Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V16_2/V16NO282.ZIP/V16NO282

Internet Message Format | 1993-07-13 | 39KB

Date: Sun,  7 Mar 93 05:00:13
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #282
To: Space Digest Readers
Precedence: bulk


Space Digest                Sun,  7 Mar 93       Volume 16 : Issue 282

Today's Topics:
                      A new cosmological model ?
       Cyrano and the Ark (was Re: Ark Discovered on the Moon)
                      Galileo Update - 03/05/93
                        Getting people into S
                              GPS Digest
                           SIR-C Fact Sheet

    Welcome to the Space Digest!!  Please send your messages to
    "[e-mail]", and (un)subscription requests of the form
    "Subscribe Space <your name>" to one of these addresses: listserv@uga
    (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle
    (THENET), or [e-mail] (Internet).
----------------------------------------------------------------------

Date: Sat, 6 Mar 93 5:58:59 EST
From: "A.Cagri YUCEL" <[e-mail]>
Subject: A new cosmological model ?
Newsgroups: sci.astro,sci.space

    Last night, at TV news I heard about a new cosmological model including
  a secodary explosion after the big-bang...

    More info required.
    Please E-mail to [e-mail]
Message-ID: <[e-mail]>
Date: 6 Mar 93 02:01:24 GMT
Organization: Middle East Technical University - Computer Center
Lines: 10
Sender: [e-mail]

Subject:    A new cosmological model ?

    Last night, at TV news I heard about a new cosmological model including
  a secodary explosion after the big-bang...

    More info required.
    Please E-mail to [e-mail]
                                                        Thanks in advence.
                                                        A.Cagri YUCEL


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

Date: 5 Mar 93 18:55:22 -0600
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject: Cyrano and the Ark (was Re: Ark Discovered on the Moon)
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Rich Travsky) writes:
> The following showed up on the sci.archaeology group. The article speaks
> for itself, as further words can hardly do it justice...
>
> +---------+    Richard Travsky   RTRAVSKY @ UWYO . EDU
> |         |    Division  of  Information  Technology
> |     U W |    University of Wyoming   (307) 766 - 3663 / 3668
> |      *  |    "Wyoming is the capital of Denver." - a tourist
> +---------+    "One of those square states." - another tourist
>
> *********************************************************
> Newsgroups: sci.archaeology
> Subject: recent discovery of ark remains
> From: [e-mail] (Eugene Powell)
> Date: Thu, 4 Mar 1993 21:01:35 GMT
> Organization: Dept. of Entomology - NCSU, Raleigh, NC
>
> About Noah's Ark:
>  Has anyone seen the followup story about the discovery of the other
> half of the ark? It seems IYF TV, a new station on the upper reaches
> of the dial, will broadcast a story from Archaicology Magazine about
> half of the famous boat found (you won't believe this) on the moon!
> A disclaimer will precede the broadcast noting that the opinions
> expressed are only those of a minority, and any resemblance to
> fanatical beliefs is unintentional.
>  The gist of the story is this. The first man on the moon (that we know
> about :-)) Neil Armstrong, noticed upon descent of the lunar module a
> curious object sticking out of HARDENED LAVA near the top of a small
> hill in a young crater. In addition to evidence for recent vulcanism
> on the moon, the object upon close examination provided corroboration
> that a strong interstellar event must have swooped up material from
> the middle east and deposited it somehow on the moon. Upon close
> examination of the object, which in video transmissions will appear
> to be solid rock that only superficially resembles a boat, but which
> occupied numerous pixels in supertopsecretadvancedspyscopes, it was
> discovered that a name is inscribed on what must be the bow of the
> ship. Several large samples of hardened, black material were obtained
> from what appears to be the inside of the ship. The name inscribed
> on the ship is to be revealed in the broadcast, but I have learned
> that the first few letters are (translated) as in BC.
>  I will try to find out more, and post later the results of carbon
> dating on the black material from the boat's floor, but you won't
> believe the date I saw-curves ad infinitum.
>
--
     O~~*           /_) ' / /   /_/ '  ,   ,  ' ,_  _           \|/
   - ~ -~~~~~~~~~~~/_) / / /   / / / (_) (_) / / / _\~~~~~~~~~~~zap!
 /       \                          (_) (_)                    / | \
 |       |     Bill Higgins   Fermi National Accelerator Laboratory
 \       /     Bitnet:     [e-mail]
   -   -       Internet:  [e-mail]
     ~         SPAN/Hepnet:      43011::HIGGINS

