Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V16_4/V16NO485.TXT

Internet Message Format | 1993-07-13 | 32KB

Date: Mon, 26 Apr 93 05:00:13
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #485
To: Space Digest Readers
Precedence: bulk


Space Digest                Mon, 26 Apr 93       Volume 16 : Issue 485

Today's Topics:
              Keeping Spacecraft on after Funding Cuts.
                               Level 5?
                      Magellan Update - 04/23/93
                   Mars Observer Update - 04/23/93
               New planet/Kuiper object found? (3 msgs)
                       Russian Email Contacts.
                space news from Feb 15 AW&ST (2 msgs)
              Space Station Redesign, JSC Alternative #4
       Space Station Redesign Chief Resigns for Health Reasons
                    Sunrise/ sunset times (2 msgs)
                    Surviving Large Accelerations?
                         Vandalizing the sky
         Weekly reminder for Frequently Asked Questions list
                What counntries do space surveillance?

    Welcome to the Space Digest!!  Please send your messages to
    "[e-mail]", and (un)subscription requests of the form
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    (THENET), or [e-mail] (Internet).
----------------------------------------------------------------------

Date: Fri, 23 Apr 1993 14:31:30 GMT
From: Ed McCreary <[e-mail]>
Subject: Keeping Spacecraft on after Funding Cuts.
Newsgroups: alt.sci.planetary,sci.space,sci.astro

>>>>> On Fri, 23 Apr 93 09:06:09 BST, [e-mail] (Greg Stewart-Nicholls) said:
GS> How about transferring control to a non-profit organisation that is
GS> able to accept donations to keep craft operational.

I seem to remember NASA considering this for some of the Apollo
equipment left on the moon, but that they decided against it.

Or maybe not...


--
Ed McCreary                                               ,__o
[e-mail]                                   _-\_<,
"If it were not for laughter, there would be no Tao."  (*)/'(*)

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

Date: 23 Apr 93 12:47:59 -0600
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject: Level 5?
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Bret Wingert) writes:
> 3. The Onboard Flight Software project was rated "Level 5" by a NASA team.
>    This group generates 20-40 KSLOCs of verified code per year for NASA.

Will someone tell an ignorant physicist where the term "Level 5" comes
from? It sounds like the RISKS Digest  equivalent of Large, Extra
Large, Jumbo... Or maybe it's like "Defcon 5..."

I gather it means that Shuttle software was developed with extreme
care to have reliablility and safety, and almost everything else in
the computing world is Level 1, or cheesy dime-store software.  Not
surprising.  But who is it that invents this standard, and how come
everyone but me seems to be familiar with it?

Of course, what Shakespeare        | Bill Higgins, Beam Jockey
ORIGINALLY wrote was "First thing  | Fermi National Accelerator Laboratory
we do, let's kill all the EDITORS."| Bitnet:           [e-mail]
But for some reason it didn't      | Internet:       [e-mail]
survive past the first draft.      | SPAN/Hepnet:           43011::HIGGINS
-- David D. "Laserdave" Levine ([e-mail])

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

Date: 23 Apr 1993 20:33 UT
From: Ron Baalke <[e-mail]>
Subject: Magellan Update - 04/23/93
Newsgroups: sci.space,sci.astro,alt.sci.planetary

Forwarded from Doug Griffith, Magellan Project Manager

                     MAGELLAN STATUS REPORT
                         April 23, 1993

1.  The Magellan spacecraft continues to operate normally, gathering
gravity data to plot the density variations of Venus in the
mid-latitudes.  The solar panel offpoint was returned to zero degrees
and spacecraft temperatures dropped 2-3 degrees C.

2.  An end-to-end test of the Delayed Aerobraking Data readout
process was conducted this week in preparation for the Transition
Experiment.  There was some difficulty locking up to the data frames,
and engineers are presently checking whether the problem was in
equipment at the tracking station.

3.  Magellan has completed 7277 orbits of Venus and is now 32 days
from the end of Cycle 4 and the start of the Transition Experiment.

