Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V16_5/V16NO525.TXT

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Date: Wed,  5 May 93 06:22:13
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #525
To: Space Digest Readers
Precedence: bulk


Space Digest                Wed,  5 May 93       Volume 16 : Issue 525

Today's Topics:
   A Little Pace o' My Heart Now (was Re: Long term Human Missions)
      Boeing TSTO (Was: Words from Chairman of Boeing) (2 msgs)
                    Drag-free satellites (2 msgs)
          Electrical Spacecraft via Magnetic field of earth?
             HST Servicing Mission Scheduled for 11 Days
                    large accelerations revisited
                     Single Launch Space Station
             Space FAQ 14/15 - How to Become an Astronaut
          Space Manuevering Tug (was HST servicing mission_)
                         Vandalizing the sky.
          Will NASA's Mars Observer Image the Face on Mars?

    Welcome to the Space Digest!!  Please send your messages to
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----------------------------------------------------------------------

Date: 3 May 93 13:28:04 -0600
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject: A Little Pace o' My Heart Now (was Re: Long term Human Missions)
Newsgroups: sci.space,sci.space.shuttle

In article <[e-mail]>, [e-mail] (Gary Coffman) writes:
> In article <[e-mail]> rek@siss81 (Robert Kaye) writes:
>>3.    Pacemakers (Kept my grandfather alive from 1976 until 1988)
>
> Pacemakers have been around since the 1940s. *Implantable* pacemakers
> required development of solid state devices and externally rechargable
> power sources.

I worked for Cordis, a major manufacturer of cardiac pacemakers, in
the summer of '75.   I don't believe they made an "externally
rechargeable" pacer at that time and I wonder whether such things
existed.

They ran on batteries (sorry, don't remember what kind).  Batteries
and electronics were potted in epoxy in an assembly about the size of
a plum.  A surgeon attached leads to the right part of the heart, and
the leads ran to a pacer implanted in the patient's abdomen.  Every
two or three years, when the battery life was ended, they would do an
operation to snip the leads, remove the pacer, and splice a fresh one
into the old lead.  This was simpler than doing more heart surgery.

The technology was old since they had to prove extreme reliability;
when I was there the first models containg integrated circuits were
just entering service.  These were clever:  they had a magnetic read
switch inside.  A physician could put a big coil against a patient's
chest and reprogram the pacer for different heart rate, etc. with a
series of pulses.

Cordis had done a lot of development on the nuclear-powered pacer,
basically  plutonium RTG like  the one that runs Voyager or Galileo.
It had a 20-year rated lifetime, but was kind of a mismatch since most
pacer patients don't live 20 years after their operation.  They were
"installed" in a few people but there were big safety concerns (what
if the plutonium gets loose in some horrible car wreck?).  The labs
were working on a 10-year model based on new lithium batteries that
threatened to make the nuclear pacemaker obsolete.  I guess they did.

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

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

Date: Mon, 3 May 1993 18:20:53 GMT
From: Henry Spencer <[e-mail]>
Subject: Boeing TSTO (Was: Words from Chairman of Boeing)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Richard A. Schumacher) writes:
>[Description of Boeing study of two-staged spaceplane using
>supersonic ramjets deleted.]
>
>In other words, Boeing is not seriously thinking about
>reliable, less-expensive access to orbit. They just like
>to fool around with exotic airplanes.

More precisely, they see themselves as basically being in the airplane
business, and prefer launcher designs that exploit, and add to, their
airplane experience.  This is probably not the best way to get to orbit,
but it may well be the optimum way for *Boeing* to try to get to orbit,
since they (rightly) think that even if they do get into the space
business, airplanes will be their main business for many years yet.

Note, though, that even if it's not the *best* way to get to orbit, it
may well be a workable way of getting reliable, less-expensive access
to orbit... if done right.  One thing that came out pretty clearly at
Making Orbit '93 is that *there are lots of ways to do cheap launchers*.
It is quite reasonable to let external factors, e.g. the nature of
Boeing's current business, dictate basic configuration, because you
don't *need* to pick the very best configuration.  Getting into orbit
simply is not that hard.  The right configuration will not automatically
give you high reliability and low costs; configuration is a secondary
issue.

