Date: Tue,  8 Dec 92 05:04:06    
From: Space Digest maintainer <digests@isu.isunet.edu>
Reply-To: Space-request@isu.isunet.edu
Subject: Space Digest V15 #520
To: Space Digest Readers
Precedence: bulk


Space Digest                Tue,  8 Dec 92       Volume 15 : Issue 520

Today's Topics:
                   Another Orbit Question (3 msgs)
                      Galileo Update - 12/07/92
                        Liquid Hydrogen Price
                             lunar flight
                       Mir, STS-53 and Galileo
             NASA town meeting question wanted on SSTO's.
                       Orbit Question? (2 msgs)
                    REPOST: 1992 Space Compendium
                 Rush Limbaugh and the SAUCER PEOPLE
         Rush Limbaugh says problems with HST are a DoD hoax!
         Rush Limbaugh says problems with HST is a DoD hoax!
                            Saturn V fates
        Soaring like and Eagle (was Re: Range Safety and DC-X)
                              spacecamp
       Terminal Velocity of DCX? (was Re: Shuttle ...) (2 msgs)
             Voyager's "message"... What did it *say*?!?

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

Date: 7 Dec 92 17:58:20 GMT
From: Craig Powderkeg DeForest <zowie@daedalus.stanford.edu>
Subject: Another Orbit Question
Newsgroups: sci.space

In article <foo> gary@ke4zv.uucp (Gary Coffman) writes:
   In article <1992Dec6.141449.761@ualr.edu> hdgarner@acs.harding.edu writes:
   >In light of the fact that a geostationary orbit above only one pole is
   >not possible, I have another question that concerns an idea that I've been
   >working on for the past few months. Is it possible to keep a body at
   >relatively the same point say about 20000 or so miles above the north pole
   >or south pole of the earth? 

   It would require exactly as much continous thrust as it weighs. Thus it
   would run out of fuel quickly. Being stationary over the Earth, and at
   only 20,000 miles, it would weigh almost the same as it weighs on the
   surface. Things in space aren't "weightless", only things in *orbit*
   are "weightless."

A point well taken: that things in space are still subject to the Earth's
gravity.  But, the Earth's radius is only about 30,000 / 6 = 5,000 miles.
At an altitude of 20,000 miles above the surface, you'd only weigh about 
1/25 of your surface weight due to the r-squared falloff in the g field.

But you still can't support anything useful for any reasonable amount
of time... :-P

--zowie
--
DON'T DRINK SOAP! DILUTE DILUTE! OK!

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

Date: 7 Dec 92 21:13:30 GMT
From: Henry Spencer <henry@zoo.toronto.edu>
Subject: Another Orbit Question
Newsgroups: sci.space

In article <1992Dec7.173742.2890@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes:
>It would require exactly as much continous thrust as it weighs. Thus it
>would run out of fuel quickly. Being stationary over the Earth, and at
>only 20,000 miles, it would weigh almost the same as it weighs on the
>surface...

Beep beep beep.  Innumeracy alert. :-)

20,000mi is five Earth radii.  Assuming it's an altitude (measured from
the surface rather than the center of the Earth), the weight of an object
at that point will be 1/36th of its Earth-surface weight.  Still enough
to run you out of fuel quickly, but *not* "almost the same".
-- 
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  henry@zoo.toronto.edu  utzoo!henry

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

Date: 7 Dec 92 22:29:20 GMT
From: M22079@mwvm.mitre.org
Subject: Another Orbit Question
Newsgroups: sci.space

In article <1992Dec6.141449.761@ualr.edu>
hdgarner@acs.harding.edu writes:
 
>
>In light of the fact that a geostationary orbit above only one pole is
>not possible, I have another question that concerns an idea that I have been
>working on for the past few months. Is it possible to keep a body at
>relatively the same point say about 20000 or so miles above the north pole
>or south pole of the earth? I assume that it would require some type of
>thrusting to keep it from orbiting around the earth in normal fashion. If
>you could give some insight on this question such as the relative amount of
>thrust this would require and whether it would have to be continuous or not
>I would appreciate it.
>
>hdgarner@harding.edu
 
The usually trick assumed for putting something way out in space is the LaGrang
e point.  This is a point of balance between gravity wells and may be very
tricky to stay in.  Your choices are quite limited and may not be suited to
your purpose.
 
