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 ; Wed, 13 Mar 91 01:28:07 -0500 (EST) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Wed, 13 Mar 91 01:27:59 -0500 (EST) Subject: SPACE Digest V13 #264 SPACE Digest Volume 13 : Issue 264 Today's Topics: Re: Reliability Re: SPACE Digest V13 #261 POTENTIAL GEOMAGNETIC STORM WARNING - 13 MARCH Re: Not about space (sorry) MANY QUESTIONS 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: Tue, 12 Mar 91 22:29:24 EST From: John Roberts Disclaimer: Opinions expressed are those of the sender and do not reflect NIST policy or agreement. Subject: Re: Reliability >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. It's generally not practical to be completely prepared for the completely unexpected. The best one can hope for is to think of as many contingencies as possible. Of course, it's also the duty of the designers to put priority on solving the problems deemed most likely to cause trouble. >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. In a way, we did. Those same thrusters are still in there. They haven't exploded, however. >(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.) And other things that have not received as much publicity. For instance, the original design would *probably* (> 50%) have failed before or during the time-critical Jupiter insertion due to radiation-induced computer errors. An effort was made to greatly increase the radiation hardening, and such an event is now considered very unlikely. >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 :-). Since you didn't mention it, I won't reply that HST was designed for repair (quite a bit of it, anyway) by visiting astronauts. :-) :-) >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. Viking had very poor on-board recovery by modern standards - no command loss timer or reacquisition software. (Did it even have a low gain antenna?) The Voyagers were launched before the Viking loss, yet they have these features, though possibly only in software. (Trivia question: what was the last US interplanetary probe launched that could not be reprogrammed from Earth?) >>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 To get back to your original comment, what can NASA *do* that's better than what it's been doing? If they build multiple probes for a multiyear mission, should they launch all of them at once, and possibly let the same unforeseen design problem zap all of them? Or should they keep some on Earth, and put up with the heat about overspending and probes that could have been used gathering dust in museums? If there's plenty of money, they can do both - launch probes every year or two, with nearly duplicate missions, and retargetable in the event of failures. Voyager came close to that - missions some months apart, plus one gathering dust. For the absolute minimum in eggmonobasketing, perhaps in many cases the best approach is what NASA has apparently done with Magellan, Galileo, etc.: for each project, build *one* probe for launch, designed to be as resilient as possible, and do everything you can to keep it alive. If problems start to come up, begin thinking about what you could have done better. If the mission fails, do your utmost to find out why it happened (NASA seems very good at this), then start begging for money for another probe. That way, when you start construction of the replacement, you know what pitfalls to avoid, and you can eliminate design problems that have turned up in the interim. (The thruster problem was known *before* Galileo was launched, but at that point it was too expensive to make changes other than in the operational algorithm. These changes do decrease