaining attitude control, flight controllers were able correct the ship. The Russian crew has now begun to integrate the 23-ton module, which was delivered without any further problems.AdvertisementBelow is a video of the crew opening the hatch for the new module. Then, a tour of Nauka follows.NASA says it isn't a huge deal that the station rolled 45 degrees instead of 540 degrees.AdvertisementHowever, the greater rotation does not affect the outcome. All other stations responded normal to the event and resumed normal operations after attitude control was restored. This was explained by a NASA spokesperson via email. The most important thing is that the maximum rate atwhich the attitude change took place, which was approximately 0.5 degrees per minute, was within the limits of the station systems. This allowed for crew members to observe the event without being noticed. Amongst the most important things was that the maximum rate at which an attitude change occurred, approximately 0.5 degrees per second, was well within the design limits of station systems and slow enough to go unnoticed by crew members on board.Scoville wrote in a tweet that it was his first spacecraft emergency. He also said that he was not happy to see the radiators and solar arrays still attached. Vladimir Solovyov (flight director for the Russian segment) of the ISS stated that the incident was caused by a short-term failure in software. A direct command to turn off the engines of the modules was misinterpreted and failed to execute. This resulted in some modifications to the orientation of the entire complex.AdvertisementNASA and Boeing had to postpone the launch of CST-100 Starliner until August 3 due to the mishap. Today's launch was delayed by a technical issue. NASA coverage will begin at 12:57 EDT.
