Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V11_3/V11_375.TXT

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Date: Wed,  9 May 90 01:46:04 -0400 (EDT)
Subject: SPACE Digest V11 #375

SPACE Digest                                     Volume 11 : Issue 375

Today's Topics:
              Re: space garbage
              Voyager Update - 05/08/90
                 Re: CD-ROMs
            Re: Voyager Update - 05/08/90
        Re: Black Holes (was Dyson spheres, heat flow)
            Re: Re: Dyson spheres?
     Astrodynamic analysis software (personal computers)
              Re: Fermi Paradox
              Re: space garbage
             Re: Manned mission to Venus
----------------------------------------------------------------------

Date: 8 May 90 15:06:36 GMT
From: cs.utexas.edu!texbell!nuchat![e-mail]  (Steve Nuchia)
Subject: Re: space garbage

In article <[e-mail]> [e-mail] (Greg Smith) writes:
>caused by a very small particle, (was it a paint chip?) a similar collision
>during EVA would pass cleanly through the unlucky person in the suit, or is it
>somehow reinforced to stop most particles? TIA for any insights.

The suits include several layers of meteor blanket material.  That's
the reflective "foil" stuff that you see wrapped around spacecraft.
In a suit it is between the wear layer and the air barrier.  Impact
with the faceplate might be exciting though.

In case you missed it, the shielding works like this: the outer
layers, together with the impacting object, vaporize.  The heat
released is reflected by the intact inner layers.  End of event.

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

Date: 8 May 90 15:46:24 GMT
From: usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Voyager Update - 05/08/90



                     Voyager Mission Status Report
                             May 8, 1990

                              Voyager 1

     Voyager 1 continues to collect routine cruise science data.  Two
high-rate Ultraviolet Spectrometer (UVS) observations of HD 217675 were
conducted on April 27. On May 2 one frame of high-rate Plasma Wave (PWS) data
was recorded.

     On April 27 a real time command mini-sequence was transmitted.  This
sequence executed as scheduled on May 1, and provided the successful playback
and recovery of the remaining "family portrait" imaging data, as well as
three frames of PWS data.  Real-time observation of the playback images
indicated that four imaging frames were fragmented as processed by the
Multimission Image Processing Subsystem (MIPS) however, three of the images
appeared to have all of the necessary data to build a complete frame.  MIPS
indicated that there were indeed internal problems during the real-time
processing and these images would be reprocessed as soon as possible.

     A real-time command file to reset the Computer Command Subsystem (CCS)
status telemetry was also transmitted on May 1.  A CCS memory read-out was
performed and verified the reset of the CCS status telemetry.

     The time offset between the CCS and the Flight Data Subsystem (FDS)
reported previously was ascribed to an FDS Power On Reset (POR) that
occurred during a tracking gap.  Real-time commanding was performed in an
attempt to correct the offset.  On April 30, a CCS timing offset determination
was transmitted that confirmed the offset.  On May 1, a clock reset sequence
was transmitted to correct the offset, followed by another CCS timing offset
determination (to verify the correction).  Unfortunately, the clock reset
sequence was not properly integrated with other activities (the planned
transmission time was insufficienty delayed from a reset of the CCS integrated
telemetry status word) and the sequence was not acted upon by the CCS.
Another attempt at removing the offset is being planned, and a CCS clock
adjustment is now scheduled for May 16.

     A spacecraft roll manuever (MAGROL) was also executed on May 1.  This
resulted in the successful execution of the ten revolution roll turn maneuver
and subsequent power down of the Attitude and Articulation Control Subsystem
(AACS) B and C gyros.

                              Voyager 2

     Voyager 2 also continues to collect routine cruise science data.
High-rate UVS observations of HD 200120 were conducted on April 30 and May 3.
(Most of these observations were not acquired due to limited Deep Space
Network (DSN) station availability.)  One frame of high-rate PWS data was
recorded on May 1.

     Memory compares of the AACS and CCS memory read-outs performed on April 25
have been completed.  These compares indicate that memory contents for the
AACS and CCS are as expected.


                      CONSUMMABLE STATUS

    P R O P E L L A N T    S T A T U S            P O W E R
               Consumption
        One Week    Propellant Remaining     Output     Margin
  Spacecraft (Gm)             (Kg)           Watts      Watts
   Voyager 1  42            36.5 + 2.0        370         59
   Voyager 2   6            39.6 + 2.0        374         66

 Ron Baalke                       |    [e-mail]
 Jet Propulsion Lab  M/S 301-355  |    [e-mail]
 4800 Oak Grove Dr.               |
 Pasadena, CA 91109               |    Go Lakers!

