Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V16_2/V16NO247.TXT

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Date: Tue,  2 Mar 93 05:05:11
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #247
To: Space Digest Readers
Precedence: bulk


Space Digest                Tue,  2 Mar 93       Volume 16 : Issue 247

Today's Topics:
                         Battery help needed!
            Cheap Mars Rocks (was Re: Moon Dust For Sale)
                    Hopkins Leaks (was Re: Blimps)
                  Hopkins Leaks Balloons to Jupiter
                            Lonely hearts
                          Refueling in orbit
                              sci.astro
                Spaceflight for under $1,000? (3 msgs)
           SSF Resupply (Was Re: Nobody cares about Fred?)
             SSTO Estimates (was Re: Refueling in orbit)
                        Stupid Centaur Tricks
                     The Future of Fred (2 msgs)
                      Victims of Space Disaster

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

Date: 28 Feb 93 00:03:50 GMT
From: Henry Spencer <[e-mail]>
Subject: Battery help needed!
Newsgroups: sci.space,sci.electronics,sci.aeronautics,sci.chem,sci.engr

In article <[e-mail]> [e-mail] (anthony.r.rizzo) writes:
>I recall reading about iron-titanium-hydride (or some similar material)
>for storing H2 in a high energy density, low pressure, room temperature,
>mostly solid form...

There has been experimental work on this kind of thing, but with the
possible exception of whatever's done inside nickel-hydrogen batteries,
I know of no operational systems using it.  My understanding is that
it is extremely heavy for the weight of hydrogen it carries.

>Since there is already O2 in the crew compartment, leakage of O2 from
>the high pressure bottle would pose little added risk...

Sorry, any source of pure oxygen is a potential hazard -- not in itself,
but because it can turn a minor fire into a roaring inferno.  That
goes double if it is in the same can as a hydrogen source.

In any case, a more fundamental problem with fuel cells is that they
are not simple, easy-to-use hardware.  They are complex and cranky.
I'm not aware of any off-the-shelf system small enough to meet this
requirement, and a new system would need extensive development effort.

I think I'd look into the sexier battery technologies, like nickel-hydrogen
or silver-zinc, first.
--
C++ is the best example of second-system| Henry Spencer @ U of Toronto Zoology
effect since OS/360.                    |  [e-mail]  utzoo!henry

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

Date: 27 Feb 93 20:18:26 GMT
From: Ron Baalke <[e-mail]>
Subject: Cheap Mars Rocks (was Re: Moon Dust For Sale)
Newsgroups: sci.space,sci.astro,alt.sci.planetary

In article <[e-mail]>, [e-mail] (Anthony Datri) writes...
>
>>To get the Mars rock I'm talking of down to earth didn't cost a single cent,
>>by the way. The 18kg SNC-meteorit simply fell out of the sky in October, 1962
>>near Zagami rock in Nigeria.
>
>I must admit some skepticism wrt meteorites that are claimed to have been
>ejected from Luna and Mars.

Most of the lunar meteorites have been recovered from the Antarctic and
have been compared with the Apollo moon rocks, and they match up very well.
Correlating the SNC meteorites from Mars is on weaker ground, but there
is still evidence that they may very well have come from there.  Last year,
analysis of water from the SNC meteorites provided a stronger case on to
their origin:

RELEASE:  92-35

METEORITES' WATER PROVIDES CLUE TO RED PLANET'S PAST
March 13, 1992

    A single drop of water rarely causes excitement in the scientific
community, but a few milligrams of liquid extracted from a meteorite may
have started to answer one of the great mysteries of planetary science.

    Dr. Everett Gibson of NASA's Johnson Space Center (JSC), Houston,
Planetary Sciences Branch; Dr. Haraldur Karlsson, formerly a National
Research Council postdoctoral fellow at JSC; and scientists at the University

of Chicago have analyzed drops of water extracted from several meteorites
believed to have come from Mars and have concluded that the oxygen
isotopes in the water were extraterrestrial.

    Photographs returned to Earth from the Mariner 9 and Viking
spacecraft show features that suggest Mars once may have had a water-rich
atmosphere and flowing water on its surface.  Sometime in its history,
however, most of the water apparently disappeared, leaving only minute
amounts of vapor in the atmosphere.

