Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v09_5/v9_577.txt

Internet Message Format | 1991-07-08 | 18KB

Return-path: <[e-mail]>
X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
Received: from corsica.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr1/ota/space/[e-mail] (->+dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl) (->ota+space.digests)
          ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/MYpe0eu00UkVQAl04=>;
          Wed,  2 Aug 89 03:18:03 -0400 (EDT)
Message-ID: <[e-mail]>
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Wed,  2 Aug 89 03:17:54 -0400 (EDT)
Subject: SPACE Digest V9 #577

SPACE Digest                                      Volume 9 : Issue 577

Today's Topics:
           Re: Don't Mess with NASA (afterburners)
         Don't Mess with NASA (afterburners)
              Re: NASA Select Broadcasts
               New satellite of Neptune
              Re: S-Band Beacon on Moon
                   Modules
               Re: Apollo 8, 9, and 10
         Voyager rebroadcast frames deciphered (long)
----------------------------------------------------------------------

Date: 21 Jul 89 19:34:01 GMT
From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Don't Mess with NASA (afterburners)

In article <[e-mail]> [e-mail] (Mary Shafer) writes:
>... Just speaking personally, as a fairly
>frequent flier, I'd really prefer that fighters be limited-distribution
>items.  There are enough things to worry about, without worrying about
>some yahoo out there in an F-something with sidewinders at my 747's six.

Anybody with any sense who wants to shoot down your 747 will just hang
the Sidewinders on a Learjet -- less conspicuous, and perfectly adequate
performance for the job.  (You can hang Sidewinders on almost anything.)

>...I have some real definite opinions about required
>piloting skills.  We require our test pilots to fly a minimum of 200
>hours per year, with specified minimums for each aircraft, to maintain
>proficiency.  That F-86 driver had very low total time, low jet time,
>and was what I'd consider non-current...
>Just because you can afford an airplane, doesn't mean you can fly it.

I have no quarrel with the idea that anyone who owns his own jet fighter
needs to be properly qualified to fly it.  I see no reason why a civilian
is incapable of acquiring the qualifications, though.

>... I don't know why those posters who despise the government and all
>its fruits are panting to buy those fruits.  Let's see some consistancy...

If a private market in such things were allowed, we wouldn't have to buy
things designed by the government.  Which sort of brings us back to
spaceflight, since that's the big problem with space launchers too...
--
1961-1969: 8 years of Apollo.  |     Henry Spencer at U of Toronto Zoology
1969-1989: 20 years of nothing.| uunet!attcan!utzoo!henry [e-mail]

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

Date: Thu, 20 Jul 89 06:27:34 EDT
From: [e-mail] (david s. channin)
Subject: Don't Mess with NASA (afterburners)

>Me too!  Unfortunately the US military wants to keep jet aviation all to
>itself, so even its tamer aircraft are never sold to civilians.  (Both
>the Starfighter and the T-38 were rebuilt from hardware that slipped out
>basically by accident.)

Hypothetical Question:

  Let's say you just happen to have hit the PA state lottery last April, and walked away with $115 Million. You will receive 5.75 M for 20 years. You save diligently for 6 -7 years. What are the laws, regulations, etc (if any) that prevent you from doing the following:
     1. Walk into the Northrop offices in wherever.
     2. Pull out a bank check for x million dollars.
     3. Say,``I'd would like that nice T-38 that's in the showroom''.
     4. Fly away with same after filling the tank. (assuming you already have a license).

     Why wouldn't this scenario work?? (or would it?).


     [e-mail]

David S. Channin
Research Fellow
Division of Orthopaedic Surgery
Pennsylvania State University
College of Medicine
The Milton S. Hershey Medical Center
717 - 531 - 6698

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

Date: 20 Jul 89 16:46:03 GMT
From: [e-mail]  (Jonathan Patrick Leech)
Subject: Re: NASA Select Broadcasts

In article <[e-mail]> [e-mail] (54317-T.EBERSOLE) writes:
>also with no luck. Has anyone been able to find NASA Select's broadcasts?
>Did you need to know anything more than the data in the excerpted paragraph?
>Is this bird viewable from the east coast with "standard" equipment, i.e.,
>is it a good quality signal or very weak?

