Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v11_0/v11_088.txt

Internet Message Format | 1991-07-08 | 20KB

Return-path: <[e-mail]>
X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/[e-mail] (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests)
          ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/kZurPUq00VcJE0mk53>;
          Wed, 28 Feb 90 01:59:46 -0500 (EST)
Message-ID: <[e-mail]>
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Wed, 28 Feb 90 01:58:39 -0500 (EST)
Subject: SPACE Digest V11 #88

SPACE Digest                                      Volume 11 : Issue 88

Today's Topics:
         NASA Headline News for 02/26/90 (Forwarded)
          Miscellaneous Satellite News Items
      Re: Fun Space Facts #1: Launcher Development Costs (long)
----------------------------------------------------------------------

Date: 26 Feb 90 19:26:02 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: NASA Headline News for 02/26/90 (Forwarded)

-----------------------------------------------------------------
Monday, February 26, 1990                     Audio: 202/755-1788
-----------------------------------------------------------------
This is NASA Headline News for Monday, February 26.....

The Kennedy Space Center Launch Director has called for a 48-hour
launch postponement of the STS-36 shuttle Atlantis due to weather
constraints.  Early today, a 2,000 foot-thick cloud cover moved
in violating the visibility rules for a return-to-launch-site
abort.

During the delay at KSC, ground crews will replenish the liquid
oxygen and liquid hydrogen propellants in the ground storage
tanks.  Commander Creighton, Pilot John Casper and Mission
Specialist Hilmers will fly back to Johnson Space Center today
for simulation training and will return to KSC for the next
launch opportunity.


Using a NASA/JPL Deep Space Network antenna located in Madrid,
Spain, the European Space Agency reestablished contact with the
Italian comet probe "Giotto" last Tuesday.  Aerospace Daily says
Giotto had been dormant since the March 1986 encounter with
Halley's comet.  ESA is now preparing systems to encounter the
comet Grigg-Skjellerup in July 1992.


Pioneer 11 crossed the orbit of Neptune -- over 2.8 billion Miles
from Earth -- and became the fourth spacecraft to leave the solar
system.  It now joins Pioneer 10 and Voyagers 1 and 2 in search
of the heliopause -- that point at which the sun's
electromagnetic influence gives way to the galaxy's influence.


Today, Langley Research Center technicians begin removing
experiments from the Long Duration Exposure Facility retrieved
from space by the STS-32 crew last January.  As each tray is
removed, close inspections and measurements include detailing the
micrometeoroid and orbital debris impacts.


Aerospace Daily reports the European Space Agency plans to put
all Arianespace launch activities on hold pending the
identification and correction of what caused Thursday's Ariane
booster explosion.


Mission STS-35/ASTRO-1 payload managers at KSC are making plans
to move the ASTRO-1 payload to Columbia's payload bay in March.
Power-on testing has been completed, site requirement testings
have been fulfilled and functional verifications tests are
complete.  Launch is scheduled for May 9.

                                 ###


-----------------------------------------------------------------
Here's the broadcast schedule for public affairs events on NASA
Select TV.  All times are Eastern.


Tuesday, February 27....

     11:30 P.M.     Weather permitting, coverage begins of the
                    launch only of the STS-36 mission.   Launch
                    window is open from 12 midnight to 4:00 A.M.


Thursday, March 1.....

      11:30 A.M.    NASA Update will be transmitted.

All events and times are subject to change without notice.
-----------------------------------------------------------------
These reports are filed daily, Monday through Friday, at 12 noon,
Eastern time.
-----------------------------------------------------------------
A service of the Internal Communications Branch (LPC), NASA
Headquarters, Washington, D.C.

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

Date:        Tue, 27 Feb 90 11:52:44 AST
To: [e-mail],
        "Space Digest" <[e-mail]>
From: [e-mail]
Subject:     Miscellaneous Satellite News Items

Miscellaneous Items from Satellite News, Penwortham, England
                  (Posted with permission)

Gravity Probe B
---------------
NASA's Marshall Space Flight Center has awarded a contract to Stanford
University's High Energy Physics Laboratory to obtain proposals for
experiments for the proposed Gravity Probe B spacecraft; first phase
involves spacecraft baseline design reviews, second phase includes
spacecraft development programme completion and third phase involves
fabrication, test, launch and on-orbit operations support.  Gravity
Probe B will operate ultra-precise gyroscopes in low Earth orbit to
detect and measure relativistic gyroscopic drifts predicted by
Einstein's General Theory of Relativity.  Expected launch date: 1994.

