henry@utzoo.uucp (Henry Spencer) (09/12/88)
ESA engineers are investigating a LOX-arm retraction problem that almost aborted the July 21 Ariane launch: the third-stage LOX arm stopped partway through its retraction sequence, but moved clear just in time for the launch to continue. SDIO fails to meet its Aug 1 target for revised recommendations on the Space Based Interceptor. A major DoD review of SBI is imminent, and with SDIO not having got its own act together, SBI's supporters are not optimistic. Flight readiness firing of the shuttle, Aug 10, goes okay. Remaining milestones before a late-Sept launch are one more SRB test, complete data review of the FRF, SSME post-FRF checkout, and successful repair of the RCS nitrogen-tetroxide leak. The FRF slipped a week after a valve problem aborted the Aug 4 attempt, but the valve replacement was completed ahead of schedule. (It now looks like the problem may have been sensor error.) The only real problem noticed during the FRF countdown was a bit of nitrogen in a fuel line; this may be a minor leak or a measurement error. Analysis of SRB aft-skirt loads will continue for several days. Infrared and mass-spectrometer hydrogen- leak detector results look clean. The next job [completed successfully] will be sealing the RCS leak. This will be done by cutting through the aft wall of the cargo bay and the forward wall of the OMS pod, clamping a clamshell fitting around the leaking joint, and filling it with sealant under pressure. The wall cutouts will be closed by bolting aluminum plates over them; the plates will be removable in case this needs to be done again, and will in fact be stronger (although heavier) than the areas of wall removed. Chinese controllers prepare to command reentry of Chinese satellite carrying a secondary West German materials payload. Inmarsat to issue RFP for new-generation Inmarsat series using multiple spot beams for marine navigation and communication. Soviet cosmonaut Anatoly Levchenko dies Aug 6 of a brain tumor. He flew on the Soyuz TM-4 mission to Mir last December, and may have been meant to be commander for the first manned mission of the Soviet shuttle. Spacehab and NASA sign deal giving Spacehab six partial shuttle flights, starting 1991, with payment deferred until after each flight. SDIO begins work on "Super", a survivable solar array hardened against the Van Allen belts, lasers, particle beams, and nuclear explosions. It will be flight-tested in 1993, maybe from the shuttle, and the test might carry piggyback experiments that could benefit from having 5-10kW of power available. Super is not yet slated for any particular uses, but the Boost Surveillance Tracking Satellite is an obvious candidate. Also underway is a less ambitious project called Scopa, started by the USAF and now getting some SDI funding too. The idea here is to put small concentrators over the individual cells of a solar array, with the concentrators designed so that light coming in at an angle will not reach the cells themselves. This shields the cells against laser attack from any direction except precisely head on. A 500W Scopa panel will fly in FY1990. SDI studies methods of retrieving malfunctioning nuclear reactors from orbit. One possibility is using a modified OMV to tow a failing reactor satellite to higher orbit. The study will probably recommend modifications to SDI's space-reactor project, SP-100, such as standard grappling fittings. SDI says a joint effort in space-reactor rescue with the USSR would be sensible, although no formal approach has yet been made. Cosmos 1900, the ailing Soviet nuclear radarsat, is due to reenter early in Sept. Shuttle-C unmanned heavylift shuttle derivative is gaining support as an interim heavylift booster, specifically for space-station assembly. The interest is especially strong since ALS no longer includes the goal of a near-term "interim ALS" heavylift booster. Phase 2 study contracts for Shuttle-C were awarded recently. It could be ready in 1993-4, using SRBs, tank, and engine section identical to the shuttle, but with the rest of the orbiter replaced by a cylindrical payload shroud. Payload to low orbit could be 178 klbs. Five shuttle-C launches could replace thirteen shuttle launches (out of twenty) in station assembly. (There is a problem in that the station people must plan on using shuttle launches unless/until Shuttle-C is officially funded for development.) Initial Shuttle-C SRBs would probably be drawn from the stock of pre-Challenger SRBs still in storage but no longer considered safe for manned flight. No attempt would be made to recover Shuttle-C's SSMEs; they would be SSMEs that are near the end of their rated lives as shuttle engines. NASA is no longer hoping for more than about 10 flights per SSME, and this will create a substantial pool of "retired" engines by the