ISS ATU's (communication panels) need water cooling? Why?

On NASA TV's STS-130 Flight Day Highlights segment aired Wednesday
afternoon, there was a short clip showing shuttle astronaut Kathryn
Hire preparing an ISS ATU (Audio Terminal Unit) for installation in
the new Cupola module. Two hoses were seen coming out of the bottom,
and a commentator said these were for a water cooling loop.

So, are all ATUs on the station similarly connected to water cooling?
Or is this one set up differently because of possible sun heating when
the Cupola windows are open?

In the former case, what is there inside that's dissipating enough
power to make this necessary? I understand that relying on forced-air
or convective cooling of electronics on ISS is undesirable, but why
would the ATU be emitting any significant heat to begin with? Isn't
it basically just an intercom/phone panel?

curious,
--
Jordan.

I'd have no idea. Seems odd that someone like that would get very warm in
any case.
Are we sure that was all it was?

I was wondering about the heat aspect of the large windows though. One
supposes they will only open for short periods or the cooling for that part
of the station could well be very big. I wonder if the inverse is also true,
ie, when in the dark, does energy radiate out that way? I thought the multi
pane design was supposed to protect people from the extremes.

Brian

--
Brian Gaff -
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"Jordan Hazen" wrote in message
...
On NASA TV's STS-130 Flight Day Highlights segment aired Wednesday
afternoon, there was a short clip showing shuttle astronaut Kathryn
Hire preparing an ISS ATU (Audio Terminal Unit) for installation in
the new Cupola module. Two hoses were seen coming out of the bottom,
and a commentator said these were for a water cooling loop.

So, are all ATUs on the station similarly connected to water cooling?
Or is this one set up differently because of possible sun heating when
the Cupola windows are open?

In the former case, what is there inside that's dissipating enough
power to make this necessary? I understand that relying on forced-air
or convective cooling of electronics on ISS is undesirable, but why
would the ATU be emitting any significant heat to begin with? Isn't
it basically just an intercom/phone panel?

curious,
--
Jordan.

On Thu, 18 Feb 2010 10:02:40 GMT, "Brian Gaff"
wrote:

I was wondering about the heat aspect of the large windows though. One
supposes they will only open for short periods or the cooling for that part
of the station could well be very big.

It's probably not a serious problem, as the Cupola is on the
Earth-facing side of the Station, so it won't be in direct sunlight
very often.

Brian

In article ,
Brian Gaff wrote:

I'd have no idea. Seems odd that some[thing] like that would get very
warm in any case. Are we sure that was all it was?

It was definitely an ATU. Similar units exist all over the station,
but others I've seen were all built into bulkheads, with any umbilical
attachments hidden away.

I found an STS-130 photo on NASA' site that shows three of these
mounted side-by-side in the airlock. All appear to be identical,
and the resolution's good enough to make out most of the controls.
Since you can't see that photo, I'll describe it.

There's a large speaker grill in the upper-left, with a microphone
jack next to it, and some unknown connector (or button?) just below
that, a 2x16 character alphanumeric display (looks like LED or EL) in
the center, above a phone-style keypad, with Transmit and Receive
LED's near the bottom.

Control buttons along the right-hand side are Push-to-talk/ON, Page,
Xmit Mode, up/down arrows, Talk/Listen, Mon, Vox, and Vol.

Center column: Dial/Ans, Hang Up, Conf/Listen, 2nd ("Shift" for keypad?)

The keypad has LOG where * would be on a phone (2nd function: "Brite"),
and CLR (2nd: "BIT?" hard to make this out) in place of pound.

Most number buttons have two extra function labels, one on the button
itself identifying places to call within ISS:

1 HAB (I wonder where this one actually ended up?)
2 no label
3 NODE (do they hit 1, 2, or 3 afterwards?)
4 LAB
5 CF ("centrifuge facility" perhaps, for the cancelled CAM?)
6 CPLA (cupola)
7 JEM
8 ESA (probably Columbus)
9 RSA (Zvezda?)
0 PIN or FIN (no idea!)

Each also has ar label above, some of which look to be outside
communication channels:

1 GND
2 UHF
3 A/L (one of those 3 airlock panels?)
4 DAG
5 DAA
6 DIA
7 EMU (for speaking to EVA crews outside?)
8 EX ON
9 EX OFF

Heh, maybe I'm the only one who considers this remotely interesting...

