Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_5/V15NO551.TXT

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Date: Wed, 16 Dec 92 05:09:29
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #551
To: Space Digest Readers
Precedence: bulk


Space Digest                Wed, 16 Dec 92       Volume 15 : Issue 551

Today's Topics:
                            Air Force One
           Apollo 10 LM (was Re: pre-fire Apollo schedule)
                                Aurora
                CFP: Workshop on AI and KBSs for Space
                           DoD launcher use
                         fast-track failures
                     Freeman Dyson biographies...
                             liquid fuels
 No asteroid flybys (was Re: Cassini Undergoes Intense Design Review)
                           Orbit Question?
                       Relay to Follow Galileo?
       Terminal Velocity of DCX? (was Re: Shuttle ...) (3 msgs)
                    Yet another antigravity device

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From: Curtis Roelle <roelle@uars_mag.jhuapl.edu>
Subject: Air Force One
Newsgroups: sci.space

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[e-mail] (John Roberts) writes:


>-From: [e-mail] (Gary Coffman)
>-Subject: Re: absolutely, positively overnight
>-Date: 11 Dec 92 17:24:37 GMT
>-Organization: Gannett Technologies Group

>->I'm sure that if certification were suitable and appropriate facilities
>->were widespread, there'd be a few executive DC-1s bought.  The Saudi
>->royal family would surely buy one.  And then there's Air Force One...

>-Take a look at Air Force One, or Two. A 747 and a 707.

>I was under the impression that there are two 747s. There was a television
>special on the history of Air Force One several months ago, but I don't
>think I saved the tape.

The impession I had was that there are several presidential airplanes,
each with different tail numbers.  The designaiton "Air Force 1" is used
only when the President is actually onboard one of them.

Curt Roelle

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

Date: Tue, 15 Dec 1992 20:59:34 GMT
From: Henry Spencer <[e-mail]>
Subject: Apollo 10 LM (was Re: pre-fire Apollo schedule)
Newsgroups: sci.space.shuttle,sci.space

In article <[e-mail]> [e-mail] (Tom A Baker) writes:
>>... the Apollo 10 LM *probably* could have
>>flown a lunar landing if some fuel had been offloaded to lighten it, but
>>the margins would have been slim and hard to predict...
>
>Scary.  As I have often recalled, there was a subtle bug in the LM
>software that flew in the Apollo 10 mission.  When in ascent mode, the
>LM was supposed to automatically stay in contact with the CSM by
>directional antenna.  If it wasn't, then the LM automatically would
>do a "random tumble" to locate it.  During Apollo 10's simulation of
>ascent, that started happening just at the beginning of the simulated
>ascent.  Stafford yelled "Son of a bitch!", which we all heard on Earth
>a while before we found out the problem.

Indeed, before the weight problem was fully clear, there was considerable
debate about whether it was worth flying the dress-rehearsal mission --
why go all that way only to back out at the last moment?  Some of the
more thoughtful people pointed out that there were still substantial
unknowns in navigation and communications with two vehicles in lunar
orbit, and it would be better to sort these out with a final test.
They were right.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: Tue, 15 Dec 1992 19:13:40 GMT
From: "Stephen R. Willson" <[e-mail]>
Subject: Aurora
Newsgroups: sci.space

For anyone who is interested, Popular Science had an article in it about
two or three years ago that made reference to Aurora.  I can't remember
what exactly was in the article, but it might be worth taking a look at again.
--
-----------------------+-------------------------------------------------------
 Stephen R. Willson    | A fitting end to a screwy campaign year...
 [e-mail]  | Here to swear in the President of the United States,
 [phone]        | Larry King!                         -The Miami Herald

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

Date: Tue, 15 Dec 92 09:09:56 GMT
From: joachim fuchs wgs <[e-mail]>
Subject: CFP: Workshop on AI and KBSs for Space
Newsgroups: sci.space

              1st Announcement and Call for Papers

  Artificial Intelligence and Knowledge Based Systems for Space
                        - 4th Workshop -

                      May 17th - 19th, 1993
                ESTEC, Noordwijk, The Netherlands


                          Organized by

                    THE EUROPEAN SPACE AGENCY
           Simulation & Electrical Facilities Division
                      Technical Directorate


Purpose
-------
The European Space Agency (ESA) has for many  years  pursued  ac-
tivities in Artificial Intelli- gence and Knowledge Based Systems
for Space. The technology has already been  successfully  applied
in  several  domains and is now widely considered a viable option
in many developments.

