Shuttle/ISS docking question

[Katipo]

Something I have always wondered...

Why is it, that after a shuttle docks with the space station, it takes
nearly two hours for them to get around to opening the hatches?

Katipo

[Lee Jay]

Post by Katipo
Something I have always wondered...
Why is it, that after a shuttle docks with the space station, it takes
nearly two hours for them to get around to opening the hatches?

Because they'd prefer to *verify* a good mechanical and pressure seal
to prevent themselves and/or all of their air from accidentally being
blown into space.

Seems like a good idea to me.

Lee Jay

[Katipo]

Post by Lee Jay

Post by Katipo
Something I have always wondered...
Why is it, that after a shuttle docks with the space station, it takes
nearly two hours for them to get around to opening the hatches?

Because they'd prefer to *verify* a good mechanical and pressure seal
to prevent themselves and/or all of their air from accidentally being
blown into space.
Seems like a good idea to me.
Lee Jay

Well I figured it would be kind of stupid to open the hatch before you
confirmed that the seal is good. However I'm surprised it takes so long.

Katipo

[Brian Gaff]

With such large masses, and the switch off of attitude control, I'd imagine
getting the whole assembly back into stability would be the best thing to do
before opening any hatches, as the stresses on the joint may have some kind
of detrimental effect. Also, presumably, some kind of equalisation of
pressures is required.

Brian
--
Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
Email: ***@blueyonder.co.uk
______________________________________________________________________________________________________________

Post by Katipo

Post by Lee Jay

Post by Katipo
Something I have always wondered...
Why is it, that after a shuttle docks with the space station, it takes
nearly two hours for them to get around to opening the hatches?

Because they'd prefer to *verify* a good mechanical and pressure seal
to prevent themselves and/or all of their air from accidentally being
blown into space.
Seems like a good idea to me.
Lee Jay

Well I figured it would be kind of stupid to open the hatch before you
confirmed that the seal is good. However I'm surprised it takes so long.
Katipo

[Pascal Bourguignon]

Post by Katipo
Something I have always wondered...
Why is it, that after a shuttle docks with the space station, it takes
nearly two hours for them to get around to opening the hatches?

Because it goes:

- Toc toc!
- Are you E.T.?
- No we're not. Are you E.T.?
- No we're not. Are you E.T.?
- No we're not. Are you E.T.?
...[one hour later]...
- No we're not. Are you E.T.?
- Oh! Ok. Perhaps you could open the door then?
- No, the key's on your side.
- No, it is on your side.
- No, it is on your side.
...[one half an hour later]...
- No, it is on your side.
- Oh! Ok, let's open both sides at the same time!
- Ok, one, two, three, <pull>
- ... <pull>
- ... <pull>
...[one half an hour later]...
- ... <pull>
- Eh! Why don't you push rather?
- Yeah, that's an idea! <push>
- <pull>
- Houra!

And that's why they congratulate themselves so much once they finally
open it...

[André, PE1PQX]

Post by Katipo
Something I have always wondered...
Why is it, that after a shuttle docks with the space station, it takes nearly
two hours for them to get around to opening the hatches?
Katipo

Because the shuttle is moving slightly (rocking back-and-forth, after
docking) opposed to the ISS.
This can cause the seal to leak, so the crew must be very sure the seal
is good, and the orbiter does not move any more.
If the docking port is bent a bit, the seal can and will leak.

that's all.

André

[John Doe]

Post by André, PE1PQX
Because the shuttle is moving slightly (rocking back-and-forth, after
docking) opposed to the ISS.
This can cause the seal to leak, so the crew must be very sure the seal
is good, and the orbiter does not move any more.

Lets say this were an emergency of biblical proportions. What would happen
if they were to complete the docking before all motion has been dampened ?

Considering that the PMA hardware is capable of suppporting Shuttle
performing atitude control and reboosts, would the PMA/docking aparatus
really be damaged if there were to complete the hard dock without waiting
an eternity ?

And once the hard dock is complete, can there still be any residual
movement ? Once docked, doesn't the shuttle form a single unit with the
station with relative motion between the two basically 0 ?

Does NASA have "emergency docking" procedures where wait times are
dramatically reduced to a bare minimum ?

For a stay of roughly a week, waiting an extra hour or two to be 300% sure
is not a big thing. But how long would it really take to just be safe ?

[Jorge R. Frank]

Post by John Doe

Post by André, PE1PQX
Because the shuttle is moving slightly (rocking back-and-forth, after
docking) opposed to the ISS.
This can cause the seal to leak, so the crew must be very sure the seal
is good, and the orbiter does not move any more.

