posted 06-19-2021 09:49 AM               

The Multiple Docking Adapter/Command Service Module Interface Verification Unit, a multi-function control panel and testing device, was physically attached to the CSM spacecraft before Skylab and ASTP. The Skylab MDA was brought from Marshall Space Flight Center to the Operations & Checkout Building (Manned Spacecraft Operations Building during the Apollo era) at Kennedy Space Center. There the CSM and and MDA were attached for testing before the MDA was taken to the VAB to be stacked with the rest of Skylab.

View of the front, with a yardstick for scale.

The top third of the control panel (communications, caution and warning, power).

A side view, again with a yardstick for scale. (It has the volume of a medium-sized refrigerator!)

The North American Aviation metal identification plate. (Always cool to see serial number "001".) Note that this was Model C54-035 — that gets mentioned later.

You can see many fascinating specifics about power, communication, and even air pressure in the controls. ("LMP" was used along with CDR because they were accustomed to that name for the astronaut in that seat.)

There are so many ports and cables, and a pressure relief valve (below), because this hardware wasn't just monitoring what was happening up in space. All of those electrical connections, and even actual air pressure, were run through this hardware to confirm during testing that the connections had occurred between the CSM and the MDA, and the astronauts would be able to work in Skylab or over in the Soyuz capsule. (This also explains why it is on wheels: with all of those cables and hoses snaking in and out of the CSM and MDA, it needed to be rolled into just the right position close to the spacecraft, then rolled back away.)

Here is from a 1971 NASA Skylab plan:

A docking test between the CSM and AM [Airlock Module]/MDA will be performed to verify the docking interfaces.

The CSM is placed in the West Integrated Test Stand. The AM/MDA is removed from its mobile transporter and lowered, MDA down, to mate with the CSM. The CSM has a probe identical to that used in Apollo and the MDA docking port has a drogue similar to that used in the Apollo LM for docking. A leak check is performed to verify the mechanical docking interface. Electrical/communications tests are accomplished to validate all electrical connections.

These tests are the only interface tests involving the flight CSM and the AM/MDA prior to launch. The next time these modules interface is following rendezvous maneuvers in earth orbit as earlier described.

A requirement exists to electrically check out the DM [docking module] at the Salyut interface and the CSM at the CSM/DM interface. The checkouts will be accomplished ... utilizing ... the C54-035 at LC-39.

So many NASA images are online nowadays that I have been surprised to not find a single image of the Skylab or ASTP testing that might include the verification unit. (Maybe I've gotten spoiled!) If anyone can find one in a book, or a report, or just a stack of photos, I would be tremendously grateful. Please point out this post to anyone you know who might have such a photo.

posted 06-19-2021 01:13 PM               

This rack would mimic the MDA for CSM testing. This would be especially important for SL-3 and SL-4 CSMs since there was no MDA available to do a docking/interface test. Skylab used the CSM S-band comm system for voice uplink and downlink. You can see that the unit was setup for testing that. Additionally, the CSM C&W system would send signals MDA to be integrated in to the cluster C&W system. Finally, the MDA would have a power umbilical to provide electricity to the CSM after the fuel cells were shut down.

The rack performs the same role for ATSP. Testing the CSM interfaces before the actual docking test.

The comment about LC-39 is likely in error. This type of testing would not be feasible at the VAB or pad. It would have been done in the MSOB.

posted 04-11-2022 05:00 PM               

OP assemblage was fabricated by NAA. NAA became NAR in 1967.

posted 04-16-2022 11:50 AM               

GSE is designed and built later in the development cycle. MDA CDR wasn't until August 1970. It wouldn't known until that timeframe what exactly the MDA was to check CSM interfaces.

quote:

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Originally posted by stsmithva:
The Multiple Docking Adapter/Command Service Module Interface Verification Unit

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posted 04-20-2022 09:12 AM               

quote:

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Originally posted by SpaceAholic:
Martin was on task as the AAP Payload integrator by 1967 under contact NAS8-21004; MAC was also already under contract at that time to produce the MDA in accordance with AAP specifications.

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Payload integration would not have had anything to do with this. Payload integration was for experiments in the MDA and workshop and not the other systems within the MDA. Martin would not have dealt with CSM interfaces until it was on contract for MDA integration. MAC produced the Airlock and not the MDA. MSFC built the MDA shell and Martin outfitted it.

From NASA TMX 64812

Year 1969 -
• Dry Workshop concept adds ATM Control & Display (C&D)
Console, deletes OWS experiment st'orage.
• MDA design, development, integration, fabrication,
test, delivery contract to Martin Marietta Corporation (MMC).
• MDA shell provided by Marshall Space Flight Center
(MSFC)

Shell construction was from May to Sep 1970 and delivered to Denver in Nov 1970. It was shipped to St Louis in 1971, and to KSC in Oct 1972.