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

Date: 6 Mar 1993 01:10 UT
From: Ron Baalke <[e-mail]>
Subject: Galileo Update - 03/05/93
Newsgroups: sci.space,sci.astro,alt.sci.planetary

Forwarded from Neal Ausman, Galileo Mission Director

                                  GALILEO
                       MISSION DIRECTOR STATUS REPORT
                                POST-LAUNCH
                         February 25 - March 4, 1993

SPACECRAFT

1.  On March 1, a periodic RPM (Retro-Propulsion Module) 10-Newton thruster
maintenance activity was performed; all 12 thrusters were flushed during the
activity.  There was a small change in velocity caused by imbalances in the
firings of the S-thrusters.  This effect was first noticed during the RPM
thruster flushing activity on February 8, 1993.

2.  On March 1, a SITURN was scheduled in the EE-12B (Earth-Earth #12B) prime
sequence.  The purpose of the SITURN was to ensure the spacecraft was at the
EE-12B prime attitude after the close of the spacecraft contingency window.

3.  On March 1, the Attitude and Articulation Control Subsystem (AACS) cone
controller parameter update mini-sequence was uplinked to the spacecraft
without incident.  This sequence which executed on March 3 verified the cone
controller performance with the current gains, updated the cone controller
gains, verified the cone controller performance with the updated gains, and
updated spin detector parameters.

4.  On March 2, an Ultra-Stable Oscillator (USO) test was performed to verify
the health status of the USO and to collect gravitational red shift experiment
data; long term trend analysis is continuing.

5.  On March 2, cruise science Memory Readouts (MROs) were performed for the
Extreme Ultraviolet Spectrometer (EUV), Dust Detector (DDS), and Magnetometer
(MAG) instruments.  Preliminary analysis indicates the data was received
properly.

6.  On March 3, real-time commands were sent to update the attitude control
subsystem cone controller and spin detector parameters in support of the AACS
mini-sequence uplinked on Monday.

7.  On March 4, real-time commands were sent to turn the Radioisotope
Thermoelectric Generator (RTG) boom heaters on and enable their temperature
control monitors in accordance with the Retro-Propulsion Module (RPM) pressure
profile strategy and to prepare for the 10.5 rpm spin up wobble compensation
scheduled for March 10.

8.  On March 4, the Energetic Particle Detector (EPD) motor maintenance
exercise was performed which stepped the motor through its eight operating
positions and then returned to the normal position (No. 4).  Later the EPD
shade was retracted nominally via the spacecraft stored sequence. Retraction
was confirmed via EPD detector temperature telemetry.

9.  On March 4, a command threshold test was performed.  Data analysis is in
progress at the writing of this report.

10. On March 4, cruise science Memory Readouts (MROs) were performed for the
Extreme Ultraviolet Spectrometer (EUV).  Analysis indicates the data was
received properly.

11. The AC/DC bus imbalance measurements have not exhibited significant change
(greater than 25 DN) throughout this period.  The AC measurement reads 19DN
(4.3 volts). The DC measurement reads 141DN (16.6 volts).  These measurements
are consistent with the model developed by the AC/DC special anomaly team.

12. The Spacecraft status as of March 4, 1993, is as follows:

       a)  System Power Margin -  40 watts
       b)  Spin Configuration - All-Spin
       c)  Spin Rate/Sensor - 2.88 rpm/Star Scanner
       d)  Spacecraft Attitude is approximately 3 degrees
           off-sun (leading) and 8 degrees off-earth (lagging)
       e)  Downlink telemetry rate/antenna- 40bps(uncoded)/LGA-1
       f)  General Thermal Control - all temperatures within
           acceptable range
       g)  RPM Tank Pressures - all within acceptable range
       h)  Orbiter Science- Instruments powered on are the PWS,
           EUV, UVS, EPD, MAG, HIC, and DDS
       i)  Probe/RRH - powered off, temperatures within
           acceptable range
       j)  CMD Loss Timer Setting - 240 hours
           Time To Initiation - 239 hours



GDS (Ground Data Systems):