Personally, I agree that Boeing's configuration is less than ideal,
if your sole objective is orbit.  Getting involved with aerodynamics
in a serious way when you don't have to (and launchers don't have to)
is silly and counterproductive.  But if you are *already* in the
aerodynamics business, and plan to stay in it, that changes things a bit.
--
SVR4 resembles a high-speed collision   | Henry Spencer @ U of Toronto Zoology
between SVR3 and SunOS.    - Dick Dunn  |  [e-mail]  utzoo!henry

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

Date: 3 May 1993 14:08:50 -0400
From: Matthew DeLuca <[e-mail]>
Subject: Boeing TSTO (Was: Words from Chairman of Boeing)
Newsgroups: sci.space

[Snipe and countersnipe about Boeing TSTO vehicle research deleted]

One thing I think people need to be careful about is falling into the
One True Faith mode of thinking where SSTO (as represented by Delta
Clipper) is the One True Way to better and cheaper access to space.
There are any number of possible ways into orbit from the ground, and
if Boeing wants to look into some of these we should be cheering them
on; perhaps their final concept won't be quite as fast and cheap as
Delta Clipper hopes to be, but it may have other benefits (greater cargo
capacity, greater on-orbit maneuverability, lower launch accelerations,
et cetera et cetera) that make it worthwhile.  Personally, I wish them
the best of luck.

Or, if you don't want to think of it in the above manner, think of it
this way: Boeing is a private airplane company (now here's a radical
concept, an aircraft company doing research into exotic aircraft) and if
they want to look into this for access to space they are more than welcome
to do so.  Even if it turns out to be hideously expensive and highly
unreliable, they're not on a mission from NASA, God, or anyone else to
provide better access to orbit.  So there.
--
Matthew DeLuca
Georgia Institute of Technology, Atlanta Georgia, 30332
uucp:      ...!{decvax,hplabs,ncar,purdue,rutgers}!gatech!prism!matthew
Internet: [e-mail]

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

Date: Mon, 3 May 1993 17:49:30 GMT
From: Henry Spencer <[e-mail]>
Subject: Drag-free satellites
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>> No.  A "dragless" satellite does not magically have no drag; it burns fuel
>> constantly to fight drag, maintaining the exact orbit it would have *if*
>> there was no drag.
>
>     Well, almost. It turns out that clever orbital mechanics can
>engineer things so that resonant interactions with the higher order
>harmonics of the Earth's gravitational field can pump energy into a
>satellite, and keep it from experiencing drag effects for periods of
>months to years.

These are two entirely different things, actually.  The "dragless"
satellites previously discussed were as I described them:  using thrust
to cancel the effects of air drag, measured relative to suspended masses
shielded against it.  Allen is talking about satellites that experience
drag, and make no particular effort to compensate for it (that is, a
sensitive accelerometer aboard one would detect a steady deceleration),
but exploit tricks of orbital mechanics to minimize the *effects* of
the drag on the overall orbit.
--
SVR4 resembles a high-speed collision   | Henry Spencer @ U of Toronto Zoology
between SVR3 and SunOS.    - Dick Dunn  |  [e-mail]  utzoo!henry

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

Date: Mon, 3 May 1993 18:16:03 GMT
From: Scott Stallcup <[e-mail]>
Subject: Drag-free satellites
Newsgroups: sci.space

Isaac Kuo ([e-mail]) wrote:
:
: In any case, the small difference from spherical that the Earth is is
: ridiculously small.  Even counting all of the mountains, etc. that make the
: Earth bumpy, the Earth is closer to a sphere than the smoothest billiard
: ball.
:
: Even if the Earth were significantly flattenned, it would be flattenned on
: the axis of rotation, and thus the gravitational field does not rotate and
: thus no orbiting satellite can derive energy from the non-changing
: gravitational field.
: --

 I don't have the numbers handy, but I can assure you that Earth
 Oblateness is one of the major factors in orbit/attitude determination
 calculations.   The three major factors are atmospheric drag,
 Earth oblateness, and solar pressure.   Surface "bumps" (mountains)
 are not a major factor but the equatorial bulge is an important factor.