The objective of this workshop is to obtain an active exchange of
information  within the European AI community, within industry as
well as within ESA. Not only  increasing  awareness  of  the  new
developments  and technologies play an important role, but inputs
obtained in this workshop will also serve ESA  to  harmonize  and
standardize the developments in Artificial Intelligence for Euro-
pean Space programmes.

Since the domain is still very evolutionary there  are  two  main
interests  in  organizing this workshop at the Space Research and
Technology Centre of the European Space Agency (ESTEC).

On one hand the applicability of proven and now almost "standard"
methods  and  technologies  of  AI should be demonstrated through
their use in operational or quasi-operational applications. There
is as well the wish to standardize where suitable the development
of Artificial Intelligence in order to  increase  the  confidence
even further.

On the other hand, new methods and techniques should be  proposed
and  their potential domain of application - particular for space
- should be identified. In this context AI could as well stand as
acronym for "Advanced Informatics".

These are the main drivers for the fourth Workshop on  Artificial
Intelligence at ESTEC.

Topics
------
The proposed issues reflect the main issues to  be  addressed  in
this  Workshop.  There is naturally a certain overlap between the
different topics (eg the boundary between "established" and  "ad-
vanced" algorithms will always be fuzzy).

The list of topics is not considered exhaustive. Authors are  en-
couraged  to submit papers to topics they consider relevant, even
if they are not mentioned below. Those will as well be  reviewed.
However, the submitted papers should be oriented towards real ap-
plications.

* Applications
  - AI in the different phases of the Spacecraft  Life-Cycle  and
    the Space Mission
    - Requirements Definition, Design, Assembly, Integration, Ve-
      rification and  Qualification of S/Cs,  Subsystems and Pay-
      loads
    - Mission Planning, Mission Preparation  and  Ground  Support
      (Operations)
    - Crew Operations, On-board S/W
    - Data Gathering and Analysis
  - AI Techniques in the Development of Intelligent Tutoring Sys-
    tems for Ground and On-board Crew Training

* Methodology
  - Knowledge Acquisition and Representation
  - Conceptual Models
  - Knowledge Based Systems Life-cycle (Development Methodology)
    - User Requirements Definition
    - Ergonomy of KBS
    - Validation and Verification of KBS (Reliability, Testabili-
      ty)

* Advanced Algorithms
  - Machine Learning
    - Case Based Learning
    - Generalization through Explanation
    - Neural Nets
  - Prediction Methods (eg for Planning)
  - Constraint Logic Reasoning
  - Genetic Algorithms/Evolutionary Programming
  - Fuzzy Logic

Round Tables
------------
Round Tables will provide a forum for a  more  active  discussion
amongst  participants.  For  this reason presentations of ongoing
work are welcome even if there are no  final  results  available.
The  final definition of subjects and number of Round Tables will
be a function of attendance and the nature of abstracts received.

The proposed subjects reflect some of the strategic objectives in
the Agency:

* Autonomy
  - On-board Autonomy
  - Ground Support
  - Reactive/Predictive Planning
  - "Real Time", Temporal Reasoning

* Knowledge Repository
  - KB-Management
  - Knowledge Integration and Knowledge Sharing
  - Query Languages
  - Visualization Tools and Methods
  - Operational Aspects, User's View

* Model Based Reasoning
  - Diagnosis and Repair
  - (Re-) Configuration
  - Qualitative Reasoning

Practical Information
---------------------
Workshop participation is free of charge.

Working languages will be English and  French.  However,  authors
are  encouraged  to  use English as a "de facto" standard because
there will no simultaneous translation be provided.