                       Kpitt@mitre.org

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

Date: Tue, 8 Dec 1992 06:08:35 GMT
From: Ron Baalke <baalke@kelvin.jpl.nasa.gov>
Subject: Galileo Update - 12/07/92
Newsgroups: sci.space,sci.astro,alt.sci.planetary

Forwarded from Bill O'Neil, Galileo Project Manager

                            GALILEO STATUS REPORT
                               December 7, 1992

     The Galileo Spacecraft is operating normally in the dual-spin mode and
is transmitting coded telemetry at 115.2 Kbps (115,200 bits/second).

     Over the weekend, no spacecraft activity was scheduled.
Continuous tracking was scheduled over over DSS-12 (Goldstone 34 meter
antenna), DSS-14 (Goldstone 70 meter antenna), DSS-42 (Canberra 34 meter
antenna), DSS-43 (Canberra 70 meter antenna) and DSS-63 (Madrid 70 meter
antenna).

     Today, December 7, 1992, part 2 of the EE-11 Earth encounter sequence
memory load is being uplinked.  Moon closest approach will occur at
approximately 7:58 PM PST.  The stored sequence controlled Sun vector update
is also scheduled. Continuous tracking is scheduled over DSS-12, DSS-14,
DSS-16 (Goldstone 26 meter antenna), DSS-42, DSS-43, DSS-61 (Madrid 34 meter
antenna) and DSS-63.

     Tomorrow, Earth closest approach will occur at approximately 7:09 AM PST.
Real-time commands are scheduled to enable the Sun algorithms, set the Command
Loss Timer to 11 days, and update attitude control bright body vectors.
Near continuous tracking is scheduled over DSS-12, DSS-16, DSS-42, DSS-43,
DSS-46 (Canberra 26 meter antenna) and DSS-63.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | baalke@kelvin.jpl.nasa.gov
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | The 3 things that children 
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | find the most fascinating:
|_____|/  |_|/       |_____|/                     | space, dinosaurs and ghosts.

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

Date: Mon, 7 Dec 1992 23:26:29 GMT
From: Bruce Dunn <Bruce_Dunn@mindlink.bc.ca>
Subject: Liquid Hydrogen Price
Newsgroups: sci.space

> Paul Dietz writes:
> I don't have a figure for the cost of LH2.  Liquifying LH2 requires
> energy equal to about 1/3 the HHV of the fuel.  It is shipped in
> tanker trucks with a volume of (2.1 to 3.5 tonnes) by rail car with
> volume of 10^5 L (7 tonnes), or by overseas container with a capacity
> of 2 x 10^4 L (fuel for Ariane is shipped to S. America by this mode).
> Losses in shipment are around 7 - 11%, with evaporation losses in LN2
> shielded tanks of < 1%/day.  A typical LH2 plant may make about 60
> tons per day.


        A 1984 publication by a Rocketdyne scientist gives the price of LH2
as $4.50 per pound, or about $10/kg.  The book "Shuttle" by Nigel NacKnight
lists the price of LH2 as $0.96 per gallon, or about $3.70/kg.  It is not
clear what era this price is from - it is possible that the price is from a
primary source at the beginning of the Shuttle era (the book is making the
point about how little the Shuttle fuel costs).

        For comparison, the book Shuttle lists the following prices of other
propellants:

LOX                                 $ 0.38 per gallon
Monomethyl hydrazine                $73.00 per gallon
N2O4                                $33.00 per gallon
Hydrazine (for APUs)                $84.00 per gallon

        Whatever the price of hydrogen is, it looks good relative to other
propellants.  Probably the only thing cheaper on the fuel side would be RP-1
or another hydrocarbon, or ammonia (which isn't used in any current engines).


--
Bruce Dunn    Vancouver, Canada   Bruce_Dunn@mindlink.bc.ca

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

Date: 8 Dec 92 00:03:48 GMT
From: Pat <prb@access.digex.com>
Subject: lunar flight
Newsgroups: sci.space

In article <1992Dec7.060331.10793@ringer.cs.utsa.edu> sbooth@lonestar.utsa.edu (Simon E. Booth) writes:
>In article <ByuA67.5o4.1@cs.cmu.edu> roberts@cmr.ncsl.nist.gov (John Roberts) writes:
>>
>>-From: henry@zoo.toronto.edu (Henry Spencer)
>>-Subject: Re: Lunar flight
>>-Date: 6 Dec 92 01:49:57 GMT
>>-Organization: U of Toronto Zoology
>>
>>-Except that Clinton & Co have already came out as opposed to any resumption
>>-of manned space exploration, or any preliminary steps towards it, no matter
>>-how cheap.
>>
>>Wrong.
>>
>I second that.  I truly hope our space program can survive the Clinton
>administration.  Based on info I read during the campaign VP-elect Gore
>is very pro technology.  While I didn't vote for Clinton/Gore, I won't
>write off our space program yet.       Simon

Clinton is enough of a politician that i doubt that he will be
slashing things ou;t of hand.  He also has some great advisers
on economic policy who believe that R&D is the most vital thing for
stimulating the economy.  

