International Space Station upset more serious than first reported

Stan Cooper

Stan Cooper

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Not exactly "aviation" but the first time an emergency has been declared at the ISS.

Space Station Did 540-Degree Roll

AVweb said:
The upset of the International Space Station a week ago was a lot more dramatic than was first revealed and there’s now a call for an independent investigation of the incident. As we reported last week the ISS was knocked off its normal attitude when a Russian module that had just docked with the station activated one of its thrusters. NASA officials initially said the mishap nudged the ISS to a bank angle of 45 degrees but they’ve since corrected that. The football-field-sized collection of modules connected by a spindly structure actually rolled 540 degrees before systems on the station fired thrusters (ironically from another Russian structure docked to the ISS) to counter the errant maneuver.
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Wow. I know the ISS has live streaming cameras on it, has anybody found video of the roll?
 
RussR said:
Wow. I know the ISS has live streaming cameras on it, has anybody found video of the roll?
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There's speculation the incident is being downplayed because of political considerations. I expect we'll see videos if the called for investigation materializes.
 
I'm curious if the errant thrust affected the ISS's orbit as well as its attitude.
 
midwestpa24 said:
I'm curious if the errant thrust affected the ISS's orbit as well as its attitude.
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Shouldn't have, or at least not much. With the thruster so far off center, most of its effort went into the roll, not adding or subtracting from the orbital speed. There'll be a bit of spiraling effect, of course. Over the hour it was happening, there might have been some orbit change, but still probably not that much.

What surprised me is that they were apparently unable to shut down the thruster, and it sounds like they basically had to wait until it ran out of propellant. All the satellites I've worked on have multiple control valves to give redundant ability to shut thrusters down. Sounds like they were completely locked out of the system, and (since they hadn't opened the hatch to the new module) they couldn't access any manual control.

Ron Wanttaja
 
540-degrees at what rate? That seems to be missing in these discussions. If the damn thing was spinning at at 30-degrees/second they had quite the emergency. If it did it over the course of an hour how bad could it be?
 
steingar said:
540-degrees at what rate? That seems to be missing in these discussions. If the damn thing was spinning at at 30-degrees/second they had quite the emergency. If it did it over the course of an hour how bad could it be?
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Michael, the Astronomy.com article includes this quote:
astronomy.com said:
Thanks to the efforts of the thrusters on the ISS Service Module and Progress — and because the ISS has a much greater mass and moment of inertia than the Gemini capsule — the station didn’t reach anywhere near that rate. It peaked at about half a degree per second, which would have seen it do a 360-degree spin in 12 minutes. But for a facility as massive as the ISS, it was a harrowing incident.
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RussR said:
Wow. I know the ISS has live streaming cameras on it, has anybody found video of the roll?
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Timelapse (not that great)
steingar said:
540-degrees at what rate? That seems to be missing in these discussions. If the damn thing was spinning at at 30-degrees/second they had quite the emergency. If it did it over the course of an hour how bad could it be?
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I think it’s impressive that they avoided an emergency over 20 years of constant operation of a spacecraft that’s so complicated, with so many people involved and so many spacecraft that have docked.
 
luvflyin said:
Who declared? Was it the station? Was it a Mayday or a Pan Pan? Or did Mission Control declare? And which one? Who gets the credit? Them or us? :devil:
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They cancelled IFR, lined up for for 20nm straight in, and popped the chute.
 
Dumb question from me .... the whole affair is in zero gravity so from the crew perspective wouldn't everything seem "normal" unless they looked outside or at instruments ??
 
A Martin said:
Dumb question from me .... the whole affair is in zero gravity so from the crew perspective wouldn't everything seem "normal" unless they looked outside or at instruments ??
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The station started to rotate. Unless the astronauts were attached to it, they wouldn't move so it would rotate into them. From their point of view, they'd start to drift towards one wall until they bumped into it. If they were moving, it would "throw them off," changing their path. If they *were* attached, they'd feel a tug on their arm/leg/whatever.

Depending on the coupling to the structure, it's possible they could hear the thrusters firing, as well.

The Station uses Control Moment Gyros (CMGs) to control attitude...basically gyroscopes where torque is applied and thus transmitted to the station itself. CMGs provide very fine control, so they wouldn't ordinarily notice any attitude travel.