Presentation time for the Workshop papers is 30 Minutes,  includ-
ing  the  time for possible discussions. Since the character of a
Round Table is more oriented towards the active discussion of the
participants,  the  time  allocated  for  each paper will be more
flexible, in average longer than for the Workshop (~45 minutes).

The infrastructure provided for the presentations  includes  sup-
port  for  viewgraphs,  slides  and video films (VHS, U Matic). A
particular attention should be given to the fact that  viewgraphs
should  not  be  copies  of the submitted paper, but rather being
edited for the purpose of presentation, eg finding more graphical
representations of the relevant issues instead of text.

There will be accommodation for poster sessions and  S/W  demons-
trations. All demonstrations need to be shipped to ESTEC prior to
the Workshop as standalone systems and installed by  the  demons-
trators. Purpose of the demonstration and requirements (power and
other connections, size) should be clearly identified and  stated
to ESTEC not later than March 22nd, 1993. They are subject to ap-
proval by ESTEC. Demonstrations showing AI applications will  get
preference over commercial demonstrations.

Papers for the Workshop and the Round Tables will be selected  on
the  base  of  abstracts  not exceeding one A4 page, which should
reach ESTEC at latest  on  February  15th,  1993.  The  abstracts
should  include complete information about the author(s) (and af-
filiation) and it should be stated under which heading the author
would place his proposal. The abstract should be sent to:

        ESTEC Conference Bureau
        Postbus  299
        NL-2200 AG Noordwijk
        The Netherlands

        Fax: [phone]
        Tel: [phone]

Fax submissions are acceptable to meet the deadline, but  authors
are  requested  to  send  a paper copy to the address above since
this will be used for the abstract book which will  be  available
at the workshop.

Full length papers (not exceeding 15 pages) should be provided to
ESTEC at latest at the Workshop (format A4).

Calendar of Events

  - 1st Announcement, Call  for  Papers     December  14th, 1993
  - Abstract submission deadline             February 15th, 1993
  - Notification of authors                     March 15th, 1993
  - Final Programme                             March 22nd, 1993
  - Registration Deadline                       April 16th, 1993
  - Workshop                               May 17th - 19st, 1993
  - Camera-ready papers                              at Workshop
  - Proceedings ready                                end of June

Organizing Committee
--------------------
U. Mortensen,     ESA/ESTEC (Workshop Chairman)
F. Allard,        ESA/ESTEC
E. Bornschlegl,   ESA/ESTEC
F.-J. Demond,     ESA/EAC
H. Laue,          ESA/ESOC
A. Moya,          Commission of the European Communities (DG XIII)
G. Muehlhauser,   ESA/ESRIN
S. Valera,        ESA/ESTEC
J. Fuchs,         ESA/ESTEC (Workshop Organizer)


===== CUT HERE ===== CUT HERE ===== CUT HERE ===== CUT HERE =====

                          Response Card
              1st Announcement and Call for Papers
  Artificial Intelligence and Knowledge Based Systems for Space
                        - 4th Workshop -

                      May 17th - 19th, 1993
                ESTEC, Noordwijk, The Netherlands



I intend to submit a paper:  O YES     O NO

(Preliminary) Title _____________________________________________

Particular requirements (video, viewgraphs, slides...)___________

_________________________________________________________________

I intend to submit a poster: O YES     O NO

(Preliminary) Title _____________________________________________

Requirements (space...)__________________________________________

_________________________________________________________________

I intend to make a S/W demonstration:  O YES    O NO

Purpose _________________________________________________________

Requirements (Connections, space...)_____________________________

_________________________________________________________________

Name             _________________________________

Affiliation      _________________________________

Mailing address  _________________________________

__________________________________________________

Telephone        _________________________________

Fax              _________________________________

Please mail or fax this form to the address listed above.

