Date: Mon, 1 Mar 93 05:37:07 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V16 #243 To: Space Digest Readers Precedence: bulk Space Digest Mon, 1 Mar 93 Volume 16 : Issue 243 Today's Topics: Apollo Missions (Recollections) Book Computers/AI in Shuttle-SSF Can Cassini Titan Probe float? Cassini Rover idea Deadhead to orbit (WAS Re: SSF Resupply) Hopkins Leaks (was Re: Blimps) Magnetic elevator? McElwaine disciplined! (somewhat long) Prez Powers Refueling in orbit Reliable Source says Freedom Dead, Freedom II to be dev Reliable Source says Freedom Dead, Freedom II to be developed Scientists Foresee Strengthening El Nino Event SOLAR gravity assist? NOPE. SOLAR gravity assist? Yup. (2 msgs) SSF Resupply (Was Re: Nobody cares about Fred?) 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: 26 Feb 93 22:15:11 GMT From: John E Childers Subject: Apollo Missions (Recollections) Newsgroups: sci.space In article gerhard@mikas.llnl.gov ((Michael Gerhard aka Elmo P. Suggins)) writes: >I don't know about you, but I never felt so good about the space program as >when the early Apollo missions were happening. People have posted about >their Challenger remembrances. How about Apollo. > [deletion] > > >Anyone else with good memories? When I returned the university life a few years ago I was forced to retake some english classes and my big assignment was to write about a big event in my life. I chose the Apollo 11 landing. I was 8 years old when it happend and it had a big impact on me. Its the reason I got into engineering. Suprize, the kids (18 year olds) that made up the majority of the class bearlly(sp? Hey I siad I was in engineering:-) knew what I was writing about. That made me fell a little older than I wanted to. John Childers | Voting for Clinton may have been University of North Carolina at Charlotte| a mistake, but voting for Bush or Electrical Engineering Department | Perot would have been just as Charlotte NC 28223 | big a mistake. :-( Internet? Try john@opticslab1.uncc.edu | --------------------------------------------------------------------------- Disclaimer? Does anyone on usenet ever offically speak for their computer? ------------------------------ Date: Fri, 26 Feb 1993 20:12:21 GMT From: kjenks@gothamcity.jsc.nasa.gov Subject: Book Computers/AI in Shuttle-SSF Newsgroups: sci.space : In article Subject: Can Cassini Titan Probe float? Newsgroups: sci.space Will the basic design of the Cassini Titan Probe allow it to float if it lands on a liquid medium? How long will Cassini be in contact with the Titan Probe after it enters the atmosphere? Cassini goes on to Saturn orbit, correct? -rabjab ------------------------------ Date: 26 Feb 1993 21:46:15 GMT From: BAIRD Subject: Cassini Rover idea Newsgroups: sci.space This is a bit of a hair brained proposal but I thought it might be a possible idea for the Cassini mission.....Again I don't have all that I need to be able to say one way or another (including enough knowledge in the area of probe and mission design since I am an undergrad and all) and that my efforts to find an email address of someone who does has been blunted left and right (politely, true for the ones that have written me back when I have inquired about someone's email address at their institution)....anyways, here is the idea for those that are interested...... The idea is to have a relatively small autonomous rover on the Cassini mission to get some mapping (visually) of the surface of Titan. It would ideally weigh about 20 kg. It would drop in to the atmosphere of Titan with the Huygens atmospheric probe. At the altitude of about 600 m it would be jettisoned and a parachute deployed to slow the small aerial rover to lower speeds. The fans in the rover (three of them in a radially symmetric configuration) would start up and allow the probe to hover at an altitude of three meters. The probe would then explore as much of Titan as it could before it succumbed to the bitter cold. The ideal mission length for the probe would be for about a month. A small attempted ascii drawing is below of the probe. __ | 0 0 <----- fans built for downward thrust and manauvering (sp) | \ / 3m 0 <------- instrument package and data dish as well as beamed power | | reciever(if applicable) | 0 <----- another fan L_ |__3m___| The probe would probably only carry a camera and some sort of atmospheric chemical analysis device. The onboard sensors for normal operation would include three laser range finders (one in each arm) in order to maintain a level flying pattern as well as a possible sonic or radar backup. The CPU would be housed in the central partition along with the camera and chem analyzer Control would be maintained by three sets of thrust vectoring flaps under the fans. (see ascii drawing below). Turbine and control flap configurations: ---------------------------------------- ^ .