performance somewhat.) Furthermore, the development of technology is on your side - there may be new and better ways to do it. In the meantime, you spread your money over a wide range of projects, so even if on project suffers a major setback, you still have valuable results coming in from the other projects. Yes, there is at least one major drawback to this approach - if the one probe fails, the team put together to control and use it must disband for a number of years (or at least cut way back on its activity) while the replacement is being built. The "standard probe" utilization that you have advocated would help to reduce this interval. John Roberts roberts@cmr.ncsl.nist.gov ------------------------------ Date: Tue, 12 Mar 1991 13:28 EST From: Kom Subject: Re: SPACE Digest V13 #261 Cc: listserv@andrew.cmu.edu, space-request+@andrew.cmu.edu X-Vms-Cc: IN%"listserv@andrew.cmu.edu",IN%"space-request+@andrew.cmu.edu" signoff space Hi, I attempted for several times to sign off from this list. Would you please remove me from this list manually? u93_ktuk@vaxc.stevens-tech.edu ------------------------------ Date: Tue, 12 Mar 91 19:26:12 MST From: oler%HG.ULeth.CA@vma.cc.cmu.edu (CARY OLER) Subject: POTENTIAL GEOMAGNETIC STORM WARNING - 13 MARCH X-St-Vmsmail-To: st%"space+@andrew.cmu.edu" /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ POTENTIAL GEOMAGNETIC STORM WARNING /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ Issued: 02:00 UT, 13 March ------------- ATTENTION: A major-storm level positive magnetic excursion has been measured locally (northerly middle latitude station) and has been associated with strong radio signal fading and flutter. Our station has only been able to catch the latter part of the larger magnetic disturbance. The magnetometer was down for routine maintanence until 01:15 UT. Hence, we only caught the falling edge of the magnetic disturbance. However, from the information we have gathered thus far, the disturbance locally measured over 234 gammas. The peak occurred sometime shortly before 01:15 UT, judging by the signature of the disturbance measured. We are not yet sure what the cause of this magnetic storm period is, or if this is a planetary disturbance. We have reason to believe this is a planetary disturbance, and until we can verify the information (very shortly), we have posted this Potential Geomagnetic Storm Warning. A bulletin will follow shortly. Until the bulletin is released, please be aware of the potential for geomagnetic storming, possible strong auroral activity, and possible poor radio conditions. The bulletin will formalize the conditions occurring so far and will list the expected conditions. A major flare alert will also follow shortly. /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ ------------------------------ Date: 10 Mar 91 21:20:26 GMT From: hoptoad!tim@ucbvax.Berkeley.EDU (Tim Maroney) Subject: Re: Not about space (sorry) In article <1991Mar07.142018.6312@convex.com> jhyde@convex.com (John Hyde) writes: >I'm writing a term paper for a class, the title of which will be >something like "Email and Electronic Bulletin Boards: Present and >Future Effects on Society." I would like to make the case that these >two media have the potential to have as much effect on the world as >the printing press did. > >The movie Star Trek VI was originally going to be done with young >actors playing the roles of the familiar characters, set at Starfleet >Academy. Word spread instantly through the net, a letter writing >campaign was initiated, and the idea was scrapped. Awesome. Move over, Amnesty International. -- Tim Maroney, Mac Software Consultant, sun!hoptoad!tim, tim@toad.com "This signature