    Through the years, several meteorites have been collected on Earth
that scientists have identified as Martian by comparing them to information
gleaned by the Viking spacecraft.  Six of these meteorites were used in the
water extraction procedure.

    Gibson said the meteorites were heated in steps in a small vacuum
system at JSC to extract trace amounts of water.  The water samples were
hand-carried to the University of Chicago for analysis of oxygen isotopes.
Although the water droplets were less than 1/64ths of an inch in diameter,
it was enough to do the analysis.

    The analysis determined that the oxygen isotopes in the water were
different from the oxygen isotopes in the silicate portion of the meteorites.
In other words, the water had a different parent source than the oxygen in
the silicate minerals in the meteorites.  That parent source could have been
the Martian atmosphere, an ancient Martian ocean or even a comet that
impacted the planet, Gibson said.

    The lack of homogeneous oxygen isotopes on Mars supports the theory
that Mars does not have plate tectonics.  If such a process had been active
on Mars, the oxygen isotopes would have been homogenized as they are on
Earth.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Choose a job you love, and
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you'll never have to work
|_____|/  |_|/       |_____|/                     | a day in your life.

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

Date: Sat, 27 Feb 1993 23:19:47 GMT
From: "Phil G. Fraering" <[e-mail]>
Subject: Hopkins Leaks (was Re: Blimps)
Newsgroups: sci.space

[e-mail] (Bill Higgins-- Beam Jockey) writes:

>In article <[e-mail]>, [e-mail] (Phil G. Fraering) writes:
>> I'm not sure in what way, but two of the rigids built in the
>> US, the Akron and Macon, were built differently from the
>> standard German design, and were judged to be better except
>> for that little modification the FAA insisted had to be made
>> to the tail design (which was ultimately responsible for the
>> loss of both craft, one with heavy loss of life, and the other
>> with only light loss of life).

>Phil, we are both descending into fuzzily remembered realms of fact.
>Strictly speaking, I don't think the FAA existed in the mid-1930s. And
>why would they dictate design of military airships?  Gotta go home and
>look at my books.

Well, as someone who is all for fuzziness (it has its place down at
the quantum level, which is I guess where Bill works ;-) I don't quite
remember the name of the agency responsible, except that it wasn't
the Navy. What I do remember is that an outside organization insisted
that for safety reasons the control cab in the rear fin be visible from
the forward gondola, and that to accomplish this the point where the
fin attached to the main structure was moved back, to the point where
it was no longer braced strongly to the central structure.

This caused the design defect where the rear part of the vehicle would
experience structural failure, causing various mayhem, and loss of
life and vehicle. I'm suprised the Net.Aeronautics.Expert hasn't
spoken yet.


[location of Bill's parents being Jupiter]:
>Nope, Melbourne.  Jupiter is further south.  Handy if you need a
>gravity assist to get to Miami.

You mean Miami isn't enough of a black hole that it just sucks you
in? Or is that someplace else?

> --
>     O~~*           /_) ' / /   /_/ '  ,   ,  ' ,_  _           \|/
>   - ~ -~~~~~~~~~~~/_) / / /   / / / (_) (_) / / / _\~~~~~~~~~~~zap!
> /       \                          (_) (_)                    / | \
> |       |     Bill Higgins   Fermi National Accelerator Laboratory
> \       /     Bitnet:     [e-mail]
>   -   -       Internet:  [e-mail]
>     ~         SPAN/Hepnet:      43011::HIGGINS


--
Phil Fraering         |"...drag them, kicking and screaming,
[e-mail]|into the Century of the Fruitbat." - Terry Pratchett,
                       _Reaper Man_

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

Date: 28 Feb 93 00:55:43 GMT
From: Josh Hopkins <[e-mail]>
Subject: Hopkins Leaks Balloons to Jupiter
Newsgroups: sci.space

>>For the following paragraph we have the headline "Hopkins Leaks News
>>of Balloon Project."  (Or maybe it's just a trial balloon?)

I'd like to suggest a moratorium on bad jokes given the potential this topic
has to balloon way out of proportion.