1.  Galileo participated in a re-test of the DSN (Deep Space Network)
Version 1.5 GCF (Ground Communications Facility) upgrade data flow test on
3 March.  The purpose of this test was to demonstrate a new Galileo data flow
path through the DSN SFOC Gateway (SG) to the Error Correction and Switching
(ECS) subsystem. The 3 March test exercised telemetry, monitor and tracking
data for Galileo only.  The test failed due to blocks of data being dropped
between the SG and the ECS for 134.4 KBPS.  The cause of this problem is
unknown and is under investigation.  Another retest will be performed prior
to March 15, 1993.  In addition, Galileo participated in a CMD data flow test
on 2 March.  The purpose of this test was to verify the CMD flow through the
SG and ECS interface.  This test was canceled at the beginning of the test
period due to the unavailability of the necessary communication resources.
A retest of the CMD data flow will be rescheduled prior to 15 March.  The
Version 1.5 GCF upgrade is scheduled to go into operations on 15 March.

2.  A MOSO System Test for GLL MGDS V18 Command was performed 2 March from
20:00 to 00:00 GMT using MGDS SIM. The purpose of this test was to exercise
the connectivity of V18 CMD with a simulated DSN station (and CPA). This test
was unsuccessful due to a configuration (setup) problem between the MGDS CMD
and the Project Database (PDB).  The configuration problems were resolved on
3 March.  Another MOSO System Test of V18 CMD will be performed prior to
8 March.  The System Test Review for V18 CMD is scheduled for 8 March.


TRAJECTORY

     As of noon Thursday, March 4, 1993, the Galileo Spacecraft trajectory
status was as follows:

    Distance from Earth         72,166,500 km (0.48 AU)
    Distance from Sun           220,187,100 km (1.47 AU)
    Heliocentric Speed          109,300 km per hour
    Distance from Jupiter       624,151,800 km
    Round Trip Light Time       8 minutes, 4 seconds


SPECIAL TOPIC

1.  As of March 4, 1993, a total of 65099 real-time commands have been
transmitted to Galileo since Launch. Of these, 59993 were initiated in the
sequence design process and 5106 initiated in the real-time command process.
In the past week, 33 real time commands were transmitted: 32 were initiated
in the sequence design process and 1 initiated in the real time command
process. Major command activities included commands to uplink the AACS cone
controller parameter update mini-sequence, update the cone controller and
spin detector parameters, reactivate the HGA unlatch function, and turn the
RTG boom heaters on and enable their temperature control monitors.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | It's kind of fun to do
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | the impossible.
|_____|/  |_|/       |_____|/                     | Walt Disney

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

Date: 5 Mar 93 13:52:00 GMT
From: Roland Dobbins <[e-mail]>
Subject: Getting people into S
Newsgroups: sci.space

JL>Could that be the vehicle commonly called the flying Bumble Bee, wh
JL>clai to fame in the ordinary world is the vehicle that opened the s
JL>and each episode of the six million dollar man. If I recall correct
JL>was aeronautically considered to be unflyable, but flew anyway and
JL>for a while touted as a great instrument for flight to and from low
JL>orbit. It finally crashed on descent when it touched down and did a
JL>up unfortunately a Helo was in the way and the two collided as the
JL>goes. I think That its prototypes and other s are still on display
JL>the yearly aeronautical show at Edwards airforce base.

As I recall, that particular lifting body was called the HL-10, and it
was most certainly _not_ designed *not* to fly . . . .

---
 . Orator V1.13  .  [Windows Qwk Reader Unregistered Evaluation Copy]


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

Date: Sat, 6 Mar 1993 01:06:26 GMT
From: Dave Michelson <[e-mail]>
Subject: GPS Digest
Newsgroups: sci.space

I'm posting this simply to let others know that it exists.  GPS Digest was
apparently announced in sci.electronics some time ago but I don't recall it
being mentioned in sci.space.  (A colleague forwarded this to me a few hours
ago.)  I won't post subsequent issues, however, so if you're interested you'll
have to subscribe.  Enjoy.  If you're not interested, type "n" and proceed
directly to the next post....