CMGs have to be "desaturated" on occasion (when the control arm gets near one of its limits), and that's generally done using the thrusters. That's probably a planned event.

Ron Wanttaja
 
Thanks for the reply Wanttaja .... makes sense to me .

I confess I have a crossed wire in my brain in regards to the following ..... if an aircraft has a cargo of birds that weigh 1000 pounds .... will the plane be 1000 pounds lighter if the birds are flying around inside ? ... apparently the answer is no .... the plane , the birds , and the air inside the plane are all "one enclosed unit" and the weight does not changed.

To this day I cannot grasp why the plane would not be lighter ..... but thats just me .... thus in my mind I considered the space lab was also .... "one enclosed unit" .... and whatever the lab was doing (rotating) would not affect the occupants.

Anyone who can figure out what I just said is genius ..... haaaa.
 
A Martin said:
Thanks for the reply Wanttaja .... makes sense to me .

I confess I have a crossed wire in my brain in regards to the following ..... if an aircraft has a cargo of birds that weigh 1000 pounds .... will the plane be 1000 pounds lighter if the birds are flying around inside ? ... apparently the answer is no .... the plane , the birds , and the air inside the plane are all "one enclosed unit" and the weight does not changed.

To this day I cannot grasp why the plane would not be lighter ..... but thats just me .... thus in my mind I considered the space lab was also .... "one enclosed unit" .... and whatever the lab was doing (rotating) would not affect the occupants.

Anyone who can figure out what I just said is genius ..... haaaa.
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Your example really isn’t comparable. The weight doesn’t change because the birds are pushing the air down with the force of their weight to keep them flying. If they didn’t, they wouldn’t stay in the air.

But in the case of the space station, if you were exactly at the center of rotation, and it were large enough to rotate around you, without touching you, you wouldn’t be effected. You’d certainly see the thing spinning around you though.

but if it’s not big enough, or you’re not at the center of rotation, you’re either going to get hit by a moving wall, or be spun in the same way the station spun. And you’d certainly feel it.

If you were space walking touching nothing, and someone gave you a spin, even with no visual references, you would feel the spin happening because it would be an acceleration.

You can’t sense that you are moving, but you can sense when you change speed.

Then there is centripetal force, in which you are constantly accelerating (around a circular path), so you can always feel it. So, even if spinning at a constant rate, with no visual references, you’d still feel the spin because your extremities would be experiencing centripetal force. Your hair would fly outward, etc.
 
A Martin said:
Thanks for the reply Wanttaja .... makes sense to me .

I confess I have a crossed wire in my brain in regards to the following ..... if an aircraft has a cargo of birds that weigh 1000 pounds .... will the plane be 1000 pounds lighter if the birds are flying around inside ? ... apparently the answer is no .... the plane , the birds , and the air inside the plane are all "one enclosed unit" and the weight does not changed.

To this day I cannot grasp why the plane would not be lighter ..... but thats just me .... thus in my mind I considered the space lab was also .... "one enclosed unit" .... and whatever the lab was doing (rotating) would not affect the occupants.

Anyone who can figure out what I just said is genius ..... haaaa.
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Newton will not be denied.
 
Capt. Geoffrey Thorpe said:
Newton will not be denied.
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Awesome as always. Do you have a video that explains why airfoils tend to be curved more on top? You sort of touch on it a bit in that one, but I think giving people a real reason for the curve might help some accept reality. And, of course, I say “tend to be curved more in top” because, of course, some are actually symmetrical.
 
Salty said:
Awesome as always. Do you have a video that explains why airfoils tend to be curved more on top? You sort of touch on it a bit in that one, but I think giving people a real reason for the curve might help some accept reality. And, of course, I say “tend to be curved more in top” because, of course, some are actually symmetrical.
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Thank you.
You can think of an airfoil as a combination of a symmetric shape combined with a curved camber line (midline). That's what tends to give you a top that is more curvish than the bottom.