Bill Wrote:

>>Oh, by the way (though this quest failed on sci.aeronautics last
>>fall):  We're looking for a textbook that details balloon design!
>>Anybody know a good one?

Phil Wrote:

>I don't know, but _Sky Ship: The Akron Era_ was a good book on
>airships.

I have a number of good books on rigid history (insert prayer of thanks to
the patron saint of one of the best libraries on the continent).  What I'm
looking for is something on design of LTA craft.  Given the near total lack
of work being done on new concepts there doesn't seem to be a market for
such things.  I'm working from first prinicples gleaned from AIAA proceedings.

>I know you'll just _love_ the ZMC-1...

:-)  Most definately.

I did briefly consider gliders as someone suggested, but the reasons for a
balloon are three-fold.

1) Passive lift can give you incredible hang time.  Maybe on the order of years
   if we get really creative and lucky.

2) Balloons are very light (because they have to be) so this could easily be
   a "faster, better, cheaper" mission, or one that would put multiple payloads
   at different lattitudes.

3) While I don't have a great profile of the Jovian atmosphere yet, to say that
   GNC for a glider is "non-trivial" would be quite an understatement.

I will post a description of what Bill and I have come up with eventually.
However, I'd like to make more progress and this may get published eventually
so I'd like to protect my investment.  In other words, I don't want a leak in
the project (there I go, breaking my own ceasefire).

I'd be more than happy to talk to anyone who wants to suggest good sources on
design or the Jovian conditions (I need as good a profile as anyone can
produce) or who wants to brainstorm.  Bill and I picked Jupiter because it's
the toughest place in the solar system to do this (okay, the chromosphere is a
little tougher), so any brilliant suggestions are welcome.
--
Josh Hopkins                                          [e-mail]

    You only live once.  But if you live it right, once is enough.
            In memoria, WDH

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

Date: Mon, 1 Mar 1993 15:24:06 MST
From: "Richard Schroeppel" <[e-mail]>
Subject: Lonely hearts

> Who was the loneliest man in the Universe?  In other words, which of the Apollo
> "third men" got furthest from his teammates, and was, hence furtherest from any
> living human?  That we know of  :-)

There are some pretty lonely places here on Earth, perhaps further from other
people than the diameter of the moon (~2160 miles).  The last survivor of the
Scott expedition to the South Pole was pretty lonely; also anyone flying solo
over the Pacific <1940 would be a candidate, depending on his flight path.

Rich Schroeppel  [e-mail]

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

Date: 27 Feb 93 15:01:07 GMT
From: Matthew DeLuca <[e-mail]>
Subject: Refueling in orbit
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:

>Suppose you are the PI of a multi-billion $$ Mars sample return mission.
>Are you going to risk your entire project on a technology which hasn't
>been done yet and which may or may not work?

>Not bloody likely.

So why do you expect NASA to do just that?

AS: "See, we can get cargo down with no problem at all for a fraction of the
cost of other methods...we just put it in a big can, stick some tiles on it,
and use a tether tied to the station to get it down."

MD: "Nobody's tried that...you want to risk tearing up the station doing
something it wasn't designed for?"

AS: "Oh, don't worry, there's this engineer guy I know that says it will work."

Not bloody likely.
--
Matthew DeLuca
Georgia Institute of Technology, Atlanta Georgia, 30332
uucp:      ...!{decvax,hplabs,ncar,purdue,rutgers}!gatech!prism!matthew
Internet: [e-mail]

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

From: [e-mail] (Jimson Vedua)
Subject: sci.astro

Is there anyone out there who could help me to subscribe to sci.astro?

thanks,

[e-mail]

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

Date: Sat, 27 Feb 1993 19:20:00 GMT
From: Mark Spiegl <[e-mail]>
Subject: Spaceflight for under $1,000?
Newsgroups: sci.space

Ok - pardon my neophite newbie question, but what kind of computers
do fly with the shuttle?