 ----------------------------------
 Scott Stallcup
 Space Telescope Science Institute

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

Date: Mon, 3 May 1993 17:45:23 GMT
From: Henry Spencer <[e-mail]>
Subject: Electrical Spacecraft via Magnetic field of earth?
Newsgroups: sci.space

In article <1s16e4$[e-mail]> [e-mail] (Pat) writes:
>>... A "dragless" satellite does not magically have no drag; it burns fuel
>>constantly to fight drag, maintaining the exact orbit it would have *if*
>>there was no drag...
>
>What is the point of it?  are they used for  laser geodesy  missions?
>triad seemed to be some sort of navy navigation bird,  but why
>be "dragless"  why not just update  orbital parameters?

The main point of it, for the missions to date, has been very accurate
measurement of gravitational phenomena, where air drag is an unwanted
complication.  You can cancel it out much more accurately than you can
measure it (in fact, the most accurate way to measure it is to measure
how hard a cancellation system is working).

It might perhaps have future applications to really serious microgravity
research, emphasis on the "micro".
--
SVR4 resembles a high-speed collision   | Henry Spencer @ U of Toronto Zoology
between SVR3 and SunOS.    - Dick Dunn  |  [e-mail]  utzoo!henry

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

Date: Mon, 3 May 1993 18:03:51 GMT
From: Henry Spencer <[e-mail]>
Subject: HST Servicing Mission Scheduled for 11 Days
Newsgroups: sci.space,sci.space.shuttle,sci.astro

In article <[e-mail]> [e-mail] writes:
>>[HST] needs occasional reboosting or it will eventually reenter.  (It has
>>no propulsion system of its own.)...
>
>If it has no propulsion system, how does it maneuver itself?

It can *point* in any direction using momentum wheels (reaction wheels whose
nominal "zero state" is a substantial spin rate) (terminology as in Wertz,
"Spacecraft Attitude Determination and Control" -- the usage of the various
terms is not consistent across the field, so please let us have no quibbles
over what the words mean).  To turn in one direction, spin an internal wheel
in the opposite direction, and the torque on the wheel will turn the
spacecraft.  Asymmetric external torques eventually have the wheels spinning
faster and faster to compensate, so you need some way of dumping momentum,
which HST does with electromagnets that exert a torque against Earth's
magnetic field.

But it has no propulsion system -- no way of changing its orbit.
--
SVR4 resembles a high-speed collision   | Henry Spencer @ U of Toronto Zoology
between SVR3 and SunOS.    - Dick Dunn  |  [e-mail]  utzoo!henry

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

Date: Mon, 3 May 1993 17:38:29 GMT
From: Henry Spencer <[e-mail]>
Subject: large accelerations revisited
Newsgroups: sci.space

In article <[e-mail]> wohlmuth@cehpx10 (Walter Wohlmuth) writes:
>Why can't an aircraft be designed so that the pilot can always be
>maintained in a upright position, perpendicular to the plane of
>acceleration? ...

Actually, for high accelerations you want the pilot perpendicular to
the acceleration vector.  (This may be what Walter meant.)

It's not impossible -- there has been work with things like auto-reclining
seats that might be considered a first approximation -- but it creates
problems, notably restricting the pilot's view.  (The nifty display
technologies that Walter mentions are nowhere near equalling the human
eye for practical combat flying.)
--
SVR4 resembles a high-speed collision   | Henry Spencer @ U of Toronto Zoology
between SVR3 and SunOS.    - Dick Dunn  |  [e-mail]  utzoo!henry

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

Date: Mon, 3 May 1993 17:26:41 GMT
From: Andrew Curtis <drseus!curtis>
Subject: Single Launch Space Station
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Karl Dishaw) writes:
>Andy Cohen <[e-mail]> writes:
>>the Single Launch Core Station concept.  A Shuttle external tank and solid
>>rocket boosters would be used  to launch the station into orbit.  Shuttle
>>main engines would be mounted to the tail of the station module for launch
>>and jettisoned after ET separation.
>
>Why jettison the SSMEs?  Why not hold on to them and have a shuttle
>bring them down to use as spares?
>
>
>Karl
>sold my soul to Uncle Sam . . . now marked down for resale.
>
It's not the same as throwing a spare tire in your trunk ;-)