Plus, he is super smart.  i think he will be very receptive to ideas.

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

Date: Mon, 7 Dec 92 22:50:31 EST
From: John Roberts <roberts@cmr.ncsl.nist.gov>
Subject: Mir, STS-53 and Galileo

-From: wats@scicom.AlphaCDC.COM (Bruce Watson)
-Newsgroups: sci.space
-Subject: Mir, STS-53 and Galileo (Was: Re: Galileo through SAA
-Date: 5 Dec 92 20:25:19 GMT
-Organization: Alpha Science Computer Network, Denver, Co.

-In article <ByrqqL.J0E.1@cs.cmu.edu| roberts@cmr.ncsl.nist.gov (John Roberts) writes:

-|I'd be interested in knowing where the Shuttle and Mir will be during the
-|flyby. If it's within a few hundred miles, they might conceivably be able
-|to track it visually.

-For Dec 8 at 15:09 UTC:
-Object        Lat       Long (West)     Height (km)
-------        ----      -----------     -----------
-Galileo       -34         6             306
-Mir Complex    +3        31             396
-STS-53        -13       151             319

Thanks for checking it out. It looks like they'll be too far away for
useful visual tracking.

John Roberts
roberts@cmr.ncsl.nist.gov

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

Date: 7 Dec 92 20:22:50 GMT
From: games@max.u.washington.edu
Subject: NASA town meeting question wanted on SSTO's.
Newsgroups: sci.space

I am going to the NASA town meeting in Seattle on DEC 15th
(or is it 16th)(anyway, I AM going...)

I want to ask a question during the question and answer period.

I am an SSTO supporter.

I also support some of the non-NASA ideas that seem like they hold much
promise for their stated goals (I.E. the Zubrin plan) (Use of the E.T. for
well, you name it...)(etc...) at a far reduced cost from the official NASA 
estimate.

So, I want to ask a QUESTION that shows that there is support for the SSTO,
and that challenges the business as usual attitude.  But I want to do it without
being obnoxious.  I also want it well phrased so that it will be taken
seriously, and as all of the space issues are intertwined, I am finding it
difficult to synthesize a question that not only shows my position, but asks
what, in the future, we can expect from NASA on these topics.  (and yes, there
are many more things I could desire to ask about, but these in order are the
top two issues in my mind...) (and yes, I read the text of Phil Phaerings
question at another meeting, but I feel that these issues need to be heard by
these guys at EVERY meeting they hold, EVERYWHERE they go.)  And at the same
time, I want a question that is not a lecture to be entitled "WHAT I BELIEVE".

Can anyone help me be eloquent?

Let me put it another way:  If you were going to ask a question on either or
both of these topics, how would YOU phrase it?

OR:  What is the BEST SSTO question that can be asked of NASA?


	John Stevens-Schlick

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

Date: 7 Dec 92 16:15:24 -0500
From: hdgarner@acs.harding.edu
Subject: Orbit Question?
Newsgroups: sci.space

In article <ByutAI.13x@access.digex.com>, prb@access.digex.com (Pat) writes:
>In article <1992Dec5.222622.758@ualr.edu> hdgarner@acs.harding.edu writes:
>>I have a question concerning geosyncrenous (please excuse my spelling, my
>>dictionary was  printed before space exploration got started) orbits. It is
>>my understanding that a body in geosyncronous orbit remains over the same
>>point on the earth and has the same rotational period as the Earth. My
>>question is what happens to a body that is in geosyncronous orbit at either
>>the north or south pole. Does it remain stationary above the pole?
>>If you can help me with this question please mail me.
>>Thanks.
>>
>>hdgarner@harding.edu
>
>
>Geo sync orbits only exist at 0 latitude.  you could put a relay
>at 90 degrees, but youd need a huge amount of fuel to hover there.
>
>To do ppolar communications,  either LEO relays sats are used
>or you can create highly inclined highly elliptical orbits that
>leave the bird hovering for a few hours at perigee, a modest tracking
>antenna can then follow the bird.  if you have several in the constellation, you can have continous coverage.
>
Okay I understand what you are saying about the geo sync orbit, but what if the
body you wanted to remain over one of the poles was able to produce its own
electricity (i.e. very large solar array) which would be used to power ion
thrusters to keep it in place? The body would not necessarily have to stay in
the exact same location, but perhaps be oscillating between a maximum and
minimum distance from the Earth's surface. 

