Undocking question

When the shuttle undocks from PMA2, springs push it off from PMA2.
(according to NASA TV commentator).

Unless the docking collar happens to be at the centre of gravity/mass of
the shuttle, wouldn't that push put the shuttle into a slow rotation ?

I take it they use vernier thrusters to compensate and give the shuttle
a nice trajectory away from station that retains same attitude ? How
soon after the undocking do they do this ? Is this done "by the seat of
their pants", or do they have precise instrumentation to fire the right
thrusters for the precise amount of time needed ?

On Mar 25, 11:52 am, John Doe wrote:
When the shuttle undocks from PMA2, springs push it off from PMA2.
(according to NASA TV commentator).

Unless the docking collar happens to be at the centre of gravity/mass of
the shuttle, wouldn't that push put the shuttle into a slow rotation ?

I take it they use vernier thrusters to compensate and give the shuttle
a nice trajectory away from station that retains same attitude ? How
soon after the undocking do they do this ? Is this done "by the seat of
their pants", or do they have precise instrumentation to fire the right
thrusters for the precise amount of time needed ?

There is an attitude hold function as part of the autopilot

On Mar 25, 10:28 am, wrote:

There is an attitude hold function as part of the autopilot

And "shuttle is commanding the stack" in the period before un-capture.

At one point, while waiting for Beta Gimble Assemblies to latch, I
heard capcom tell Dom that "you have 2 hours prox left". Which leads
to my question -- is the limit on time set by the attitude control
requirements, or by some expendable?

(Remember when hatch closing was the night before?)

Thanks!

/dps

snidely wrote:
(Remember when hatch closing was the night before?)

Hatch closing could be delayed for this mission because of the items
involving the OBSS that had to be done before undock. So the undock day
wasn't as busy.

--
Darren Dunham
Senior Technical Consultant TAOS http://www.taos.com/
Got some Dr Pepper? San Francisco, CA bay area
This line left intentionally blank to confuse you.

On Mar 26, 1:12 pm, (Darren Dunham) wrote:
snidely wrote:
(Remember when hatch closing was the night before?)

Hatch closing could be delayed for this mission because of the items
involving the OBSS that had to be done before undock. So the undock day
wasn't as busy.


Okay.

What about the limit to prox ops?

/dps

snidely wrote:
On Mar 26, 1:12 pm, (Darren Dunham) wrote:
snidely wrote:
(Remember when hatch closing was the night before?)
Hatch closing could be delayed for this mission because of the items
involving the OBSS that had to be done before undock. So the undock day
wasn't as busy.


Okay.

What about the limit to prox ops?

I don't think that's what CAPCOM said. I heard "two hour prop limit".

On Apr 5, 9:27 am, "Jorge R. Frank" wrote:

What about the limit to prox ops?

I don't think that's what CAPCOM said. I heard "two hour prop limit".

So that's how long Shuttle can control the stack? Or does that
include the fly-around budget?

/dps

snidely wrote:
On Apr 5, 9:27 am, "Jorge R. Frank" wrote:
What about the limit to prox ops?
I don't think that's what CAPCOM said. I heard "two hour prop limit".

So that's how long Shuttle can control the stack? Or does that
include the fly-around budget?

No, it's wrong; I misremembered. I guess CAPCOM must have used the word
"prox" on the A/G loop, but the preceding discussion on the Flight loop
regarded TCS/APDS thermal limits. If the undocking had been delayed much
longer, they would have needed to power them down to give them time to
cool off.

On Apr 14, 8:31 pm, "Jorge R. Frank" wrote:
snidely wrote:
On Apr 5, 9:27 am, "Jorge R. Frank" wrote:
What about the limit to prox ops?
I don't think that's what CAPCOM said. I heard "two hour prop limit".

So that's how long Shuttle can control the stack? Or does that
include the fly-around budget?

No, it's wrong; I misremembered. I guess CAPCOM must have used the word
"prox" on the A/G loop, but the preceding discussion on the Flight loop
regarded TCS/APDS thermal limits. If the undocking had been delayed much
longer, they would have needed to power them down to give them time to
cool off.

Okay, thanks. That's an interesting view into the practicalities of
operations.

/dps