---
Dave Michelson                             University of British Columbia
[e-mail]                                  Antenna Laboratory

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

 GPS Digest                                         Volume 1 : Issue 2

                                                  Moderators: Andy Arkusinski
 Today's Topics:                                                  Ken Jongsma

1. Administrivia        (Andy Arkusinski)
2. Low Cost GPS Receivers    (Rob Robinson)
3. OEM GPS Receivers        (Rich Gopstein)
4. Re: ION 92            (Bill Gawne)
5. CANSPACE            (Richard Langley)


 The GPS Digest is a forum for the discussion topics related to the USAF
 Global Positioning System (GPS) and other satellite navigation positioning
 systems. The digest is moderated and is not presently available via
 USENET newsgroup. Submissions should be made to [e-mail].
 Administrative requests should be made to [e-mail].
---------------------------------------------------------------------------
1. Administrivia

This is the second issue of GPS Digest.  The subscriber list continues to
grow, and has reached over 80 at this time.  We've discovered that there
already exists a GPS-related mailing list.  The Canadian Space Geodesy Forum
and its associated archives contain a lot of information about GPS.  We've
included information on how to access CANSPACE.

Three submissions this issue are requests for information regarding GPS
receivers.  I encourage those of you who have such information available to
submit it to gps-digest.  We'll compile and summarize the responses and
include them in a future issue of the Digest.

As always, the quality of the Digest depends on the submissions we receive.
GPS Digest will only be useful if the subscribers take an active part in
sharing problems, solutions, and information with each other.

Andy Arkusinski   [e-mail]

----------------------------
2. Low Cost GPS Receivers    (Rob Robinson)

 I'm interested in low-cost (<$10,000) non-military GPS receivers and
 applications for them.  If at some time in the future a list of available
 books on the subject of GPS in general or on receiver applications appears
 in the Digest, I'll read it with great interest.  Thanks.

      Rob Robinson
      [e-mail]

----------------------------
3. OEM GPS Receivers        (Rich Gopstein)

 I sent a request to sci.electronics for information on which low-cost
 GPS receivers were available, but I didn't get much of a response.  Perhaps
 this will be a better forum.

 I am interested in obtaining an inexpensive (less than US$1000), small,
 low-power OEM GPS receiver for experimentation purposes.  I have some
 old Magellan and Rockwell information, but was looking for any recent
 information or recommendations on which units to consider.  Any interest
 in a group buy would be helpful, also.  Thanks.

 Rich Gopstein
 [e-mail]

-----------------------------
4. Re: ION 92

Quoting from issue 1:

 New Approaches to Circumventing GPS Signal Encrypting

 I was impressed with the innovative ideas that are being put forth to
 circumvent virtually all of the means built into GPS to deny non-military
 users the full accuracy of the GPS signal.  Use of differential GPS provides
 a way to get around the errors produced when Selective Availability is on.
 In anticipation of activation of the Y code in the near future, at least 4
 approaches have been developed to retain most of the potential accuracy of
 GPS in the Anti-Spoofing signal environment.

 This information is at variance with other information I have.  How sure are
 you of this?

 Also, what do you know about the low budget GPS receivers being sold in
 boating supply stores?  I'd be interested in knowing how they compare to
 something like the Magellan for example.

 Thanks,

 -Bill Gawne
 [e-mail]

----------------------------
5.                        CANADIAN SPACE GEODESY FORUM

As an aid to improving communication among scientists and engineers working
with the techniques of space geodesy, an information dissemination and
discussion group, called the Canadian Space Geodesy Forum, has been set up
on the Internet/BITnet/NetNorth/EARN computer communications network.
Messages consisting of news, comments, questions, and answers are exchanged
among forum participants by means of a LISTSERV list.  LISTSERV is an
electronic mail utility that allows a message to be sent "simultaneously" to
a list of individuals simply by sending the message to the list address.
The address of the Canadian Space Geodesy Forum is [e-mail].  Files
can also be distributed or retrieved from CANSPACE including the monthly
message archives.

Any topic related to the space geodetic techniques of GPS, Transit, VLBI,
SLR, satellite altimetry, etc., may be discussed.  Information concerning
satellite launches and orbital elements may be posted.  Questions are
particularly encouraged.  GPS Constellation daily status reports and
ionospheric disturbance warnings are posted.

CANSPACE is directly accessible through computers on the Internet/BITnet/
NetNorth/EARN networks.  CANSPACE is also accessible from other networks
such as CSnet, UUCP, Telemail, etc. through various gateways.  Individuals
may also communicate through CompuServe and the various bulletin board
systems on the FidoNet network.  Although initially intended to link
Canadian geodesists and geophysicists together, CANSPACE now has a wide
international subscriber list and is open to all.