early 1990s. SSME recovery for Shuttle-C is considered too complex and costly. Various payload masses could be accommodated by using either two or three SSMEs, running them at either 100% or 104% of rated thrust, and by using either ordinary shuttle SRBs or the new ASRMs which will be available in the 90s. A three-SSME, 104%, ASRM Shuttle-C could launch 190 klbs into low orbit from the Cape. Development costs including first flight are estimated at $1.9G, although NASA thinks that number (derived from general cost models rather than detailed analysis) is too high, given that the only major work needed is the payload shroud and the return to production of orbiter aft thrust structures. A generally-favorable OTA report said that $800M should be adequate; NASA is studying the issue. The OTA study said that Shuttle-C is not cost-effective if flight rate rises above 2-3 flights per year, given its high incremental costs ($235M per launch), but it could be quite cost effective at those rates as a way of offloading the shuttle. Inmarsat awards $8M contract to China Satellite Launch and Tracking Control General to provide tracking/telemetry/command services for the Pacific-area Inmarsat 2 satellites, starting in 1990. A dedicated tracking station near Beijing will be used. -- NASA is into artificial | Henry Spencer at U of Toronto Zoology stupidity. - Jerry Pournelle | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
ewiles@netxcom.UUCP (Edwin Wiles) (09/12/88)
In article <1988Sep12.032459.25617@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >No attempt would be made to recover Shuttle-C's SSMEs; they would be >SSMEs that are near the end of their rated lives as shuttle engines. Am I correct in believing: a) These are the 'main' liquid fuel engines for a shuttle? and b) That they would make it to the same orbit as the payload? If so, these engines could be recovered in orbit, for use in 'scooters'. Some sort of small craft that didn't need much in the way of thrust, so that they could be run at something like 10% (or less) of their normal thrust. If the Shuttle-C would have OMS engines as well, these would be even more useful in this capacity. The SSMEs being used for larger versions, and the OMSs being used for smaller 1 or 2 man versions. Would their 'wear-and-tear' at that point in their life make them totally unuseable? Even if they were severely downrated for maximum thrust? What does the net think? Does anyone know what NASA thinks? -- ...!hadron\ "Who?... Me?... WHAT opinions?!?" | Edwin Wiles ...!sundc\ Schedule: (n.) An ever changing | NetExpress Comm., Inc. ...!pyrdc\ nightmare. | 1953 Gallows Rd. Suite 300 ...!uunet!netxcom!ewiles | Vienna, VA 22180
dep@cat.cmu.edu (David Pugh) (09/13/88)
In article <972@netxcom.UUCP> ewiles@netxcom.UUCP (Edwin Wiles) writes: >If so, these engines could be recovered in orbit, for use in 'scooters'. >Some sort of small craft that didn't need much in the way of thrust, so >that they could be run at something like 10% (or less) of their normal >thrust. If the Shuttle-C would have OMS engines as well, these would be >even more useful in this capacity. The SSMEs being used for larger >versions, and the OMSs being used for smaller 1 or 2 man versions. I don't think this would work, for several reasons. First, the SSMEs probably have some minimum thrust (10%?). Even 10% of a SSME would give a scooter quite a kick. Might not be a bad idea to use them for an OTV, though -- just park it next to the space station and use it (once) to put something heavy into a Clarke orbit or (here's hoping) a lunar or escape orbit. Another problem is that SSMEs need a lot of maintenance after a launch -- which the space station isn't equiped to provide. Not to say this isn't a good idea, however. Perhaps we could sell SSMEs to the Soviets for use in building their solar power satellites, manned mars missions, etc.. -- David Pugh ....!seismo!cmucspt!cat!dep
bob@etive.ed.ac.uk (Bob Gray) (09/13/88)
In article <972@netxcom.UUCP> ewiles@netxcom.UUCP (Edwin Wiles) writes: >In article <1988Sep12.032459.25617@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >>No attempt would be made to recover Shuttle-C's SSMEs; they would be >>SSMEs that are near the end of their rated lives as shuttle engines. > >... these engines could be recovered in orbit, for use in 'scooters'. and this time NASA, if the Shuttle-C is goint to be mostly expendable, build the space station resource nodes onto the external tank and deliver the whole thing to orbit. You double the useable volume of the space station in one go. Use the empty tank as a large experimental chamber, as a gymnasium, as a zero g garden, anything! Maybe ESA could buy an external tank for this purpose. Even better if it is the one on the shuttle-C delivering Columbus to orbit. (if things ever get that far). Bob.