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

Date: Tue, 15 Dec 1992 20:48:01 GMT
From: Henry Spencer <[e-mail]>
Subject: DoD launcher use
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Josh 'K' Hopkins) writes:
>>>... SR71s and U2s that can fly above anything Iraq had right?
>>I don't know whether Iraq had any of the Soviet heavy SAMs, but unless
>>those aircraft have capabilities far beyond what's revealed, they can't
>>fly above *those* missiles' ceilings.
>
>Just what is the ceiling on those missiles?  And it should be noted that even
>if they can reach the required altitude they probably are no match for SR-71
>speeds and ECM.

Ceilings are poorly known and references differ, but the SA-5 Gammon must
surely have a ceiling of at least 100,000ft and probably more -- it's
substantially larger than the Nike-Hercules, which has made practice
intercepts (of missiles!) at 150,000.  Reaching extreme altitudes briefly
is no big deal for a large, heavy SAM.

There is no requirement to match the SR-71's speed.  Being in the right
place at the right time is sufficient.  The SR-71 may be fast, but it
is not very maneuverable, meaning it can't dodge much.

Countermeasures are a valid point, but now we're into ECM and ECCM and
etc. -- a seesaw battle rather than inherent invulnerability.

>>As far as I know, SR-71s never actually overflew the USSR...
>
>According to Burrows' _Deep Black_ "The Russians have repeatedly charged that
>they have been overflown by SR-71s, and the Cubans have made the same
>allegation: the Pentagon has denied the former and admitted the latter."  Now
>just who you believe (and what definition of "overflown" you use) is up to
>you.  But the Soviets have repeatedly expressed frustration over the fact that
>they can't shoot Blackbirds down...

Partly because, according to Belenko, the SR-71s never did come in close
to give the air defences a chance to function at full effectiveness.
There's a big difference between taunting them with occasional approaches
and routinely flying overhead saying "go ahead, do your worst".
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: Tue, 15 Dec 1992 21:25:19 GMT
From: Henry Spencer <[e-mail]>
Subject: fast-track failures
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>>Just which aircraft were you thinking of, Gary?  I can think of one
>>aircraft that had a bad performance shortfall but was redesigned and
>>continued into a successful program (the F-102).  I can't think of
>>*any* F-series "gap" in the last 40 years that fits your description.
>
>Yeah, bad line of argument, most of the systems that made it as far
>as being assigned a number weren't technical failures even if they
>were market failures. Actually I was thinking of the P-39...

Actually, in fairness I should say that on doing a bit more digging
out of curiosity, I did discover that the F-103 was having problems
with its engines and this was a minor factor in its cancellation...
although the problems were not in the Mach 3.7 ramjet or in the turbojet-
ramjet switchover, but in the supposedly-off-the-shelf turbojet.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: Tue, 15 Dec 1992 16:06:35 GMT
From: Greg Moore <[e-mail]>
Subject: Freeman Dyson biographies...
Newsgroups: sci.space

In article <[e-mail]> [e-mail] ("Phil G. Fraering") writes:
>/Also, for a good read, check out "The Starship and the Canoe" a biography
>\of both Freeman Dyson and his son Chris.  Talks about Freeman's work on
>/Daedelus.
>
>I've read it. It's passable in most parts, but altogether it's horrible.
>The author feels so much more morally superior to both Dysons but
>apparently especially to Freeman Dyson himself.
>

    I must admit it has been years since I've read it, but I do
want to defend it a bit.  I agree taht the author in some ways comes
across believing himself to be morally superior that Freeman.  In the
case of his son Chris, the author seems to be saying "Nice, quaint, but
someday he'll have to grow up."  I disagree with it being horrible
though.  I was greatly intrigued by the idea of canoeing up and
down the west Canadain coast.  The builind og the canoes was interesting
also.
    The author tries to paint a picture in contrasts of the
son exploring "inner-space" and the father exploring "outer-space".
While a neat idea, it falls flat.

>I was also disturbed by the general attitude its author seemed to
>have towards people working in the physical sciences and/or engineering.
>
    This I don't recall to be honest.

>If you want to read a good biography of Dyson, that is fair and
>still (IMHO) doesn't pull any punches, try the biographical parts
>scattered through his own works. They're better written, more fun,
>and also have a lot of good ideas, _firsthand_.
>
    For a good biography, I'd ahve to agree.

