Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from hogtown.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests) ID ; Tue, 12 Mar 91 01:31:46 -0500 (EST) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Tue, 12 Mar 91 01:31:38 -0500 (EST) Subject: SPACE Digest V13 #259 SPACE Digest Volume 13 : Issue 259 Today's Topics: Pioneer 11 Update - 03/08/91 Pegasus and Taurus Re: German conference highlights doubts about ESA's manned space plans * SpaceNews 11-Mar-91 * Re: German conference highlights doubts about ESA's manned space plans Re: Value per pound vs. cost per pound Re: Reliability Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription requests, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Date: 12 Mar 91 00:42:58 GMT From: usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@ucsd.edu (Ron Baalke) Subject: Pioneer 11 Update - 03/08/91 PIONEER 11 STATUS REPORT March 8, 1991 Additional scans of Canopus were made by the Pioneer 11 spacecraft at lower gain settings on March 2, but again produced multiple locks. The data is being compared with previous data to see if one of the contacts could be Canopus. The 36-hour receiver switch timer was re-enabled on March 2, in an attempt to cause a receiver switch during long tracking gaps. ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@mars.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |___ M/S 301-355 | Change is constant. /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | |_____|/ |_|/ |_____|/ | ------------------------------ Date: 12 Mar 91 00:18:44 GMT From: news-server.csri.toronto.edu!utzoo!henry@rutgers.edu (Henry Spencer) Subject: Pegasus and Taurus In article dlbres10@pc.usl.edu (Fraering Philip) writes: >... It also seems that Pegasus >is meant to be military than commercial in that commercial payloads >don't need to be launchable from anywhere. At the expense (additional, >it may seem, for with Taurus OSC seems to be abandoning the approach) >of having to pay for a carrier aircraft, Pegasus can launch anywhere >the plane can take off... Actually, Taurus is also being sold initially to the military, and one of the conditions of the initial purchase is that Taurus demonstrate the ability to launch from (nearly) bare concrete on a few days' notice. Commercial payloads don't need to be launchable from anywhere, but that's not the only thing the air launch buys you. For one, you can get an equatorial launch without an equatorial launch site, which is non-trivial because current equatorial sites are not readily available except to their owners. In general, air launch bypasses a lot of launch-site hassles. > But if >Pegasus is so good, why are they developing Taurus? I think the answer is basically "larger payload". -- "But this *is* the simplified version | Henry Spencer @ U of Toronto Zoology for the general public." -S. Harris | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 11 Mar 91 02:36:00 GMT From: zephyr.ens.tek.com!tektronix!sequent!crg5!szabo@uunet.uu.net (Nick Szabo) Subject: Re: German conference highlights doubts about ESA's manned space plans In article <9466@exodus.Eng.Sun.COM> agn@bovic.Eng.Sun.COM (Andreas G. Nowatzyk) writes: >True, but I read the original argument slightly differently: It is possible >to design Solar Max, etc. for in-orbit repair by robots, which was not done. I didn't mean this, but this is a good point. Incidentally, Solar Max did need special design changes to allow repair (as opposed to retrieval and relaunch) by astronauts. It would be interesting to compare the cost of redesign for robotic vs. the cost of redesign for human repair, and then factor in the costs of human EVA time vs. telerobotic repiar time. >....For example, a lot of consumer equipment (VCRs & such) and >some computer gear (Mac's, printers, etc.) are now routinely designed for >robotic assembly. Lots of tiny details reqire attention: aviod screws, >avoid round screw-in connectors, provide guide-paths for modules, >snap-into-place things are king, locking mechanisms that require tools to >push in several places are fine, but ones that require rotary action are not, >avoid ill shaped objects like cable harnesses, ... nothing really fancy, but >it is quite a departure from the way current space probes are designed. > >Furthermore, in-orbit repairs are limited to module swaps. It's hard to >imagine someone replacing a 300+ pin surface mounted chip during EVA. Good