Date: Sun, 7 Mar 93 05:00:13 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu 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 "space@isu.isunet.edu", and (un)subscription requests of the form "Subscribe Space " to one of these addresses: listserv@uga (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle (THENET), or space-REQUEST@isu.isunet.edu (Internet). ---------------------------------------------------------------------- Date: Sat, 6 Mar 93 5:58:59 EST From: "A.Cagri YUCEL" 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 CONSULT0@TRMETU.BITNET Message-ID: <93064.120251CONSULT0@TRMETU.BITNET> Date: 6 Mar 93 02:01:24 GMT Organization: Middle East Technical University - Computer Center Lines: 10 Sender: news@CRABAPPLE.SRV.CS.CMU.EDU 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 CONSULT0@TRMETU.BITNET Thanks in advence. A.Cagri YUCEL ------------------------------ Date: 5 Mar 93 18:55:22 -0600 From: Bill Higgins-- Beam Jockey Subject: Cyrano and the Ark (was Re: Ark Discovered on the Moon) Newsgroups: sci.space In article <1993Mar5.083819.501@news.uwyo.edu>, rtravsky@news.uwyo.edu (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: gpowell@ent1.ent.ncsu.edu (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: HIGGINS@FNAL.BITNET - - Internet: HIGGINS@FNAL.FNAL.GOV ~ SPAN/Hepnet: 43011::HIGGINS ------------------------------ Date: 6 Mar 1993 01:10 UT From: Ron Baalke 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 | baalke@kelvin.jpl.nasa.gov | | | | __ \ /| | | | 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 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 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 davem@ee.ubc.ca 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 gps@esseye.si.com. Administrative requests should be made to gps-request@esseye.si.com. --------------------------------------------------------------------------- 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 arkusinski_andy@si.com ---------------------------- 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 rrobin@ew0019.astro.ge.com ---------------------------- 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 gopstein@helix.bms.com ----------------------------- 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 gawne@stsci.edu ---------------------------- 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 CANSPACE@UNB.CA. 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 LISTSERV@UNB.CA (***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 LISTSERV@UNB.CA: REV CANSPACE To have a message distributed to CANSPACE subscribers, send the message to CANSPACE@UNB.CA. The message will be automatically distributed. Additional CANSPACE archive material can be obtained via the File Transfer Protocol (FTP). Send a message to LANG@UNB.CA 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 SE@UNB.CA or by phone at (506) 453-4698 or by fax at (506) 453-4943. 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 (LANG@UNB.CA) 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 LISTSERV@UNB.CA 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 LISTSERV@UNB.CA 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 ftpmail@decwrl.dec.com. 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: LANG@UNB.CA or SE@UNB.CA Geodetic Research Laboratory BITnet: LANG@UNB or SE@UNB Dept. of Surveying Engineering Phone: (506) 453-5142 University of New Brunswick FAX: (506) 453-4943 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 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 | baalke@kelvin.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |__ M/S 525-3684 Telos | It's kind of fun to do /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | the impossible. |_____|/ |_|/ |_____|/ | Walt Disney ------------------------------ End of Space Digest Volume 16 : Issue 282 ------------------------------