I was wondering about the heat aspect of the large windows though.
One supposes they will only open for short periods or the cooling for
that part of the station could well be very big. I wonder if the
inverse is also true, ie, when in the dark, does energy radiate out
that way? I thought the multi pane design was supposed to protect
people from the extremes.

It was implied during installation commentary that there are water
loops running through the window frames as well, so that probably
helps. There could also be a coating on one set of panes to reflect
all/most infrared back out (common enough with energy-efficient
windows on the ground).

--
Jordan.

In article ,
Brian Thorn wrote:
On Thu, 18 Feb 2010 10:02:40 GMT, "Brian Gaff"
wrote:

I was wondering about the heat aspect of the large windows though. One
supposes they will only open for short periods or the cooling for that part
of the station could well be very big.

It's probably not a serious problem, as the Cupola is on the
Earth-facing side of the Station, so it won't be in direct sunlight
very often.

Early assembly sequences had it going on the port side of Node 1,
though, and a later revision on Node 3 forward (with Node 3 on Unity
nadir, as originally intended).

So, Cupola's design must have been able to accomodate any increased
sun exposure from either of those locations.

Brian


--
Jordan.

I don't see any provision for water cooling of the ATU from these
photos. Are you sure she was talking about the ATU?

http://www.angelfire.com/ego/porterclark/airmock/


Dave

Another possibility, the cooling lines were for all the electronics
in the cupola not just the ATU?

Cooling could then be provided either directly through metal-on-metal
conduction or via fans blowing convection air across cooling fins
directly coupled to the water lines.

?

Dave

David Spain writes:

I don't see any provision for water cooling of the ATU from these
photos. Are you sure she was talking about the ATU?

http://www.angelfire.com/ego/porterclark/airmock/

The captions on these photos make clear that these ATUs are *not*
configured for flight. So one thought is that perhaps the flight
ready configuration has a metal 'jacket' surrounding it that contains
the plumbing for water cooling?

The rear-facing photo also show an unattributed connector at the
top of the ATU box, I have no idea what this does or is for.

The captions also state that the boxes work in the rack as they
are with no special cooling apparatus present that I can see. They
say the boxes are only 'warm' to the touch not hot, which isn't
surprising.

I'm not a NASA sub, so I can't get access to their technical database
for ISS that might allow me to pull the schematics on the ATU and
the Harris Corp. website isn't helpful here either (not surprising).

Sounds like you'll need help from an insider....

Jorge? Charlie?

Dave

First thought was that ATUs are considered essential equipment and would
have to work even in a depressurised environment (where air cooled can't
work). But in a depressurised environment, sound carries rather poorly :-)


One needs to consider that the CBM provides for air flow in one
direction only (I believe that it draws air from compartment and ducts
it to destiny). So with the CBM hatch closed, there would be no actual
air ventilation. Air temperatuve in the Copulate would then rise
significantly. This might explain the need to water cool the unit. (CBM
provides for bidirectional water cooling flows).

Whether all ATUs are water cooled or only those in environments that are
harsh, I do not know. If there is an ATU in the airlock for instance,
it would also likely be water cooled. Even though it might not be of use
when the airlock is depressurised, it would still need to be kept at
proper temperature as to not fry the electronics.

ATUs in normal compartments such as nodes and labs might be air cooled
since they would not be exposed to any harsh environments.

David Spain wrote:
David Spain writes:

I don't see any provision for water cooling of the ATU from these
photos. Are you sure she was talking about the ATU?

http://www.angelfire.com/ego/porterclark/airmock/

The captions on these photos make clear that these ATUs are *not*
configured for flight. So one thought is that perhaps the flight
ready configuration has a metal 'jacket' surrounding it that contains
the plumbing for water cooling?

The rear-facing photo also show an unattributed connector at the
top of the ATU box, I have no idea what this does or is for.

The captions also state that the boxes work in the rack as they
are with no special cooling apparatus present that I can see. They
say the boxes are only 'warm' to the touch not hot, which isn't
surprising.

I'm not a NASA sub, so I can't get access to their technical database
for ISS that might allow me to pull the schematics on the ATU and
the Harris Corp. website isn't helpful here either (not surprising).

Sounds like you'll need help from an insider....

Jorge? Charlie?

Porter Clark used to post here... maybe he will de-lurk.