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  Apollo Block I spacecraft lifespan on orbit

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Author Topic:   Apollo Block I spacecraft lifespan on orbit
Jim_Voce
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Posts: 273
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Registered: Jul 2016

posted 07-11-2018 01:29 AM     Click Here to See the Profile for Jim_Voce   Click Here to Email Jim_Voce     Edit/Delete Message   Reply w/Quote
In 1962, when the Space Task Group was developing the earliest version of the Apollo command and service module, it was envisioned that the CSM would fly solo missions in Earth orbit for up to 14 days, so this became the primary objective of the Apollo 1 mission.

Does anyone know what the maximum life support duration was of the Block I Apollo CSM past 14 days? Was it 21 days?

oly
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Posts: 971
From: Perth, Western Australia
Registered: Apr 2015

posted 07-11-2018 06:16 AM     Click Here to See the Profile for oly   Click Here to Email oly     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Jim_Voce:
...for up to 14 days, so this became the primary objective of the Apollo 1 mission.
What reference are you using for this information?

oly
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Posts: 971
From: Perth, Western Australia
Registered: Apr 2015

posted 07-12-2018 02:30 AM     Click Here to See the Profile for oly   Click Here to Email oly     Edit/Delete Message   Reply w/Quote
The specification requirements for the Apollo Command and Service Module Environmental Control Systems required a duration of 14 days. To meet this, 78.29 kg (172.6 lb] of oxygen supply was specified, along with additional consumables like water, power etc.

As the Gemini spacecraft tested longer duration spaceflight, and systems such as fuel cells were tested and improved, the Apollo consumables were streamlined.

The oxygen supply was designed to cater for three astronauts, included crew consumption, cabin leakage, cabin repressurizations, LM support, one CM puncture, tank bleeds, cabin and WMS purges and EVA flow. Additional water was generated as a by-product of power generation from fuel cells, and most missions ended with more than they began with.

So up until the first flight of Apollo 7, mission duration was an unconfirmed number, and following the first mission, was an ever-improving number. Duration depended upon crew activity and oxygen usage. Carbon dioxide scrubber endurance was made available for the designed duration of the available life support, and fuel supply was dependent on mission usage. No mission was planned beyond the duration of the Environmental Control System (life support) for obvious reasons.

When you state that the "CSM would fly solo missions in Earth orbit for up to 14 days, so this became the primary objective of the Apollo 1 mission," this statement is incorrect for 1962. The specifications were drawn up and systems needed to be designed and built to meet these specifications.

Skylab proved that the CSM could stay on orbit for longer than 14 days.

This document references the systems specifications and requirements.

Blackarrow
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Posts: 3160
From: Belfast, United Kingdom
Registered: Feb 2002

posted 07-12-2018 08:15 AM     Click Here to See the Profile for Blackarrow     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by oly:
Skylab proved that the CSM could stay on orbit for longer than 14 days...
I assume the Skylab CSMs were powered down to allow for missions up to (and possibly beyond) 84 days.

On Apollo 13, the CSM was famously "switched off" to save power. My understanding is that the CSM was not designed to be switched off, and there were (unfounded) concerns about powering the CSM up again (if only because of short-circuits from condensation getting into the electrical contacts).

How did the powering down of the Skylab CSMs differ from what happened on Apollo 13?

SpaceAholic
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From: Sierra Vista, Arizona
Registered: Nov 1999

posted 07-12-2018 12:34 PM     Click Here to See the Profile for SpaceAholic   Click Here to Email SpaceAholic     Edit/Delete Message   Reply w/Quote
The CSM was not completely powered down — some critical subsystems remained energized drawing power through an umbilical connected to Sklyab's MDA (multiple docking adapter).

oly
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Posts: 971
From: Perth, Western Australia
Registered: Apr 2015

posted 07-13-2018 07:27 AM     Click Here to See the Profile for oly   Click Here to Email oly     Edit/Delete Message   Reply w/Quote
For me, this took a little research, and someone here may know more detail.

The Skylab Service Module had one of the fuel cells removed and additional batteries installed.

The Skylab Command Module flight plan identified that the fuel cells are shut down as the Hydrogen fuel supply was depleted, which occurred 19 days after lift-off for Skylab 4, and the CSM was placed in quiescent mode. After shutdown, the hydrogen vent was opened and the small amount of residual hydrogen was vented overboard through the nonpropulsive vent. The remaining oxygen was managed by flowing oxygen through the polychoke orifice into the command module.

Power could be transferred to and from the Command module and Skylab, the additional batteries were used to power the CSM from undocking through to re-entry.

I am trying to locate a better copy of the flight manual and flight plan to find additional details

Space Cadet Carl
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Posts: 225
From: Lake Orion, Michigan
Registered: Feb 2006

posted 07-14-2018 09:14 AM     Click Here to See the Profile for Space Cadet Carl   Click Here to Email Space Cadet Carl     Edit/Delete Message   Reply w/Quote
I just learned the Skylab command modules were painted white instead of using silver Kapton foil. After all these years, I'm still finding stuff out!

oly
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Posts: 971
From: Perth, Western Australia
Registered: Apr 2015

posted 07-14-2018 09:39 AM     Click Here to See the Profile for oly   Click Here to Email oly     Edit/Delete Message   Reply w/Quote
There are many interesting facts about the Skylab project, such as this: Skylab space station airlock module: Gemini hatch.

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