It's undoubtedly cheaper to dispose of a set of SSMEs which are nearing the
end of their operational life cycle (they are all refurbished and re-used
already) than to design, build, test, certify, and fly the single use hardware
necessary to secure the SSMEs in the cargo bay.  That doesn't even include
the cost of the EVAs or other crew operations necessary to transfer the SSMEs
from the station to the shuttle cargo bay.

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

Date: 3 May 1993 12:23:56 -0400
From: Jon Leech <[e-mail]>
Subject: Space FAQ 14/15 - How to Become an Astronaut
Newsgroups: sci.space,sci.answers,news.answers

Archive-name: space/astronaut
Last-modified: $Date: 93/05/03 12:07:55 $

HOW TO BECOME AN ASTRONAUT

    First the short form, authored by Henry Spencer, then an official NASA
    announcement.

    Q. How do I become an astronaut?

    A. We will assume you mean a NASA astronaut, since it's probably
    impossible for a non-Russian to get into the cosmonaut corps (paying
    passengers are not professional cosmonauts), and the other nations have
    so few astronauts (and fly even fewer) that you're better off hoping to
    win a lottery. Becoming a shuttle pilot requires lots of fast-jet
    experience, which means a military flying career; forget that unless you
    want to do it anyway. So you want to become a shuttle "mission
    specialist".

    If you aren't a US citizen, become one; that is a must.  After that,
    the crucial thing to remember is that the demand for such jobs vastly
    exceeds the supply.  NASA's problem is not finding qualified people,
    but thinning the lineup down to manageable length.    It is not enough
    to be qualified; you must avoid being *dis*qualified for any reason,
    many of them in principle quite irrelevant to the job.

    Get a Ph.D.  Specialize in something that involves getting your hands
    dirty with equipment, not just paper and pencil.  Forget computer
    programming entirely; it will be done from the ground for the fore-
    seeable future.  Degree(s) in one field plus work experience in
    another seems to be a frequent winner.

    Be in good physical condition, with good eyesight.    (DO NOT get a
    radial keratomy or similar hack to improve your vision; nobody knows
    what sudden pressure changes would do to RKed eyes, and long-term
    effects are poorly understood.  For that matter, avoid any other
    significant medical unknowns.)  If you can pass a jet-pilot physical,
    you should be okay; if you can't, your chances are poor.

    Practise public speaking, and be conservative and conformist in
    appearance and actions; you've got a tough selling job ahead, trying
    to convince a cautious, conservative selection committee that you
    are better than hundreds of other applicants.  (And, also, that you
    will be a credit to NASA after you are hired:  public relations is
    a significant part of the job, and NASA's image is very prim and
    proper.)  The image you want is squeaky-clean workaholic yuppie.
    Remember also that you will need a security clearance at some point,
    and Security considers everybody guilty until proven innocent.
    Keep your nose clean.

    Get a pilot's license and make flying your number one hobby;
    experienced pilots are known to be favored even for non-pilot jobs.

    Work for NASA; of 45 astronauts selected between 1984 and 1988,
    43 were military or NASA employees, and the remaining two were
    a NASA consultant and Mae Jemison (the first black female astronaut).
    If you apply from outside NASA and miss, but they offer you a job
    at NASA, ***TAKE IT***; sometimes in the past this has meant "you
    do look interesting but we want to know you a bit better first".

    Think space:  they want highly motivated people, so lose no chance
    to demonstrate motivation.

    Keep trying.  Many astronauts didn't make it the first time.




    NASA
    National Aeronautics and Space Administration
    Lyndon B. Johnson Space Center
    Houston, Texas

    Announcement for Mission Specialist and Pilot Astronaut Candidates
    ==================================================================

    Astronaut Candidate Program
    ---------------------------

    The National Aeronautics and Space Administration (NASA) has a need for
    Pilot Astronaut Candidates and Mission Specialist Astronaut Candidates
    to support the Space Shuttle Program. NASA is now accepting on a
    continuous basis and plans to select astronaut candidates as needed.

