From: Wales.Larrison@ofa123.fidonet.org (Wales Larrison)
Newsgroups: sci.space.shuttle
Subject: Re: Extended Duration Orbiter (1 of 2)
Date: Thu, 09 Apr 92 21:40:40 PDT
Organization: Universal Electronics Inc. (Public access BBS)

To all:
 There has been a set of questions posted about the Extended 
Duration Orbiter (EDO).  This is to put some rough answers to them,  
but since it is done from memory some of the exact figures should be 
checked before requotation... 
 
wmetz@vax1.umkc.edu writes:
> I just read that the new Extended Duration fitting in Columbia will only 
> allow for 16 day missions...Am I wrong or has it been rather 
> recent that they were still claiming 28 day missions would be 
> possible?  What caused the considerable downsizing and is a 
> further upgrade planned? 
 
Jonathan (jdeitch@umiami.miami.edu) writes:
>Just to throw more fat on the fire, I've heard that the 28 day 
>missions are possible with the EDO pallet and Endeavour, but not 
>the other shuttles. 
 
   Josh Hopkins writes:
> I believe the 28 day figure refers to Endeavor.  It may also be 
>that they plan to start Columbia out at 16 and work their way up.  
 
  EDO is a series of modifications and to a shuttle orbiter and a 
cryo pallet kit.  These modifications include: 
  o Crew Stowage.  As you can imagine, stowage space in the shuttle 
crew module is limited.  EDO makes a series of small modifications 
to add some more stowage lockers to take advantage of some unused 
volumes. 
  o A new Shuttle toilet (WCS - Waste Collection System).  One of 
the previous limits on mission life was the toilet's capacity.  The 
EDO WCS uses a compactor to fill "WCS Fecal Cannisters".  Once full, 
they are capped, bagged and can be stowed with other trash.  Longer 
mission durations require the carrying of more empty cannisters.
  o A new atmospheric CO2 removal system.  The EDO RCRS (Regenerable 
CO2 Removal System) replaces the Lithium Hydroxide cannisters now 
used to remove CO2 from the cabin air.  The RCRS is a device which 
has two beds of a solid amine material.  This material selectively 
absorbs CO2 from the air.  When vented to vacuum, the CO2 "desorbs" 
from the bed, regenerating its capability to absorb CO2.  The two 
beds are used as one is absorbing CO2 while the other is desorbing 
to vacuum.  The lithium hydroxide system capability is retained as a 
backup system with the capability for at least 72 hours. 
  o Added atmospheric gaseous nitrogen (GN2)tanks. The shuttle's 
atmosphere is maintained at 80% (??) nitrogen and 20% (??) oxygen. 
Nitrogen is lost overboard during a mission due to cabin leakage, 
wet trash venting, and a small amount through the RCRS.  For a 16 
day mission, 2 additional GN2 tanks are carried (total of 6); for a 
28-day mission 4 additional GN2 tanks are carried. 
  o Software changes.  There was some concern about the ability of 
the crew to remain conscious and land a shuttle after multiple weeks 
in orbit.  As part of EDO, the existing autoland software was re-
verified and rechecked to act as a backup to the crew.  In case of 
emergency, the crew can set the autoland which will fly the vehicle 
back to a landing.  However, the crew still must throw some switches 
- first to start the autoland sequencing, and then as prompted by 
the computer ("put the landing gear down now", etc.)
  o A new cryogenic pallet.  The pallet carries additional liquid 
hydrogen (LH2) and liquid oxygen (LO2) to be reacted in the orbiter 
                                                           (cont)

--  

Wales Larrison
Internet: Wales.Larrison@ofa123.fidonet.org
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