From: sylvia@email.invalid   
      
   On 14/11/2022 12:09 am, Alain Fournier wrote:   
   > 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   
   >   
      
   I think the problem with aerobraking is that there's a limit on how much   
   energy it can shed on the first pass. So the question then, is where   
   will it go? I suppose it won't leave the Earth-Moon system - probably.   
   But it could then be in a highly elliptical orbit taking days for each   
   pass. Perhaps with no limits on time in space it would be doable, but   
   the shuttle did have such limits.   
      
   So we're still on zero ;)   
      
   Sylvia.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)