    Persons from both the civilian sector and the military services will be
    considered.

    All positions are located at the Lyndon B. Johnson Space Center in
    Houston, Texas, and will involved a 1-year training and evaluation
    program.

    Space Shuttle Program Description
    ---------------------------------

    The numerous successful flights of the Space Shuttle have demonstrated
    that operation and experimental investigations in space are becoming
    routine. The Space Shuttle Orbiter is launched into, and maneuvers in
    the Earth orbit performing missions lastling up to 30 days. It then
    returns to earth and is ready for another flight with payloads and
    flight crew.

    The Orbiter performs a variety of orbital missions including deployment

    and retrieval of satellites, service of existing satellites, operation
    of specialized laboratories (astronomy, earth sciences, materials
    processing, manufacturing), and other operations. These missions will
    eventually include the development and servicing of a permanent space
    station. The Orbiter also provides a staging capability for using higher
    orbits than can be achieved by the Orbiter itself. Users of the Space
    Shuttle's capabilities are both domestic and foreign and include
    government agencies and private industries.

    The crew normally consists of five people - the commander, the pilot,
    and three mission specialists. On occasion additional crew members are
    assigned. The commander, pilot, and mission specialists are NASA
    astronauts.

    Pilot Astronaut

    Pilot astronauts server as both Space Shuttle commanders and pilots.
    During flight the commander has onboard responsibility for the vehicle,
    crew, mission success and safety in flight. The pilot assists the
    commander in controlling and operating the vehicle. In addition, the
    pilot may assist in the deployment and retrieval of satellites utilizing
    the remote manipulator system, in extra-vehicular activities, and other
    payload operations.

    Mission Specialist Astronaut

    Mission specialist astronauts, working with the commander and pilot,
    have overall responsibility for the coordination of Shuttle operations
    in the areas of crew activity planning, consumables usage, and
    experiment and payload operations. Mission specialists are required to
    have a detailed knowledge of Shuttle systems, as well as detailed
    knowledge of the operational characteristics, mission requirements and
    objectives, and supporting systems and equipment for each of the
    experiments to be conducted on their assigned missions. Mission
    specialists will perform extra-vehicular activities, payload handling
    using the remote manipulator system, and perform or assist in specific
    experimental operations.

    Astronaut Candidate Program
    ===========================

    Basic Qualification Requirements
    --------------------------------

    Applicants MUST meet the following minimum requirements prior to
    submitting an application.

    Mission Specialist Astronaut Candidate:

    1. Bachelor's degree from an accredited institution in engineering,
    biological science, physical science or mathematics. Degree must be
    followed by at least three years of related progressively responsible,
    professional experience. An advanced degree is desirable and may be
    substituted for part or all of the experience requirement (master's
    degree = 1 year, doctoral degree = 3 years). Quality of academic
    preparation is important.

    2. Ability to pass a NASA class II space physical, which is similar to a
    civilian or military class II flight physical and includes the following
    specific standards:

     Distant visual acuity:
          20/150 or better uncorrected,
          correctable to 20/20, each eye.

     Blood pressure:
          140/90 measured in sitting position.

    3. Height between 58.5 and 76 inches.

    Pilot Astronaut Candidate:

    1. Bachelor's degree from an accredited institution in engineering,
    biological science, physical science or mathematics. Degree must be
    followed by at least three years of related progressively responsible,
    professional experience. An advanced degree is desirable. Quality of
    academic preparation is important.

    2. At least 1000 hours pilot-in-command time in jet aircraft. Flight
    test experience highly desirable.

    3. Ability to pass a NASA Class I space physical which is similar to a
    military or civilian Class I flight physical and includes the following
    specific standards:

     Distant visual acuity:
          20/50 or better uncorrected
          correctable to 20/20, each eye.

     Blood pressure:
          140/90 measured in sitting position.

    4. Height between 64 and 76 inches.

    Citizenship Requirements

    Applications for the Astronaut Candidate Program must be citizens of
    the United States.