To subscribe to CANSPACE it is necessary for you to send a message to
[e-mail] (***not*** to CANSPACE) with the following text:

SUB CANSPACE yourname

To find out who else is participating in the forum, send the following
message to [e-mail]:

REV CANSPACE

To have a message distributed to CANSPACE subscribers, send the message to
[e-mail].  The message will be automatically distributed.

Additional CANSPACE archive material can be obtained via the File Transfer
Protocol (FTP).  Send a message to [e-mail] to request further
information.

CANSPACE is maintained at the University of New Brunswick by Terry Arsenault
and moderated by Richard Langley.  They can be reached directly via
[e-mail] or by phone at [phone] or by fax at [phone].

If you have any difficulties in accessing CANSPACE or want more information
on the use of a LISTSERV message/file server, consult your local LISTSERV
resource person or contact the Dept. of Surveying Engineering at UNB.

Richard B. Langley ([e-mail])
Geodetic Research Laboratory
Dept. of Surveying Engineering
University of New Brunswick
Fredericton, N.B.
Canada  E3B 5A3

Message Archives
----------------
All messages posted to the LISTSERV-based CANSPACE mailing list are archived
in monthly notebooks.

Archived postings can be recovered using the LISTSERV DATABASE function.
Here is an example of how to use this function.  To list the sequenced index
(item) numbers of the postings in the archives which contain, for example,
the word "launch" and to list the contents of these particular postings, the
body of a message sent to [e-mail] should look like this:

   //  JOB  ECHO=NO
   DATABASE SEARCH DD=RULES
   //RULES DD  *
   SELECT LAUNCH in CANSPACE
   INDEX
   PRINT
   /*

The result of the archive search will be sent back to you as an e-mail
message.  You can substitute any other word or phrase for the word "launch".
If you just want the item numbers, dates, and subject headers of the postings
containing the particular word or phrase, leave out the PRINT command.  You
can print selected items by specifying the item number(s) with the PRINT
command; e.g.,

   PRINT 62, 74

To find out more about the LISTSERV DATABASE function, send the one-line
message

   INFO DATABASE

to [e-mail] or any machine on BITnet/EARN/NetNorth which supports
LISTSERV.  You'll get the DATABASE manual back as an e-mail message.


File Archives
-------------
CANSPACE also supports an archive of information files related to space
geodesy.  Such files include basic descriptions of GPS, lists of GPS
information sources, GPS satellite Keplerian elements, etc.  These files may
be retrieved using anonymous ftp -- either directly or via an e-mail <-ftp
server.

CANSPACE-related files are on UNBMVS1.CSD.UNB.CA (131.202.1.2) in the
"sub-directory" PUB.CANSPACE.  Note that after you connect to UNBMVS1 you
must give a CHANGE DIRECTORY command before you can list file names -- there
is no initial default directory.  To learn more about the vagaries of the
MVS FTP facility at UNB, read the file PUB.$README.

Additional files for inclusion in the CANSPACE FTP file archives are welcome.


25 May 1991; Revised 26 September 1991; Revised 16 December 1991;
Revised 6 March 1992; Revised 4 July 1992

INDEX OF FILES UNDER PUB.CANSPACE
---------------------------------

$README                     Introduction to CANSPACE, the Canadian Space
                            Geodesy Forum, a LISTSERV-based news and
                            discussion mailing list.

ARCHIVES                    Information on accessing the CANSPACE archives.

CDNGEOPH.BULTIN88           Text of the geodesy chapter of the 1988 edition of
                            the Canadian Geophysical Bulletin.

CDNGEOPH.BULTIN89           Text of the geodesy chapter of the 1989 edition of
                            the Canadian Geophysical Bulletin.

DAILY.SOLARGEO.DATABCST.FORMAT
                            Description of the format used for the daily solar
                            geophysical data broadcasts from Cary Oler's Solar
                            Terrestrial Dispatch data service.

FTP.BITNET.EMAIL.ACCESS     This document describes how to retrieve files from
                            anonymous ftp sites (such as unbmvs1.csd.unb.ca) via
                            the Princeton BITNET ftp server.  You must be on a
                            BITNET node to use this service.  If you are not on
                            a BITNET node, see FTP.GENERAL.EMAIL.ACCESS.

