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Subject: SPACE Digest V12 #560

SPACE Digest                                     Volume 12 : Issue 560

Today's Topics:
             Re: LNLL Inflatable Stations
           Re: Pity The Much Abused Shuttle
          Re: Space Station Work Package #3
    Re: Free flying lab (was: Re: LLNL Astronaut Delivery)
             Re: LNLL Inflatable Stations
            Re: Ted Molczan -- online !!!
             Re: LNLL Inflatable Stations
             Re: LNLL Inflatable Stations

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----------------------------------------------------------------------

Date: 14 Nov 90 03:52:36 GMT
From: pilchuck!amc-gw!thebes!polari![e-mail]  (Charles Radley)
Subject: Re: LNLL Inflatable Stations


13140
Article 13140 (72 more) in sci.space:

>Since LLNL is a large lightweight structure it will be subject to high drag,
>compared with, say Freedom.  This means more reboosting, more propellant
+Already included in their budgets. They will use (from memory) 3T a year
+of fuel for this. An alternativ+e they are looking at is a 10KW ion engine
+which will reduce fuel demand by ~80%.
-
The 3T/yr sounds comparable to Freedom, which is much heavier. Weight is a
precious commodity, and budgeting extra propellant to allow for
high drag is inefficient.  Better to reduce the drag.
Also increases risk.  The LLNL will decay faster than Freedom if its untried
ferry craft becomes grounded.
Ion engines are a high cost item apparently not included in their baseline
price.

> (already a problem on Freedom), and higher engine duty cycles. Is there any
> way they can make it smaller ?
+An inflatable station could be made smaller for 0G however if they are
+to maintain artificial grav+ity, it is about as small as they can get. It's
-
Sounds like an inherent disadvantage for stations with artifical gravity.

>Structure must carry centrifugal loads, makes it heavier.
+Already calculated (see the ILC Dover report). Stresses are welll within
+the strength of the materials used.
-
That is not the point.   Any material can carry any load, if it has big
enough cross section.   It is a question of how heavy it has to be to get low
enough stress.     Structure carrying centrifugal loads is heavier than
structure which does not.

>Reboost thrusters must be gimballed,
+Or reboost partially whenever the thrusters point the right way. Either
-
I don't think that works because the station spin axis is fixed in space,
while its orbital plane is continuously changing due to nodal regression.
The correct alignment will occur very seldom.  Either the thrusters must be
gimballed or the entire station spin axis reoriented for each burn.  Heavy
on propellant .  While that is OK for small satellites, space
stations are much bigger.
  Why exactly do LLNL want to spin the thing anyway ?  I cannot see any
advantage where crews are rotated every 90 days.  And half the fun for the
astronauts is the zero-gee....

>In practice the station will need a spun section attached to a despun
>section.
+As I said, already in there. The airlock is at 0G.
-
I would still want to despin the station for EVA which could be fairly often.
Cannot risk losing an astronaut.  Or else LLNL will have to give all their EVA
crew Manouevering Units; those are quite expensive and were deleted from
Freedom.  Is that included in LLNLs price ?

>Crew transfer between the two is tricky.  EVA transfer hazardous.
>And designing a leak-free IVA tunnel with slip rings and airtight bearings is
>at least a few hundred $M.
+Already included in the cost. This has been anticipated, designed, and
+included in weight as well as cost budgets.
-
No, I do not think it is included in the cost if the airlock is at 0G,
because airtight bearings would not then be needed.

>Plus lots of lost sleep worrying about when the
>thing will seize or rupture, sometime it WILL do one or the other, or both.
+If it fails, the access ports closes and locks. There may be a slight drop in
+pressure in the central core but that would be it. The two ends of the
+station would also be out of contact with each other until it was fixed.
+There would be no loss of either sleep or life.
-
You are now presumably talking an airlock at 0G with no airtight bearings, so
that concern has gone away, I will sleep well tonight   !-)

------------------------------

Date: 15 Nov 90 04:16:09 GMT
From: munnari.oz.au!sirius.ucs.adelaide.edu.au!hydra![e-mail]  (Francis Vaughan)
Subject: Re: Pity The Much Abused Shuttle

This is too good to resist.

In article <[e-mail]>,
[e-mail] (Barak Pearlmutter) writes:

|> For instance, many of our ballistic missiles are based on civilian
|> launchers

I always thought that if anything it was the other way around.

|> The shuttle's electronics are certainly proof
|> against EMP, with core memories and high redundancy.

This I doubt. There is a LOT more to EMP proofing than a bit of
core memory. EMP would wipe out all of the radio aids and radar, all
of the control electronics etc. Proofing this sort of stuff is non-trivial.


|> The large cargo
|> space can hold a couple weapons, allowing the shuttle to act as a
|> roving satellite killer.  In the event that manned space stations are
|> important, people could be tossed in a pressurized can in the cargo
|> compartment, allowing a considerable boarding party to be transported
|> to an enemy space station if necessary.