Any thoughts?

hdgarner@harding.edu

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

Date: 7 Dec 92 22:16:41 GMT
From: M22079@mwvm.mitre.org
Subject: Orbit Question?
Newsgroups: sci.space

In article <n1063t@ofa123.fidonet.org>
David.Anderman@ofa123.fidonet.org writes:
 
>
>Your polar geosyncronous satellite takes out one equatorial geosynchronous
>satellite every 24 hours as it passes over the equator at 24,000 miles
>altitude.....
>
A few comments about Geosynchronous satellites,
1) They are never perfectly geosynchronous due to external effects such
as solar radiation (.004 eccentricity with yearly variation)
2)  As was mentioned they must be equatorial to be geostationary
3)  If they are inclined with respect to the equator the subsatellite
point is a figure eight
4)  They drift toward specific points on the equator due to J(2,2)
effects of the Earth's shape (a bump on the ellipsoid)
5)  Placing a satellite in Geosychronous orbit is usually coordinated with
international organizations
6)  A geostationary satellite can see up to about 82 degrees North Latitude
 
                                      Kpitt@MITRE.ORG
>--- Maximus 2.00

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

Date: 7 Dec 92 03:14:49 GMT
From: tflavell@pbs.org
Subject: REPOST: 1992 Space Compendium
Newsgroups: alt.education.distance,misc.education,sci.edu,sci.space

TO:     Education Liasons, School Librarians, ITV Coordinators
FR:     PBS Elementary/Secondary Service
RE:     Space Compendium
DT:     November 11, 1992

INVESTIGATE AND CELEBRATE SPACE EXPLORATION! 

The "1992 International Space Year" Compendium has been jointly 
produced by PBS E/SS and the Student Space Foundation with 
support from the National Science Teachers Association's 
Space, Science & Technology Division to assist educators in 
grades K-12 in their planning and celebration for the 1992 
International Year of Space.  It is also designed to help 
educators and students investigate and celebrate space 
exploration for many years to come.  This comprehensive 
compendium lists hundreds of classroom resources, including 
videos, books, research reports, posters, computer software, 
space societies, teacher training workshops, music, and more!  
Parents may also find this useful in supporting budding 
scientists/astronomers.  135 pgs.  To order copies of the 
compendium, send a $10.00 check to: PBS E/SS; Space Compendium; Att: Tom; 
1320 Braddock Place; Alexandria, VA 22314-1698.  SORRY, 
NO PURCHASE ORDERS ACCEPTED.

END 

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

Date: 7 Dec 92 16:53:58 GMT
From: Spiros Triantafyllopoulos <c23st@kocrsv01.delcoelect.com>
Subject: Rush Limbaugh and the SAUCER PEOPLE
Newsgroups: sci.space

In article <ByrEn5.9xq.1@cs.cmu.edu> pgf@srl03.cacs.usl.edu ("Phil G. Fraering") writes:
>I didn't hear his statement but Mr. Limbaugh, when I listened
>to him many years in the past, frequently engaged in satire.
>Since he is known to be on computer networks, where the SAUCER
>PEOPLE find an EASY OUTLET for their UPPER-CASE rantings, I
>suppose that might be where he got the idea.

And, by coincidence of course, this week's Ziggy cartoon on the Indianapolis
News/Star Sunday edition, is like this:

Picture of Ziggy and his dog sitting under a tree. To the right, a
flying saucer hovering a bit above ground. The top hatch is open and
two alien green men are standing. One of them says:

   "We have been monitoring your radio transmissions for a while.
    Which one of you is Rush Limbaugh?"

I pretty much rolled over laughing...