________/_\________. | Propelling Fan |_____________________ | | | | | | | | To main instrument package ----------> | | _______________________ .-------------------./ O O O O O | | | | | | | | | | | | | | | <----- control flaps for the probe's fans Fan direction and probe movement: --------------------------------- Each of the probes fans have the thrust vectoring flaps under the fans that would be positioned perpendicular to the pylon attaching the fans to the CPU and instrument package. This would allow the probe to have a wide range of possible movement directions and types (spins, forward on any axis, etc) Possible problems that would need to resolved: ---------------------------------------------- The com units that would be needed for this probe to communicate with the stations on earth might be too heavy for the fans to carry as well as the same problem with the electrical source for the probe as well. The possible solution that might be looked at would be to leave a small orbiting satellite that would have multiple functions. The first would be to be a communications relay for the probe. The second would be the possible use of a set of RTG's of batteries that were mounted on the satellite to provide power to a dual purpose microwave transmitter. The first would be to power the probe (purpose of the microwave transmitter) and the second would be to map the terrain the probe was transversing with the microwave energy (ie radar style like what is being done with Magellan and Venus). Advantages and disadvantages: ----------------------------- The probe as is would be advantageous in one major way: it could care less about the terrain it was covering. Whereas a ground contacting rover would have problems if the Huygens ended up over a "sea of hydrocarbons". This design would just hover over it just the same while the ground contacting rover would sink. The major problems would be the battery weight and transmitter weight as well. Those might be overcome though (?). Now that I have babbled about the idea, what do others think of it? Too far fetched like the ice resupplying of SSF from the asteriod belt/outer planets&moons? Questions, comments, suggestions? Will ------------------------------ Date: 26 Feb 93 23:14:00 GMT From: wingo%cspara.decnet@Fedex.Msfc.Nasa.Gov Subject: Deadhead to orbit (WAS Re: SSF Resupply) Newsgroups: sci.space In article <1993Feb26.174102.16101@mksol.dseg.ti.com>, mccall@mksol.dseg.ti.com (fred j mccall 575-3539) writes... >In <26FEB199300340539@judy.uh.edu> wingo%cspara.decnet@Fedex.Msfc.Nasa.Gov writes: > >Are you postulating that the typical Shuttle launch will be going to >the station with over 20% deadhead carge space? Sounds like time to >build another vehicle and switch to it, to me, if that's the case then it >is time to switch to another launch vehicle Hey Fred if you look at the Expendables, most of them go up with anwhere from 5 to 25% deadhead. The one that I am most familiar with is the Delta and on the GPS missions has almost 1000 pounds of excess capacity. In addition to this there is over 2000 lbs of excess fuel left in the second stage after orbit insertion. It is very hard in the space world to exactly match the capabilities of the launchers with the payload. Getting within 10% of that is a very good goal. This is why secondary payloads are a very good market for expendable vendors to pursue. Why this is not done every day escapes me, but NASA is paying MacDac millions for our secondary payload of 75 kg. Not bad for basically free money. Arianne does this with the ASEP platform that launched the microsats. It would be interesting to see a survey of launcher capability vs launcher payload. I will bet you there is a lot of wasted capability in every program out there. Dennis, University of Alabama in Huntsville ------------------------------ Date: 26 Feb 93 22:27:23 GMT From: John E Childers Subject: Hopkins Leaks (was Re: Blimps) Newsgroups: sci.space In article <1993Feb25.201026.1@fnalf.fnal.gov> higgins@fnalf.fnal.gov (Bill Higgins-- Beam Jockey) writes: >In article , jbh55289@uxa.cso.uiuc.edu (Josh Hopkins) writes: > >For the following paragraph we have the headline "Hopkins Leaks News >of Balloon Project." (Or maybe it's just a trial balloon?) > >> Lighter than air vehicles do indeed have lots of potential for Mars, though the >> difficulties can't be ignored. It is however _far_ easier than floating a >> balloon on Jupiter, something Bill Higgins and I have been puttering around >> with. > >Not much lately, though-- haven't had the time. Most weekends I can't >even *get* to Jupiter... > Have you considered using a glider at Jupiter? With all that convection soaring might be practical. The control system would be much more complex than for a ballon but a glider would be realitively strong compaired to a ballon. Also, a windmilling propeller could be used to generate electrical power if the soaring part worked. John Childers | Voting for Clinton