mce@tc.fluke.COM (Brian McElhinney) (09/13/88)
henry@utzoo.uucp (Henry Spencer) writes: > No attempt would be made to recover Shuttle-C's SSMEs; they would be > SSMEs that are near the end of their rated lives as shuttle engines. > NASA is no longer hoping for more than about 10 flights per SSME, and > this will create a substantial pool of "retired" engines by the early > 1990s. So SSMEs do not last forever. :-) Some questions: 1) How much does a single SSME cost? They can't be cheap! 2) What was the intended number of flights per SSME? 3) Does NASA's latest budget include the costs of a new SSME every ten flights? Brian McElhinney mce@tc.fluke.com
henry@utzoo.uucp (Henry Spencer) (09/14/88)
In article <972@netxcom.UUCP> ewiles@netxcom.UUCP (Edwin Wiles) writes: >>No attempt would be made to recover Shuttle-C's SSMEs; they would be >>SSMEs that are near the end of their rated lives as shuttle engines. > >Am I correct in believing: > a) These are the 'main' liquid fuel engines for a shuttle? Yes, SSME is Space Shuttle Main Engine. > b) That they would make it to the same orbit as the payload? Yes. >If so, these engines could be recovered in orbit, for use in 'scooters'. >Some sort of small craft that didn't need much in the way of thrust, so >that they could be run at something like 10% (or less) of their normal >thrust... This would not work, I'm afraid. For one thing, there are limits to how much you can throttle a rocket engine; I doubt very much that an SSME would work at 10%. Certainly they aren't rated for it and aren't designed for it. For another thing, most booster engines -- I think the SSMEs are included -- are not restartable without an overhaul. Their ignition systems, in particular, are basically one-shot. That is not a trivial problem; starting a big engine safely can be quite tricky. > If the Shuttle-C would have OMS engines as well, these would be >even more useful in this capacity... Now *that* sounds like a reasonable idea. The OMS engines are down in a practical thrust range, and they are restartable. One possible wart: I don't know how easy it would be to refuel them in orbit. -- NASA is into artificial | Henry Spencer at U of Toronto Zoology stupidity. - Jerry Pournelle | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
henry@utzoo.uucp (Henry Spencer) (09/15/88)
In article <5163@fluke.COM> mce@tc.fluke.COM (Brian McElhinney) writes: > 1) How much does a single SSME cost? They can't be cheap! It depends on what assumptions you make, but no, they are not cheap. > 2) What was the intended number of flights per SSME? I think they started out hoping for 50. Then they scaled it back to 20. Now it's 10. > 3) Does NASA's latest budget include the costs of a new SSME > every ten flights? Three new SSMEs every ten flights, actually. I don't know whether it's explicitly in the budget, but with all the trouble they've been having with the SSMEs, I would expect so. -- NASA is into artificial | Henry Spencer at U of Toronto Zoology stupidity. - Jerry Pournelle | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall) (09/15/88)
In article <2961@pt.cs.cmu.edu> dep@cat.cmu.edu (David Pugh) writes: : In article <972@netxcom.UUCP> ewiles@netxcom.UUCP (Edwin Wiles) writes: : >If so, these engines could be recovered in orbit, for use in 'scooters'. : : I don't think this would work, for several reasons. First, the SSMEs : probably have some minimum thrust (10%?). Even 10% of a SSME would : give a scooter quite a kick. Might not be a bad idea to use them for : an OTV, though -- just park it next to the space station and use it : (once) to put something heavy into a Clarke orbit or (here's hoping) : a lunar or escape orbit. Another problem is that SSMEs need a lot : of maintenance after a launch -- which the space station isn't equiped : to provide. I suspect the greatest problem is simply that they use liquid oxygen & hydrogen, and you wouldn't be able to park your "scooter" very long without losing your propellant. They also might be difficult to start in 0 gee. But it might be worthwhile if we had an orbital storage facility for lunar oxygen. But by then SSME's will be old stuff. Would YOU trust a used SSME salesman? Larry Wall lwall@jpl-devvax.jpl.nasa.gov
