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Space Forum / Space Flight / January 2004HST: why considered "dead" without Shuttle visits?
Hello! I've read in few articles dealing with the priorities change in NASA that HST will be let to naturally die as a result of Shuttle service missions cancellation. Why is it considered such an absolute requirement to have a manned service mission? If memory serves, a Shuttle mission cost is around 450-475 M$, how much could it cost to designin a robotic mission? Take the design of the Shuttle's RMS or maybe even the complete hardware if spares exist, attach to it another similar "arm" with different "tool-holding adaptors", also attach few cameras, telemetry and have some fuel reserve to boost the HST to a higher orbit. Launch the "thing", attach it the same way Shuttles RMS would attach and boost it to a higher orbit or perform a repair via telemetry, with the operator wearing a VR gougles. How difficult/expensive such a design/mission would be? ****************************************************************************** * Arie Kazachin, Israel, e-mail: ariek@attglobal3.14159265358979323846.net * ****************************************************************************** NOTE: before replying, leave only letters in my domain-name. Sorry, SPAM trap. >...Why is it considered such an absolute >requirement to have a manned service mission? Because current operational space robotics hardware cannot even come close to equaling the manual dexterity of a spacesuited astronaut. Hubble is complicated, and it wasn't designed for robotic servicing. Adequately-dextrous robotics are probably possible, but they are an advanced research topic, not something you can confidently ship up with a high probability of things working right the first time. >...Take the design of the Shuttle's RMS or maybe even >the complete hardware if spares exist, attach to it another similar "arm" >with different "tool-holding adaptors"... Uh, the "hand" at the end of the shuttle arm is the size of a garbage can, and all it can do is grab objects (which in practice have to be of equal or greater size) which have standard grapple fixtures. It's not something you can use to disconnect walnut-sized electrical connectors.  SignatureMOST launched 30 June; science observations running | Henry Spencer since Oct; first surprises seen; papers pending. | henry@spsystems.net > Hello! > [quoted text clipped - 4 lines] > mission cost is around 450-475 M$, how much could it cost to designin > a robotic mission? As I understand Hubble, it is not meant for maintenance in space, or at least not optimized for maintenance in space. A great deal of manual dexterity is required to handle the small screws and tight spaces inside the Hubble. I don't know that teleoperated systems deliver adequate performance yet. Mike Miller, Materials Engineer >As I understand Hubble, it is not meant for maintenance in space, or >at least not optimized for maintenance in space. A great deal of >manual dexterity is required to handle the small screws and tight >spaces inside the Hubble. No, Hubble *was* meant for maintenance in space, although as usual (repeating a mistake made on Skylab), they cheaped out and decided that some portions of it wouldn't break and hence wouldn't need to be set up for maintenance... and of course, some of those *have* needed maintenance. But it was always planned that things like instrument changes would be done by spacewalking astronauts, and that was very definitely designed in. >I don't know that teleoperated systems deliver adequate performance yet. Definitely not. Some of the more ambitious designs have a goal of equaling the capabilities of a spacesuited astronaut, but they're not there yet. SignatureMOST launched 30 June; science observations running | Henry Spencer since Oct; first surprises seen; papers pending. | henry@spsystems.net [snip] >No, Hubble *was* meant for maintenance in space, although as usual >(repeating a mistake made on Skylab), they cheaped out and decided that >some portions of it wouldn't break and hence wouldn't need to be set up >for maintenance... and of course, some of those *have* needed maintenance. That reminds me one of the great bits from "The Hitchhiker's Guide to the Galaxy" trilogy, book 5: "The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at or repair". :-) :-) :-) >But it was always planned that things like instrument changes would be >done by spacewalking astronauts, and that was very definitely designed in. [quoted text clipped - 4 lines] >equaling the capabilities of a spacesuited astronaut, but they're not >there yet. OK, so if currently there is nothing close to being ready for "one launch solution", maybe a two step approach might be used: first laucn something that need only to grab the HST (at the same point the Shuttle RMS grabbed it) and which has fuel reserve to boost the HST to a higher orbit where it can stay for few good years. Later on, when robotic "hands" will become capable enough, launch a repair mission (robotic). Another possibility (assuming HST orbit had been boosted): since NASA intends to develop a CEV (Crew Exploration Vehicle) capable of carrying a crew far beyound LEO, a service mission to HST is a good candidate for a test flight for such a vehicle. ****************************************************************************** * Arie Kazachin, Israel, e-mail: ariek@attglobal3.14159265358979323846.net * ****************************************************************************** NOTE: before replying, leave only letters in my domain-name. Sorry, SPAM trap. henry@spsystems.net (Henry Spencer) wrote in message > Definitely not. Some of the more ambitious designs have a goal of > equaling the capabilities of a spacesuited astronaut, but they're not > there yet. Underwater construction rovers on oil rigs and pipelines etc.. have largely replaced deep sea divers for most new construction work. Its not by very dexterous robots but by deliberately avoiding structures that need very dexterous robots, ie special nuts and bolts with large clearances and highly specialised manipulators. One big difference is that there is a lot more experience with underwater construction