    ^
   |U|     Mark C. Spiegl
   |S|     Motorola Inc.
  /|A|\    [e-mail]
  ~~U~~

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

Date: Sat, 27 Feb 1993 22:50:53 GMT
From: "Russell J. Pagenkopf" <[e-mail]>
Subject: Spaceflight for under $1,000?
Newsgroups: sci.space

In article <spiegl.730840800@lead15> [e-mail] (Mark Spiegl) writes:
>Ok - pardon my neophite newbie question, but what kind of computers
>do fly with the shuttle?

International Business Systems (IBM).  There are five main computers.
Four of them are online at one time with the spare as a backup.  Each of
the four computers are in constant consultation with each other and if
there is a disagreement about how something should be done they vote on
it.  These computers have very little RAM (as has been mentioned recently)
but are special in that they are designed to survive in space, which is an
extrememly harsh environment for computers.

[please note that followups have been redirected to sci.space.shuttle]

--
Russ Pagenkopf                    "Heading, Sir?"
[e-mail]                 "Out there. Thataway."
[e-mail]         "A most logical choice, Captain."

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

Date: Sun, 28 Feb 1993 00:30:53 GMT
From: Henry Spencer <[e-mail]>
Subject: Spaceflight for under $1,000?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Guillot, Burt J.) writes:
>>Yes, but those computers and that memory will survive conditions which
>>would turn your PC into a paperweight...
>
>So what were to happen if John Doe takes his 386 to orbit with 4 megs
>of memory on board with, say, a 40 megabyte hard disk.  Would it
>affect the memory only or the storage of the hard disk as well?  And,
>what is "it"?

"It" is launch vibration, higher radiation levels, and some complications
like the lack of convection for cooling.  Assuming his hard disk survived
the trip up, and his cooling-fan setup was good enough to avoid problems
with overheating, John would find that his machine would work, but not
too reliably (especially when passing through the South Atlantic Anomaly,
where radiation levels are particularly high).  More-or-less off-the-shelf
commercial laptops see extensive use for non-critical functions aboard
the shuttle, but the flight computers -- without which the orbiter cannot
be landed, among other things -- have to meet far more demanding specs.
--
C++ is the best example of second-system| Henry Spencer @ U of Toronto Zoology
effect since OS/360.                    |  [e-mail]  utzoo!henry

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

Date: 27 Feb 93 15:08:58
From: Steinn Sigurdsson <[e-mail]>
Subject: SSF Resupply (Was Re: Nobody cares about Fred?)
Newsgroups: sci.space

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

   References: <[e-mail]> <[e-mail]> <[e-mail]> <[e-mail]>
   NNTP-Posting-Host: access.digex.com

   In article <[e-mail]> [e-mail] (Steinn Sigurdsson) writes:
   |In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:
   |
   |Well, Allen, I could ship you a brick FedEx (or USPO express) (COD of
   |course ;-) - you will be rather astonished to find that the charge for
   |shipping the brick will not be the cost of the truck+flight from here

   Allen was arguing that you can't get deadhead space free from anyone.
   True.  Most drivers operate under the "Gas, Grass or Ass, No-one rides
   for free" policy.  Steinn, to argue marginal cost is irrelevant to allens argument.

Well, in some places truck drivers will actually give hitchhikers a
free ride, they figure they're heading that way anyway and the
marginal cost from the extra weight is negligible.
    Even airlines offer free standby seats if you know the
right people, for example some airlines offer employees free seats
on standby figuring (correctly) that the marginal cost is negligible,
the price charged to regular standbys is what the market will bear,
based on how big a discount people will demand to accept the
uncertainty of not getting a flight.

   Wingo was trying to claim that thrusters fly for free.  Allen pointed
   out that was a crock.  You then come up with some argument on the
   cost being the operating cost divided by payload.   Sadly, that's
   allen's point, too.  The cost of dragging thrusters to orbit does
   cost 10,000/pound under any rational accounting scheme.  any claims to
   the contrary is a fiction.