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

Date: 8 May 90 18:47:23 GMT
From: usc!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!aplcen!haven!uvaarpa!murdoch!astsun8.astro.Virginia.EDU![e-mail]  (Greg S. Hennessy)
Subject: Re: CD-ROMs

Darik Datta writes:
#Could anyone please mail me the address of the NSSDC.

Since several people have asked, I will post the info. I get all my
data from the NSSDCA by mailing to

Dr. Wayne H. Warren Jr.
Astronomy Data Center
NASA NSSDC
GSFC 633
Greenbelt MD 20771

-Greg Hennessy, University of Virginia
 USPS Mail:     Astronomy Department, Charlottesville, VA 22903-2475 USA
 Internet:      [e-mail]
 UUCP:        ...!uunet!virginia!gsh7w

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

Date: 8 May 90 21:38:34 GMT
From: usc!samsung!umich!sharkey!amara![e-mail]  (S. Khai Mong)
Subject: Re: Voyager Update - 05/08/90

In article <[e-mail]> [e-mail] (Ron Baalke) writes:
>       One Week    Propellant Remaining     Output     Margin
>    Spacecraft (Gm)             (Kg)           Watts      Watts
>      Voyager 1  42            36.5 + 2.0        370         59

What does the +2.0 mean?
--
Sao Khai Mong:   Applied Dynamics, 3800 Stone School Road, Ann Arbor, Mi48108
[phone]    (uunet|sharkey)!amara!khai   khai%adi.com

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

Date: 8 May 90 22:05:56 GMT
From: zaphod.mps.ohio-state.edu!uwm.edu!ux1.cso.uiuc.edu!dino!ceres.physics.uiowa.edu![e-mail]
Subject: Re: Black Holes (was Dyson spheres, heat flow)

In article <[e-mail]>, [e-mail] (Tom Roden) writes:
> in article <[e-mail]>, [e-mail] (Brian or James) says:
> [Stuff Deleted]
> | [I'm saying this badly, but if you drop an object
> | into an existing black hole, you won't see it cross the event horizon,
> | but just get closer and closer as its velocity approaches C].
>
>     I thought that it would never see itself cross the event
> horizon (due to time dilation), but that you could see it
> from the outside just fine.  Is that correct?

    The outsider detects the object by measuring its radiations.
    You can think of the frequency of the radiation as a kind of
    clock, since frequency is 1/period of the radiation wave.
    As a result of time dilation, the outsider observes an increase
    in the period of the wave, so that the frequency decreases.
    Thus, the radiation becomes redshifted in the frame of the
    outsider.  As the object approaches the horizon, the outsider
    observes the object being redshifted out of existence;outsider
    never observes the object crossing the horizon.  In the frame
    of the object, the clock appears to run normally.  Ie., the
    radiation frequency of the object in the frame of the object
    is the rest frequency.  So the observer riding with the object
    is able to observe the approach and entry into the horizon.


>
> --
> Thomas A. Roden                     uucp:      ...!uunet!ccicpg!legs!rodentia
> AST Research Inc. Dept 659
> P.O. Box 19658                      Voice:     [phone]
> Irvine, CA  92713-9658              Fax:       [phone]

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

Date: 9 May 90 04:10:35 GMT
From: cs.utexas.edu!news-server.csri.toronto.edu!helios.physics.utoronto.ca!physics.utoronto.ca![e-mail]  (Christopher Neufeld)
Subject: Re: Re: Dyson spheres?

In article <[e-mail]> [e-mail] (Christopher Neufeld) writes:
>
>   Yes, but that makes the sphere less useful as a heat engine. BTW, in
>the scenario I described in the first section, each surface would see
>about three times the solar momentum flux (twice on absorption and once
>on emission) or about 1.4E-5 kg / m s. In real units, that's one
>kilogram for 425 m^2 of exposed surface, assuming solar momentum flux is
>the only force which opposes the gravitational attraction.
>
   I left out some geometric factors in the integrals. Unless I missed
some others, it should be closer to 9E-6 kg / m s^2 (correct units this
time), or one kilogram for 630 m^2 of exposed surface. This is because
non-orthogonal incidence changes that "three times the solar momentum
flux" to about twice the solar momentum flux (only the radial component
of the flux is important).


--
 Christopher Neufeld....Just a graduate student  |  "Spock, comment?"
 [e-mail]              |  "Very bad poetry
 [e-mail]          Ad astra! | captain."
 "Don't edit reality for the sake of simplicity" |

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

Date: 8 May 90 08:00:16 GMT
From: fernwood!portal!cup.portal.com![e-mail]  (John Paul Serafin)
Subject: Astrodynamic analysis software (personal computers)


   Cygnus Engineering has developed two software products for doing
astrodynamic analysis on IBM compatible personal computers running
under the MS-DOS operating system.   Versions for the Apple Macintosh
computer are under development.   Other platforms are under consideration.
Much effort has gone into making these products accurate, fast, useful,
easy to learn, and convenient to use.