Just how proof to an air launched guided sat-killer missile do you think
the shuttle is? Sitting duck is the term that comes to mind. It can't even
run.

At boarding range a high velocity rifle could cripple the shuttle in
a minute. Just loose a few of those nice tiles in critical places and
its a goner on reentry. Let alone what would happen if you disabled
any of the host of critical systems. You could nearly kill the shuttle with
a slingshot and a well aimed rock.

|> And--here's
|> the coup de gras--it can just reach out it's arm and plop an enemy
|> satellite in the cargo bay!  This would be of incalculable
|> intelligence benefit.

" Is the satelite in the enemy shuttle cargo bay Igor?"

"Yes Ivan"

"Activate the self destruct Igor"


Get real, this is 1990, not Duck Dodgers in the 25th and a half centrury.

                    Francis Vaughan.

------------------------------

Date: 13 Nov 90 21:13:43 GMT
From: wuarchive!emory!hubcap!ncrcae!ncrlnk!ncr-mpd![e-mail]  (Mike McManus)
Subject: Re: Space Station Work Package #3

In article <[e-mail]> [e-mail] ("Allen W. Sherzer") writes:
>   As a result of the 91 appropriation, NASA is to redesign the station in
>   90 days. This redesign is to provide a modular incrimentally growable
    ^^^^^^^^
>   design buildable within more reasonable budget numbers. They are also to
>   assume reasonable launch numbers for the Shuttle and make better use of
>   cheaper expendables.

Ackkk!  What exactly constitutes a "redesign"?  New concept?  Partial rework?
Total rework from top to bottom?  Detailed engineering?  Given the pace at
which things have gone up to now, what can be done for SSF in 90 days?
--
Disclaimer: All spelling and/or grammar in this document are guaranteed to be
            correct; any exseptions is the is wurk uv intter-net deemuns,.

Mike McManus                        [e-mail], or
NCR Microelectronics                ncr-mpd![e-mail], or
2001 Danfield Ct.                   uunet!ncrlnk!ncr-mpd!garage!mikemc
Ft. Collins,  Colorado
[phone]   Ext. 378

------------------------------

Date: 14 Nov 90 17:24:17 GMT
From: usc!wuarchive!rex!rouge![e-mail]  (Fraering Philip)
Subject: Re: Free flying lab (was: Re: LLNL Astronaut Delivery)

In article <[e-mail]> [e-mail] (Edwin Wisse) writes:

>That is exactly what ESA is doing right now. Freedom does not only consist of
>the permanently manned lab, it also includes a polar platform for Earth
>observation and a man-tended free flyer.

Why do people keep saying the polar platform is part of freedom?

It's not as if someone in Freedom could put on a space suit, strap on
his MMU and go out to the polar platform (unless the MMU has antimatter
thrusters...). The velocity difference is some 3 km/sec (corrections
welcome) or so between leo 28 degrees and polar orbit.

Phil

------------------------------

Date: 14 Nov 90 22:32:19 GMT
From: sdd.hp.com!zaphod.mps.ohio-state.edu!mips!wdl1.wdl.fac.com!wdl76![e-mail]  (Jon W Meyer)
Subject: Re: LNLL Inflatable Stations

[e-mail] (Charles Radley) writes:


>13140
>Article 13140 (72 more) in sci.space:
>
>>Since LLNL is a large lightweight structure it will be subject to high drag,
>>compared with, say Freedom.  This means more reboosting, more propellant
>+Already included in their budgets. They will use (from memory) 3T a year
>+of fuel for this. An alternativ+e they are looking at is a 10KW ion engine
>+which will reduce fuel demand by ~80%.
>-
>The 3T/yr sounds comparable to Freedom, which is much heavier. Weight is a
>precious commodity, and budgeting extra propellant to allow for
>high drag is inefficient.  Better to reduce the drag.

Just speculation, but although the lighter station is more susceptable to
drag, wouldn't the lighter weight also be a benefit?  What I'm talking
about is that it will take less fuel to accelerate a lighter station
X meters per second than it would to accelerate the heavier station by
the same amount.  Perhaps these effects could balance each other, leading
to comparable fuel budgets for the two stations?

Comments?

Jon

------------------------------

Date: 14 Nov 90 12:41:28 GMT
From: eru!hagbard!sunic!mcsun!hp4nl!dutrun![e-mail]  (aad van der kooij)
Subject: Re: Ted Molczan -- online !!!

The orbital elements of T.S. Kelso were very useful for our work and
hobby, and we also miss them very much. So if there is another source we
would be very interested.
B.T.W. does anyone have current orb.elements of Dr. Kelso himself, i.e.
knows why he stopped his service to this newsgroup ?