may have been University of North Carolina at Charlotte| a mistake, but voting for Bush or Electrical Engineering Department | Perot would have been just as Charlotte NC 28223 | big a mistake. :-( Internet? Try john@opticslab1.uncc.edu | --------------------------------------------------------------------------- Disclaimer? Does anyone on usenet ever offically speak for their computer? ------------------------------ Date: 26 Feb 93 17:09:48 GMT From: Henry Choy Subject: Magnetic elevator? Newsgroups: sci.space What if we use a vertical maglev train to launch into space? Would it be feasible for a large number of trips? -- Henry Choy choy@cs.usask.ca We are Borg. You will be assimilated. Resistance is futile. ------------------------------ Date: Fri, 26 Feb 1993 16:01:10 GMT From: Robert Wiegand Subject: McElwaine disciplined! (somewhat long) Newsgroups: sci.skeptic,sci.space,sci.astro,sci.space.shuttle btd@iastate.edu (Benjamin T Dehner) writes: > The issue here is not about content, but about volume. McElwaines >megalithic posted at frequent intervals take up network resources and disk >space wether or not I read them or kill them. Furthermore, it seems that >McElwaine himself never discussed his posts, but simply reposts and reposts >and reposts; in short, an automated pamphlet mailer, as someone else pointed >out. Perhaps we should return his articles since we don't want them. Just imagine if he received a thousand copys back of each artice he sends out. He he he. It might be fun. :-) -- ------------------------------------------------------------------------------ Robert Wiegand - Motorola Inc. motcid!wiegand@uunet.uu.net uunet!motcid!wiegand Disclamer: I didn't do it - I was somewhere else at the time. ------------------------------ Date: Sun, 28 Feb 93 23:13:29 EST From: Tom <18084TM@msu.edu> Subject: Prez Powers [congress is given the power to tax & spend, voters should be responsible] >>... if you'll continue your perusal of the document >>mentioned above, you will also notice the tenth amendment, which limits the >>powers of congress to those enumerated within the document. >Yes, but your problem seems to be an incorrect or inadequate >definition of 'powers'. Actually, my problem is in trying to interpret the Constitution based on what it meant to the writers, rather than what it means to the people who gain something from it...but that's something for E-mail, not the net. >>If you'd like some info on what the Libertarians are doing... >No thanks. I'm not interested in impractical or unworkable >'solutions'. Ah, than you didn't vote for Clinton :-) Seriously, if you are going to prejudge something, then you can hardly understand it. But hey, you have your free will... ---------- >>I'm a little hazy on the legal picture, but I've got an inkling that since >>the fed agencies are considered part of the executive, that Prez. Clinton >>can do what he damn well pleases (notwithstanding politics) WRT fred, etc. >He can do anything he wants -- right up until the point where it costs >money. The Executive Branch is allowed to 'execute', but not to >authorize spending. That takes legislation (guess who does that). So, if he has the inkling, he can cancel the program outright, assuming he wants to deal with the political heat? -Tommy Mac ------------------------------------------------------------------------- Tom McWilliams | 517-355-2178 (work) \\ Inhale to the Chief! 18084tm@ibm.cl.msu.edu | 336-9591 (hm)\\ Zonker Harris in 1996! ------------------------------------------------------------------------- ------------------------------ Date: 26 Feb 93 23:17:49 GMT From: Steinn Sigurdsson Subject: Refueling in orbit Newsgroups: sci.space In article <1993Feb25.232248.28808@ee.ubc.ca> davem@ee.ubc.ca (Dave Michelson) writes: In article <1993Feb25.154112.18992@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes: >I was under the impression that Centaur has flown on unmanned launchers >many times since 1962. Didn't both Vikings ride Centaurs without Shuttle >assist? Certainly Titan IV can carry anything a Shuttle can into orbit. >Why is Centaur a Shuttle only playload? If nothing else, this whole discussion underscores the need for rational long term planning for space science probes and solar system exploration. My hair practically stood on end while I read some parts of Bruce Murray's "Journey into Space". No offence to Bruce Murray, but take some of the episodes with a small grain of salt. For example the evolution of Voyager/Viking and the role of JPL and launcher selection is not entirely consistent with Burrows account of the same process... Centaur continues to evolve. AW&ST recently carried an item about General Dynamics looking for funding to develop a single engine version of the Centaur to increase both payload (marginally) and reliability. I guess price would also decrease slightly as well since it's easier to test and verify one