4.  Magellan scientists were participating in the Brown-Vernadsky
Microsymposium at Brown University in Providence, RI, this week.  This
joint meeting of U.S. and Russian Venus researchers has been
continuing for many years.

5.  A three-day simulation of Transition Experiment aerobraking
activities is planned for next week, including Orbit Trim Maneuvers
and Starcal (Star calibration) Orbits.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | The aweto from New Zealand
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | is part caterpillar and
|_____|/  |_|/       |_____|/                     | part vegetable.

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

Date: 23 Apr 1993 20:36 UT
From: Ron Baalke <[e-mail]>
Subject: Mars Observer Update - 04/23/93
Newsgroups: sci.space,sci.astro,alt.sci.planetary

Forwarded from the Mars Observer Project

                       MARS OBSERVER STATUS REPORT
                             April 23, 1993
                              10:00 AM PDT

Flight Sequence C8 is active, the Spacecraft subsystems and instrument
payload performing well in Array Normal Spin and outer cruise
configuration, with uplink and downlink via the High Gain Antenna; uplink
at 125 bps, downlink at the 2 K Engineering data rate.

As a result of the spacecraft entering Contingency Mode on April 9, all
payload instruments were automatically powered off by on-board fault
protection software.  Gamma Ray Spectrometer Random Access Memory
was successfully reloaded on Monday, April 19.  To prepare for
Magnetometer Calibrations which were rescheduled for execution in Flight
Sequence C9 on Tuesday and Wednesday of next week, a reload of Payload
Data System Random Access Memory will take place this morning
beginning at 10:30 AM.

Over this weekend, the Flight Team will send real-time commands to
perform Differential One-Way Ranging to obtain additional data for
analysis by the Navigation Team.  Radio Science Ultra Stable Oscillator
testing will take place on Monday .

The Flight Sequence C9 uplink will occur on Sunday, April 25, with
activation at Midnight, Monday evening April 26.  C9 has been modified to
include Magnetometer Calibrations which could not be performed in C8 due
to Contingency Mode entry on April 9.  These Magnetometer instrument
calibrations will allow the instrument team to better characterize the
spacecraft-generated magnetic field and its effect on their instrument.
This information is critical to Martian magnetic field measurements
which occur during approach and mapping phases. MAG Cals will require
the sequence to command the spacecraft out of Array Normal Spin state
and perform slew and roll maneuvers to provide the MAG team data points
in varying spacecraft attitudes and orientations.

Today, the spacecraft is 22,971,250 km (14,273,673 mi.) from Mars
travelling at a velocity of 2.09 kilometers/second (4,677 mph) with
respect to Mars.  One-way light time is approximately 10 minutes, 38
seconds.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | The aweto from New Zealand
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | is part caterpillar and
|_____|/  |_|/       |_____|/                     | part vegetable.

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

Date: 23 Apr 1993 18:44:19 GMT
From: Jeff Foust <[e-mail]>
Subject: New planet/Kuiper object found?
Newsgroups: sci.space

In a recent article [e-mail] (James Davis Nicoll) writes:
>    If the  new  Kuiper belt object *is*  called 'Karla', the next
>one  should be called 'Smiley'.

Unless I'm imaging things, (always a possibility =) 1992 QB1, the Kuiper Belt
object discovered last year, is known as Smiley.

--
Jeff Foust              [49 days!]    "You're from outer space."
Senior, Planetary Science, Caltech    "No, I'm from Iowa.  I only work in
[e-mail]             outer space."
[e-mail]            -- from Star Trek IV: The Voyage Home

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

Date: 23 Apr 93 13:02:46
From: Steinn Sigurdsson <[e-mail]>
Subject: New planet/Kuiper object found?
Newsgroups: sci.space

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

   In a recent article [e-mail] (James Davis Nicoll) writes:
   >    If the  new  Kuiper belt object *is*  called 'Karla', the next
   >one  should be called 'Smiley'.

   Unless I'm imaging things, (always a possibility =) 1992 QB1, the Kuiper Belt
   object discovered last year, is known as Smiley.