Locstar
-------
Marconi Space Systems Ltd. has won a major order as the lead on the
European Locstar satellite; Marconi is the major UK partner in this
Franco-British consortium led by Matra Espace of France and would have
overall responisbility for the design and manufacture of the
satellites' multi-frequency telecommunications payloads.  Locstar is
[a European version of the Geostar] satellite system capable of
locating mobile ground users and their operating bases.  Trucks,
boats, trains, and aircraft will use the service to locate their
positions and to relay short messages to and from their headquarters
or operating bases; Locstars will provide a regional service covering
Europe initially but capable of extension to serve the Middle East and
Africa.  Expected launch date for the first Locstar satellite is March
1992.

Radarsat
--------
Spar Aerospace has awarded a contract to Ball Corporation's Aerospace
Systems Group for spacecraft structure construction and integration
support services for the Canadian Radarsat remote-sensing spacecraft
programme; spacecraft will be used primarily in natural resources
management, control of ship and vessel movements, sea ice information,
oil slick monitoring, global mapping and sea state information.
Scheduled for launch aboard a Delta vehicle from the Western Test
Range in June 1994, Radarsat 1 will have a nominal five-years
operating lifetime.

========================================================================
Richard B. Langley                  BITnet:  [e-mail] or [e-mail]
Geodetic Research Laboratory        Phone:   [phone]
Dept. of Surveying Engineering      Telex:   014-46202
University of New Brunswick         FAX:     [phone]
Fredericton, N.B., Canada  E3B 5A3
========================================================================

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

Date: Tue, 27 Feb 90 14:31:38 CST
From: [e-mail]
Subject: Re: Fun Space Facts #1: Launcher Development Costs (long)

>> uunet!attcan!utzoo!henry [e-mail] (Henry Spencer)

>> In article <[e-mail]> [e-mail] writes:
>> >>> The USAF's demands for a bigger orbiter with more cross range
>> >>> increased the size of the bird considerably but didn't affect
>> >>> complexity much.
>> >
>> >A much bigger and more capable bird (at least in theory) built at
>> >the same degree of sophistication would seem to me to indicate a
>> >much more 'complex' vehicle, with a commensurate increase in
>> >processing time between flights.  After all, NASA couldn't just make
>> >all the parts bigger.
>>
>> No, but they could build much the same thing on a slightly larger scale.
>> Things like the electronics wouldn't have to be scaled at all.  There
>> is no inherent reason why a bigger vehicle has to be more complex.

Other than the problem with having gone from a bird that had to be
"considerably" larger to one that is now "slightly larger", you are
still faced with the problem of the larger version being more
complex, having parts that must take more stress, or both.

Look at it this way.  If you simply scale everything up, that says
that supporting structures, fasteners, etc., must now take more
stress (this is a result of what is usually referred to as the
Square Cube Rule, or something similar).

Try to avoid this by something as simple as increasing the number of
fasteners to keep them the same distance apart that they were on
your original before you scaled it up, and you have increased the
complexity of the vehicle by some amount because you have more
fasteners.  And since even something that simple is not a totally
independent failure point with only independent modes of failure (in
other words, how it behaves depends on what the stuff around it is
doing), complexity doesn't even increase linearly.  Double the
number of fasteners and you *more* than double the contribution to
vehicle complexity from the fasteners.

>>
>> >And even if it were possible to just scale up everything (which I've
>> >been assured is almost never the case), you're still greatly
>> >increasing the stresses on the parts, and it would still require
>> >much more processing.
>>
>> I must have missed something here -- why does being bigger automatically
>> imply operating with smaller safety margins, nearer the limits of the
>> parts?  If it doesn't, why "greatly increasing the stresses" and "much
>> more processing"?  You'll have to explain this one.