is not to be quoted." -- Erland Sommarskog ------------------------------ Date: Tue, 12 Mar 1991 15:14 EST From: LONGWJ@splava.cc.plattsburgh.edu Subject: MANY QUESTIONS X-Organization: SUNY at Plattsburgh, New York, USA X-Envelope-To: SPACE+@ANDREW.CMU.edu I'VE BEEN READING THIS LIST FOR ABOUT A YEAR NOW AND AM FINALLY GETTING AROUND TO POSTING SOME QUESTIONS. iF YOU HAVE ANSWERS YOU CAN E-MAIL THEM TO ME DIRECTLY OR POST TO THE LIST. 1. I HAVE WHAT I CALL A "MEMORIAL WALL" IN MY SHOP WHERE I HAVE PICTURES OF MOST OF THE HUMANS WHO HAVE DIED IN SPACE OR IN RELATED TRAINING. I ALSO HAVE A PICTURE OF LAIKA AS A REPRESENTATIVE OF THE "ANIMALS" THAT HAVE ALSO BEEN SACRIFICED IN THE EXPLORATION OF SPACE. I KNOW THAT 3 RHESUS MONKEYS (ALBERT- 1948, MIKE & PAT-1952) AND OTHER DOGS, CATS, ETC. DIED BEFORE ABLE AND BAKER (RHESUS MONKEYS) WERE SUCCESSFULLY RETRIEVED AFTER THEIR ROCKET FLIGHT IN 1959 CAN SOMEONE PROVIDE ANY SOURCES OF INFORMATION CONCERNING THIS EARLY PHASE OF SPACE RESEARCH WHICH MAY PROVIDE MORE COMPLETE INFORMATION ABOUT THESE "ANIMAL PIONEERS"? 2. ON THE SAME WALL I HAVE A NICE PICTURE OF YURI GAGARIN, WHO DIED IN A MIG-15 TRAINING JET CRASH IN 1968. DOES ANYONE KNOW WHERE I CAN GET A PICTURE OF VLADIMIR SEREGIN, WHO DIED IN THE SAME CRASH BEFORE HE HAD A CHANCE TO GET INTO SPACE? 3. BEING A MACHINIST, I HAVE PRETTY GOOD APPRECIATION FOR THE KINDS OF HAZARDS WHICH ACCOMPANY ALMOST ANY KIND OF MECHANICAL/ELECTRICAL ASSEMBLY WORK. I REMEMBER HEARING ABOUT 2 TECHNICIANS WHO SUFFOCATED AT KSC AFTER ENTERING A ROOM OR CHAMBER WHICH HAD BEEN PURGED OF OXYGEN. I BELIEVE THIS HAPPENNED BEFORE THE FIRST SPACE SHUTTLE FLIGHT. ALSO, I THINK ANOTHER TECHNICIAN WAS KILLED IN A CRANE ACCIDENT JUST RECENTLY...ALTHOUGH I CAN'T REMEMBER EXACTLY WHERE. CAN ANYONE VERIFY THIS? COULD YOU PLEASE FORWARD THEIR NAMES TO ME? I FEEL THAT THEY SHOULD ALSO BE REMEMBERED FOR GIVING THEIR LIVES TO ADVANCE THE CAUSE OF SPACE EXPLORATION. 4. MORE MORBID CURIOSITY...SINCE THE CHALLENGER EXPLOSION HAS THERE BEEN ANY EFFORT TO REDESIGN THE SHUTTLE ORBITER SO THAT THE CREW CABIN COULD BE USED IN AN EMERGENCY SPLASHDOWN? MAYBE SOMETHING LIKE THE PRESENT CREW CABIN WITH ITS OWN PARACHUTE SYSTEM AND HEAT SHEILD? THEN IT COULD BE USED IN AN EMERGENCY DEORBIT IF THE SHUTTLE ORBITER HAD ENOUGH DAMAGE TO PREVENT A NORMAL RE-ENTRY (AS MIGHT BE SUSTAINED FROM A COLLISION WITH ORBITAL DEBRIS). I REMEMBER THAT RESCUE AND RECOVERY SHIPS COULD NOT APPROACH THE AREA WHERE CHALLENGER FELL BECAUSE LARGE PARTS OF THE CRAFT CONTINUED TO FALL FOR NEARLY AN HOUR AFTER THE ACCIDENT. COULD A SUBMARINE HAVE APPROACHED THE CREW CABIN ANY SOONER OR WITH ANY GREATER DEGREE OF SAFETY? ASSUMING THAT A CREW COULD HAVE SURVIVED THE INITIAL SHOCK AND THE SUBSEQUENT IMPACT WITH THE WATER COULD A SUPPLY OF OXYGEN BE PROVIDED THAT WOULD SUSTAIN THE CREW UNTIL RESCUE COULD BE ACHIEVED? I REALIZE THAT WE ARE TALKING ABOUT A SPECIAL CASE AND THAT BECAUSE THE VEHICLE BEHAVED A CERTAIN WAY IN THE PAST IT MIGHT NOT ALWAYS BEHAVE THE SAME IN THE FUTURE BUT I'M INTERESTED WETHER ANY OF THESE IDEAS WERE CONSIDERED AND WHY THEY ARE OR AREN'T POSSIBLE. 5. ON THE LIGHTER SIDE...ARE THERE ANY SHUTTLE MISSIONS PLANNED THAT CALL FOR CARRYING THE EXTERNAL TANKS INTO LEO? I THINK IT MAY BE USEFUL AS TRAINING FOR THE SPACE STATION EVEN IF THE TANKS THEMSELVES CAN'T BE USED AS BUILDING MATERIAL. TO RENDEVOUS WITH AN EXTERNAL TANK THAT IS ALREADY IN ORBIT AND ATTACH ANOTHER TANK TO IT WOULD REQUIRE SOME OF THE SKILLS THAT WILL BE NEEDED TO ASSEMBLE THE STATION. COULD THE EXTERNAL TANKS HAVE OTHER USES IN ORBIT (MICROGRAVITY EXPERIMENTS PLATFORM, STORAGE FACILITY)? I QUESS I REALLY WANT TO KNOW WHY THIS ISN'T BEING DONE ALREADY. 