On the same token, if you've not yet read any of the books by
Dr. Feynman, I highly suggest them.  The man had a ready wit and
led an interesting life.

>--
>Phil Fraering
>"...drag them, kicking and screaming, into the Century of the Fruitbat."
><<- Terry Pratchett, _Reaper Man_
>PGP key available if and when I ever get around to compiling PGP...

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

Date: Tue, 15 Dec 1992 21:33:20 GMT
From: Henry Spencer <[e-mail]>
Subject: liquid fuels
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Dave Michelson) writes:
>>>The major problem with cryogenic fuels is that they boil off and the
>>>gas must be vented.  This becomes a real problem if the upper stage
>>>is located inside the shuttle cargo bay.  The modifications that must
>>>be made to the shuttle are non-trivial.
>>
>>Sorry, wrong.  Cryogenic fuels fly in the payload bay on every extended-
>>duration shuttle flight.  The shuttle's fuel cells use liquid hydrogen
>>and liquid oxygen, and the extended-duration pallet for the cargo bay
>>(first flown recently) is basically a set of LH2 and LOX tanks.
>
>Are you disputing that the modifications that must be made to the shuttle
>to accomodate Centaur are non-trivial? ...

Nope.  My point is that these are accidents of design details of Centaur,
and are *not* fundamental obstacles to carrying liquid fuels in the payload
bay.  It can be done -- it *has* been done -- without such difficulty.
The EDO modifications for this are minor.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: 15 Dec 92 12:10:08 GMT
From: Ben Burch <[e-mail]>
Subject: No asteroid flybys (was Re: Cassini Undergoes Intense Design Review)
Newsgroups: sci.space,sci.astro,alt.sci.planetary

In article <[e-mail]> Richard A. Schumacher,
[e-mail] writes:
>Swell. WIth our luck the damn thing will probably wind up colliding
>with an asteroid, which collision would have been recognized had
>we but continued the search for flyby possibilities...

I should probably let this one go...  Oh well...  Have you ANY concept of:

A. How unlikely this is? I mean, I am more likely to win the lottery by
   a long stretch, and I don't buy tickets.

B. How lax this would be on the part of mission planners?  I'm quite
   sure that they know of all of the close encounters with asteroids,
   probably this is spit out from a standard piece of mission planning
   software.

I mean, its very slightly likely that this mission could run afoul of
a misplaced pebble, but one can hardly plan around that.

-Ben Burch

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

Date: Tue, 15 Dec 1992 21:29:37 GMT
From: Henry Spencer <[e-mail]>
Subject: Orbit Question?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Tom A Baker) writes:
>[Molniya series]
>they spend only about a half an hour south of the equator, and the other
>11 and a half north of it.  Very efficient.  I wonder why the Canadians
>don't lease time on the CIS's satellites?

Canada doesn't do much in the far Arctic, where Clarke-orbit satellites
are impractically low on the horizon, so we don't really have the need
for the extra complexities of moving satellites.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: Tue, 15 Dec 1992 21:20:52 GMT
From: Henry Spencer <[e-mail]>
Subject: Relay to Follow Galileo?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Ryan Korniloff) writes:
>Well why did the HGA have to be cloed up in the first place? If it is too
>big, then couldn't they have used a more powerful transmitter? I would
>have rather tried to avoid such a chance for failure...

They would have preferred a rigid antenna, and some early Galileo designs
had one.  But power is always in very limited supply aboard a spacecraft,
and as they got more ambitious the data-rate requirements grew, and once
the rim of the dish got big enough to hit the edges of the shuttle cargo
bay, there wasn't much to do except go for a folding antenna.  Very similar
antennas have worked very reliably on the TDRS series.  It looked okay,
especially since the plan was to unfold it before Centaur ignition, when
the astronauts could have dealt with problems (in the same way they dealt
with Compton's snagged antenna).  The revised flight plan, including the
Venus encounter that required keeping the antenna folded for thermal
protection, was put together on a shoestring in the wake of Challenger.
(This is also why they can't back off the antenna motor -- the relay
that would have permitted that got used for something else in the
hardware changes needed for the new flight plan.)
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: Tue, 15 Dec 1992 20:07:52 GMT
From: Paul Dietz <[e-mail]>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