This is false; you repeatedly assume that the cost per pound is the
total operation cost+amortised cost divided by pounds flown; it is
no such thing - if NASA stopped in its tracks and flew nothing
it would still cost several billion per year.

   |   Except that with automated refueling we can use $35 million Delta's
   |   instead of half a billion $$ shuttle flights for refueling.
   |
   |   If we re-fueled automatically and left the thrusters in place we would
   |   go from ~50 shuttle flights costing $25 billion and go to ~50 Delta
   |   flights costing less than $2 billion. A savings of over $23 billion.
   |
   |Allen, what is the development cost of learning how to do
   |automatic refuelling and over how many flights will you amortise it?
   I believe allen did those numbers.  He proposed that at 8% rate of return
   and 4 Billion up front in engineering, you payback in 4 years.

Which is sheer fantasy, the $4 billion up front don't exist and
therefore there is no payback. NASA doesn't get a tax write off
for investments, if they reduce future operations they probably
just get less money to operate with. More importantly they never
get the upfront money in the first place - they certainly can't
borrow it on the open market!

   |    Do you propose flying fewer shuttle flights without the
   |resupply (in which case the marginal cost on the remaining flights
   |increase) or should NASA redirect those flights to another purpose?
   |Or should they simply fire 20,000 support staff - in which case what
   |is the cost of severance (including any welfare support to the
   |government)?

   Neither of these questions are relevant to the Freedom PMO.  THey are
   a problem for Johnson, kennedy and HQ.   IT is the job of Reston to
   do the most with the least dollars.   It's HQ's job to figure out how to
   rebalance missions.   What if we signed a deal on 5 energiyas.  suddenly
   26 shuttle missions go by the way.  Is that restons fault?  of course not.
   The assumption is HQ will either direct new shuttle missions or
   reduce the program size.   simple enough and nobody's problem
   but theirs.

This is pure nonsense. NASA is not a group of trading companies,
and its purpose is to find out how to carry out certain objectives,
if possible, given this years budget. They can't borrow upfront costs
and they are not free to buy from arbitary suppliers, a significant
part of their mission has been to find out how to carry out certain
objectives in space and to maintain a group of people who have the
experience of carrying out those activities.

   >    You make good points, but your accounting methods are, shall
   >we say systematically skewed.
   >

   Allen makes good points,  and given i have a masters in Business and
   Public administration, I would say in keeping with accepted practice.
   Politically naive, oftentimes, but acceptable.

   I would challenge you steinn to find any textbook which dictates
   that allen is wrong.

Allen is wrong because he treats NASA as if it were a small business
operating in a free market, and it isn't. It is not at all clear to
me that it should be either.

|  Steinn Sigurdsson    |I saw two shooting stars last night        |
|  Lick Observatory    |I wished on them but they were only satellites    |
| [e-mail] |Is it wrong to wish on space hardware?        |
| "standard disclaimer"    |I wish, I wish, I wish you'd care - B.B. 1983    |

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

Date: 27 Feb 93 14:50:10
From: Steinn Sigurdsson <[e-mail]>
Subject: SSTO Estimates (was Re: Refueling in orbit)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:

   In article <[e-mail]> [e-mail] (Steinn Sigurdsson) writes:

   >    SSTO fans would do well to re-read the history of some
   >modern launchers, including the original Shuttle concept and how
   >it evolved.

   I have. I note with pleasure that SDIO seems to have as well and has
   learned from those mistakes.

I hope so, I'd like to see DC succeed.

   >Might make some a little less firm in their cost estimates

   You will note that my detailed cost estimates for SSTO which I
   posted a while back had costs about twice other estimates. But
   with an SSTO with its emphasis on rapid turnaround, the costs
   come down fast as the market grows.

Hmm, the STS came in at about 40% over budget, where they failed
completely was in rapid turnaround - they needed at least 50 flights
per year to come anywhere near the original claims, preferably 2-300.

   Now it may be that the turnaround goals can't be met yet. But
   SSTO is still a good idea because even if it fails it will tell
   us exactly what we need to do to make it work and will suggest
   solutions to those problems.

   >and a little less ready to cut other transport systems before the
   >SSTOs have demonstrated operational ability..

   Nobody is talking about cutting all transport system, only those
   which aren't cost effective and can only survive via wasteful
   government subsidy.

That would be all space launch systems, unless of course you
agree to write off the development costs as sunk costs.