Lets say this were an emergency of biblical proportions. What would
happen if they were to complete the docking before all motion has been
dampened ?

You mean, "if they were to try to complete the docking..."

The answer is that the docking mechanism would jam and they would not
successfully complete it.

Post by John Doe
And once the hard dock is complete, can there still be any residual
movement ? Once docked, doesn't the shuttle form a single unit with
the station with relative motion between the two basically 0 ?

Yes. But they still need to perform leak checks.

Post by John Doe
Does NASA have "emergency docking" procedures where wait times are
dramatically reduced to a bare minimum ?

No. If they got into that situation, they'd have to wing it.

[André, PE1PQX]

Post by Jorge R. Frank

Post by John Doe

Post by André, PE1PQX
Because the shuttle is moving slightly (rocking back-and-forth, after
docking) opposed to the ISS.
This can cause the seal to leak, so the crew must be very sure the seal
is good, and the orbiter does not move any more.

Lets say this were an emergency of biblical proportions. What would
happen if they were to complete the docking before all motion has been
dampened ?

In case of an emergency there always is a Soyuz docked...

Post by Jorge R. Frank
You mean, "if they were to try to complete the docking..."
The answer is that the docking mechanism would jam and they would not
successfully complete it.

Post by John Doe
And once the hard dock is complete, can there still be any residual
movement ? Once docked, doesn't the shuttle form a single unit with
the station with relative motion between the two basically 0 ?

Yes. But they still need to perform leak checks.

Post by John Doe
Does NASA have "emergency docking" procedures where wait times are
dramatically reduced to a bare minimum ?

No. If they got into that situation, they'd have to wing it.

[Brian Gaff]

As I said, these are large masses, and they have resonances, and I don't
think you would want to bend things just because you were too hasty.
However, I suppose if there were to be some kind of emergency, though I
cannot think of one that would require it, you could get the hatches open
in about half an hour.

Still a long time, and the interconnecting node would need pressurising
presumably, and pressures equalised or there might be problems opening the
door.

Brian
--
Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
Email: ***@blueyonder.co.uk
______________________________________________________________________________________________________________

Post by André, PE1PQX
Because the shuttle is moving slightly (rocking back-and-forth, after
docking) opposed to the ISS.
This can cause the seal to leak, so the crew must be very sure the seal is
good, and the orbiter does not move any more.

Lets say this were an emergency of biblical proportions. What would happen
if they were to complete the docking before all motion has been dampened ?

Considering that the PMA hardware is capable of suppporting Shuttle
performing atitude control and reboosts, would the PMA/docking aparatus
really be damaged if there were to complete the hard dock without waiting
an eternity ?

And once the hard dock is complete, can there still be any residual
movement ? Once docked, doesn't the shuttle form a single unit with the
station with relative motion between the two basically 0 ?

Does NASA have "emergency docking" procedures where wait times are
dramatically reduced to a bare minimum ?

For a stay of roughly a week, waiting an extra hour or two to be 300% sure
is not a big thing. But how long would it really take to just be safe ?

[John Doe]

Post by Brian Gaff
Still a long time, and the interconnecting node would need pressurising
presumably, and pressures equalised or there might be problems opening the
door.

Lets say it was a medical emergency with immediate need to transfer
medecine to/from the station. Couldn't they equalise in a real hurry as
soon as the hard dock is done, verify that there isn't a masive leak
(should take a minute or two) and then open the hatch, transfer what needs
to be transfered. And at a later stage, you close the hatches and perform
the full leak test which takes a long time to check that there aren't any
minute leaks.


If the shuttle is to remain for a week with the hatches always opened, I
can understand you want to make sure you have a perfect seal. Over a period
of a week a lot of air could be lost. (and I assume some very annoying
noises). And should a leak be discovered after docking is complete, it
would be a real pain to have to perform just about all tasks for undocking
(removing air ducts, umbilicales etc) and probably partially release the
docking mechansm and re-engage it and perform the full tests. This could
really disrupt the schedule of tasks during the week. So better spend a bit
more time to do it properly at the first time so you don't have to worry in
mid mission.

Question: lets say they had a faulty seal. Can they partially release the
docking clamps (without pushing the shuttle away) and re-engage them ? Or
is the only way to fully release the clamps let the shuttle take enough
distance for station cameras to inspect the shuttle docking collar (and
shuttle photograph the PMA2 collar) and have the shuttle perform a full
docking operation once again ?