    I tuned in SELECT numerous times from UNC-Chapel Hill, which has a
pretty good view of F2R.  While I'm no expert on satellite TV, both I
and our communications director had trouble getting a good signal.
Generally we had to fiddle with the skew setting of the receiver and
nudge the antenna back and forth. It seemed to be best ~2 degrees
further east than the claimed position, in general.
--
    Jon Leech ([e-mail])
    Apple Integrated Systems
    __@/

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

Date: Thu, 20 Jul 89 10:17:57 PST
From: Peter Scott <[e-mail]>
Subject: New satellite of Neptune
X-Vms-Mail-To: EXOS%"[e-mail]"

Excerpted without permission from NASA _Voyager Bulletin_, Mission Status
Report No. 88, July 12:

ADD A NEW NEPTUNIAN MOON

A new moon has been discovered orbiting Neptune.  Temporarily designated
1989 N1, the new moon was initially seen in images transmitted to Earth
by Voyager 2 in mid-June.  Its existence was confirmed upon examination
of other images after the moon's orbital motion had been calculated and
its position could be predicted.

The new Neptunian satellite could range in diameter from 200 to 600 km (about
125 to 400 miles) and oribts in a very nearly circular and equatorial orbit
about 92,700 km (about 57,600 mi) from the planet's cloud tops (or about
117,500 km) (73,000 mi) from the planet's center).

A permanent name will be given to the moon at a later date by the International
Astronomical Union (IAU).

According to Dr. Stephen P. Synnott, a Voyager imaging team scientist at
JPL, the satellite appeared as a small, bright smudge in Voyager pictures
due to the long (46-second) exposure.  At this point, the moon is too
indistinct to appear in photographic prints made from the Voyager images.
Pictures taken in coming weeks will show the moon more clearly.

1989 N1 cannot be seen from Earth because the moon is so close to Neptune
that the brightness of the planet itself masks the tiny point of light.
Voyager 2 will continue to study the moon and will conduct searches for
others on approach to the planet.  [...]

The moon orbits well outside the orbits of the postulated ring arcs.  Its
existence lessens concerns about radiation hazards to the spacecraft near
the planet, since the moon probably sweeps charged particles out of the
area as it orbits Neptune.


Peter Scott ([e-mail], speaking only for myself)

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

Date: 21 Jul 89 23:17:43 GMT
From: vsi1!v7fs1![e-mail]  (Andrew D. Daniel)
Subject: Re: S-Band Beacon on Moon

In article <[e-mail]> [e-mail] (Ed Morin) writes:
>[e-mail] (Bill Chiarchiaro) writes:
>"Unix Public Access for the Masses!"

Now Ed, lets enforce the consitutional separation of church and (solid) state.

--

Andrew D Daniel, Video Seven, Inc.           Angels fear to tread
..ames!vsi1!v7fs1!add                        where fools login:

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

Date: 20 Jul 89 11:08:52 GMT
From: cs.utexas.edu!usc!orion.cf.uci.edu![e-mail]  (Doug Krause)
Subject: Modules


I lost a couple of articles.  Was Snoopy an LM or CM?  If it was
an LM, a historic quote would have a whole new feel.

"Houston, Tranquility Base here.  Snoopy has landed."  :-)

Douglas Krause                     One yuppy can ruin your whole day.
---------------------------------------------------------------------
University of California, Irvine   Internet: [e-mail]
Welcome to Irvine, Yuppieland USA  BITNET: DJKrause@ucivmsa

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

Date: 20 Jul 89 14:46:07 GMT
From: mfci![e-mail]  (Paul Rodman)
Subject: Re: Apollo 8, 9, and 10

In article <[e-mail]> [e-mail] (Norman C. Kluksdahl) writes:
>
>My memory indicates that the descent stage was cut free, and the ascent
>stage was used for the rendezvouz.  Again, the book "Chariots for Apollo"


Mine too. And I also recall the the LEM underwent some very scary
gyrations when the ascent stage was fired.....which were not worried
about afterward, as this was the only time anyone planned to fire the
ascent stage/jettision the descent stage in flight.

pkr

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

Date: Thu, 20 Jul 89 10:27:02 PST
From: Peter Scott <[e-mail]>
Subject: Voyager rebroadcast frames deciphered (long)
X-Vms-Mail-To: EXOS%"[e-mail]"
Lines:  172

Extracted without permission from NASA _Voyager Bulletin_, Mission Status
Report No. 88, July 12:

WHAT DO THE HIEROGLYPHICS MEAN?