   >in particular Allen
   >might be astonished to realise that some of his DC claims look
   >like they were cut out from a NASA report circa 1971-1974 providing
   >STS claims ;-)

   The problem with this arguement is it doesn't address just why
   Shuttle failed and what is different this time. This arguement amounts
   to a proof that space will never be cheap for no other reason than
   that the Shuttle failed. Without more analysis it's not a very good
   arguement.

Well, the reason it failed is multifold. First the STS did not
receive the level of development funding needed back then to
build that radical a system, hence the bastardised piggyback
system we have now with SRBs. Secondly, the STS turned out to be
far more complex than expected, require more overhaul and more
inspection than allowed for. Most importantly, NASA essentially
can't terminate people, so it maintains a huge staff many of
which are charged to STS, also a lot of ongoing research that
would be done anyway is charged to STS - hence the perennial
argument here on sci.space that the marginal launch cost of
a shuttle is an order of magnitude less than you claim; if all
the shuttles were grounded NASA's budget would not decrease in
proportion. This is where DC has a real advantage, if they can
get it flying with the level of groundstaff claimed and it
will not require too much overhaul between flights, they
don't have a pre-existing army of support people who need
to be kept on. From what
you've said it really does look like they could. That's
assuming that it is the MD of DC-3 that's working on it,
not the C-17 or the DC-10...

|  Steinn Sigurdsson    |I saw two shooting stars last night        |
|  Lick Observatory    |I wished on them but they were only satellites    |
| [e-mail] |Is it wrong to wish on space hardware?        |
| "standard disclaimer"    |I wish, I wish, I wish you'd care - B.B. 1983    |

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

Date: Sat, 27 Feb 1993 23:25:30 GMT
From: "Phil G. Fraering" <[e-mail]>
Subject: Stupid Centaur Tricks
Newsgroups: sci.space

[e-mail] (George William Herbert) writes:

>In article <[e-mail]> [e-mail] (Phil G. Fraering) writes:
>>
>>I don't understand why it's more reliable to have a single engine than
>>two engines with a gimballing system that would allow it to function
>>on one engine.
>>
>>I guess they're just into newspeak (half the engines, half the chance
>>of failures!).

>Hi Phil, actually they're right.

>They have to do something about the engine out problem.
>Right now, the easy way (read: cheap) is to do a structural
>redesign to one engine but use the same pointing mechanism
>as the existing engines do.  This also gives a 300lb higher
>payload (amazing, you leave a 315 lb engine off and gain 300 lb
>of payload 8-).  The other alternative was to develop a new
>guidance and engine pointing system.  This theoretically
>gives a higher reliability, but it's not worth the added expense.
>The one-engine variant has half the failures the current two
>engine one does; the enhanced two engine option is past the
>point of diminishing engineering investment return.

>-george william herbert
>President, Retro Aerospace
>[e-mail]  [e-mail]

I think they may be ignoring other factors, like that the amount of
transverse in the gimballing system only needs to be increaced in
_one_ dimension...

All this still sounds suspect to me...

--
Phil Fraering         |"...drag them, kicking and screaming,
[e-mail]|into the Century of the Fruitbat." - Terry Pratchett,
                       _Reaper Man_

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

Date: 27 Feb 1993 16:26 EST
From: "David B. Mckissock" <[e-mail]>
Subject: The Future of Fred
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] writes...
>>
>>
>Yes you are indeed flying off the handle.  When NASA Lewis first was given
>responsiblity for the electrical power system architecture on SSF they came
>up with this utterly weird 20Khz AC power distribution systeem.  The theory
>was that it was lighter and more efficient.  Well NASA (lets say center b)
>wanted to keep the Skylab type DC power system due to its simplicty and
>ease of integrating experiments.  Due to congresional pressure center b was
>overruled and development work on 20Khz went ahead.  When a demonstration
>of the 20Khz system was developed and brownt to center b it was connected in
>the same room where the center b proposed 75KVA DC system was already up
>and operating. (Actually it had been there in one form or another since
>Skylab). Well when the 20Khz system was powered up all of the terminals in
>the room locked up! All of their computers also went south from the rich
>RFI environment that the system produced.  Needless to say the 20Khz system
>soon went the way of the dodo bird.
>
Interesting perspective on history. The SSF program
accepted the WP-04 recommendation of a 20kHz
distribution frequency back in the mid 80's. Lewis
Research Center has been doing extensive ground
testing of 20 kHz systems for *YEARS*, and the
Rocketdyne/TRW/NASA team from WP-4 did analyses
showing the benefits of a high frequency AC
system (higher distribution efficiency than DC,
lower weight, safety benefits, etc.). In addition,
we had a solar dynamic system baseline for power
generation, and with the rotating equipment it
was easy to generate AC.