Direct consequence of the Sqaure Cube Rule.  Double the size of
everything and it is now eight times as massive as it was.  But your
structural cross sections only went up by four times, and so your
structure must operate closer to the failure points of the materials
in order to get the same performance.

In the case of simply scaling size, complexity is held constant.
However, since that pushes us closer to the failure point of our
design, what usually happens is that we make things more complex to
reduce those kinds of loads.  Multiple supports, fasteners, etc.,
which share the load (and interact with each other, creating more
failure modes).  More tiles to cover the thing, instead of just
making the existing tiles bigger, to allow us to match the curves
better and lower thermal stresses back to where they were.  Bigger
engines to lift it, which, since we can't make them eight times the
size and still get them in, must push the technology harder to get
more thrust out of the same size engine.  Eight times the flow rates
through piping which is only four times the flow area, increasing
operating pressures, or else using more pipes to deliver the flow
(increasing complexity again).  Eight times the mass with only four
times the wing area, leading to higher wing loading (yes, I'm aware
that much of the lift of the Shuttle is derived from the body, so
let's leave that nit unpicked, shall we?), leading to both higher
stresses on the wings and greater impact loads on the landing gear
due to higher sink rates (not to mention higher stress on the braking
surfaces, since they're subject to the same Square Cube Rule as far
as things like swept area go).

And everything we add requires additional inspection.  And servicing.
And replacement sooner, because it is stressed more (because we're
balancing increasing stress and increasing complexity to stay within
the abilities of the materials).

And even the things that *do* simply scale require more inspection.
Control surfaces are bigger, so have more area to inspect.  They are
further apart, and wires, pipes, conduits, etc. take longer to
inspect simply because they're physically longer.  Double the size
and you've increased the surface that needs to be inspected by *at
least* four, even if everything else remained the same, which it
doesn't.

Do you see my point now, Henry?

Generally what happens is some of both, once a design has to be
pushed hard enough.  The parts take more stress and the vehicle
becomes more complex, both.

>> >...mention something about it being much easier to design, build, and
>> >maintain smaller liquid hydrogen engines than it was larger ones,
>> >which was why one usually saw hydrogen fueled stages appear as the
>> >smaller upper stages of boosters first.
>>
>> Um, you've misunderstood what I said (it was me).  The reason why people
>> start small with hydrogen engines is the same reason why engineers start
>> small in almost any new technology:  smaller hardware is cheaper to build
>> and debug, so you try to make your learning-phase mistakes on a small
>> scale.  There is no inherent complexity gain as the engines get bigger.

Ah, but I think there must be.  Either that, or you're pushing the
stress loads on the parts.  In fact, you seemed to allude to it with
the comment about ArianeSpace not being able to handle an all
hydrogen vehicle when they first started.

Once again consider.  We double the size of the engine, and
everything in it.  But, in order to keep the same thrust to weight
ratio it must have eight times the mass flow.  It must get that mass
in in the form of fuel and oxidizer through openings that have only
four times the area, so either input pumps must produce twice the
pressure (increasing stress), or there must be twice as many of them
(increasing complexity), or something of both.  The same problem
applies to exhaust, although in that case much of it can probably be
alleviated by changing the design of the nozzle (not my field by a
long shot).  So your new, bigger engine probably has both more
pumps, nozzles, etc and operates things at somewhat higher pressures.

>> I have no quarrel with that, but you haven't justified your assertions
>> that smaller size means fewer parts and less stress.

I trust they're now justified?  Seems like a lot of net bandwidth to
have to expend to (over)state the obvious.

>> Actually, welcome to the "real world" of agencies that have been in
>> business too long.  The problem is *not* fundamental to the budgetary
>> process, given competent people who are motivated to deal with it
>> well, as witness some of the things that are occasionally accomplished
>> under the current budgetary process (notably by SDI, which hasn't had
>> time for its arteries to harden).  The problem *is* fundamental to today's
>> NASA, and nothing short of massive reform is going to cure it, I'm afraid.