FTP.GENERAL.EMAIL.ACCESS    This document describes how to retrieve files from
                            anonymous ftp sites via e-mail using the ftpmail
                            facility at decwrl.dec.com.  To retrieve files using
                            this facility, compose an e-mail message using the
                            commands listed in this document and send the
                            message to [e-mail].

GEODESY.IN.CANADA           Text of the quadrennial Canadian National Report on
                            Geodesy for the International Union of Geodesy and
                            Geophysics as presented at the XX General Assembly
                            of the IUGG, Vienna, 11 - 24 August 1991.

GPS.CONSTEL.STATUS.Dyymmdd  The latest Navstar GPS Constellation Status summary.

GPS.ELEMENTS.NASA.#nnn      Current GPS constellation orbit element sets in
                            NASA Prediction Bulletin 2-line format.

GPS.ELEMENTS.NASA.#nnn.MACSAT
                            Current GPS constellation orbit element sets con-
                            verted from NASA Prediction Bulletin 2-line format
                            to MacSat tracking program format.

GPS.GUIDE.INFO              Information on Canadian GPS Associates' Guide to
                            GPS Positioning.

GPS.INFO.SOURCES            A brief directory of sources of information on the
                            Global Positioning System.

GPS.MANUFACT                A list of GPS equipment manufacturers.

GPS.SYSTEM.DESCRIPT.USNO    A description of GPS with emphasis on its use for
                            accurate time transfer.  This file was obtained from
                            the USNO ADS where it exists as file GPSSY.

GPS.WORLD.INDEX.PS.Z        A detailed index to GPS World magazine in PostScript
                            print file format.  The file has been compressed
                            using the standard Unix format.

GPS.WORLD.INDEX.TEXT.Z      Plain text version of the above file.

GPS.WORLD.INFO              Information on GPS World magazine.

GPSIC                       Description of the services provided by the U.S.
                            Coast Guard's Information Center.  This file was
                            prepared by the U.S. Naval Observatory.

LOG9011                     CANSPACE archive for November 1990 (missing from
                            LISTSERV archives).

LOG9012                     CANSPACE archive for December 1990 (missing from
                            LISTSERV archives).

MACSAT.USERS.GUIDE.HQX      BinHexed file containing the user's guide for the
                            Macintosh-based MacSat satellite tracking program.

TEC.M9108.Z                 A summary of hourly total electron content data as
                            reported by seven western hemisphere and four
                            eastern hemisphere stations for part of the month
                            of August 1991. Report prepared by Cary Oler of
                            the Solar Terrestrial Dispatch from data supplied
                            by the Space Environment Laboratories, NOAA. This
                            is a binary file in compressed Unix format.

TEC.Myymm.ZIP               As above for month mm, 19yy. Compressed ZIP format.

UNB.GPS.BIBLIO              A bibliography of UNB's publications relating to
                            the Global Positioning System.

WHEN.HQX                    A BinHexed Macintosh HyperCard stack for converting
                            a UTC or GPS time epoch to the GPS Week, seconds of
                            week, and day of the year. It also computes the
                            Julian Date and Modified Julian Date of the
                            corresponding UTC epoch. Requires HyperCard 2.0
                            or later.

==============================================================================
 Richard B. Langley                        Internet: [e-mail] or [e-mail]
 Geodetic Research Laboratory              BITnet:   LANG@UNB or SE@UNB
 Dept. of Surveying Engineering            Phone:    [phone]
 University of New Brunswick               FAX:      [phone]
 Fredericton, N.B., Canada  E3B 5A3        Telex:    014-46202
==============================================================================

End of GPS Digest V1 #XXX
****************************

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

Date: 6 Mar 1993 01:19 UT
From: Ron Baalke <[e-mail]>
Subject: SIR-C Fact Sheet
Newsgroups: sci.space,sci.space.shuttle,sci.geo.geology,sci.geo.meteorology

FACT SHEET:                SIR-C/X-SAR
                           March 1993

     Since the late 1970s a variety of NASA satellite missions
have used imaging radar to study the Earth and our planetary
neighbors.  The joint U.S./German/Italian Spaceborne Imaging
Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) is the next
step in that program.

     SIR-C/X-SAR will fly aboard the space shuttle Endeavour in
late 1993 or early 1994 as part of the Space Radar Laboratory
(SRL).  This will be the first of at least three flights, with
the following two launches scheduled for 1995 and 1996.

