From: alain245@videotron.ca   
      
   On Nov/13/2022 at 02:41, Sylvia Else wrote :   
   > On 13/11/2022 5:36 pm, JF Mezei wrote:   
   >> Catching up on "For all Mankind" (season 2, I am very late).   
   >>   
   >> They depict the shuttle as going to/from the moon.  Forgetting   
   >> landing/taking off on moon (and reality):   
   >>   
   >> If the payload pay had been filled with hydrazine tanks, could the OMSs   
   >> have gotten the shuttle to a moon orbit and back?   
   >>   
   >> Easy with plenty of space left in payload bay?   
   >> Close but no cigar?   
   >> Not even close?   
   >>   
   >> Any issue with the OMS engines running long enought for TLI delta-V (and   
   >> leaving moon orbit?) Or can all hydrazene engines run for short or long   
   >> period?   
   >>   
   >> Would fuel needed to go from LEO to moon and back have exceeded the   
   >> roughlty 15 tonnes payload max for takeoff?   
   >>   
   >>   
   >>  From a re-entry point of view at much higher speed, could tweating the   
   >> insulation (tiles, RCC) make this possible (thicker tiles and   
   >> carbon-carbon surfaces), or is this a "not even close" situation?   
   >>   
   >> And generic question: say payload bay has plenty of fuel: coming back to   
   >> Earth, would retrograde firing of OMS to put Shuttle into speed its   
   >> tiles could support end up costing roughly the same amount of fuel as   
   >> the TLI to get to moon? much less? more ?   
   >>   
   >>   
   >> If this is within realm of "possible", would it have costed less than   
   >> SLS to go around the moon? (and perhaps of there is space in payload   
   >> bay, drop off a LEM and bring it back).   
   >   
   > I'm pretty sure the shuttle orbiter could not survive a direct entry   
   > into the atmosphere from the moon. Not only would the thermal   
   > environment be too severe, but the mechanical stresses would likely   
   > exceed the limits of the structure. The Apollo missions pulled some   
   > serious gs on reentry, and the shuttle was never designed for that.   
   >   
   > The Wikipedia article for the Apollo missions indicate that the   
   > translunar injection required a delta-v of somewhat over 3km/s. If we   
   > assume that the shuttle were put onto a free return trajectory, and that   
   > on the return it needed to shed the same 3km/s of delta-v, then it would   
   > need 6km/s of delta-v.   
   >   
   > The Wikipedia article for the Shuttle's OMS system indicates that it   
   > used about 10 tonnes of propellant to achieve a 300m/s delta-v, for a 29   
   > tonne payload. We're talking about 20 times the delta-v, which even   
   > ignoring the propellant required to accelerate the propellant, is 200   
   > tonnes, or way above anything plausible. And note that this just takes   
   > you around the moon and back - you don't even get into lunar orbit.   
   >   
   > So, unless some gravity assist method can be found to get to the moon,   
   > the shuttle is not going there, and it's definitely not coming back intact.   
   >   
   > Sylvia.   
      
   You wouldn't need to shed the 3 km/s of delta-v on the way back. You use   
   aero-breaking, making multiple passes. So instead of having zero   
   probability to make it to the Moon and back as Sylvia was saying your   
   probability of doing it is double that ;-)   
      
      
   Alain Fournier   
      
   --- SoupGate-Win32 v1.05   
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