    Note on Academic Requirements

    Applicants for the Astronaut Candidate Program must meet the basic
    education requirements for NASA engineering and scientific positions --
    specifically: successful completion of standard professional curriculum
    in an accredited college or university leading to at least a bachelor's
    degree with major study in an appropriate field of engineering,
    biological science, physical science, or mathematics.

      The following degree fields, while related to engineering and the
    sciences, are not considered qualifying:
      - Degrees in technology (Engineering Technology, Aviation Technology,
    Medical Technology, etc.)
      - Degrees in Psychology (except for Clinical Psychology, Physiological
    Psychology, or Experimental Psychology which are qualifying).
      - Degrees in Nursing.
      - Degrees in social sciences (Geography, Anthropology, Archaeology, etc.)
      - Degrees in Aviation, Aviation Management or similar fields.

    Application Procedures
    ----------------------

    Civilian

    The application package may be obtained by writing to:

    NASA Johnson Space Center
    Astronaut Selection Office
    ATTN: AHX
    Houston, TX 77058

    Civilian applications will be accepted on a continuous basis. When NASA
    decides to select additional astronaut candidates, consideration will be
    given only to those applications on hand on the date of decision is
    made. Applications received after that date will be retained and
    considered for the next selection. Applicants will be notified annually
    of the opportunity to update their applications and to indicate
    continued interest in being considered for the program. Those applicants
    who do not update their applications annually will be dropped from
    consideration, and their applications will not be retained. After the
    preliminary screening of applications, additional information may be
    requested for some applicants, and person listed on the application as
    supervisors and references may be contacted.

    Active Duty Military

    Active duty military personnel must submit applications to their
    respective military service and not directly to NASA. Application
    procedures will be disseminated by each service.

    Selection
    ---------

    Personal interviews and thorough medical evaluations will be required
    for both civilian and military applicants under final consideration.
    Once final selections have been made, all applicants who were considered
    will be notified of the outcome of the process.

    Selection rosters established through this process may be used for the
    selection of additional candidates during a one year period following
    their establishment.

    General Program Requirements

    Selected applicants will be designated Astronaut Candidates and will be
    assigned to the Astronaut Office at the Johnson Space Center, Houston,
    Texas. The astronaut candidates will undergo a 1 year training and
    evaluation period during which time they will be assigned technical or
    scientific responsibilities allowing them to contribute substantially to
    ongoing programs. They will also participate in the basic astronaut
    training program which is designed to develop the knowledge and skills
    required for formal mission training upon selection for a flight. Pilot
    astronaut candidates will maintain proficiency in NASA aircraft during
    their candidate period.

    Applicants should be aware that selection as an astronaut candidate does
    not insure selection as an astronaut. Final selection as an astronaut
    will depend on satisfactory completion of the 1 year training and
    evaluation period. Civilian candidates who successfully complete the
    training and evaluation and are selected as astronauts will become
    permanent Federal employees and will be expected to remain with NASA for
    a period of at least five years. Civilian candidates who are not
    selected as astronauts may be placed in other positions within NASA
    depending upon Agency requirements and manpower constraints at that
    time. Successful military candidates will be detailed to NASA for a
    specified tour of duty.

    NASA has an affirmative action program goal of having qualified
    minorities and women among those qualified as astronaut candidates.
    Therefore, qualified minorities and women are encouraged to apply.

    Pay and Benefits
    ----------------

    Civilians

    Salaries for civilian astronaut candidates are based on the Federal
    Governments General Schedule pay scales for grades GS-11 through GS-14,
    and are set in accordance with each individuals academic achievements
    and experience.

    Other benefits include vacation and sick leave, a retirement plan, and
    participation in group health and life insurance plans.

    Military

    Selected military personnel will be detailed to the Johnson Space Center
    but will remain in an active duty status for pay, benefits, leave, and
    other similar military matters.