Spiros
-- 
Spiros Triantafyllopoulos                    c23st@kocrsv01.delcoelect.com
Software Technology, Delco Electronics       (317) 451-0815
GM Hughes Electronics, Kokomo, IN 46904      [A Different Kind of Disclaimer]

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

Date: 7 Dec 92 12:55:30 EST
From: "John F. Woods" <jfw@ksr.com>
Subject: Rush Limbaugh says problems with HST are a DoD hoax!
Newsgroups: sci.space

graham@venus.iucf.indiana.edu (JIM GRAHAM) writes:
>>The rumor is still ridiculous.

>As are many rumors, but what, exactly makes you think this one is
>"ridiculous"?

If the fact that a simple assessment of the physics of the situation (not only
is an optical telescope useless for radio astronomy, Hubble isn't even BIG
enough to contain a "secret" radio telescope) renders the rumor impossible
doesn't qualify the rumor as "ridiculous", then I am afraid that I must be
completely unacquainted with the meaning of the word "ridiculous".

>| BBS:      The PORTAL DOLMEN BBS/ParaNet ALPHA-GAMMA (sm) (9:1012/13) |

Is this a key to why you asked the question?

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

Date: Mon, 7 Dec 1992 20:44:54 GMT
From: Doug Page <dpage@ra.csc.ti.com>
Subject: Rush Limbaugh says problems with HST is a DoD hoax!
Newsgroups: sci.space

In article <1992Dec5.025621.15607@mnemosyne.cs.du.edu>, rkornilo@nyx.cs.du.edu (Ryan Korniloff) writes:
|> 
|> 
|> Wait a minute.. for thoes of you who thought I believed any of this, that
|> is not the case. I was merely presenting the info with some resoning.
|> Although I know that it isn't possible to detect radio emissions with an
|> optical instument, I did fail to state this in my original message. I
|> don't like the guy either. I think he is a radical right-wing GOP who pays
|> no mind to any opinions contrary to his own. 

Interesting that you state your opinion that he pays no mind to any opinions
contrary to his own.  It was posted long ago in this newsgroup that he
prefaced this "story" as being ridiculous.  Please note the number of
"open-minded" posters who freely posted what Limbaugh "thinks".  Perhaps
someday they too will stop paying "no mind to any opinions contrary to" their
own.

|> 
|> So, we can put this crap to rest. And as you can see from a previous post
|> there have been other rumors - most likely because of what Rush said. That
|> is all they are, just rumors.
|> 
|> 
|>         -- Ryan Korniloff
|>         -- rkornilo@nyx.cs.du.edu
|> 

dp

*** The opinions are mine (maybe) and do not necessarily represent those of ***
*** my employer.                                                            ***

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

Date: 7 Dec 92 20:25:24 GMT
From: Robert Waisnor <waisnor@norland.diag.stratus.com>
Subject: Saturn V fates
Newsgroups: sci.space.shuttle,sci.space

Does anybody happen to know what the flight schedule would have been if the Apollo 1 fire
had not occurred?????  

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

Date: 7 Dec 92 16:29:38 -0600
From: Bill Higgins-- Beam Jockey <higgins@fnalo.fnal.gov>
Subject: Soaring like and Eagle (was Re: Range Safety and DC-X)
Newsgroups: sci.space

In article <1992Dec7.164541.2299@ke4zv.uucp>, gary@ke4zv.uucp (Gary Coffman) writes:
> Let's hope it flies like a Pheonix, rising gracefully out of it's own flames. 
> It certainly can't soar like an Eagle. :-)

Oh, I don't know, Gary.  The thrust-to-weight ratio on DC-X probably
compares favorably with an F-15 Eagle...

Bill Higgins, Beam Jockey              | Here Lies Bill Higgins:
Fermi National Accelerator Laboratory  | He Never Ever Learned 
Bitnet:           HIGGINS@FNAL.BITNET  | To Play Guitar So Well
Internet:       HIGGINS@FNAL.FNAL.GOV  | But He Could Read and Write
SPAN/Hepnet:           43011::HIGGINS  | Just Like Ringing A Bell

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

Date: 7 Dec 92 17:52:34 GMT
From: Bill Gripp <billg@bony1.bony.com>
Subject: spacecamp
Newsgroups: sci.space

In article <168B186C5.M22079@mwvm.mitre.org> M22079@mwvm.mitre.org writes:
>Would someone please Email me the standard stuff on the Astronaut Camp in FL.

I thought it was in Huntsville, AL.  How many SPACE CAMPs are there?  