engine than two. well, the Atlas-Centaur and Titan-Centaur combos have a interesting development history. It is quite sad to read of the problems of Atlas-Centaur in the early 1960's and then pick up news reports showing essentially the same problems occuring with depressing frequency in the early 1990's. :-( SSTO fans would do well to re-read the history of some modern launchers, including the original Shuttle concept and how it evolved. Might make some a little less firm in their cost estimates and a little less ready to cut other transport systems before the SSTOs have demonstrated operational ability... in particular Allen might be astonished to realise that some of his DC claims look like they were cut out from a NASA report circa 1971-1974 providing STS claims ;-) | Steinn Sigurdsson |I saw two shooting stars last night | | Lick Observatory |I wished on them but they were only satellites | | steinly@lick.ucsc.edu |Is it wrong to wish on space hardware? | | "standard disclaimer" |I wish, I wish, I wish you'd care - B.B. 1983 | ------------------------------ Date: 26 Feb 93 20:23:54 GMT From: Nick Szabo Subject: Reliable Source says Freedom Dead, Freedom II to be dev Newsgroups: sci.space,talk.politics.space It's amazing how many people still think that the space station is the Mother of All Space Projects. Our current concept of "the space station" is obsolete: space stations at this point in space development by their nature get put in the wrong orbit, are overcentralized, and claim far too large a share of the space budget. No space fan likes to see space projects cut, but few negative outcomes are more productive than eliminating SSF from our plans. It wouldn't have accomplished any major breakthrough in space development, even in its original form. It's time to put our current overpriced, underfunctional concept of the "space station" on the scrap heap of history along with the zeppelin, and get on with developing an efficient, real space program based on today's technology, not on the expectations and artistic renderings of the 1950's. Specifically, we have seen many proposals for making space operations more self-sufficient by using materials on Mars, asteroids, comets, etc. Let's start putting NASA money into that. Our commercial space industry is the most competitive in the world, especially in the rapidly growing communications satellite industry; let's put NASA research funds into improving and extending our commercial space capabilities. Let's put some more lobbying effort and funds into COMET and its small-scale competitors, a far more productive way of developing microgravity industry. Let's put money into lowering launch costs with SSTO, gun launchers and electric upper stages. The space station budget at $2 billion/yr could fund all of the above, if we didn't spend so much time trying to save useless, lost causes like the space station. -- Nick Szabo szabo@techboook.com ------------------------------ Date: 26 Feb 93 22:56:00 GMT From: wingo%cspara.decnet@Fedex.Msfc.Nasa.Gov Subject: Reliable Source says Freedom Dead, Freedom II to be developed Newsgroups: sci.space In article <1mldmaINNm7l@access.digex.com>, prb@access.digex.com (Pat) writes... >But if you have properly plumbed the ET, then most of the work the >on orbit specialists do is Pallett changeout and installs. > >plus you get such abig gain in costs savings and space. >Really dennis, there have been a lot of serious ET proposals >in the past. just because Fred shit canned the idea doesn't >make it bad. > >pat > Hey I think using ET's are a great idea. I even worked on a Space Station design for our NSS chapter a few years ago. BUT if you think the EVA times are long for SSF, they will be horrendus for an ET system. The first problem is that the insulation on the ET will detoriate within a short time period in space. The second problem is that micrometoroid protection is zero. The third problem is that unless you take and do a lot of work to modify the tank BEFORE lauch, (Which costs big bucks) YOu will be doing EVA until the Moon turns blue to get it ready for doing real work. Then you have the problem of stabilization to deal with. Then you have the problem of attaching external devices and drilling the holes for the wiring and etc.... Actually the best Idea I have seen on here is to have a module attached to the tank that will provide all of the utilities, but then all you have is a big gymnasium in space with a space station attached to it. Maybe we can dock on to SSF one day and get the best of both worlds. The most serious proposals that I have seen for the use of ET's is for a large gamma ray imaging telescope. That one could be done cheap and would be a heck of a device. BUT you need a station like SSF, where the manpower is available to do all of the EVA necessary to make the system work. Dennis, University of Alabama in Huntsville ------------------------------ Date: 26 Feb 1993 22:10 UT From: Ron Baalke Subject: Scientists Foresee Strengthening El Nino Event Newsgroups: sci.space,sci.geo.meteorology Brian Dunbar Headquarters, Washington, D.C. (Phone: 202/358-1547) February 26, 1993 Mary Hardin Jet Propulsion Laboratory, Pasadena, Calif. (Phone: 818/354-5011) RELEASE: 93-39 SCIENTISTS FORESEE STRENGTHENING EL NINO EVENT Scientists studying data from the U.S.