     The most useful feature of imaging radar, also called
synthetic aperture radar (SAR), is its ability to collect data
over virtually any region at any time, regardless of weather or
sunlight conditions.   The radar waves can penetrate clouds, and
under certain conditions the radar can also see through
vegetation, ice and dry sand.  In many cases, radar is the only
way scientists can explore inaccessible regions of the Earth's
surface.

     A synthetic aperture radar transmits pulses of microwave
energy toward Earth and collects the energy that is scattered
back to the antenna.  The motion of the shuttle is used to
"synthesize" an antenna (the aperture) that is much longer in
length than the actual SIR-C/X-SAR antenna in the shuttle.  A
longer antenna produces images of finer resolution.

     The SIR-C/X-SAR mission is a major technical step forward in
the evolution of spaceborne imaging radar.   It is the first
spaceborne radar system that will simultaneously acquire images
at multiple wavelengths and polarizations.

     SIR-C, built by JPL and the Ball Communications Systems
Division for NASA, is a two-frequency radar including L-band (23-
cm wavelength) and C-band (6-cm wavelength).  SIR-C will have the
capability to transmit and receive horizontally and vertically
polarized waves at both frequencies.

     X-SAR is built by Dornier and Alenia Spazio companies for
the German space agency, Deutsche Agentur fuer
Raumfahrtangelegenheiten (DARA), and the Italian space agency,
Agenzia Spaziale Italiana (ASI).  It is a single-polarization
radar operating at X-band (3-cm wavelength).

     SIR-C/X-SAR  will allow scientists to make highly detailed
studies of the Earth's surface on a global scale, including new
types of measurements such as biomass and soil moisture.

     The SIR-C/X-SAR system is a precursor mission to the Earth
Observing System (EOS) SAR, a polar-orbiting satellite that will
carry radars operating at the same three frequencies.


SCIENCE

      Scientists will use SIR-C/X-SAR to measure vegetation
structure and seasonal changes in wetlands.  SIR-C/X-SAR data
will also provide measurements of soil moisture and surface
roughness, tropical forest flooding, seasonal changes in snow
cover and glacier properties, and the distribution of snow over
mountainous regions.  Oceanographers will use SIR-C/X-SAR to
image currents, eddies, frontal boundaries, ocean swells,
internal waves and ocean bottom topography.

     The radar's ability to penetrate arid soil will help
scientists understand Earth's ancient climate and water patterns.
SIR-C/X-SAR will also play an important role in monitoring
present-day geologic activity such as volcanic eruptions,
tectonics, erosion, and desertification.

     Initial plans call for SIR-C/X-SAR to collect a total of 50
hours of data, roughly corresponding to 50 million square
kilometers (18 million square miles) of ground coverage.
Several "supersites" of extreme scientific interest, such as the
Galapagos Islands and the Sahara Desert, have been identified and
will be continually monitored during the mission.  SIR-C/X-SAR
will be flown during different seasons which will allow
scientists to make comparative measurements of these same sites.

     The scientists will also establish "ground truth" teams that
will make simultaneous measurements of vegetation, soil moisture,
sea state, snow and weather conditions during the mission.  Data
from these teams will be supplemented with information taken from
aircraft and ships to ensure an accurate interpretation of the
data taken from space.  In addition, the astronauts will record
their personal observations of weather and environmental
conditions in coordination with SIR-C/X-SAR operations.


BACKGROUND

     SIR-C is the latest in a series of spaceborne imaging radar
missions that began in June 1978 with the launch of Seasat SAR
and continued with SIR-A in November 1981 and with SIR-B in
October 1984.  Both the SIR-A and SIR-B sensors were derived from
the Seasat SAR, and all three were capable of transmitting and
receiving horizontally polarized radiation (commonly referred to
as HH polarization) at a frequency of 1.28 gigahertz (L-band
frequency).

     The major difference between the Seasat and SIR-A sensors
was the orientation of the radar's antenna with respect to the
Earth's surface.  Microwave radiation transmitted by Seasat
struck the surface at a fixed angle of approximately 23 degrees
from the local zenith direction.  SIR-A was designed to view the
surface at a fixed 50 degree angle.

     SIR-B improved upon both those missions because its antenna
could be mechanically rotated.  This allowed SIR-B to obtain
multiple radar images of a given target at different angles
during successive shuttle orbits.