NEXT: FAQ #15/15 - Orbital and Planetary Launch Services

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

Date: Mon, 3 May 1993 17:27:58 GMT
From: fred j mccall 575-3539 <[e-mail]>
Subject: Space Manuevering Tug (was HST servicing mission_)
Newsgroups: sci.space

In <1s15p6$[e-mail]> [e-mail] (Pat) writes:

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

>>Second, remember why they had to improvise during Intelsat 6?  They were trying
>>to attach a motor to a piece of hardware that wasn't designed to do that.
>>Trying to shortcut the training is only going to make a repeat more likely.
>>

>Also because they significantly lacked on-orbit EVA experience.
>The HST is designed for on-orbit servicing.  it should be a lot easier.

There is a difference between 'on orbit servicing' and taping a motor
to its butt and firing it, Pat.  Keep in mind that this motor is going
to have to thrust exactly through the center of mass of the HST or
you're going to tumble.  It is then going to have to cease firing
cleanly, unbolt itself from HST, and move away (all without leaving
any contamination).  Note that most of this is not a problem when
using the Shuttle for reboost, because it can basically wrap itself
around the HST and all that stuff with center of mass is already
computed.  Plus, there are people on scene if anything goes wrong.

>>
>>"All they have to do is soup it up?"  Just what does that mean?
>>

>I suspect, the BUS-1, may not have enough basic thrust for the HST
>re-boost.  it mayu need bigger tanks,  or bigger thrusters.

I see.  So we change a bunch of stuff on it, then take it up and duct
tape it to a $1G instrument and hope everything comes out ok?  I think
not.

>>
>>Pat, not only is this messy and less reliable than a device that's _made_ to
>>perform this task, it also ignores the point.  There is a desire to have
>>astronauts available so that if the door fails to open, something can be done
>>about it.  Unless you can provide a very reliable way of reopening the door,
>>you haven't solved the problem.


>That door has cycled, X times already.  Once after massive G loading.
>I somehow think they can work ou;reliability  methods to ensure the
>door works.

>Also,  please tell me how some sort of sublimated  material  like
>CO2, or H2O  would manage to contaminate the mirror,  anything
>that goes to vapor state, shouldn't adhere to the mirror.

Sounds like you're thinking of things in atmosphere, Pat.  Any stray
molecule in space may adhere to any solid surface it hits, whether
it's 'vapor' or not.  That's why there's a worry about contamination
of the instruments by thruster exhaust, which is something of a vapor,
last time I checked.


--
"Insisting on perfect safety is for people who don't have the balls to live
 in the real world."   -- Mary Shafer, NASA Ames Dryden
------------------------------------------------------------------------------
[e-mail] - I don't speak for others and they don't speak for me.

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Date: Mon, 3 May 1993 17:58:07 GMT
From: kevin patrick kretsch <[e-mail]>
Subject: Vandalizing the sky.
Newsgroups: sci.astro,sci.space

Batman is one thing but K-Mart is another!
Light pollution is bad enough but imagine a three mile
long Coca-Cola sign!!
And no, even if it is overcast, it doesn't make it O.K.
I'm sick of the commercials on T.V., I don't want to see
them when I go for a walk!!
The sky was never intended to be a billboard (if it
was intended at all!) and hopefully it never shall be.

    Imagine some artist painting a landscape...
          ...trees, mountains, river, sunsetting behind the giant
Coca-Cola can...
Great picture, huh ??

            Kev.

--
[e-mail]                 Dept. of pure and applied physics
Undergrad                             Trinity College Dublin, Ireland

Heaven is a big guitar shop that never charges...

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Date: Mon, 3 May 1993 17:51:33 GMT
From: Henry Spencer <[e-mail]>
Subject: Will NASA's Mars Observer Image the Face on Mars?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gene Wright) writes:
>All consipiracy theories aside, (they are watching though :-)), will NASA
>try to image the Cydonia region of Mars where the "Face" is?

They plan to try.  It's not particularly high priority.  Nobody in the
planetary-science community believes the "face" is anything but a natural
rock formation that happens to resemble a face when lit from the right
angle.  (Such formations exist on Earth too.)
--
SVR4 resembles a high-speed collision   | Henry Spencer @ U of Toronto Zoology
between SVR3 and SunOS.    - Dick Dunn  |  [e-mail]  utzoo!henry

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End of Space Digest Volume 16 : Issue 525
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