point. Are there any large differences between design for robotic and astronautic EVA repair? -- Nick Szabo szabo@sequent.com "What are the _facts_, and to how many decimal places?" -- RAH ------------------------------ Date: 11 Mar 91 03:56:19 GMT From: ka2qhd!kd2bd@rutgers.edu (John Magliacane) Subject: * SpaceNews 11-Mar-91 * SB SPACE @ AMSAT < KD2BD $SPC0311 * SpaceNews 11-Mar-91 * Bulletin ID: $SPC0311 ========= SpaceNews ========= MONDAY MARCH 11, 1991 SpaceNews originates at KD2BD in Wall Township, New Jersey, USA. It is published every week and is made available for unlimited distribution. * VOICES FROM SPACE * ===================== This past week radio amateurs around the world heard the voice of the recently launched AO-21. The voice message, coming from the AO-21 downlink frequency of 145.983 MHz spoke the following words: "I'm completely operational and my ciruits are functioning perfectly." This voice mode is referred to as Mode 8 among the AMSAT-DL and AMSAT-U-ORBITA groups responsible for AO-21's design and assembly. At this time it is not known how often Mode 8 will be in operation on AO-21. Also, engineering checkout is still ongoing and it could be some time before the operational schedule for AO-21 is known. Users should monitor the downlink of 145.983 MHz to see which mode AO-21 is currently operating. As soon as a schedule is available from AMSAT-DL, it will be published immediately and made available to all amateurs. OSCAR-21 Frequency Allocations and Modes of Operation: Linear Transponder Uplink: 435.030 - 435.120 MHz (90 KHz) Linear Transponder Downlink: 145.880 - 145.970 MHz (inverted) O/P Power: 12 watts max. Beacon : 145.810 MHz, CW telemetry. Gain of satellite RX/TX antennas: 2.3 dBi each (dipoles) Input sensitivity: -125 dBm (435 MHz) for a C/No of 45 dB/Hz SAT-RX-1: 435.016 MHz +-10 KHz 1200 bps, FSK, NRZIC/Biphase-M (JAS, PACSAT) SAT-RX-2: 435.155 MHz +-10 KHz (AFC) 2400 bps, BPSK, Biphase-S SAT-RX-3a: 435.193 MHz +-10 KHz (AFC) 4800 bps, RSM, NRZIC/Biphase-M SAT-RX-3b: 435.193 MHz +-10 KHz (AFC) 9600 bps, RSM, NRZI (NRZ-S) +Scrambler SAT-RX-4: 435.041 MHz +-10 KHz (digital AFC) RX for RTX-DSP experiments The downlink can be switched to the following operating modes: Transmit frequency: 145.983 MHz Mode 1: 1200 bps, BPSK, NRZI (NRZ-S) (like FO-20) Mode 2: 400 bps, BPSK, Biphase-S (AMSAT mode for OSCAR-13 beacon) Mode 3: 2400 bps, BPSK, Biphase-S (planned for OSCAR-13) Mode 4: 4800 bps, RSM, NRZIC (Biphase-M) (like 4800 bps uplink) Mode 5: 9600 bps, RSM, NRZI (NRZ-S) + Scrambler (like 9600 bps uplink) Mode 6: CW keying (only for special events) Mode 7: FSK (F1 or F2B), e.g. RTTY, SSTV, FAX, etc. (only for special events) Mode 8: FM modulated by D/A signals from DSP-RISC processor (e.g. speech) * U2MIR NEWS * ============== By: John Shalamskas, KJ9U -- 02 March 1991 A probable first in Amateur Radio was achieved today when 16 two way FM voice contacts were conducted with the MIR spacecraft by Hawaii "hams" in a single pass. Ham operators on Oahu and Maui exchanged greetings with Musa Maranov, U2MIR, in the orbiting Soviet space station. From approxinately 7:54 AM to 8:05 AM HST, excited Amateurs passed their callsigns and names to their counterparts who were streaking by 400 km overhead. The relatively small number of Amateur Radio stations in Hawaii and a great deal of pre-pass planning allowed many participants to make contact in a limited time, using only modest equipment. After difficulty had been encountered during early packet contacts, Joe Weite (KH6GDR) suggested emulating the military/commercial process of parcelling out time slots in a manner that would make best use of the geographical location of each ground station. The first attempt at using this method for voice contacts has proven to be extremely beneficial. The [tentative] list of happy operators follows: WA6EMV + NH6XW NH6VT AH6HU K6WR WH6CJO NH6RY KA6NEI KH6GDR WY0H KZ0A + KJ9U AH6GR + NH6UY KH6GPI + KH6QR A '+' denotes contacts that I did not hear directly, but were confirmed by others immediately after the pass. Congratulations! Musa did not use the expected "list" format, but everyone adjusted quickly. Even though Musa was waiting for calls instead of calling us, everyone did their best to remain in sequence. It worked exceedingly well! Musa kept up a good rate all through the pass, even contacting a couple of stations on Maui and Hawaii that weren't aware of the list. These