>In <[e-mail]> [e-mail] (Gary Coffman) writes:

> Snide remarks not withstanding, chamber pressure isn't the only form
> of stress on a vehicle. While I like Truax's Sea Dragon proposal
> on several grounds, the low chamber pressures lead to very high
> loads on the turbopumps because so much more fuel per unit time
> has to flow to achieve the high thrust required with low pressure
> engines. Reducing stress in one area can lead to increased stress
> in another area when the objective remains to get a vehicle from
> surface to orbit in a single leap. The high speed pumps, not combustion
> chamber stresses, are the main reliability concern of liquid fuel rockets
> anyway.


Uh, Gary, the Sea Dragon concept used *pressure fed* engines, which
don't *have* pumps.  Instead, it used big, dumb, strong fuel tanks,
pressurized with compressed gas.  This limits you to lower chamber
pressures than in pump fed engines (otherwise the tanks are too
heavy), but can be much simpler.

Moreover, your comment is nonsense even without this fact.  Lower
chamber pressure lowers thrust mainly because it lowers the mass flow
rate through the engine (the coefficient of thrust also decreases a
bit, but not enormously).  Viewed another way, the mass flow required
to get a given amount of thrust is proportional to one over the Isp.
Isp does increase somewhat with increasing chamber pressure, but
rather slowly.  The load on a pump increases linearly with the
pressure it is required to supply, however.

    Paul F. Dietz
    [e-mail]





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

Date: 15 Dec 1992 20:57:31 GMT
From: Pat <[e-mail]>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>on several grounds, the low chamber pressures lead to very high
>loads on the turbopumps because so much more fuel per unit time
>has to flow to achieve the high thrust required with low pressure
>engines. Reducing stress in one area can lead to increased stress
>


I dont think that is an unsolvable problem.   THe Saturn F-1's sucked
fuel like no tomorrow.   The soviet's haul fuel to feed those
big protons and energiya engines.

I suspect packaging and design are bigger problems  then just mass flow.


>tankage and structure are required as well. Certainly I agree that HTHL
>is most efficient since you don't need as much fuel to get to orbit, or
>to get landing fuel to orbit when aerodynamic lift can help out. That
>means your vehicle can be smaller and have a better mass ratio than the
>pure brute force approaches. Certainly a launcher that is never intended
>to re-enter the atmosphere is more efficient without wings, but if the
>wings can handle the bulk of the return trip as passive systems not
>requiring high speed high precision machinery, they deserve serious
>consideration.




These have been consifdered and dropped.

Horizontal take off  is not simple.   while it makes people comfortable
it means the bird has to sit a long time in the soup,  sucking in
O2  and feeding the engines.   The stress is high.  the heat buildup
is enormous.     NASP is going berserk on this problem.
Flight near MACH 12  can be a real trick.

McDaC, chaose to just fly right out of this soup  and take a simpler
approach.

Wings are not useful if they only generate lift up to abou;t  20 miles,
and you have to keep climbing another 130 miles.

Henry posted something on this.

Also if an HTHL, is going to be mostly lifting body,  then so will the DC.

As i understand it, it will blunt fly down to mach 3 and then roll
tail first.  engines will provide terminal management.  most velocity
will be shed by passive shielding.

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

Date: Tue, 15 Dec 1992 16:10:47 GMT
From: "Michael V. Kent" <[e-mail]>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

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

>In article <[e-mail]> [e-mail] (Michael V. Kent) writes:

>It would include finishing
>the tests of prototype cryogenic tanks and test the composite structures.

Are these the same cryo tanks that McDonnell Douglas is building for NASP?

>>What I don't believe is that you'd get any knowldgeable
>>volunteers to fly a Spacelab mission on a Titan IV.

>Well we will launch that 400 pound Italian satellite. You remember, the
>one NASA spent half a billion launching instead of putting it on a $10M
>Pegasus?