Images and some of the other data received at JPL from the two Voyager
spacecraft are sent to display devices at JPL from the computers in JPL's
Multimission Image Processing System.  A subset of these data, primarily
images, is being broadcast on the NASA Select TV channel by the GE Satcom F2R
satellite.  Currently there is a one-hour broadcast every Tuesday through
August 8.  Broadcasts will probably be more frequent as Voyager 2 nears its
closest approach to Neptune on August 25.

The frames that appear on the monitors are black and white only and include
basic identification information for the image being displayed, as well as
information about the processing that has been applied to that image.  Data from
the Planetary Radio Astronomy and Plasma Wave investigations can also be
displayed on video devices.  The following is a brief summary of the information
shown for imaging, PRA, and PWS frames.

IMAGING FRAMES

Each Voyager spacecraft carries two imaging cameras: a 200-mm, f/3.5 wide-angle
camera using a refracting telescope and a 1500-mm f/8.5 narrow-angle
(telephoto) camera using a reflecting telescope.  Each camera uses a one-inch
selenium-sulfur vidicon to convert an optical signal into electrical signals.
Each frame consists of 640,000 pixels, each of which is expressed as a level of
gray on a scale from 0 (black) to 255 (white).  Color scenes are reconstructed
on Earth by electronically combining images taken through different filters.
The sensitivity of the filters ranges from 3460 (ultraviolet) to 6184 angstroms
(red-orange).

[The rest of this extract contains mostly information of interest to those
people receiving the images.]

The elements of the displayed imaging frames are described below:

[1-5 run left-to-right across the top line of the frame]

1.  MIPL  Multimission Image Processing System (a JPL facility).

2.  Spacecraft identifier

3.  System Source:  RLTM  Real Time.  The data is displayed from telemetry as
soon as the data arrives at JPL; this data may be only 4 hours old (as long as
it took for the data to travel from the spacecraft to Earth); it may have been
taken earlier, recorded on the spacecraft's digital tape recorder, and played
back to Earth at an optimum time; or it may have been stored at the Data
Capture and Staging computer and read from there later. (See item 13, to learn
when the data was received at Earth.)
                    INTR  Interactive.  Image is displayed from a work station
where a scientist or analyst is interactively enhancing the data.
                    RPLA  Replay, for NASA Select TV, of data received earlier.

4.  Target Body (Neptune, Triton, Nereid, rings, etc).

5.  FDS Count.  Image identifiction in units of spacecraft clock time (the
spacecraft's clock is in the spacecraft's Flight Data Subsystem computers).

6.  Frame identification in units of picture number, planet, spacecraft,
and days from encounter  [displayed under #5].

7.  Frame.  The data are displayed at half resolution.  As displayed, the
image area is 400 lines by 400 rows [sic] of picture elements.  A full Voyager
image frame is 800 lines of 800 elements, but since the display devices
can display only 640x480 pixels, every other pixel of every other line is
displayed.

8.  Reference Gray Scale [along left edge]

9.  Histogram (frequency distribution) of number of bits at each of the
gray levels in the incoming image [top right].

10. Histogram of number of bits at each of the gray levels in the image
as displayed at left.  [Center right].  (Note: the histograms are an aid
in evaluating the quality of the displayed image; e.g., how bright was the
image, how good was the exposure, etc).

11.  [Text under #10]  Describes processing that has been done to transform
the input image to the output image, e.g., magnification factor, dark current
subtraction, contrast enhancement.