   Orbital Workbench is a comprehensive package for performing a wide
range of orbital mechanics and mission analysis tasks.   Several
modules graphically display simulation status and results as they are
calculated.

   OrbitView enables three-dimensional visualization of animated
satellite orbits to aid in mission planning and orbit selection.

   Both programs support output to the video screen, hardcopy, and
data files and both are driven by an intuitive menu interface which
works equally well with a mouse or cursor keys.

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

Seven modules comprise Orbital Workbench:

 Ephemeris Generation and Coverage - with user selectable perturbations
 and over 20 possible data plots, including orbital elements, relative
 motion, ground station contact times, and Earth shadow periods.

 Ascent Trajectories - select from rocket database or customize parameters

 Optimal 2-Impulse Orbit Transfers - computes minimum delta-V orbit
 transfers

 Relative Motion - creates plots of intrack, crosstrack, and radial
 motion

 Astrodynamic Calculator - any of over 30 orbital parameters may be entered
 in any order.   As each parameter is entered, any parameter dependent on
 previous entries is calculated and displayed.

 Planetary Positions - accurate to one arc-minute over a 600 year time span

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

  The original version of OrbitView was developed for the US Air Force.
OrbitView allows you to select a viewpoint in Earth centered inertial
space, onboard a satellite, or on the Earth's surface for visualization
of orbits above a rotating Earth.

Features include:

 Earth surface updated several times per second, sattelite positions
 over 20 times per second

 User selectable time step

 Multiple satellites animated simultaneously with or without space tracks

 Effects of J2 oblateness included

 Interactive control of field-of-view (zoom), view direction (pan), view
 position, and time step.

 Interactive toggles for:

   Display of Sun, Moon, and planet positions

   Day/Night terminator display

   Orbit traces (space tracks)

   Status window

   Help window

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

   For more detailed technical information, a free demonstration disk, and
price list please contact:

                      Cygnus Engineering
                      918 Leighton Way
                      Sunnyvale, CA 94087   USA

                      [phone]

                      [e-mail]

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

Date: Tue, 8 May 90 18:56:22 -0500
From: [e-mail] (Thomas A. Bitterman)
Subject: Re: Fermi Paradox

    The role playing game Traveller (tm) by Game Designer's Workshop
has a ready made solar system generation method, part of a galaxy generation
method.  A patient player could build his own universe :>.  I'm not sure of
the accuracy of this method, but it works for the purpose intended (that is,
a role-playing setting).  The game as a whole seems reasonably well thought
out as far as technology goes, no magic, just good engineering.  Anyone who
knows some astronomy and the Traveller system would be more illuminating.
Look in the Scout advanced character generation system booklet.  It might be
out of print, so good luck.

- Thomas Bitterman  [e-mail]
- a budding technocrat, just ask my friends

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

Date: 8 May 90 15:13:53 GMT
From: swrinde!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: space garbage

In article <[e-mail]> [e-mail] (Greg Smith) writes:
>Does anyone know what kind of survival procedure NASA has in place in the
>event of a suit puncture, during EVA, by 'space garbage' or other particles?
>Is there some type of automatic mechanism that would seal small holes?

No, they simply rely on the suit being tough.

>Also I would assume that judging by the degree of damage to the shuttle window
>caused by a very small particle, (was it a paint chip?) a similar collision
>during EVA would pass cleanly through the unlucky person in the suit, or is it
>somehow reinforced to stop most particles? ...

The major outer layer of the suits is combination thermal insulation and
debris/micrometeorite armor.  Windows are unusually vulnerable because their
materials are brittle; a similar collision with a suit probably would do no
significant damage.
--
If OSI is the answer, what is |     Henry Spencer at U of Toronto Zoology
the question?? -Rolf Nordhagen| uunet!attcan!utzoo!henry [e-mail]

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

Date: 7 May 90 18:13:55 GMT
From: decvax.dec.com!zinn!ubbs-nh!siia![e-mail]  (David Dick)
Subject: Re: Manned mission to Venus

[e-mail] (Mark SOKOLOWSKI) writes:

>I would like to start a new discussion about a manned mission to Venus.
>I know that given the inferno that's there, it sounds crazy, but Venus has
>many advantages over Mars:
...
>- 8 times the mass of Mars, which means that it can trap any spaceship more
>  easily than the red planet.

I would think the deep planetary gravity well would make things
worse by requiring more energy to go in and come back out.

David Dick
Software Innovations, Inc. [the Software Moving Company(sm)]

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

End of SPACE Digest V11 #375
*******************