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Russian module suddenly fires thrusters after docking with space station:
Flight controllers at NASA and Roscosmos averted a disaster on Thursday after a large Russian module docked with the International Space Station and began to "inadvertently" fire its thrusters.
The Russian "Nauka" module linked to the space station at 8:30 am CT (13:30 UTC), local time in Houston, where NASA's Mission Control is based. After that, Russian cosmonauts aboard the station began preparing to open the hatches leading to Nauka, but at 11:34 am Houston time, Nauka unexpectedly started to fire its movement thrusters.
Within minutes, the space station began to lose attitude control. This was a problem for several reasons. First of all, the station requires a certain attitude to maintain signal with geostationary satellites and talk to Mission Control on the ground. Also, solar arrays are positioned to collect power based upon this predetermined attitude.
Another concern is G forces on the station's structure. The various components of the extensive space station were assembled in microgravity and designed to operate at zero-G. So even small stresses on the vehicle can induce small cracks or other problems with the station's structure.
For all of these reasons, space station flight controllers in Houston and Moscow acted quickly after the station started to drift. Attitude control was fully lost at 11:42 am, and engines on the space station's service module were fired. This was followed by a handover to the Russian Progress vehicle attached to the station, which began to fire its thrusters. This tug-of-war offset the Nauka module thruster activity, which eventually stopped after fuel supplies were exhausted. By 12:29 pm on Thursday, attitude control was restored. It made for quite an hour on the ground and in space.
[...] By late Thursday afternoon, when NASA officials held a teleconference to brief reporters, the situation appeared to be well in hand.
Previously:
Russia's MLM Nauka Makes Triumphant Docking to ISS.
(Score: 0) by Anonymous Coward on Saturday July 31 2021, @01:31AM (4 children)
After watching the Scott Manley video, it sounds like there were cascading failures involved. Something failed mechanically. They were able to compensate and everything seemed OK for docking. Then after it docked it tried to back away from the station! If I had to guess, I'd say there was some edge case in the software for which there was no test coverage.
How do you not have a master over-ride on the thrusters? That's what I want to know. You should be able to flip the big red switch somewhere and have them ignore anything that's telling them to fire. That would give you the time to figure out why the computer is telling them to fire when you don't want them to--assuming the computer was telling them to fire and they were not firing due to mechanical issues, or lower level issues. Also, if firing the thruster is some kind of low-level safety feature then you have to leave that in there I suppose. At the lowest level, if the motor is experiencing over-pressure somewhere that would cause it to explode, and if firing can relieve that pressure, it should chose to fire rather than explode.
They're lucky it looks safe now, and they should have plenty of data to look at and get a real answer and not just an Internet guess.
(Score: 0) by Anonymous Coward on Saturday July 31 2021, @03:46AM (2 children)
The master controls, including manual shutdown, are on the Zvezda module, but Nauka wasn't hooked up to that yet. The only other control is from Russian ground control, which was out of contact due to the previous problems delaying the docking and then due to the severe list cutting off all contact with the station.
(Score: 0) by Anonymous Coward on Saturday July 31 2021, @07:16AM (1 child)
Maybe after completing the post-incident failure analysis, they'll decide that the equivalent of the Russian ground-control should be available on the station.
(Score: 0) by Anonymous Coward on Saturday July 31 2021, @03:48PM
After Roscosmos completes their post-incident analysis they will blame the USA and Jewish Space Lasers for being mean to them and then sulk about it for a while after the actual cause gets leaked by a disgruntled intern. My money is on Nauka still thinking that it was supposed to be the station's propulsion module like it was originally designed to be and it tried to "fix" the station being "sideways".
(Score: 1, Funny) by Anonymous Coward on Saturday July 31 2021, @06:02AM
They were using MCAS, no switch necessary.