Conference 7.286::space

From: [email protected]
Newsgroups: sci.space.shuttle
Subject: Re: Extended Duration Missions
Message-ID: <[email protected]>
Date: 10 Apr 92 14:06:04 GMT
Organization: NASA Johnson Space Center

In article <[email protected]>, [email protected] (Michael V. Kent) writes:
> In article <[email protected]> [email protected]
(Josh 'K' Hopkins) writes:
>>[email protected] writes:
> 
> There is a planning effort underway to use the 28-day capability for Freedom
> utilization flights during the man-tended phase of the space station.  This
> effort appears to be moving forward.  Previously, there was a study going on
> concerning the requirements for a 60- and 90-day orbiter, but the latest 
> word I have is that the requirements were just too great.
> 
The Long Duration Orbiter (LDO) study is not dead.  Current plans call for a
three phase implementation of the LDO.  The first phase in about 1996 would be
a 30 day capability, followed in about a year with a 60 day capability, with
the final phase being the 90 day Orbiter.  LDO is different from EDO in that
LDO requires the space station to supply some services.  Most of the power will
come from the space station with all but one Orbiter fuel cells being shut 
down.  Look for a Development Test Objective (DTO) next year which will perform
an on-orbit shutdown and restart of a fuel cell.

Unlike LDO, the EDO is totally self-contained and thus does not require
external power and services from other vehicles.  To date, only the 16 day
EDO capability has been purchased for OV-102.  Very little EDO hardware has
been purchased for OV-105.  Endeavour will most likely have a Regenerative
CO2 Removal System (RCRS) installed sometime before flight 12, but that is
about it.  To get a 28-day Orbiter will require some hard requirements for a
28-day free flying Orbiter and of course the budget to purchase the EDO
hardware.

-- 

Pat Oliver -  	Lockheed Engineering and Sciences Company at NASA JSC
		[email protected]
		All standard disclamers apply.

Newsgroups: sci.space.shuttle,sci.space
From: [email protected] (Michael V. Kent)
Subject: Long duration orbiter: SPEDO (long)
Summary: Possible way to increase orbiter's time on orbit
Organization: Rensselaer Polytechnic Institute, Troy, NY
Date: Tue, 27 Oct 1992 06:32:05 GMT

The 26 Oct 92 issue of Aviation Week contains a fascinating 3 page article
written by Owen K. Garriott (astronaut aboard Skylab in 1973 and Spacelab in
1983) and Frank L. Echols of Teledyne Brown Engineering in Huntsville, AL.

They and NASA are looking at ways to extend the on-orbit capability of the
Shuttle.  NASA is currently looking at:
             1) adding more cryo tanks [EDO once more]
             2) docking orbiter to Space Station Freedom (SSF)

They suggest 3) Solar Powered Extended Duration Orbiter (SPEDO)

The current limitation to on-orbit ops is electrical power.  The orbiter 
requires 10.5 kW for life support and mid-deck payloads and Spacelab needs
5.5 kW to be useful, which yields a total of 16 kW.  [Discovery and Atlantis
can do 8 days with this load, and Columbia and Endeavour can normally do 10.]
Columbia has done 14 days with the EDO pallet, and it should be able to do 18.

SPEDO consists of 4 solar panels each 40 ft X 20 ft and a battery system.  The
batteries draw power from the panels during daylight and provide power during
the orbit's eclipse.  The panels and boom fold into the cargo bay, and its
bus is kept separate from the fuel cell's bus.  Overall the system is like
SSF's solar panels in miniature but does not have alpha and beta joints.
Instead, flexible cables rout power across the rotating joints.  Momentum
disturbances are eliminated by reaction wheels.  Average power output = 12kW.

Two possible uses for SPEDO and necessary equipment:
   
   1) Spacelab (12kW SPEDO + 4kW cryo = 16kW total)
         orbiter (flight deck and middeck for lab/hab/stowage volume)
         SPEDO solar panels
         EDO cryo tanks (optional)
         Spacelab long module (lab space)
         Spacehab (lab/hab/stowage space)
      Time: 80 days with EDO (9 tanks) or 42 days without (5 tanks)
   
   2) Space Station at Man-Tended Configuration (MTC)
         orbiter (flight deck and middeck for lab/hab/stowage volume)
         SPEDO solar panels
         EDO cryo tanks (optional)
         Spacelab long module (lab space)
         modified short tunnel
         mating system (to dock with SSF)
      Time: 70 days with EDO (9 tanks) or 30 days without (5 tanks)

Advantages:
   SPEDO can be folded and left at SSF, saving its 5200 lb on next flight.
   At MTC, 11 kW available to user stays available instead of feeding STS.
   160/120 vdc to 28 vdc power converter (SSF to STS) not necessary

