ISS loses attitude control after Nauka module docking | Hacker News Reader

ISS loses attitude control after Nauka module docking

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145 pointsNewLogic31 comments

People might wonder why attitude control is important. First and foremost: power. Solar power requires that the solar arrays be directed toward the sun. Losing attitude control means that they'll lose efficiency and thus power. This isn't a big deal in the short run, but long term is a big deal. Surely they'll have this fixed before that comes into play.

Aside from that, there's a lot of other smaller factors such as being able to orient the station to boost orbit every so often. Even though they're in Low Earth Orbit, there is a just enough atmosphere to cause the orbit to decay slightly over time, and this has to be compensated for by boosting the orbit. No attitude control = no orienting thrusters.

Obligatory Scott Manley video that's way better than what I just said: https://www.youtube.com/watch?v=fDp8jbP_22c

Perhaps more important than keeping the solar arrays pointed at the sun is keeping the radiators out of direct sunlight. The problem in space isn't so much freezing as cooking because there is no atmosphere between you and the sun and the only way to vent heat is inefficiently as radiation.

If the radiators started cooking in direct sunlight the station would get uncomfortably hot in a hurry.

I believe the ISS also orients its solar panels edge-on to prograde (direction of orbit) at night to minimize drag, so that’s another consideration of attitude control failure. Still second order to the radiators, though.

I love the fact that 'at night' is still a correct term but it's only 45 min for ISS.

>Even though they're in Low Earth Orbit, there is a just enough atmosphere to cause the orbit to decay slightly over time, and this has to be compensated for by boosting the orbit

Just to expand on this a little (since it's gaining new relevance with the lower LEO and VLEO large constellations getting planned/launched), orbital life times drop non-linearly with altitude, atmospheric drags plays a big role fast until hundreds of km above the Karman line. An oldie and simplified but goodie site here [0] gives a decent basic overview. Remember that this will also vary, the atmosphere is affected by temperature and other factors.

Particularly since the ISS is manned and mass was very restricted, its altitude is a tight balancing act between high enough to not need to boost too often for comfort/practicality and as low as possible to reduce radiation exposure and stay away from the inner Van Allen radiation belt, which can get quite low indeed on occasion based on solar activity and geographic areas. It does mean though that ISS reboosts have to happen fairly regularly.

One big area of current interest this has an impact on is orbital debris lifetimes. There's an excellent Gabbard diagram animation [1] on Reddit that's worth a look if you haven't seen it before. You can see the decay rate very visually. Having constellations be very low is valuable for passive fail-safety in case of loss of control or collisions.

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0: https://www.spaceacademy.net.au/watch/debris/orblife.htm

1: https://old.reddit.com/r/space/comments/ld4vlq/gabbard_diagr...

Seems like they're out of the immediate problem area: https://twitter.com/SciGuySpace/status/1420798716554928132

Still lots of investigation to do and probably a permanent fix incoming, but no big risk of them falling out of the sky right now.

I wonder how much fuel was lost as a result of this.

Being reported as a flight computer state machine fault. https://twitter.com/NASASpaceflight/status/14208042826857922...

Aside: Today I learned about the existence of "video.ibm.com" which seems to be where NASA now streams its live video. I'd never heard of it before.

Live ISS stream: https://video.ibm.com/channel/live-iss-stream (Currently no video, intermittent audio.)

I hope NASA will team up with Starlink for providing multiple 24-7 live streams. At least full hd please.

IBM bought Ustream a few years ago and it’s now rebranded as IBM Cloud Video

As an IBM employee, my condolences to anyone who relied on ustream.

`nslookup` shows that the IP addresses for ustream.tv and video.ibm.com are the same ones. I also recall looking at ISS live streams on ustream.tv a couple of years ago.

THANKS!

Never knew a livestream existed and now I'm clued to my headset.

Spacedashboard have a nice summary of the streams and the position over earth. https://spacedashboard.com/

for people curious, when that website is not broken https://www.internationaldockingstandard.com/download/IDSS_I... , there is the list of the moment of inertia of the ISS around various axes and the force and torque limits a docking ship as to respect.

attitude control, yeah, we've all had one of those days.

attitude control huh?

Yes, "attitude" is an aerospace industry term for "the way you are pointing/oriented".

So like heading, course, angle, direction, vector, and other terms that make more sense?

those all have distinct but specific meanings. Attitude refers to a collection of those terms, specifically as they relate to the frame of reference (the ground, in nearly all cases) https://aviation.stackexchange.com/questions/35933/what-is-t...

I mean "attitude" makes perfect sense to those of us who actually work in aerospace. It's related to all the terms you listed but none of them are strictly equivalent.

But go ahead and be snarky if it makes you feel better?

https://en.wikipedia.org/wiki/Attitude_control

As in many other areas of life, your attitude determines your altitude!

Attitude?! Why I never …

It’s all about the orientation, #headduck

Where's Attitude Adjuster when one's needed ...

It's alright, those NASA boys have got the Steely Glint in their eyes.

GCU Funny, It Worked Last Time is on its way.

Well, fix the fucking thing!

(I have been waiting decades to make that joke.)

Was it everything you hoped it would be?

Yeah, actually. Worth it.

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