As it happens the _second_ one is Karla. The first one was
Smiley. All subject to the vagaries of the IAU of course,
but I think they might let this one slide...

*  Steinn Sigurdsson               Lick Observatory                    *
*  [e-mail]        "standard disclaimer"                *
*  "The worst thing you can say to a true revolutionary is that his       *
*  revolution is unnecessary, that the problems can be corrected without  *
*  radical change. Telling people that paradise can be attained without   *
*  revolution is treason of the vilest kind."  -- H.S. 1993          *


Just had to try out my new .sig# on this forum ;-)

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

Date: Fri, 23 Apr 1993 20:42:45 GMT
From: James Davis Nicoll <[e-mail]>
Subject: New planet/Kuiper object found?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Steinn Sigurdsson) writes:
>In article <[e-mail]> [e-mail] (Jeff Foust) writes:
>
>   In a recent article [e-mail] (James Davis Nicoll) writes:
>   >    If the  new  Kuiper belt object *is*  called 'Karla', the next
>   >one  should be called 'Smiley'.
>
>   Unless I'm imaging things, (always a possibility =) 1992 QB1, the Kuiper Belt
>   object discovered last year, is known as Smiley.
>
>As it happens the _second_ one is Karla. The first one was
>Smiley. All subject to the vagaries of the IAU of course,
>but I think they might let this one slide...

    Gee, I feel so ignorant now...

    Research, then post.

                            James Nicoll

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

Date: Fri, 23 Apr 1993 18:58:50 GMT
From: [e-mail]
Subject: Russian Email Contacts.
Newsgroups: sci.space

I am coordinating the Space Shuttle Program Office's e-mail traffic to
NPO Energia for our on-going Joint Missions.  I have several e-mail
addresses for NPO Energia folks, but I won't post them on the 'Net for
obvious reasons.  If you need to know, give me a yell.

-- Ken Jenks, NASA/JSC/GM2, Space Shuttle Program Office
      [e-mail]  [phone]

     "The earth is the cradle of humanity, but mankind will not stay in
     the cradle forever." -- Konstantin Tsiolkvosky

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

Date: Fri, 23 Apr 1993 20:16:24 GMT
From: "George F. Krumins" <[e-mail]>
Subject: space news from Feb 15 AW&ST
Newsgroups: sci.space

[e-mail] (James B. Reed) writes:

>In article <[e-mail]>, [e-mail] (Henry Spencer) writes:
>|> [Pluto's] atmosphere will start to freeze out around 2010, and after about
>|> 2005 increasing areas of both Pluto and Charon will be in permanent
>|> shadow that will make imaging and geochemical mapping impossible.

It's my understanding that the freezing will start to occur because of the
growing distance of Pluto and Charon from the Sun, due to it's
elliptical orbit. It is not due to shadowing effects.

>Where does the shadow come from?  There's nothing close enough to block
>sunlight from hitting them.  I wouldn't expect there to be anything block
>our view of them either.  What am I missing?

Pluto can shadow Charon, and vice-versa.

George Krumins
--
--------------------------------------------------------------------------------
|  George Krumins                                                              |
|  [e-mail]                                                   |
|  Pufferfish Observatory                                                      |

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

Date: Fri, 23 Apr 1993 20:50:34 GMT
From: Henry Spencer <[e-mail]>
Subject: space news from Feb 15 AW&ST
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>|> [Pluto's] atmosphere will start to freeze out around 2010, and after about
>|> 2005 increasing areas of both Pluto and Charon will be in permanent
>|> shadow that will make imaging and geochemical mapping impossible.
>
>Where does the shadow come from?  There's nothing close enough to block
>sunlight from hitting them.  I wouldn't expect there to be anything block
>our view of them either.  What am I missing?

You're assuming that their normal rotation carries all areas of the surface
into sunlight.  Not so.  Even on Earth, each pole gets several weeks without
sunlight in mid-winter.  Pluto and Charon have much more extreme axial
tilt and a much longer orbit.  Pluto's north pole, for example, gets over
a century of darkness followed by over a century of perpetual light.