And why is it that SDI can do those things and Nasa (and other parts
of DoD, I might add) can't?  In large part it's because SDI isn't
subject to quite the same order of bureaucratic red-tape from above
that everyone else is, being the current 'fair haired boy'.  While
this quite often correlates to the age of the program/agency (after
all, 'fair haired boys' don't last that long - they age), I think
you have the causality there wrong.

Yes, NASA needs lots of changes.  I can think of bunches myself.
But, a large part of what needs changed is being mandated by
micro-management of programs by the next highest layer of
bureaucracy, and that problem extends all the way to Congress.  So I
say to fix it where it *starts*, at the top.

>>  As I've said before, people who have studied this tradeoff [between
>> launching in one piece or assembling in orbit] closely tend to
>> conclude that the split is a net win.

I would think that there has to be some optimum point to this, and
that you can't just claim it as a general rule.  Since you've
apparently read the studies, I'd be interested if the folks who
studied this expressed any point at which the curves crossed over
and costs started going back up once the pieces got below a certain
size.

Seems like there would have to be a point (assuming constant launch
costs per pound) at which the extra resources required to do the
assembly on orbit and the kind of fasteners required would catch up
with the decrease by it no longer being necessary to 'over-engineer'
things to take the stress of liftoff.

After all, if there isn't, that seems to say that it's cheaper to
simply throw electrical components, screws, bolts, etc. up into
orbit and build all circuit boards, wall panels, etc. on orbit.

And that just seems to run counter to reason.

>> >>> I dimly recall a design sketch from Jordin Kare's group for a laser
>> >>> launcher costing about half a billion dollars that could launch more
>> >>> than the entire shuttle fleet, for that matter.
>> >
>> >Great!  Let's build it!
>>
>> Sounds like a great idea to me, and probably to Jordin.  Are *you* going
>> to provide the money?

Well, maybe we can wait for *Canada* to fund it?  If it's really
that much cheaper, then it's economically viable and someone will be
happy to fund it.  That rather depends, of course, on just how firm
all those numbers are and how many problems remain to be solved in
making it work.

If it can be seen (or at least sold) as making money, somebody will
buy it and build it.  After all, lower cost to orbit allows higher
profit margins!

>> >>> It takes *one* of those 2000-pound launches to add a human to the
>> >>> collection of payloads comprising a mission.
>> >
>> >And how long is your man-in-a-can's life support good for?  ...
>>
>> Mercury, using 1950s technology, got several days (with never-realized
>> plans to extend it to a week or more) for one man with 3000 pounds.
>> I'd hope we could do a little better today.

There's a lot of difference between the life support required for a
person just sitting there and one trying to work in zero-g
conditions.  There were some suprised folks when they found out just
how much difference there is there.  Work under gravity doesn't give
a good idea of the difficulty of work under zero-g.

In any case, I think you underestimate the time, fuel, and
difficulty involved in chasing down a couple dozen pieces and
getting them to go together properly.  Especially given the
inevitable failures in fasteners.

>> >I remember when the 'conventional wisdom' was that it took at least
>> >3 stages to get a reasonable payload to orbit.  And I'm not that
>> >old...
>>
>> Um, Grandpa, that was disproven decisively in 1961, when the first orbital
>> Mercury launch went up on a 1.5-stage Atlas.

Let's see.  If remembering things prior to 1960 makes one a "Grandpa"
to Henry, that says that Henry must have been born sometime after
1980 (if we assume this 'Grandpa' was 6 in 1960 (which is easily old
enough to remember things) and that both Henry's grandfather and his
father had their first child at puberty - if they waited longer, Henry
could have been born later yet.).

Uh, how old did you say *you* were, Henry?  :-)

>> How old did you say you were? :-)

Old enough to remember things prior to 1961.  Let's see, that makes
me all of at least in my mid-thirties.  :-)


==============================================================================
| Fred McCall  ([e-mail]) | My boss doesn't agree with anything  |
| Military Computer Systems           | I say, so I don't think the company  |
| Defense Systems & Electronics Group | does, either.  That must mean I'm    |
| Texas Instruments, Inc.             | stuck with any opinions stated here. |
==============================================================================

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

End of SPACE Digest V11 #88
*******************