In article <C6DvGH.ApH@news.cso.uiuc.edu> jbh55289@uxa.cso.uiuc.edu (Josh Hopkins) writes: >prb@access.digex.net (Pat) writes: > >>I wrote: >>>prb@access.digex.net (Pat) writes: > >My data shows that the OMS engines hold 10,900 kg of propellant.  Of that, a  >substantial fraction is going to be used for the first OMS burn, the reentry >burn and the reserve.  So Pat, tell us how much fuel the altitude change is >going to take, and how much the EDO pallet, BUS-1 and extra parts are going >mass.  If you can make the numbers work out, _then_ I'll be interested.  After >you show us that it can be done, then tell us how much the EDO pallet, BUS-1 >and extra equipment is going to cost.   >  I don't know.  Does anyone in NASA land know how much fuel is budgeted for the altitude change?  Henry,  any figures on the mass  (full)  for the EDO pallet  plus it's dry weight?  How about for the dry mass of Bus-1?  it was being de-classified as i checked last.  Also, I need.  1)  current orbital parameters of HST   2)  projected  orbital parameters after re-boost.  3)  Discovery's  DRY weight  4) HST's Dry weight.   >>I somehow think they could train up a new  EVA in  8 months. > >First, while astronauts certainly have done EVAs with minimal planning, that was >because they _had_ to.  They don't like to do that as a general rule. >  So how long do they need to train?  a year?  2 years?  somehow I think 2-3 moths should be adequate.  >Second, remember why they had to improvise during Intelsat 6?  They were trying >to attach a motor to a piece of hardware that wasn't designed to do that.   >Trying to shortcut the training is only going to make a repeat more likely. >  Also because they significantly lacked on-orbit EVA experience.   The HST is designed for on-orbit servicing.  it should be a lot easier.  >Third, they don't have eight months.  They have however much time is left  >after someone comes up with a plan, shows it can work and gets it approved. >You may think I have a pessimistic attitude.  I think it's realistic.  I'm not >saying that the engineering task is impossible (few engineering tasks are).   >What I'm saying is that this is neither cost effective nor feasible under NASA >management. >  There comes a time in every project, to kill the management.  They can if neccessary, re-schedule the  HST mission.  December is not a drop dead date, unlike say the LDEF retrieval mission.     > >"All they have to do is soup it up?"  Just what does that mean?   >  I suspect, the BUS-1, may not have enough basic thrust for the HST re-boost.  it mayu need bigger tanks,  or bigger thrusters.   My understanding is the Second HST servicing mission is not a contingency.  My understanding is the mission  needs both a new FOC  and work on the electrical system,  plus another re-boost.     > >>If the SMT can avoid a second servicing mission that's $500 million >>saved. > >No Pat.  That's $500 million minus the cost of the new hardware, minus the cost >of the extra struff you want to bring along, minus development and mangement  >costs, minus extra operating costs.  TANSTAAFL. >  Somehow, i think the cost of an expendable SMT will be less then $500 million.  and the extra stuff is real cheap.  NASA has lots of suits,  MMU's, and the EDO pallets are re-usable.  Oh, one double magnum of champagne, now there's a couple hundred bucks.  >   > >Pat, not only is this messy and less reliable than a device that's _made_ to  >perform this task, it also ignores the point.  There is a desire to have  >astronauts available so that if the door fails to open, something can be done >about it.  Unless you can provide a very reliable way of reopening the door, >you haven't solved the problem.   That door has cycled, X times already.  Once after massive G loading. I somehow think they can work ou;reliability  methods to ensure the door works.  Also,  please tell me how some sort of sublimated  material  like CO2, or H2O  would manage to contaminate the mirror,  anything that goes to vapor state, shouldn't adhere to the mirror.  somehow, the door,  problem can be worked.  maybe they can put a one time spring on it.  what do they do now, if the door hangs up.  that door is part of a intrument safing mechanism.  if it hangs up tomorrow,  it'll be 8 months until someone gets up there witha crowbar to fix it.