At the moment, we're in luck -- Pluto and Charon are just past their
equinox, when the Sun was just on the horizon at both poles (of each).
If we get probes there soon, only the immediate vicinity of one pole
(on each) will be in long-term shadow.  This will get steadily worse the
longer we wait.
--
All work is one man's work.             | Henry Spencer @ U of Toronto Zoology
                    - Kipling           |  [e-mail]  utzoo!henry

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

Date: Fri, 23 Apr 1993 18:47:32 GMT
From: [e-mail]
Subject: Space Station Redesign, JSC Alternative #4
Newsgroups: sci.space

I have 19 (2 MB worth!) uuencode'd GIF images contain charts outlining
one of the many alternative Space Station designs being considered in
Crystal City.  Mr. Mark Holderman works down the hall from me, and can
be reached for comment at [phone], or via e-mail at
[e-mail].

Mark proposed this design, which he calls "Geode" ("rough on the
outside, but a gem on the inside") or the "ET Strongback with
integrated hab modules and centrifuge."  As you can see from file
geodeA.gif, it uses a Space Shuttle External Tank (ET) in place of much
of the truss which is currently part of Space Station Freedom.  The
white track on the outside of the ET is used by the Station Remonte
Manipulator System (SRMS) and by the Reaction Control System (RCS)
pod.  This allows the RCS pod to move along the track so that thrusting
can occur near the center of gravity (CG) of the Station as the mass
properties of the Station change during assembly.

The inline module design allows the Shuttle to dock more easily because
it can approach closer to the Station's CG and at a structurally strong
part of the Station.  In the current SSF design, docking forces are
limited to 400 pounds, which seriously constrains the design of the
docking system.

The ET would have a hatch installed pre-flight, with little additional
launch mass.  We've always had the ability to put an ET into orbit
(contrary to some rumors which have circulated here), but we've never
had a reason to do it, while we have had some good reasons not to
(performance penalties, control, debris generation, and eventual
de-orbit and impact footprint).  Once on-orbit, we would vent the
residual H2.  The ET insulation (SOFI) either a) erodes on-orbit from
impact with atomic Oxygen, or b) stays where it is, and we deploy a
Kevlar sheath around it to protect it and keep it from contaminating
the local space environment.  Option b) has the advantage of providing
further micrometeor protection.  The ET is incredibly strong (remember,
it supports the whole stack during launch), and could serve as the
nucleus for a much more ambitious design as budget permits.

The white module at the end of ET contains a set of Control Moment
Gyros to be used for attitude control, while the RCS will be used
for gyro desaturation.  The module also contains a de-orbit system
which can be used at the end of the Station's life to perform a
controlled de-orbit (so we don't kill any more kangaroos, like we
did with Skylab).

The centrifuge, which has the same volume as a hab module, could be
used for long-term studies of the effects of lunar or martian gravity
on humans.  The centrifuge will be used as a momentum storage device
for the whole attitude control system.  The centrifuge is mounted on
one of the modules, opposite the ET and the solar panels.

This design uses most of the existing SSF designs for electrical,
data and communication systems, getting leverage from the SSF work
done to date.

Mark proposed this design at Joe Shea's committee in Crystal City,
and he reports that he was warmly received.  However, the rumors
I hear say that a design based on a wingless Space Shuttle Orbiter
seems more likely.

Please note that this text is my interpretation of Mark's design;
you should see his notes in the GIF files.

Instead of posting a 2 MB file to sci.space, I tried to post these for
anon-FTP in ames.arc.nasa.gov, but it was out of storage space.  I'll
let you all know when I get that done.

-- Ken Jenks, NASA/JSC/GM2, Space Shuttle Program Office
      [e-mail]  [phone]

     "...Development of the space station is as inevitable as
      the rising of the sun." -- Wernher von Braun

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

Date: 23 Apr 1993 16:53 EST
From: "David B. Mckissock" <[e-mail]>
Subject: Space Station Redesign Chief Resigns for Health Reasons
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Charles J. Divine) writes...
>Writer Kathy Sawyer reported in today's Washington Post that Joseph Shea, the
>head of the space station redesign has resigned for health reasons.
>
>Shea was hospitalized shortly after his selection in February.  He returned
>yesterday to lead the formal presentation to the independent White House panel.
>Shea's presentation was rambling and almost inaudible.