A while later, some other program participants
began complaining about the need to interface
with an AC system ("we've never done this before"
type of an argument). As I recall, MSFC, JSC,
NASDA, and ESA wanted DC, and CSA and Level II
supported 20 kHz. The decision was maintain
20 kHz as the distribution frequency, but
convert it to DC before entering the modules.

The 'hybrid' stayed as the baseline for a while,
and then it was decided to go to an all-dc
distribution system (which is today's baseline).
I am unfamiliar with the problems referred to
at MSFC using 20 kHz in the testbed. I can
only repeat that LeRC has been testing 20 kHz
components for years, and in the early-mid '80s
setup a end-to-end 20 kHz system using SSF
advanced development funds.

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

Date: Sun, 28 Feb 1993 00:26:24 GMT
From: Henry Spencer <[e-mail]>
Subject: The Future of Fred
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Michael Pereckas) writes:
>I remember hearing something about 20 kHz power a few years ago...

It's best forgotten. :-)

The basic idea had its attractions.  Transformers work with AC, not DC,
so power supplies are often easier to build with an AC input.  Moreover,
transformer weight falls off rapidly as frequency rises; modern switching
power supplies often run their transformers at many kHz.  Finally, with
a solar-dynamic power system -- superior to solar arrays for several
reasons -- the hardware generates AC by its nature.

The problem was that it required redesigning *everything*.  And the
redesign was distinctly non-trivial.  At a time when 20kHz was still the
official station supply and things were allegedly well in hand, I was
told privately:  "it's great in theory, but right now they can't even
make a 20kHz lighting system actually *work* reliably, never mind
complex electronics".

The sensible thing to use would have been 400Hz AC.  That's the standard
power supply on large aircraft, and a wide range of off-the-shelf hardware
is available for it.  It's high enough to get most of the transformer
weight reduction and low enough to avoid things like RFI problems, and
it still gets you the major benefits of AC.
--
C++ is the best example of second-system| Henry Spencer @ U of Toronto Zoology
effect since OS/360.                    |  [e-mail]  utzoo!henry

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

Date: 27 Feb 1993 21:00:24 GMT
From: CLAUDIO OLIVEIRA EGALON <[e-mail]>
Subject: Victims of Space Disaster
Newsgroups: sci.space

I am reading the book "Countdown" by the previous astronaut  Frank Borman and
Robert Serling and read  a very interesting passage in which  Borman describes
what happened to certain persons during the investigation of the Apollo 1 fire.
Borman himself was chosen to work in the committe that investigated the accident
and he mentioned that the fire  affected emotially lots of people involved in the
program. Here is a passage that follows from his book:

"The first crack-up occurred without warning and right before our eyes. We were in
Houston, having finished writing our three-thousand-page report  (...). One of the
engineers (not a NASA Man) got up, a glazed look on his face, and walked over to a
blackboard in the room.

"He began to draw what looked lilke one of those corporate organizational charts,
with one large box at the top and lines leading down to smaller boxes.

"'This is my organizational chart for heaven,' he announced. 'At the top is God,
whom we'll call Big Daddy. ...'

" On he went, drawing the chart with a running commentary that became totally
incoherent. We called an ambulance and his company flew him  home in a
stratjacket. After long psychiatric therapy, including shock treatments, he recovered
his health. (...)"

For me, this looks very dramatic. Of course there were other cases too that I am not
mentioning. I would like to know if someone in the NET has any recollection like
this one regarding not only to the Apollo fire but also the Challenger  accident. It is
really amazing how these things get in the way of people.

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End of Space Digest Volume 16 : Issue 247
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