     The X-SAR antenna is a follow-on to Germany's Microwave
Remote Sensing Experiment (MRSE) which was flown aboard the first
shuttle Spacelab mission in 1983.


SIR-C/X-SAR SENSOR CHARACTERISTICS

     The SIR-C antenna is the most massive piece of flight
hardware ever built at JPL, and will nearly fill the entire
shuttle cargo bay.  Its mass is 10,500 kg (23,100 lbs) and it
measures 12 meters by 4 meters (39.4 feet by 13.1 feet).  The
antenna consists of three leaves and each is divided into four
subpanels.

     Unlike previous SIR missions, the SIR-C radar beam is formed
from hundreds of small transmitters embedded in the surface of
the radar antenna.  By properly phasing the energy from these
transmitters, the beam can be electronically steered without
physically moving the large radar antenna.  This feature will
allow images to be acquired from 15 degree to 55 degree angles of
incidence.   Advancements in radar technology will allow SIR-C to
acquire simultaneous images at L-band and C-band frequencies with
HH, VV, HV, and VH polarizations.

       Polarization describes how the radar wave travels in
space.  For example, when data is acquired with HH polarization
the wave is transmitted from the antenna in the horizontal plane
and the antenna receives the backscattered radiation in the
horizontal plane.  With HV polarization, the wave is transmitted
horizontally, but is received by the antenna in the vertical
plane.  It is the interaction between the transmitted waves and
the Earth's surface that determines the polarization of the waves
received by the antenna.  Multi-polarization data contains more
information about surface conditions than single polarization
data.

     X-SAR will use a slotted-waveguide antenna which is mounted
on a bridge structure that is tilted mechanically to align the X-
band beam with the L-band and C-band beams.  X-SAR will provide
VV polarization images.

     Both SIR-C and X-SAR can be operated as either stand alone
radars or in conjunction with each other.  The width of the
ground swath varies from 15 to 90 kilometers (9 to 56 miles),
depending on the orientation of the antenna beams.  The
resolution of the radars can be varied from 10 to 200 meters (33
to 656 feet.)


DATA PROCESSING

     All data will be stored onboard the shuttle using new high-
density, digital, rotary-head tape recorders with portions
relayed to the ground via the Tracking and Data Relay Satellite
System (TDRSS) data link.  There will be 160 digital tape
cartridges (similar to VCR tape cartridges) carried aboard the
shuttle to record the 50 hours of data.

     The mission will return 32 terabits of data (32 X 1012 bits
of data) or the equivalent of 20,000 encyclopedia volumes.
The raw data will be digitally processed into images using JPL's
advanced digital SAR processor and by processors developed by
Germany and Italy for the X-SAR data.

     Historically, processing SAR data has required a great deal
of computer time on special purpose computer systems, however,
SIR-C/X-SAR scientists will benefit from rapid advances in
computer technology that make it possible to process the images
with a standard super mini-class computer.   Yet even with these
advances, it will still take five months to produce survey images
from the large volume of data acquired.  Detailed processing will
take another nine months to complete.  Data will be exchanged
among Italy, Germany and the United States to meet the needs of
the science investigators.


SCIENCE TEAM

     An international team of 49 science investigators and three
associates will conduct the SIR-C/X-SAR experiments.  A dozen
nations are represented, including:  Australia, Austria, Brazil,
Canada, China, England, France, Germany, Italy, Japan, Saudi
Arabia and the United States.  A list of investigators and their
affiliations is attached.

     Dr. Diane Evans of the Jet Propulsion Laboratory is the U.S.
project scientist.  Dr. Herwig Ottl of DFVLR is the German
project scientist and Dr. Paulo Pampaloni is the Italian project
scientist.


MANAGEMENT

     The SIR-C mission is managed by the Jet Propulsion
Laboratory for NASA's Earth Science and Applications Division
within the Office of Space Science and Applications.   Michael
Sander is the JPL project manager.

     X-SAR is managed by the Joint Project Office (JPO) located
near Bonn, Germany.  Dr. Manfred Wahl of DARA is the project
manager and Dr. Paulo Ammendola of ASI is the deputy project
manager.

                            #####
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | It's kind of fun to do
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | the impossible.
|_____|/  |_|/       |_____|/                     | Walt Disney

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End of Space Digest Volume 16 : Issue 282
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