I missed the presentations given in the morning session (when Shea gave
his "rambling and almost inaudible" presentation), but I did attend
the afternoon session. The meeting was in a small conference room. The
speaker was wired with a mike, and there were microphones on the table for
the panel members to use. Peons (like me) sat in a foyer outside the
conference room, and watched the presentations on closed circuit TV. In
general, the sound system was fair to poor, and some of the other
speakers (like the committee member from the Italian Space Agency)
also were "almost inaudible."

Shea didn't "lead the formal presentation," in the sense of running
or guiding the presentation. He didn't even attend the afternoon
session. Vest ran the show (President of MIT, the chair of the
advisory panel).

>
>Shea's deputy, former astronaut Bryan O'Connor, will take over the effort.

Note that O'Connor has been running the day-to-day
operations of the of the redesign team since Shea got sick (which
was immediately after the panel was formed).

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

Date: 23 Apr 93 08:10:07 GMT
From: Theo Wawers <[e-mail]>
Subject: Sunrise/ sunset times
Newsgroups: sci.space

There is a nice little tool in Lucid emacs. It's called "calendar".
On request it shows for given longitude/latitude coordinates times for
sunset and sunrise. The code is written in lisp.
I don't know if you like the idea that an editor is the right program to
calculate these things.


Theo W.

Theo Wawers                                  LAHMEYER INTERNATIONAL GMBH
email : [e-mail]                  Lyonerstr. 22
phone : [phone]                     D-6000 Frankfurt/Main
fax   : [phone]                     Germany

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

Date: Fri, 23 Apr 93 16:15:23 GMT
From: "Daniel A. Asimov" <[e-mail]>
Subject: Sunrise/ sunset times
Newsgroups: sci.misc,sci.math,sci.space

In article <[e-mail]> [e-mail] (Joseph Wetstein) writes:
>
>Hello. I am looking for a program (or algorithm) that can be used
>to compute sunrise and sunset times.
>
>Joe Wetstein

There is a wonderful book by Jean Meeus called
"Astronomical Algorithms," (1991) which I am fairly sure
contains an algorithm for sunrise and sunset times.


Dan Asimov
Mail Stop T045-1
NASA Ames Research Center
Moffett Field, CA 94035-1000

[e-mail]
[phone]

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

Date: Fri, 23 Apr 1993 07:26:42 GMT
From: Lan Pham <[e-mail]>
Subject: Surviving Large Accelerations?
Newsgroups: sci.space

Amruth Laxman <[e-mail]> writes:
> Hi,
>     I was reading through "The Spaceflight Handbook" and somewhere in
> there the author discusses solar sails and the forces acting on them
> when and if they try to gain an initial acceleration by passing close to
> the sun in a hyperbolic orbit. The magnitude of such accelerations he
> estimated to be on the order of 700g. He also says that this is may not
> be a big problem for manned craft because humans (and this was published
> in 1986) have already withstood accelerations of 45g. All this is very
> long-winded but here's my question finally - Are 45g accelerations in
> fact humanly tolerable? - with the aid of any mechanical devices of
> course. If these are possible, what is used to absorb the acceleration?
> Can this be extended to larger accelerations?

are you sure 45g is the right number? as far as i know, pilots are
blackout in dives that exceed 8g - 9g. 45g seems to be out of human
tolerance. would anybody clarify this please.

lan


>
> Thanks is advance...
> -Amruth Laxman
>

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

Date: 23 Apr 93 12:55:06
From: Steinn Sigurdsson <[e-mail]>
Subject: Vandalizing the sky
Newsgroups: sci.space

In article <[e-mail]> [e-mail] ("F.Baube[tm]") writes:

   From: "Phil G. Fraering" <[e-mail]>

   > Finally: this isn't the Bronze Age, [..]
   > please try to remember that there are more human activities than
   > those practiced by the Warrior Caste, the Farming Caste, and the
   > Priesthood.