I did put all of this sort of thing in a playlist
https://www.youtube.com/playlist?list=PL3ea3YrO-K5iBBX-IWrHFQz-NWJZlt2kg
 
A Martin said:
To this day I cannot grasp why the plane would not be lighter ..... but thats just me .... thus in my mind I considered the space lab was also .... "one enclosed unit" .... and whatever the lab was doing (rotating) would not affect the occupants.
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One way to think of it: The station isn't flying, it's falling with style. It's not using lift/gravity/thrust/drag to maintain its path, its path is determined solely by velocity and gravity. The fact that the occupants are inside a pressurized shell is neither here nor there. The people are going to maintain their own path even if the station deviates, up to the point where they clunk into the wall.

Think of someone floating in the Vomit Comet. If the pilot pushes harder on the stick, the plane is going to angle downwards, but the occupants will follow their original path and bump into the ceiling.

Ron Wanttaja
 
Capt. Geoffrey Thorpe said:
Newton will not be denied.
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I think this guy is wrong when he says Bernoulli is not causing lift in a wing ..... he wants to say Newton is at work and the downwash of the rotor is what makes lift ..... fine .... agreed , in his test it is partly true .... because his demonstration is using ground effect to produce lift .... same principle in a hovercraft etc ..... but move that drone up into free air at 50 feet where Newton is not at work and only Bernoulli is making lift ..... the guy is not as smart as he thinks he is .... if he was a pilot he would have known these things.
 
A Martin said:
I think this guy is wrong when he says Bernoulli is not causing lift in a wing ..... he wants to say Newton is at work and the downwash of the rotor is what makes lift ..... fine .... agreed , in his test it is partly true .... because his demonstration is using ground effect to produce lift .... same principle in a hovercraft etc ..... but move that drone up into free air at 50 feet where Newton is not at work and only Bernoulli is making lift ..... the guy is not as smart as he thinks he is .... if he was a pilot he would have known these things.
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Lol. “This guy” is quite smart and understands it a whole lot better than you or I do.
 
Our esteemed resident YT professor is not incorrect.

Navier-Stokes already went through the drudgery of explaining how lift is fundamentally a Newtonian law derivative. For the record, deflection of flow is not dependent on plate restrictions to the flow field (what ground effect is one example of). Again, N-S describes this pretty well. Flow deflection around a solid is a newtonian physics interaction. Velocity is a vector quantity, direction change is indeed a contributor to that acceleration vector eg Force.

The real point is that Bernoulli's conception is not incompatible with Newtonian physics. The problem is that people create false dichotomies when they juxtapose Bernoulli and Navier-stokes. The Bernoulli description proponents are merely misapplying Bernoulli to a finite wing 3-D flow, especially with the application of "equal transit time" particle condition to determine velocity profile, and "venturi flow" conditional assumptions to describe the former's velocity change profile (velocity as a Vector quantity, for which dV/dt describes a FORCE). Venturi flows do not describe finite airfoils in 3-D flight.

For the record, it is also equally reductionist and incomplete for the Newtonian camp to describe lift as only the reaction force of fluid being deflected on the bottom of a lifting surface (misapplication of 3rd law). As N-S clearly describes, the contribution of Lift for the entire body also depends on the fluid deflection on the side of the surface the Lift vector points to (usually described as the "top" of the airfoil, but it could be any, depending on angle of attack).

Now, can't we all just utilize the correct assumptions to describe the dynamic, and get along already? :D

For the more long winded explanation of the miscommunication, see Glenn Research Center's position on the question.
 
A Martin said:
I think this guy is wrong when he says Bernoulli is not causing lift in a wing ..... he wants to say Newton is at work and the downwash of the rotor is what makes lift ..... fine .... agreed , in his test it is partly true .... because his demonstration is using ground effect to produce lift .... same principle in a hovercraft etc ..... but move that drone up into free air at 50 feet where Newton is not at work and only Bernoulli is making lift ..... the guy is not as smart as he thinks he is .... if he was a pilot he would have known these things.
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First of all, it's pretty easy to derive Bernoulli's equation from Newton's second law using nothing more than simple algebra (two page derivation here). So, anything Bernoulli explains, so does Newton.
Second, Bernoulli can't explain lift (or low pressures) without first there being a difference in velocity since Bernoulli's equation is nothing more (and nothing less) than conservation of energy along a streamline. Where do the differences in velocity come from?
Third, what Mr.. Hindsight2020 said.
The big problem is that, as pilots, we have been told a lot of fairy tales and it is sometimes hard to tell fact from fiction.

Apologies for derailing the thread.
 
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