henry@utzoo.uucp (Henry Spencer) (09/16/88)
In article <776@etive.ed.ac.uk> bob@etive.ed.ac.uk (Bob Gray) writes: >and this time NASA, if the Shuttle-C is goint to be mostly >expendable, build the space station resource nodes onto the >external tank and deliver the whole thing to orbit. Unfortunately, if you do things NASA's way, it is almost as expensive to use an external tank as it is to launch modules in the cargo bay. There are some non-trivial problems, like the fact that the ET's insulation will outgas in vacuum. These things can be solved, but it's not quite as easy as it looks. And of course, NASA doesn't really want to solve them, since it would take money away from politically-powerful contractors. >Maybe ESA could buy an external tank for this purpose. At the moment, I believe sales of ETs are restricted to US buyers. -- NASA is into artificial | Henry Spencer at U of Toronto Zoology stupidity. - Jerry Pournelle | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
wooding@daisy.UUCP (Mike Wooding) (09/16/88)
In article <776@etive.ed.ac.uk>, bob@etive.ed.ac.uk (Bob Gray) writes: > Use the empty tank as a large experimental chamber, as a > gymnasium, as a zero g garden, anything! > > Maybe ESA could buy an external tank for this purpose. > Even better if it is the one on the shuttle-C delivering > Columbus to orbit. (if things ever get that far). > Bob. Presumably before moving into the ET, some modifications would be required? The tanks are designed to seperate and contain LOX and LH, and are presumably short on access portals and life support systems. Would such modifications be feasible in orbit? m wooding
henry@utzoo.uucp (Henry Spencer) (09/18/88)
In article <1631@daisy.UUCP> wooding@daisy.UUCP (Mike Wooding) writes: > Presumably before moving into the ET, some modifications > would be required? The tanks are designed to seperate and > contain LOX and LH, and are presumably short on access > portals and life support systems. Would such modifications > be feasible in orbit? It's a significant problem. First, one must stabilize the tank -- it has no attitude control of its own. Then, one has to get into it. The tanks do have access hatches, although one would have to cut the sprayed-on insulator off the hatches first. The hatches are not as large as one would like, but they are adequate. If one is going to keep the tank pressurized, one must supply it with a "meteor bumper" shield against space debris -- the tank walls are not that thick. The shield can also help keep tank-produced debris under control: the sprayed-on insulator will outgas in space, and there will probably be some "popcorning" as a result, which will throw off bits of debris unless there is something to catch them. Temperature control will also be simplified by putting an outer shield on. Lastly, one needs a highly reliable solution to the reboost/de-orbit problem -- NASA is paranoid about a repetition of Skylab. All the above looks feasible. The people who are working on turning an ET into a gamma-ray telescope -- this is the only NASA-funded ET project at the moment -- have to do all this, and they say "no big deal". To use the tank as a space station, obviously more work is needed. A lot of equipment needs to be moved in. The tank's own internal frames are well suited for attaching stuff, but there is some worry about the overall structural strength -- during launch, the tank is stiffened to a considerable extent by high internal pressure. By itself, it's weaker than you'd like. One might like to have more than one hatch into the tank, for safety reasons. (NB all of this considers mostly use of the hydrogen-tank portion, which is several times the size of the LOX section, but that doesn't alter the issues much.) It would be better to strip the insulation off