Amateurs were also quite courteous, even using remote-controlled stations at high elevations to monitor Oahu in order to prevent interfering with others. A discussion was held on the 146.88 MHz repeater after the pass. The general consensus was that this was a very special event! The mutual cooperation made it easy to hear and work Musa. There were also a number of requests for an "official" list of contacts from U2MIR. We'll have to wait and see if that will happen. It's quite likely that it will, if we ask Musa to make it available on his packet radio Personal Message System (PMS.) The Soviet cosmonauts aboard MIR have been active on 145.550 MHz, using either packet radio (a digital communications mode) or narrow-band FM voice. Scanner enthusiasts should hear the signals from MIR easily. Some hams heard Musa using only handheld radios! I learned a lot of things from this experiment. The strongest impression I am left with, however, was that the people here in Hawaii are among the nicest in the world! When the operation could easily have become a "pileup", everyone restrained the urge to talk, waiting their turn in a civilized fashion. Hats off to all who helped make this event so successful! * SAREX NEWS * ============== The Shuttle hardware problems that are forcing a delay of this month's shuttle mission will NOT delay next month's SAREX mission. Therefore, a joint ham-radio contact between the Shuttle and Soviet space station Mir appears possible. * TNX RPT! * ============ A special thanks to all those who sent e-mail messages to SpaceNews: WB3JFS, KB5NFN, KC6HEW, N6WDV, N7PDE 73, de John, KD2BD /EX -- John A. Magliacane FAX : (908) 747-7107 Electronics Technology Department AMPR : KD2BD @ NN2Z.NJ.USA.NA Brookdale Community College UUCP : ...!rutgers!ka2qhd!kd2bd Lincroft, NJ 07738 USA VOICE: (908) 842-1900 ext 607 ------------------------------ Date: 11 Mar 91 16:56:26 GMT From: news-server.csri.toronto.edu!utzoo!kcarroll@rutgers.edu (Kieran A. Carroll) Subject: Re: German conference highlights doubts about ESA's manned space plans Nick Szabo szabo@crg5.UUCP write: Subject: Re: German conference highlights doubts about ESA's manned space plans Date: 8 Mar 91 01:53:56 GMT > In article <1991Mar7.172412.17631@zoo.toronto.edu> > henry@zoo.toronto.edu (Henry Spencer) writes: > > >Experience so far says very strongly that if you plan to do in-space repairs, > >you had better plan to have humans (or the imaginary just-as-flexible > >teleoperated robots which will be available almost right away now for sure, > >really, trust us) on hand. > > Or, if you prefer not to pay the $1,000,000++/hour cost of an EVA, you > could make sure it works before you launch it. Nick, to ``make sure'' that a satellite ``works'' before you launch it, you might have to spend anywhere from millions to tens of millions of dollars, depending on the complexity of the spacecraft. What level of reliability do you want to design into the satellite, and verify via ground testing? 99%? Or three nines? Or four? Do you want dual-string redundancy? Or are you going to make your designers hate you forever, and insist on triple-string? All those satellites that we've seen fail on orbit, including the ones that the Shuttle was sent up to repair, were designed by people who tried to ``make sure that it works'' befoire launch. Many of the people involved in design of these are very smart, and very conscientious, probably more so than you and I. Satellites don't typically fail because of sloppy design or construction. They fail because >nobody< can imagine beforehand >all< the things that might go wrong with a complicated, custom-built device. My view is the cost of using spacecraft could be made cheaper if moderately-priced on-orbit check-out and servicing facilities were available to be rented out. That way, a great deal of the expense in designing spacecraft could be eliminated (``the NASA way'' of design wouldn't have toof the expenses of ground-testing the beasts. However, this assumes that you have >people< in orbit to do the testing and repair --- because the things that will go wrong with your satellite will be exactly those that you didn't anticipate, and so you won't have built your teleoperated robot to handle that unexpected contingency, and so the robot won't be able to effect the repair. -- Kieran A. Carroll @ U of Toronto Aerospace Institute uunet!attcan!utzoo!kcarroll kcarroll@zoo.toronto.edu ------------------------------ Date: 11 Mar 91 18:34:41 GMT From: news-server.csri.toronto.edu!utzoo!henry@rutgers.edu (Henry Spencer) Subject: Re: Value per pound vs. cost per pound In article gaserre@isis.isis.cs.du.edu (Glenn A. Serre) writes: >Henry says: >>...There may be a slight constraint to avoid major releases >>into sensitive regions of the upper atmosphere, but I can't imagine this >>having much impact, given that launchers climb through those regions >>very quickly for other reasons already. > >Nick: >This "coasting phase to protect the ozone" is yet another constraint that >must be imposed on a system already strained to its technical limits. > >Me: >Who mentioned a "coasting phase"? Just don't use solid fuel boosters that >produce Chlorine compounds, use rp1-lox, lh2-lox, or NO4-N2H2. Actually, the possibility of a coasting phase came up in private mail, so it's not *quite* out of left field. There may be some concern about release of even water vapor into sensitive regions. Nick's problem here is that he doesn't know much about launcher design, or he wouldn't make ridiculous statements like "already strained to its technical limits". Launcher designers commonly trade off performance for reliability, ease of handling, use of existing hardware, etc.; you would not find such tradeoffs in systems that were stretched to their limits. As a case in point, almost every launcher designer uses 3 or even 4 stages to get to orbit, when Atlas did it with 1.5 over thirty years ago. There are large margins of performance available if environmental constraints become serious enough to justify major redesign. -- "But this *is* the simplified version | Henry Spencer @ U of Toronto Zoology for the general public." -S. Harris | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 11 Mar 91 22:59:56 GMT From: news-server.csri.toronto.edu!utzoo!henry@rutgers.edu (Henry Spencer) Subject: Re: Reliability In article <9103090139.AA04460@cmr.ncsl.nist.gov> roberts@CMR.NCSL.NIST.GOV (John Roberts) writes: >>peculiar myth within NASA that all possible problems can be anticipated, >>and you really can be certain that the thing will work before you launch it. >>The universe keeps trying to tell NASA that this is wrong... > >That last statement sounds a little too broad. Just about everything they >launch is chock full of backup systems, and the unmanned devices have both >on-board recovery systems and provision for ground-based reconfiguration. All of which can handle only expected classes of failures, by and large. On-board recovery systems and provision for reconfiguration are of limited help if your thrusters explode when fired continuously... and we very nearly sent Galileo up with thrusters that did exactly that. (The thruster problem was discovered only because TVSat 1 used the same thrusters, and it fired them long and hard in attempts to shake its stuck solar array loose. Had Galileo been launched on schedule, it would have been very lucky to reach Jupiter. TVSat 1 went up during the post-Challenger hiatus.) On-board recovery systems and provision for reconfiguration are of limited use if your solar arrays flap every time you cross from sunlight into darkness... last I heard the HST people had given up on ever being able to get full compensation for this, as the onboard systems just don't have enough crunch. It would be unfair to also mention the mirror-distortion actuators that don't have enough muscle to take the spherical aberration out, so I won't :-). On-board recovery systems and provision for reconfiguration didn't save Seasat, or the Viking 1 lander, or the attitude-control system on Solar Max either. All of these things deal only with expected classes of problems. They can still be blind-sided by something unexpected. >If you're thinking of simpler multiple probes, I think that has both good >and bad points, and has to be evaluated on the merits of each case... Simplicity vs. multiple missions is a complex tradeoff. But putting all your eggs in one basket is foolish whether that basket is simple *or* complex, because *failures do happen*. Complex systems, while often better equipped to cope with failures, also are more prone to them. -- "But this *is* the simplified version | Henry Spencer @ U of Toronto Zoology for the general public." -S. Harris | henry@zoo.toronto.edu utzoo!henry ------------------------------ End of SPACE Digest V13 #259 *******************