-French TOPEX/POSEIDON oceanographic spacecraft have observed an ocean phenomena in the equatorial Pacific that will strengthen the ongoing El Nino event off the western coast of South America. The scientists have been analyzing a prominent Kelvin wave that has appeared in recent TOPEX/POSEIDON altimeter data. A Kelvin wave is a large warm water mass that moves along the Equator in the Pacific Ocean. These Kelvin wave pulses give rise to El Nino conditions in the eastern equatorial Pacific. The Kelvin wave pulse seen in the TOPEX/POSEIDON data also was predicted by the global ocean numerical models developed on supercomputers at the Naval Research Laboratory, Washington, D.C. The Kelvin wave pulse was excited by westerly wind anomalies in the western Pacific in December 1992 and is projected to arrive at the South American coast in late February or early March. The satellite data indicates an arrival in the early part of the window, while the Navy model points to a slight later date. The imminent arrival of this Kelvin wave pulse suggests that the current warm conditions in the western Pacific will continue or possibly intensify during March. The strengthening of the El Nino means that the weather conditions associated with it are likely to continue said Dr. Jim Mitchell of the Naval Research Laboratory. These conditions include wetter than normal weather in California, wetter and colder winters than normal in the eastern United States and warmer and dryer summers than normal across the southern hemisphere. Launched Aug. 10, 1992, TOPEX/POSEIDON also is addressing long-term climate issues. By mapping the circulation of the world's oceans over several years, scientists can better understand how oceans transport heat, influence the atmosphere and affect long-term climate, said Dr. Lee-Leung Fu of the Jet Propulsion Laboratory (JPL), Pasadena, Calif. Dr. Fu is the TOPEX/POSEIDON Project Scientist for NASA. Data from TOPEX/POSEIDON is distributed monthly to more than 200 scientists around the world for their analysis. TOPEX/POSEIDON is the second satellite in NASA's Mission to Planet Earth, a comprehensive research program to study the Earth's environment as a global system. JPL manages the NASA portion of the mission for the Earth Science and Applications Division of the Office of Space Science and Applications, Washington, D.C. - end - ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@kelvin.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |__ M/S 525-3684 Telos | If you don't stand for /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | something, you'll fall |_____|/ |_|/ |_____|/ | for anything. ------------------------------ Date: 26 Feb 1993 21:30:55 GMT From: "Robert M. Unverzagt" Subject: SOLAR gravity assist? NOPE. Newsgroups: sci.space,alt.sci.planetary In article <21474@mindlink.bc.ca> Bruce_Dunn@mindlink.bc.ca (Bruce Dunn) writes: > In addition to a direct solar gravity assist for a Pluto, there might > be some benefit in carrying propellant deep into the energy well of the sun, > and burning it there to provide a boost to Pluto. Is anyone familiar enough > with the calculations to estimate what the benefit might be? Sure, I'll take a stab at it. The delta-v for a direct injection to Pluto is about, er, 38,771 ft/sec. That's 38,771 ft/sec added to the earth's orbital velocity of 97,719 ft/sec in order to give us an apoapsis of about 40 AU (Pluto's mean orbital radius, if memory serves). If we wanted to do a close pass of the sun, we could add that 38,771 IN THE OPPOSITE DIRECTION OF EARTH'S MOTION AROUND THE SUN to give us a periapsis closer to the sun (something like a closest approach of 0.2 AU. Do I need to go any further to show that there is no net benefit of doing this? Maybe I do -- obviously more delta-V will have to be added at closest approach to raise apoapsis to Pluto's orbital radius. About 27,500 ft/sec. In fact, for decreasing periapsis altitudes the penalty decreases. Note that this assumes a Pluto flyby, not rendezvous. The penalty of the "gravity well drop" would be even greater if we wanted to match orbits with Pluto. In the orbital mechanics world this is called a bi-elliptic transfer with interior conjunction. Can the person who originally claimed a benefit for this please explain again? Maybe I missed something, but this sure sounds like what you were talking about. Shag -- Rob Unverzagt | Last call for alcohol. shag@aerospace.aero.org | Last call for freedom of speech. unverzagt@courier2.aero.org | - Jello Biafra ------------------------------ Date: Fri, 26 Feb 1993 21:05:49 GMT From: Paul Dietz Subject: SOLAR gravity assist? Yup. Newsgroups: sci.space >> Paul, go back and read Bill's posting much more carefully. He really >> is talking about a Jupiter-style gravity assist, not an Oberth gravity- >> well maneuver. And no, he has not lost his marbles. >Thanks, Henry. This is the nicest thing anybody's said about me all week... Yeah, yeah, I know, Henry. I reacted as I did because the purely gravitational boost from the acceleration of the sun by Jupiter is going to be very small; naively, the effect at infinity will be at most on the order of the velocity of the sun in the solar system rest frame, which is on the order of 10 meters per second. The potential benefit from the Oberth effect is more than 3 orders of magnitude larger. Paul ------------------------------ Date: 26 Feb 93 22:17:39 GMT From: "Mark D. Looper" Subject: SOLAR gravity assist? Yup. Newsgroups: sci.space higgins@fnalf.fnal.gov (Bill Higgins-- Beam Jockey) writes: > (lotsa interesting stuff regarding a pure gravity assist using the mass of the sun and its distance from the true solar system barycenter, which I hope to tackle during an airplane flight next week...) >Extra credit questions: ... >... 4. How *do* you engineer a spacecraft to go arbitrarily close to the >Sun? (Spare me Brin's "refrigerator laser," I already know about it >and his ship uses magic technology for its other systems.) The Solar Probe spacecraft, a proposed mission to whip by the sun at about 3 solar radii above the photosphere, will hide behind a big conical heat shield of "carbon-carbon" (whatever that is) composite material. It will not take pictures of the sun, but rather will carry instruments to measure fields and particles that can come behind the shield to be observed; it may also carry a camera to look _away_ from the sun to photograph light backscattered off tenuous coronal material. The weird-o thing about this is that, whereas outer-planet spacecraft have to carry Radioisotope Thermal Generators (RTG's) for power where sunlight is too weak for solar panels, the Solar Probe will have to use RTG's where the sunlight is too _strong_ for solar panels! Of course, in order to kill its angular momentum enough to get that close to the sun, it may make use of Jupiter for a gravity assist (as Ulysses did to get kicked out of the ecliptic plane), at which distance it'd need RTG's anyway. In a previous post, I mentioned that the idea of a "Fire and Ice" trajectory using a solar assist to get to the outer solar system more rapidly has been considered for the Interstellar Probe (a mission _designed_ to reach the heliopause and the local interstellar medium, where the Voyagers only _hope_ to do so); the composite heat-shield idea was to be used there as well, I think. Note, however, that this was not the "pure gravity assist" being discussed, but rather incorporated a delta-v burn at perihelion; presumably, whatever the merits of a pure gravity assist, it works better to use thrusters too. --Mark Looper "Hot Rodders--America's first recyclers!" ------------------------------ Date: Fri, 26 Feb 1993 19:20:24 GMT From: Gary Coffman Subject: SSF Resupply (Was Re: Nobody cares about Fred?) Newsgroups: sci.space In article <1993Feb25.182645.27397@iti.org> aws@iti.org (Allen W. Sherzer) writes: >In article <1993Feb25.145255.18392@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes: >>Since we *are* counting on Shuttle for the >>short run, there's no reason to incur the upfront costs of modifying >>off the shelf thruster packs now. > >Let's see, we are looking at one to two flights a year dedicated to >replacing thrusters. That's roughly 50 flights over the life of the >station. Half could be eliminated with refueling so we are looking >at a savings of over $12 billion by refueling in space. > >Are you actually saying that saving $12 BILLION isn't a good reason to >incur that upfront expense for something you say is simple to do? I'm saying the reality of SSF upfront funding (remember the chart you so convienently deleted?) is so constrained that we're using hydrazine thrusters because development money wasn't available for H2/O2 thrusters. It doesn't matter how much a technology may save in the out years if funding to develop it isn't available in current year budgets. This is similar to the situation that led to Shuttle having SRBs instead of liquid flyback boosters, though on a smaller scale. Without the upfront funding, you make do with what you already have available. Gary -- Gary Coffman KE4ZV | You make it, | gatech!wa4mei!ke4zv!gary Destructive Testing Systems | we break it. | uunet!rsiatl!ke4zv!gary 534 Shannon Way | Guaranteed! | emory!kd4nc!ke4zv!gary Lawrenceville, GA 30244 | | ------------------------------ End of Space Digest Volume 16 : Issue 243 ------------------------------