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

Date: Mon, 7 Dec 1992 19:41:32 GMT
From: _Floor_ <gene@wucs1.wustl.edu>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

In article <1992Dec5.165219.18302@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes:
] always mean higher reliability. A truck engine is usually good for
] a million miles while a formula one engine may last 100. They both
] put out roughly the same amount of power, but one masses a lot more
] than the other.
] 

What?!? What kind of a comparison is that? I don't really think this is
an appropriate example of your point. A formula one engine is tortured
by blipping rapidly back and forth between 3,000 and 13,000 rpm continually
for two hours. It isn't the size that's the factor, is the use! I think
a tree trunk versus a twig is a better example of your scale/reliability
dependence point.

  _____    "But you can't really call that a dance. It's a walk." - Tony Banks
 /  ___\  ___  __ ___   ___      _____________   gene@cs.wustl.edu
 | / __  / _ \ | /   \ / _ \     |  physics  |   gene@lechter.wustl.edu
 | \_\ \ | __/ |  /\ | | __/     |racquetball|   gev1@cec2.wustl.edu
 \_____/ \___/ |_| |_| \___/     |volleyball |   gene@camps.phy.vanderbilt.edu
 Gene Van Buren, Kzoo Crew(Floor), Washington U. in St. Lou - #1 in Volleyball

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

Date: 7 Dec 92 23:54:33 GMT
From: Pat <prb@access.digex.com>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

In article <1992Dec7.173321.2812@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes:
>>
>>I think formula one race engines are good for about 1,000 miles.
>>they need to be able to do the Daytona 500;-).
>
>NASCAR stock cars do the Daytona 500, USAC Indy cars do Indy, Formula
>One races are much shorter, and twisty.
>

Oh.

>>But you see.  you are proving my point.  The DC will be a beefy
>>version of a spaceship.  it will be the model-T of space, not a
>>Daimler Roadster.  A truck compared to a racecar.  
>
>That's what they said about Shuttle at a similar point in it's development.
>A space truck. As a *beefy* version of a spaceship, DC-X would qualify
>with a mass ratio of 2:1, but it's only intended to reach 30,000 feet,
>not orbit. DC-Y has a mass ratio of 100:1. That doesn't leave much
>room for "beefy".
>

Yeah, but with the shuttle, it was kinda bullshit from the start.  
A truck does not have to be rebuilt everytime it returns to base.
Certainly, shuttle was a different approach from expendables, but it
really was a poor design approach.  i think it was too ambitious
for technology,  and starved for cash.  i think had they spent some
more money up front and built the STS properly, we wouldn't have the problems
it has.

DC-Y may have a narrow mass margin, but i'll still consider it a success
if it makes a working ballistic shot.  I am sure to pull of a decent
SSRT, yoou will need some better engines or higer performance 
structural members or maybe even some solid boosters, but that
to me the real point of DC-Y is not to go to orbit and back with
cargo,  but to even make it up there and back.  

If you can show the approach to be right,  from their it can be improved.

>>Gary,  you have hit the point of the argument.  It's religious.
>>You believe certain things about spacecraft, and not your mind
>>or your senses will alter it.  People used to believe the same thing
>>about aircraft.  Would you want to commute on a wright flyer?
>>how about on a COmet.  People used to say Aircraft have to push the margins.
>>Well, somebody found away to increase the envelope.
>>Sure. early rockets were very marginal,  but if you scale back your
>>expectations, you can increase reliability.
>
>Mass ratio is a very good measure of margin, and DC-Y's will be very
>very much pushing the envelope.
>

It's supposed to.  it's a research plane.  if it can consistently
get to a ballistic trajectory and demonstrate multiple re-entry
techniques,  it will be a major advance.


>>>Look, I'm not trying to be dense here, but in circuit design we know
>>>that the more parts you have in a circuit, and the harder you push
>>>them, the more likely you'll have a failure. So you try to simplify,
>>>and beef up what remains to stand the maximum expected stress. Redundant
>>>power supplies tend to fail redundantly into a shorted load. Add protective
>>>circuits, and the protective circuits will fail in such a way as to take
>>>the system off line at the most critical moment. Simplicity, two wires
>>>make a light, the lever and the inclined plane, strict quality control, 
>>>extensive testing, never depend on an active system when a passive system
>>>will do, never have two critical systems with a common failure point, always
>>>have a totally separate backup system, these are the routes to reliability 
>>>in my business.
>>>
>>Exactly Gary.  Your complaints are the shuttle.  Your solutions are the DC.
>>The shuttle has 4 engine types, separate engines for each mode of flight,
>>three different heat protections, 8 cargo bay doors, .
>
>Yes, *totally* separate systems, completely different backup systems,
>*exactly* what I'm calling for above.
>

Yeah, but it's not redundancy.  redundancy is the 747.  4 engines
with the ability to limp home on 2.  would you consider a 747 to be
safer and more reliable if it had 8 engines.  four props, four jets
where you run on jets at high altitude but exhaust all the fuel
and land and takeoff using props?