6. ARE THERE ANY PLANS WHICH CALL FOR 2 ORBITERS TO BE FLOWN AT THE SAME TIME AND RENDEVOUS WITH EACH OTHER? 7. ARE THERE ANY PLANS FOR JOINT MISSIONS WITH NASA'S RUSSIAN COUNTERPART? I THINK IT WOULD BE A GREAT P.R. OPPORTUNITY IF AN ASTRONAUT WERE TO GO TO MIR ABOARD A SOYUZ AND A COSMONAUT TO FLY ABOARD THE SHUTTLE. THEN THE SHUTTLE COULD RENDEVOUS WITH MIR, DO SOME INTERNATIONAL GOOD-WILL TYPE STUFF, MAYBE EVEN SOME REAL SCIENCE, AND THEN, AFTER SOME TYPE OF EVA THE ASTRONAUT WOULD COME HOME WITH THE SHUTTLE. IS THERE ANYTHING PREVENTING SUCH A MISSION? 8. WHEN (OR IF) WE SEND A MANNED MISSION TO MARS ARE THERE ANY PLANS TO LEAVE SOMETHING LIKE THE SPACE TELESCOPE THERE? THE DIAMETER OF MARS' ORBIT AVERAGES ABOUT 283,420,000 MILES (ABOUT 1.5 TIMES THAT OF EARTH) SO A MARTIANSCOPE DOING PARALLAX MEASUREMENTS COULD INCREASE THE RANGE FOR WHICH THIS TYPE OF MEASURE- MENT IS ACCURATE. THE MARTIAN YEAR EQUALS 687 EARTH DAYS (BETWEEN 22 AND 23 EARTH MONTHS) SO COLLECTING DATA FROM OPPOSITE ENDS OF THE MARTIAN ORBIT WOULD ONLY TAKE TWICE AS LONG AS IT DOES NOW (HOW LONG DOES PLUTO TAKE TO GET TO THE OPPOSITE POINT IN ITS ORBIT?) AND THE SCOPE COULD BE USED AT CERTAIN TIMES IN CONJUNCTION WITH EARTH BASED TELESCOPES TO GET INSTANTANEOUS PARALLAX MEASUREMENTS...AS LONG AS THE DISTANCE FROM EARTH TO MARS IS KNOWN. FOR MY MONEY ANYTHING THAT INCREASES THE AMOUNT OF RELIABLE DATA THAT WE CAN MAKE OUR EDUCATED GUESSES AND STATISTICAL COMPARISONS FROM IS A GOOD INVESTMENT. HAS ANYONE CONSIDERED THIS OPTION YET? 9. AS AN AMATEUR ASTRONOMER I FIND THE SOLAR TERRESTRIAL FORECAST AND REVIEW USEFUL AS A GUIDE FOR WHERE AND WHEN TO LOOK FOR SUNSPOTS, FLARES, AND AURORA. WHENEVER THERE IS A FLARE ALERT IT MAKES ME WONDER WHAT PRECAUTIONS THE MIR COSMONAUTS TAKE TO AVOID LETHAL EXPOSURE. DOES MIR HAVE A SHIELDED AREA OR IS IT PROTECTED BY THE EARTH'S MAGNETOSPHERE? WHAT SORT OF PROBLEM WILL SOLAR FLARES PRESENT TO THE MARS MISSION AND ITS CREW WHILE THEY ARE FAR REMOVED FROM THE PROTECTION OF EARTH. IS IT FEASABLE TO HAVE A LOT OF MASSIVE SHIELDING ON SUCH A MISSION WITHOUT AFFECTING THE OVERALL DURATION OF THE TRIP? AND ONCE THE CREW HAS ARRIVED IS THE MARTIAN MAGNETOSPHERE STRONG ENOUGH TO PROVIDE ADEQUATE PROTECTION OR WILL THEY STILL NEED SOME FORM OF SHIELDING (LIKE WAIT OUT THE STORM IN A CAVE )? DOES THE INTENSITY OF THE EJECTA DIMINISH BY ENOUGH OF AN AMOUNT TO MAKE SOLAR SHIELDING LESS CRITICAL FOR A SHIP IN ORBIT AROUND MARS? 10. AND FINALLY (WHEW) I'VE DECIDED THERE ARE THREE DISTINCT TYPES OF POSTS TO THIS LIST. THEY ARE THE FACTUAL POSTINGS, SUCH AS THE UPDATES, PAYLOAD STATUS, SPACE NEWS, AND ORBITAL ELEMENTS, THE QUESTION AND ANSWER POSTINGS, AND THE SPECULATION AND REPLY POSTINGS. DEPENDING ON THE SUBJECT, I OFTEN DELETE MOST OF THE SECOND TWO CATAGORIES BEFORE SAVING THE FILES AND ONLY INCLUDE THEM WHEN I FIND THE SUBJECT INTERESTING (ANIMAL SPACE EXPLORERS, TERRAFORMING, THE 'FACE', AND FUTURE PROPULSION FOR EXAMPLE). IS THERE A LIST DEVOTED TO DIS- CUSSION OF THESE SPECULATIVE ISSUES THAT I CAN REACH FROM BITNET LAND? ARE PEOPLE AS INTOLERANT OF OTHERS OPINIONS AS SOME FLAMERS ON THIS LIST:-)? THANX AGAIN FOR YOUR HELP. HAVE A NICE DAY! .............................................................................. : : : : BILL LONG N2LAG : : : LAB MECHANICIAN : THE MOST DIRECT ROUTE : : STATE UNIVERSITY OF NEW YORK : TO A DESIRED GOAL IS : : PLATTSBURGH, N.Y. 12901 : NEVER A STRAIGHT LINE : : (518)564-3007/493-2378 : : : LONGWJ@SPLAVA.CC.PLATTSBURGH.EDU : : :.....................................:......................................: ------------------------------ End of SPACE Digest V13 #264 *******************