   Right, the Profiting Caste is blessed by God, and may
    freely blare its presence in the evening twilight ..

The Priesthood has never quite forgiven
the merchants (aka Profiting Caste [sic])
for their rise to power, has it?

;-)

*  Steinn Sigurdsson               Lick Observatory          *
*  [e-mail]         "standard disclaimer"      *
*  Ya know... you penguin types offend me. ...            *
*  My Gosh... Life is offensive!!                   *
*  Offensensitivity.        - BB 1984            *

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

Date: 23 Apr 1993 13:25:49 -0400
From: Jon Leech <[e-mail]>
Subject: Weekly reminder for Frequently Asked Questions list
Newsgroups: sci.space,sci.astro,sci.space.shuttle

    This notice will be posted weekly in sci.space, sci.astro, and
sci.space.shuttle.

    The Frequently Asked Questions (FAQ) list for sci.space and sci.astro is
posted approximately monthly. It also covers many questions that come up on
sci.space.shuttle (for shuttle launch dates, see below).

    The FAQ is posted with a long expiration date, so a copy may be in your
news spool directory (look at old articles in sci.space). If not, here are
two ways to get a copy without waiting for the next posting:

    (1) If your machine is on the Internet, it can be obtained by anonymous
FTP from the SPACE archive at ames.arc.nasa.gov (128.102.18.3) in directory
pub/SPACE/FAQ.

    (2) Otherwise, send email to '[e-mail]'
containing the single line:

help

    The archive server will return directions on how to use it. To get an
index of files in the FAQ directory, send email containing the lines:

send space FAQ/Index
send space FAQ/faq1

    Use these files as a guide to which other files to retrieve to answer
your questions.

    Shuttle launch dates are posted by Ken Hollis periodically in
sci.space.shuttle. A copy of his manifest is now available in the Ames
archive in pub/SPACE/FAQ/manifest and may be requested from the email
archive-server with 'send space FAQ/manifest'. Please get this document
instead of posting requests for information on launches and landings.

    Do not post followups to this article; respond to the author.

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

Date: 23 Apr 93 12:17:25 PST
From: [e-mail]
Subject: What counntries do space surveillance?
Newsgroups: sci.space

      Ethnocentric USian that I am, I've assumed that we and the
xUSSR were the only countries with significant capabilities to track
non-cooperative objects in low Earth orbit. Grazing in a couple of
databases recently,  I found that Japan has some optical capabilities
along this line, and also uses a radar designed for other purposes
for orbital debris surveys (it isn't clear whether the radar can
determine orbital elements for the objects it detects). Abstracts of
the articles are appended.


    This leads to the more general question: do yet other people than
the US, Russia, and Japan do space surveillance, and if so, how and
why?

Allen Thomson              SAIC                        McLean, VA, USA
-----------------------------------------------------------------------
                         ABSTRACTS

Optical tracking of the experimental geodetic satellite (EGS)
TAKABE, MASAO; ITABE, TOSHIKAZU; ARUGA, TADASHI
Radio Research Laboratory, Review (ISSN 0033-801X), vol. 34,
March 1988, p. 23-34. In Japanese, with abstract in English.
     This paper reports the optical tracking results of EGS
(experimental geodetic satellite) which was launched on August 13,
1986, by NASDA. The EGS optical tracking experiment process and an
outline of the Radio Research Laboratory (RRL) optical ground       <----
station are discussed. A star tracking technique for optical
equipment calibration and satellite tracking technique for orbit
prediction improvement are also described. The accuracy of EGS
tracking data obtained by RRL at the request of NASDA is also
discussed. In addition, it is briefly demonstrated that the
position of the Japanese amateur satellite (JAS-1) which was
launched with the EGS, was accurately determined by means of a      <----
satellite tracking video. It is clear from this experiment that     <----
optical observation data (i.e., satellite direction data) are very  <----
useful for satellite orbit determination during initial launch      <----
stages. Furthermore, the results confirm the effectivenes of these  <----
two satellite optical tracking techniques.                          <----