Could NASA have put the IRIS upper stage on that Pegasus too?  While I have
not heard it stated explicitly, I suspect that launching IRIS was every bit
as important to the Italians as launching LAGEOS.  (They sunk several hundred
million into its development only to have its intended market banned from the
Shuttle.)  Was the development effort of integrating Pegasus and IRIS also
included in that $10 million?

What about Mephisto?  The Lambda point experiment?  The United States Micro-
gravity Payload (which carried the two aforementioned experiments)?  What
about the Space Vision System and all of the rest of the CanEx payloads?
Could these all have been launched on the Pegasus?  The same $10 million
Pegasus?  Could they also have flown the Lower Body Negative Pressure appar-
atus and several astronauts to wear it?  Could that Pegasus have returned the
robot arm, USMP, and our brave Pegasus-riding astronauts?

Can't you just admit that a lot more happened on STS-52 than the launch of
LAGEOS so we can put this issue to rest?

Mike

--
Michael Kent                                   [e-mail]
Flight Test Engineer                           Tute-Screwed Aero '92
McDonnell Douglas                              Rensselaer Polytechnic Institute
These views are solely those of the author.    Apple II Forever !!

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Date: Tue, 15 Dec 1992 14:41:46 GMT
From: Thomas Clarke <[e-mail]>
Subject: Yet another antigravity device
Newsgroups: sci.physics,sci.space

J. Baez's posting of a plausible antigravity device inspires
me to describe one of my own.

Imagine a spinning superconducting rotor of suitably clever
configuration.  I think of something like one of those toy flying
devices with a hub, several radially disposed airfoils with
non-zero angle of attack, and an outer ring surrounding all the
airfoils:
          _________
         /___    __\
    //   |  |  \\
       //    |  |   \\
      //     |  |    \\
     ||_____/    \____||   / \
     | _____      ____ |    |
     ||     \    /    ||    |
      \\     |  |    //     |
        \\   |  |   //
         \\__|  |__//
          \________/

Now the magnetic field equations have the same form as the
hydrodynamic equations and since the devide is superconducting
these will be the Euler equations.  Thus in the earth's magnetic
field the rotor will act like the toy and produce lift.  Since
the conduction is perfect, the lift will be without drag (Euler
equation paradox).  The spinning rotor will thus produce a constant
force against the earth mediated by the magnetic field.

If the force vector is oriented vertically and the rotor is large
enough and spins fast enough it should levitate.  Note that nothing
is violated.  As the rotor rises, it will loose mechanical energy of
rotation and slow down until its weight balances the magnetic lift.
Conversely if it falls, gravitational potential energy increases the
speed increasing the mangetic lift.  Thus the rotor should leviatate
stably at a fixed height.  To raise it spin the rotor faster, to
lower it decrease the spin rate.  [This reminds me not only on
Dick Tracy's space coupe, but of the levitation devices described by
Heinlein in _Door into Summer_ Don't worry how they work, just
absorb the engineering properties and use them.]

Lots of problems of engineering problems of course, probably need
counterotating pairs to counter torque reactions. There would be
difficulties in handling the varying direction of the geomagnetic
field.  How do you start the rotor: rotate then cool or cool then
rotate? etc. etc.

More seriously, could it work?  Is there a clever superconducting rotor
design that losslessly converts angular rotation into magnetic lift?
Given the in-principle possiblity of such a rotor, could one built
out of realistic materials be rotated fast enough to generate useful lift
in the earth's magnetic field?  If these devices were practicle and
came into general use, would they cause some environemntal catastrophe
like reversing the earth's magnetic field :-)?

I'm not sure about how to answer these questions.  Given indefinitely
large currents in the rotor, the answer would seem to be yes.  But
maybe I'm missing something.
--
Thomas Clarke
Institute for Simulation and Training, University of Central FL
12424 Research Parkway, Suite 300, Orlando, FL 32826
[phone], FAX: [phone], [e-mail]

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End of Space Digest Volume 15 : Issue 551
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