Potentinal Problems:
   1) Stowage volume: consumables, waste storage, habitable volume
         lightly packed Spacehab used for hab/stow space on Spacelab flights
         US lab and node used for same on SSF flights
   2) Cryo storage
         H2 and O2 boil off are potential problems (needed for reentry)
         batteries for eclipse can also be used for reentry
         NASA already plans to measure boil-off and to cycle fuel cells
   3) Autoland: after 80 days in orbit pilot may be unable to land orbiter
         partial Autoland done but needs testing
         full Autoland do-able but is seen as too risky within NASA
         with Shuttle shuffle at SSF, new pilot can be flown to SSF to land
            old orbiter, but requires dual-ops capability
   4) [Water: fuel cells also provide potable water for crew
         carrying water tanks adds weight]

Advantages for SSF:
   1) Faster:
         SSF becomes permanently manned at MTC (Jun 97 instead of Jun 00)
         dual ops necessary for this to occur
   2) Cheaper: 
         ACRV no longer necessary for PMC since Shuttle is at SSF
         allow alternate launch options post-MTC w/o jeopardizing PMC
            [some of us feel CIS and Energiya are too risky to risk SSF]
   3) Better:
         5 times on-orbit time for Spacelab
         10 times crew time for SSF after flight 6 (instead of 17)

-----
Note: Stuff in [brackets] is my own.  The rest is paraphrased from the article.

Does anyone else think this is an idea worth looking into?  Any comments?

Mike

-- 
Michael Kent                                   [email protected]
McDonnell Douglas                              Rensselaer Polytechnic Institute

Tute Screwed Aero Class of '92                              Apple II Forever !!

Newsgroups: sci.space.shuttle
From: [email protected] (Michael C. Matthews)
Subject: Re: Long duration orbiter: SPEDO (long)
Reply-To: [email protected]
Organization: NASA/JSC Engineering Computation Facility
Date: Thu, 29 Oct 1992 17:58:01 GMT

In article <[email protected]> [email protected] (Michael V. Kent) writes:
>Potentinal Problems:
>   3) Autoland: after 80 days in orbit pilot may be unable to land orbiter
>         partial Autoland done but needs testing
>         full Autoland do-able but is seen as too risky within NASA
>         with Shuttle shuffle at SSF, new pilot can be flown to SSF to land
>            old orbiter, but requires dual-ops capability

It should be noted (or perhaps reiterated) that the reason an autoland
hasn't been tried (and the first scheduled one was recently cancelled)
is NOT because it's "seen as too risky".  We've simulated the hell out
of autoland, and the software and hardware have been ready for years.
The reason the previously scheduled autoland test was cancelled, and
why there won't be one for at least a couple more years, is because
the Associate Administrator for Spaceflight is an old Navy pilot who
believes that it is "ridiculous" to think that a pilot might be unable
to land his aircraft, and that if by some chance the pilot was
incapacitated, you'd just send up another crew to fly him home.  It's
not a question of risk; it's a basic philosophical opposition to the
concept.  The fear is not that autoland might not work -- the fear is
that it will work, and may open up the possibility of Unmanned Orbiter
and other operational modes that don't require quite so many hot-shot
pilots in the astronaut corps. Of course, Pearson isn't the only one
with this attitude; there are several astronauts who also think it
isn't macho to let a computer land the orbiter.

Depressing, isn't it?
--
Mike Matthews, ex-Tether Dude +------------->   [email protected]
"Had the Shuttle on a String"  \_ Now accepting NeXTMail via KlugeNet(TM)!
Lockheed-ESC                  |  
Houston, TX                   |          *** WILL HACK FOR FOOD ***

I should think that one problem with any EDO is that in using it you commit a
very scarce resource (an orbiter) to be "away" for a good long time.  Before
SSF is around, this may be a reasonable tradeoff since there is no other way to
get extended time in orbit.  However after SSF is around it will be harder to
justify.

You would also be somewhat limited in the allowable payloads:  You would not be
able to fly stuff that required a VERY low level of acceleration, I would guess.
Despite the momentum wheels to damp panel motion, I'm sure it would cause some
acceleration.

Interesting concept, though.

Burns

  Early on it would have a big payoff in that Space Station Freedom has no
escape system. I'll bet that for quite some time the station will only be
manned when the shuttle is attached. That will probably be the practice until
the space plane comes along. 

  I've heard talk of using either Apollos or Soviet space craft as a rescue
craft for Space Station Freedom but neither makes much sense. Both are very
hard to fly, very hard on the passengers and crew (8G's and a dry landing
respectively) and would require either a total redesign of their flight avionics
for compatibility or a massive effort put into training of very talented test
pilots. That's a lot to put into an emergency system that is not used under
normal circumstances.

  Shuttle launches are very expensive. Dedicating several launches per year to
drop off and pick up passengers would be expensive and dangerous in that any
failed or aborted pick up flight would leave people stranded at the station. 

  By comparison, leaving one Shuttle up there for a month would not effect the
schedule all that much. Visits to the station could be planned and would be as
often as a Shuttle could be used for that purpose and would last only as long
as it could stay up there. 

  George