I instinctively like the DC concept of multiple engines all using
the same design.  if you want to improve redundancy, put dual fuel pumps
and feeder lines to each engine just like on the LM.  

Actually the LM is a great example.  the Ascent engine only had
one nozzle and chamber,  but it had serial parallel valves on
fuel feed.

The shuttle uses all these differient systems, each ahs to operate
within 5% of norm or you are screwed.  look at launch.
3 SSME's, 2 SRBs must light, Exactly, precisely as planned.
if an SRB fails,  write off the crew and vehicle.  If an SSME fails,
You may have to do a RTLS abort at Hypersonic speed or have to jam
down in Gambia or spain.

Then you are getting to orbit.  Youre SRBs are gone, the SSME's have
no fuel.  You have two OMS engines to hit target orbit and make your
re-entry burn.  If something fails, you end up using a lot of RCS
fuel up or scrubbing the mission.  

THen finally, you make course adjustments and attitude control with
a final RCS system, using totally different fuels.

a DC can be more flexible and redundant with a single fuels system 
and segregated tankage then the shuttle is.

If you have triple controllers,  dual fuel lines.  dual wiring to each controller,  lots of isolation valves, i think you can make the system, very reliable 
and redundant.  and with less mass penalty then what the shuttle has.


>>DC,x,y,1  will have one common set of engines.  the RCS i think uses
>>LH2/LOX.  The same engines will do orbital manuevers, landing, takeoff.
>
>Single point failure. One system must do everything.
>
Make sure there are no single points.  8 engines are not a single failure
point.  put dual controllers.  put dual fuel lines.  put serial/parallel
feed valves.  put isolation valves.  do what airliners fdo.


>>Gary.  If the DC-X can pull off 100 flights in 1 year of testing, and no
>>major problems show up, will you stop complaining that it's unreliable?
>
>Absolutely. If anyone wants a craft with *no* payload capacity, a max 
>altitude of 30,000 feet, and $10 million per flight, after 100 flights 
>I'd concede that DC-X is just the ticket. Now if *DC-1* can deliver
>10 kilopounds to *orbit* 100 times in a year with no failures, I'd
>be much more impressed. I'd even consider buying a ticket. But there
>are many *giant* steps between DC-X and DC-1.
>

And i am sure everyone expects the DC-1 one to be many years off.  
I guess you feel the X-15 was a useless waste of time.  what kind of
spacecraft needs a mother ship, only hits 150,000 ft, wont beat Mach 7
and costs 200,000/flight.  DC-X will prove the flight profile of the DC-Y,1
and hopefully demonstrate high reliability, fast turnaround...
Besides the DC-X may actually have some uses.

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

Date: 8 Dec 92 00:52:08 GMT
From: Josh 'K' Hopkins <jbh55289@uxa.cso.uiuc.edu>
Subject: Voyager's "message"... What did it *say*?!?
Newsgroups: sci.astro,sci.space

henry@zoo.toronto.edu (Henry Spencer) writes:

>In article <1992Dec6.104628.13150@ringer.cs.utsa.edu> sbooth@lonestar.utsa.edu (Simon E. Booth) writes:
>>Pardon the odd question, but is there a recording of the "Voyager Record"
>>available?

>It's just recently come out on CD, although it's expensive ($80 or so).

The CD was reviewed in Air & Space (page 95 of the most recent issue) in which 
the reviewer says that it feel victim to a phenomenon I wish I had a name for.
It's one of those things which would have been _really_ great if it had been
done well.  Apparently they took most of the sound tracks from a third 
generation recording that was poorly done, so many of the musical numbers are
possibly the worst recordings of their songs in existance.  This sounds like
something for your library to get so you don't have to.

-- 
Josh Hopkins                                          jbh55289@uxa.cso.uiuc.edu
                        Ho^3     !=L

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End of Space Digest Volume 15 : Issue 520
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