Chaotic ISS attitude after Nauka misfires thrusters (resolved)

[mfb]

TL;DR Summary

Nauka is the most recent ISS module. After docking, it unexpectedly fired thrusters, changing the orientation of the ISS. The situation has been resolved.

Nauka, a Russian multipurpose science module and one of the largest ISS modules, was docked to the ISS. During the checkout procedures after docking the module suddenly fired its thrusters, rotating the ISS quite rapidly (up to 0.5 degree/s). The Zvezda module and a docked Progress resupply ship were able to stabilize the attitude of the ISS and the situation is under control. People are still investigating what happened.
The Crew Dragon docked to the station was powered up in between in case of an emergency, but it was not used. The second uncrewed Starliner test, planned for tomorrow, was delayed by a few days to better understand what happened.

Shorter video here
NASA briefing

Telemetry - the 11:00-14:00 changes were intentional for docking, the 16:30 changes were from Nauka.
The 90 minute cycle of the solar panels after the incident is intentional to maximize power while minimizing drag when the ISS is in the shadow.

 

[berkeman]

Something just occurred to me -- when there are astronauts outside on EVA, there must be precautions taken to disable any nearby attitude control thrusters, right? But do they use some fool-proof lockout (like turning off power, similar to locking out an electrical breaker box), or do they just trust the systems to honor the temporary disabling of the relevant thrusters (which apparently would not have worked in this case near Nauka)?

 

[hutchphd]

My guess is that the Nauke module had not been fully integrated into the ISS system at the point of the incident, and there are presumably global interrupts that will come into play. But it is not a monolithic system nor is it simple. Nor has it been comprehensively tested I would bet...

 

[256bits]

I would say the "test" was successful.

Complicated systems are going to have glitches, and this glitch was resolved towards a positive resolution.
I doubt if anyone sane would have ever proposed, or anyone agreeing, to see what happens when a thruster fires off inadvertently.
And now they know that they can bring it back under control under such a situation.

Good job ISS and team.

 

[mfb]

Russia says the firing was a software problem.
They could bring it under control only after Nauka stopped firing - I don't know how/why it stopped.

The ISS is not made to handle the forces it experiences during such a relatively rapid spin. So far it looks like nothing was damaged, but this could have been pure luck.

 

[hutchphd]

More than any sane person would need to know about the ISS acceleration modes

https://www.nasa.gov/sites/default/...ion-environment-iss-mini-book_detail-508c.pdf

 

[mfb]

0.5 degree/s at 10 m leads to an acceleration of 75 micro-g. That's far more than the "micro-g's or less" quasi-steady acceleration of page 8 despite the relatively small radius chosen for the example. It's likely some people will now run additional simulations how such a large acceleration could have impacted their experiments.

"Crew push-off and landing" seems to be a major vibration source.

 

[hutchphd]

And of course any resonance is likely not externally damped (free floating and no air!). I think they said the large scale modes are in the 0.1-1.0 Hz range (like soldiers on a bridge but higher Q)

 

[anorlunda]

The incident provides a good reminder that space habitats will always be hazardous.

I'm sure that the real astronauts need no reminders.

 

[256bits]

0.5 degree/s at 10 m leads to an acceleration of 75 micro-g. That's far more than the "micro-g's or less" quasi-steady acceleration of page 8 despite the relatively small radius chosen for the example. It's likely some people will now run additional simulations how such a large acceleration could have impacted their experiments.

"Crew push-off and landing" seems to be a major vibration source.

so, your saying the rotating craft in interstellar ( where bad guy crashes into it, the good guy docks asking the robot to take control to fire thrusters to slow the rotation ) is using cinema license it would seem. The rotation in the movie seemed excessive.

 

[mfb]

The craft in Interstellar was intended to rotate to create artificial gravity. It would have been designed with a healthy safety factor. Maybe not as much as needed for the movie, but at least it's not completely out of question.

 

[russ_watters]

My guess is that the Nauke module had not been fully integrated into the ISS system at the point of the incident...

So maybe attitude control hadn't been disabled (or integrated with ISS sensors/computers[if that's a thing] yet). It decides it needs a little attitude correction (because zero is too exact) and bumps the thruster. Nothing detectable happens because now it's mass has increased by a factor of a thousand. So it goes full blast...

 

[hutchphd]

Computers can be persistent...

 

[berkeman]

when there are astronauts outside on EVA, there must be precautions taken to disable any nearby attitude control thrusters, right? But do they use some fool-proof lockout (like turning off power, similar to locking out an electrical breaker box), or do they just trust the systems to honor the temporary disabling of the relevant thrusters (which apparently would not have worked in this case near Nauka)?

https://ambit.artstation.com/projects/xznRO2

 

[hutchphd]

Big knife switches somewhere? How integrated are the systems? Surely they are triply redundant in the usual NASA way.
And the routine attitude control is done with the flywheels (I think) so the use of thrusters is likely not automatic although necessary occasionally (I wonder how often?) as is the occasional orbit boost.

 

[berkeman]

How integrated are the systems? Surely they are triply redundant in the usual NASA way.

Good question. I wonder if there will be a NASA after-action report or similar accident report. It better not just be "a software glitch occurred", IMO.

 

[mfb]

It's a Russian module so I expect most of the report by Russia, with NASA cooperation.

About one and a half rotations: Animation by Scott Manley

 

[Ivan Seeking]

Wow! A buddy at work told me how bad it was today. At first I thought he was joking.

 

[etudiant]

Am astounded that the 'International Space Station' does not have an international command and control communications setup.
Apparently the Nauka malfunction could not be diagnosed because the station was out of direct contact with any of the Russian control centers.
Surely it would be possible to relay the data via a NASA relay, but clearly that was not being done.
Dumb turf fight or security paranoia, whatever the cause, it caused a near disaster.

 

[hutchphd]

Dumb turf fight or security paranoia, whatever the cause, it caused a near disaster.

The maximum rotation rate was about half a degree per second. This is not the stuff of rending metal, so as long as there was nothing to run into it seems not that terrifying. I suppose there may be some microgravity experiments which will require annotation. Not that losing attitude control is a good thing, and resonances are the real problem, but this was smooth.
The errant thruster fire on Gemini 8 caused rates approaching 1 revolution /s which is worse by a bit.
What is the worst foreseeable negative outcome from this level of excursion from nominal?

 

[Benjies]

The maximum rotation rate was about half a degree per second. This is not the stuff of rending metal, so as long as there was nothing to run into it seems not that terrifying.

A fair point, perhaps Etudiant was being a bit dramatic with the diagnosis of the issue. I wouldn't know, material science isn't really my forte. But I want to footstomp his comment regarding shared comms to the ISS- I am assuming that we aren't cleared to know exactly how information is relayed between the ISS and Earth, but if there truly was an issue of "oh sorry it's over on the other side right now", then that is a serious, serious issue IMO.

 

[berkeman]

but if there truly was an issue of "oh sorry it's over on the other side right now", then that is a serious, serious issue IMO.

We've come a long way from the Mercury program! Or have we?

 

[wrobel]

as for me I am surprised at how it could leave the start table at all