entirely, since the space station would prefer to minimize outgassing (it's a big enough problem already). Temperature control becomes more critical. Life support will need to be moved in. Internal partitions, preferably sound-absorbing ones, will be needed. And so on. There is potential there, but it's not quite as simple as one would like. Note especially that *any* modifications to the tank before launch are going to have to be approved as safe for flight, which is a massive headache. -- NASA is into artificial | Henry Spencer at U of Toronto Zoology stupidity. - Jerry Pournelle | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
knudsen@ihlpl.ATT.COM (Knudsen) (09/19/88)
In article <1988Sep17.222225.9422@utzoo.uucp>, henry@utzoo.uucp (Henry Spencer) writes: > highly reliable solution to the reboost/de-orbit problem -- NASA is > paranoid about a repetition of Skylab. Is an ET much of a threat if it re-enters at an unpredictable time? Are there any massive solid parts of it that would reach the ground in one piece at high velocity, like the Skylab's telescope mount? Overall the ET is pretty flimsy. There might be some 17-inch valves -- pretty heavy stuff, but maybe these are all on the orbiter. Would appreciate the facts from one who knows. Thanks, mike k
tneff@dasys1.UUCP (Tom Neff) (09/22/88)
With the frequent mention of insulation outgassing on the ET and the problems this would pose for re-use, it occurs to me to wonder if there isn't some non-gassing insulation we could use on ETs slated for re-use, or some kind of sealer coat we could apply over the existing insulation. -- Tom Neff UUCP: ...!cmcl2!phri!dasys1!tneff "None of your toys CIS: 76556,2536 MCI: TNEFF will function..." GEnie: TOMNEFF BIX: t.neff (no kidding)
bob@etive.ed.ac.uk (Bob Gray) (09/22/88)
In article <1988Sep17.222225.9422@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >.... Note especially that *any* modifications to >the tank before launch are going to have to be approved as safe for >flight, which is a massive headache. This is why I specifically mentioned the Shuttle-C and the proposals to use it to launch the major structural components of the space station. Including the ET in the design of the station components which make up the bulk of the Shuttle-C means a much larger habitable volume in the final space station, or a much more quickly growing station. Bob.
henry@utzoo.uucp (Henry Spencer) (09/22/88)
In article <6768@ihlpl.ATT.COM> knudsen@ihlpl.ATT.COM (Knudsen) writes: >Is an ET much of a threat if it re-enters at an unpredictable >time? Are there any massive solid parts of it that would >reach the ground in one piece at high velocity, like the Skylab's >telescope mount? Overall the ET is pretty flimsy. Skylab's biggest problem was its film safe, actually. There's nothing particularly massive on the ET, since it's built to be thrown away; I would think probably the biggest single lumps are the attachment struts, which have to be strong. However, there's just plain a *lot* of metal there, even if it's mostly fairly thin tank walls. And NASA is paranoid about the whole issue. -- NASA is into artificial | Henry Spencer at U of Toronto Zoology stupidity. - Jerry Pournelle | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
henry@utzoo.uucp (Henry Spencer) (09/25/88)
In article <794@etive.ed.ac.uk> bob@etive.ed.ac.uk (Bob Gray) writes: >>.... Note especially that *any* modifications to >>the tank before launch are going to have to be approved as safe for >>flight, which is a massive headache. > >This is why I specifically mentioned the Shuttle-C and the >proposals to use it to launch the major structural >components of the space station... Given the lack of spares, any Shuttle-C launch carrying major station components is going to have to meet very nearly the same safety specs as a manned launch. It's not going to gain you much. -- NASA is into artificial | Henry Spencer at U of Toronto Zoology stupidity. - Jerry Pournelle | uunet!attcan!utzoo!henry henry@zoo.toronto.edu