12.  [Text, bottom left to center]  Identification information:
    INSTR  Instrument:  ISSWA  Imaging camera, Wide angle
                ISSNA  Imaging camera, Narrow angle
    FILTER  Clear, green, orange, blue, ultraviolet, methane (6910 or
        5410 angstroms), or sodium.
    EXP  Exposure time (seconds)
    IMODE  Shutter mode:
        NAONLY  Narrow angle only
        WAONLY  Wide angle only
        BOTALT  Wide and narrow angle shuttered alternately
        BOTSIM  Both wide and narrow shuttered simultaneously
        BODARK  Neither wide nor narrow shuttered (used to calibrate
            background noise (or "dark current"))
        NOSHUT  Neithr wide nor narrow read out
    TMODE  Spacecraft telemetry mode at which data is read out (e.g.
           compressed, edited, slow scan, etc).
    RANGE  Distance from spacecraft to center of target body, in km.
    INA  Lighting angle (incidence angle of sunlight striking target)
    EMA  Viewing angle (emission angle of sunlight reflected from target)
    PHA  Phase angle (angle between incoming sunlight and emitted or
         reflected light from target)
    SCALE  Distance across frame (at the target body)

13. [Bottom right]  Time signal was received at Earth (day of year:hour:minute)
in Universal Time Coordinated (UTC).

14. [Right of #13]  Calendar day (JPL local time), MIPS computer ID, display
device ID.


PLANETARY RADIO ASTRONOMY (PRA)

The planetary radio astronomy experiment uses two 10-meter whip antennas to
listen for radio emissions from the Sun, planets, and lightning in planetary
atmospheres over a range from 1.2kHz to 40.5MHz.  The PRA high-rate receiver
gives high time resolution at two fixed frequencies that will be selected by
the PRA science team when the spacecraft is a few weeks away from the planet.
At Uranus the frequencies were 35.9424MHz and 1.230MHz.

Data from the PRA is sometimes displayed on the video devices.  The following
discussion indicates information that differs from the Imaging frames:

7.  Frame.  A high-rate PRA frame contains 48 seconds of data formatted as 800
lines, each containing 800 8-bit samples.  The total time per line is 0.06
second.  Only 1/4 of the PRA data is displayed in the video convrsion of the
frame.  The first 24 seconds of the displayed frame represents signals at the
first fixed frequency, at two antenna polarizations.  The last 24 seconds show
only one polarization at the second fixed frequency.  "Real" signals show as
horizontal white (or light) streaks running across the frame [an example is
pictured showing lightning-like electrical discharges at Uranus].

The pattern observed in each line represents the "loudness" as a function of
time, of an "audio" noise signal in a narrow band centered on the receiver
frequency.  Real data increases the "loudness" of the signal, just like extra
static in a home radio.  The amount and type of noise gives information about
what causes it.

9.  Histogram of signal intensity as received (input).

10. Histogram of signal intensity values as displayed (output).

12.  Only INSTRU and TMODE have any meaning for PRA and PWS frames.


PLASMA WAVES (PWS)

Plasma waves are low-frequency oscillations in the plasmas in interplanetary
space and in planetary magnetospheres.  The plasma wave instrument detects and
measures plasma wave interactions in planetary magnetospheres and detects
interactions between a planetary magnetosphere and the solar wind.  It can
detect particles in the ring plane and measure their impact rate on the
spacecraft.  The PWS shares the two whip antennas with the PRA investigation to
provide the equivalent of a single 7-meter antenna.  PWS covers the frequency
range from 10Hz to 56.2kHz.

The PWS high-rate receiver is a very sensitive audio amplifier.  In the display
of a Fourier transform of the data, the horizontal axis is time (one 48-second
frame) and the vertical axis is frequency.  Plasma wave scientists interpret
the signal patterns in terms of various mechanisms the interactions of charged
particles and elctromagnetic waves.  Steady frequencies generally are associated
with interference signals from other subsystems on the spacecraft; for example,
the 2.4kHz hum of the spacecraft's power supply [shows up as a horizontal line
near the bottom of the sample frame].


Peter Scott ([e-mail])          Standard disclaimers.

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

End of SPACE Digest V9 #577
*******************