MU radar measurements of orbital debris
SATO, TORU; KAYAMA, HIDETOSHI; FURUSAWA, AKIRA; KIMURA, IWANE
(Kyoto University, Japan)
AIAA, NASA, and DOD, Orbital Debris Conference: Technical Issues and
Future Directions, Baltimore, MD, Apr. 16-19, 1990. 10 p.
RPN: AIAA PAPER 90-1343
     Distributions of orbital debris versus height and scattering cross
section are determined from a series of observations made with a high-
power VHF Doppler radar (MU radar) of Japan. An automated data
processing algorithm has been developed to discriminate echoes of
orbiting objects from those of undesired signals such as meteor trail
echoes or lightning atmospherics. Although the results are preliminary,
they showed good agreement with those from NORAD tracking radar      <----
observations using a much higher frequency. It is found that the     <----
collision frequency of a Space Station of 1 km x 1 km size at an
altitude of 500 km with orbiting debris is expected to be as high as
once per two years.


Monitoring of the MU radar antenna pattern by Satellite Ohzora (EXOS-C)
SATO, T.; INOOKA, Y.; FUKAO, S. (Kyoto Univ., Japan); KATO, S.
Kyoto Univ., Uji (Japan). Radio Atmospheric Science Center.
In International Council of Scientific Unions, Middle Atmosphere Program.
Handbook for MAP, Vol. 20 5 p
Publication Date: Jun. 1986
      As the first attempt among MST (mesosphere stratosphere
troposphere) type radars, the MU (middle and upper atmosphere) radar
features an active phased array system. Unlike the conventional large
VHF radars, in which output power of a large vacuum tube is distributed
to individual antenna elements, each of 475 solid state power amplifier
feeds each antenna element. This system configuration enables very fast
beam steering as well as various flexible operations by dividing the
antenna into independent subarrays, because phase shift and signal
division/combination are performed at a low signal level using
electronic devices under control of a computer network. The antenna
beam can be switched within 10 microsec to any direction within the
zenith angle of 30 deg. Since a precise phase alignment of each element
is crucial to realize the excellent performance of this system, careful
calibration of the output phase of each power amplifier and antenna
element was carried out. Among various aircraft which may be used for
this purpose artificial satellites have an advantage of being able to
make a long term monitoring with the same system. An antenna pattern
monitoring system for the MU radar was developed using the scientific
satellite OHZORA (EXOS-C). A receiver named MUM (MU radar antenna
Monitor) on board the satellite measures a CW signal of 100 to 400
watts transmitted from the MU radar. The principle of the measurement
and results are discussed.


Equatorial radar system
FUKAO, SHOICHIRO;  TSUDA, TOSHITAKA; SATO, TORU; KATO, SUSUMU
(Kyoto University, Uji, Japan)
(COSPAR, IAGA, SCOSTEP, et al., Plenary Meeting, 27th,
Workshops and Symposium on the Earth's Middle Atmosphere,
Espoo, Finland, July 18-29, 1988) Advances in Space Research
(ISSN 0273-1177), vol. 10, no. 10, 1990, p. 151-154.
     A large clear air radar with the sensitivity of an incoherent
scatter radar for observing the whole equatorial atmosphere up to 1000
km altitude is now being designed in Japan. The radar will be built in
Pontianak, West Kalimantan, Indonesia (0.03 deg N, 109.29 deg E). The
system is a 47-MHz monostatic Doppler radar with an active phased array
configuration similar to that of the MU radar in Japan, which has been
in successful operation since 1983. It will have a PA product of about
3 x 10 to the 9th W sq m (P = average transmitter power, A = effective
antenna aperture) with a sensitivity of approximately 10 times that of
the MU radar. This system configuration enables pulse-to-pulse beam
steering within 20 deg from the zenith. As is the case of the MU radar,
a variety of operations will be made feasible under the supervision of
the radar controller. A brief description of the system configuration
is presented.

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End of Space Digest Volume 16 : Issue 485
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