------------------------------

Date: 15 Nov 90 04:56:18 GMT
From: ubc-cs!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: LNLL Inflatable Stations

In article <[e-mail]> [e-mail] (Jon W Meyer) writes:
>Just speculation, but although the lighter station is more susceptable to
>drag, wouldn't the lighter weight also be a benefit?  What I'm talking
>about is that it will take less fuel to accelerate a lighter station
>X meters per second than it would to accelerate the heavier station by
>the same amount.  Perhaps these effects could balance each other...

It turns out that the mass of the station is entirely irrelevant, to a good
first approximation, to the reboost fuel requirements.  A heavier station
needs more fuel to reboost but needs it less often.  The requirement is that
the thrust of the reboost engines, averaged over the period between reboosts,
equal the average air-drag forces.  Said forces are influenced heavily by
frontal area and somewhat by shape but not at all by mass.  Other things
being equal -- which they probably aren't -- the LLNL station will probably
need somewhat more reboost fuel because it is bigger.  However, I dimly
recall that it is meant for a somewhat higher altitude, which will help.
Its spin will also help; Fred, in a gravity-gradient orientation, would
always be broadside-on to the "slipstream", while the LLNL station will
spend much of its time at an angle.
--
"I don't *want* to be normal!"         | Henry Spencer at U of Toronto Zoology
"Not to worry."                        |  [e-mail]   utzoo!henry

------------------------------

Date: Wed, 14 Nov 90 16:40:30 -0500
From: "Allen W. Sherzer" <[e-mail]>
Subject: Re: LNLL Inflatable Stations
Newsgroups: sci.space
Cc:

In article <[e-mail]>:
>>Since LLNL is a large lightweight structure it will be subject to high drag,
>+Already included in their budgets. They will use (from memory) 3T a year
>+of fuel for this. An alternativ+e they are looking at is a 10KW ion engine

>The 3T/yr sounds comparable to Freedom, which is much heavier. Weight is a
>precious commodity, and budgeting extra propellant to allow for
>high drag is inefficient.  Better to reduce the drag.

If the LLNL Great Exploration plan is enacted, this will not be a problem.
The Earth Station will be next to several hundred tons of fuel. A few years
after launch, the lunar base will begin returning fuel from the moon. These
guys will have fuel coming out of their ears.

However, if they are using the same amount of fuel as Freedom then there
shouldn't be a problem.

>Also increases risk.  The LLNL will decay faster than Freedom if its untried
>ferry craft becomes grounded.

First of all, since you don't know the Earth Station orbit, I don't see how
you can make that claim. Second of all, who cares if the ferry becomes
grounded? Since the Earth Station provides artificial gravity the crew
can stay up for arbitrary amounts of time. We send up fuel/consumables on
ELV's (at less cost than the Shuttle) and wait it out.

>Ion engines are a high cost item apparently not included in their baseline
>price.

Correct. It is just an example of their constant attention to potential
cost reductions.

>> (already a problem on Freedom), and higher engine duty cycles. Is there any
>> way they can make it smaller ?
>+An inflatable station could be made smaller for 0G however if they are
>+to maintain artificial grav+ity, it is about as small as they can get. It's

>Sounds like an inherent disadvantage for stations with artifical gravity.

To me it is an advantage. They provide a great lab for researching any
level of gravity from 0 to 1G. Crews can stay up longer periods and cut
billions of $$ from lifetime logistics costs.

>That is not the point.   Any material can carry any load, if it has big
>enough cross section.   It is a question of how heavy it has to be to get low
>enough stress.     Structure carrying centrifugal loads is heavier than
>structure which does not.

As I said, it is all calculated in (see the ILC report).

>  Why exactly do LLNL want to spin the thing anyway ?

I have already said: more research can be conducted and crews/equipment
can be qualified for the moon and Mars. It also allows crews to stay
up longer which saves billions in lifecycle cost.

>I cannot see any advantage where crews are rotated every 90 days.

Why am I not suprised that a Freedom engineer doesn't think saving money
is a good reason to do something? :-)

>And half the fun for the astronauts is the zero-gee....

They aren't there to have fun. However, there is a zero gee module in
the Earth Station. They can have fun there.

>>In practice the station will need a spun section attached to a despun
>>section.
>+As I said, already in there. The airlock is at 0G.

>I would still want to despin the station for EVA which could be fairly often.

And they don't.

>Cannot risk losing an astronaut.

Then don't send them up.

>Or else LLNL will have to give all their EVA
>crew Manouevering Units;

Why?

    Allen
--
+---------------------------------------------------------------------------+
|Allen W. Sherzer| I had a guaranteed military sale with ED-209. Renovation |
|   [e-mail]  | programs, spare parts for 25 years. Who cares if it      |
|                | works or not?  - Dick Jones, VP OCP Security Concepts    |

------------------------------

End of SPACE Digest V12 #560
*******************