and maintenance than equivalent space activities. Also the rovers don't have the weight constraints (they are very heavy) and still cost a lot (about $5M). Older rigs still need to use divers but usually smaller crews with rover aids. The point i wish to make is that it would be better to meet half way between highly dexterous robots and structures specifically designed to be constructed and maintained by robots. IMHO of course. Greg > henry@spsystems.net (Henry Spencer) wrote in message >> Definitely not. Some of the more ambitious designs have a goal of [quoted text clipped - 6 lines] > that need very dexterous robots, ie special nuts and bolts with large > clearances and highly specialised manipulators. Which HST most definitely does not have. > One big difference is that there is a lot more experience with > underwater construction and maintenance than equivalent space [quoted text clipped - 5 lines] > between highly dexterous robots and structures specifically designed > to be constructed and maintained by robots. IMHO of course. A valid point for future spacecraft, but alas it will do HST no good. SignatureJRF Reply-to address spam-proofed - to reply by E-mail, check "Organization" (I am not assimilated) and think one step ahead of IBM. >> Definitely not. Some of the more ambitious designs have a goal of >> equaling the capabilities of a spacesuited astronaut, but they're not [quoted text clipped - 5 lines] >that need very dexterous robots, ie special nuts and bolts with large >clearances and highly specialised manipulators. The robotics people have been suggesting for a number of years now that the spacecraft people do likewise. So far, the spacecraft guys haven't bought into it -- they have assessed the chances that their stuff will ever be serviced by a robot as so slight that it's not worth the cost in mass and design problems. Given their historical preoccupation with squeezing absolute maximum functionality out of absolute minimum mass, selling this idea to them will be very difficult. The more dextrous the robots are -- and thus, the fewer the compromises needed to permit robotic servicing -- the easier it will be. SignatureMOST launched 30 June; science observations running | Henry Spencer since Oct; first surprises seen; papers pending. | henry@spsystems.net > No, Hubble *was* meant for maintenance in space, although as usual > (repeating a mistake made on Skylab), they cheaped out and decided that > some portions of it wouldn't break and hence wouldn't need to be set up > for maintenance... and of course, some of those *have* needed maintenance. Being an optimist, I was half correct. :) Heh. I learn so much by being wrong on these newsgroups. Mike Miller, MatE >>As I understand Hubble, it is not meant for maintenance in space, or >>at least not optimized for maintenance in space. A great deal of [quoted text clipped - 5 lines] >some portions of it wouldn't break and hence wouldn't need to be set up >for maintenance... It's not cheaping out, it's designing for the real world. It's very difficult to provide every component with clear access, and large (spacesuit operable) connectors and fasteners etc... If you had infinite volume available the problem becomes much simpler, but the designers/builders of Hubble didn't have infinite volume. There are many things to cast aspersions at NASA about, but doing so over simple engineering decisions and cost v. benefit analyses that don't meet some absurd standard is not helpful to anyone. >and of course, some of those *have* needed maintenance. Again, welcome to the real world, vice the ivory tower. In the real world constants aren't and variable won't. D. SignatureThe STS-107 Columbia Loss FAQ can be found at the following URLs: Text-Only Version: http://www.io.com/~o_m/columbia_loss_faq.html Enhanced HTML Version: http://www.io.com/~o_m/columbia_loss_faq_x.html Corrections, comments, and additions should be e-mailed to om@io.com, as well as posted to sci.space.history and sci.space.shuttle for discussion. >>No, Hubble *was* meant for maintenance in space, although as usual >>(repeating a mistake made on Skylab), they cheaped out and decided that [quoted text clipped - 6 lines] >infinite volume available the problem becomes much simpler, but the >designers/builders of Hubble didn't have infinite volume. Unfortunately for this theory, some of the problems occurred in places where there were no volume constraints (e.g., no provision for replacing the magnetometers, which were external). People simply made assumptions, some of which turned out to be wrong, about which things would need fixes. On Skylab it was even worse, with major areas of the exterior lacking in handholds because they were put only in places where somebody could *prove* that they would be needed. There is designing for the real world, and then there is designing for an imaginary world in which your predictions are always right and there is no need to take even simple precautions when the predictions say they are unnecessary. NASA is very big on predictions, but is not consistently attentive to the possibility that the predictions might be wrong. They do get this right sometimes -- the ISS airlock gear includes "contingency toolboxes", with an assortment of general-purpose gear to "provide a generic capability to react to unforeseen situations" -- but not always. SignatureMOST launched 30 June; science observations running | Henry Spencer since Oct; first surprises seen; papers pending. | henry@spsystems.net > There is designing for the real world, and then there is designing for an > imaginary world in which your predictions are always right and there is no > need to take even simple precautions when the predictions say they are > unnecessary. In other areas of human endeavour, this is called, e.g., defensive driving or indeed defensive engineering. > -- the ISS airlock gear includes "contingency > toolboxes", with an assortment of general-purpose gear to "provide a > generic capability to react to unforeseen situations" -- but not always. Possibly triggered by that little "problem" some Mir cosmonauts had when they barely managed to pry open a stuck hatch in time? Jan |
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