From: mooregr@deletethisgreenms.com   
      
   "JF Mezei"  wrote in message news:74qYK.341737$wLZ8.104544@fx18.iad...   
   >   
   >On 2022-09-26 08:34, David Spain wrote:   
   >   
   >> As Rand Simberg points out on his blog a whole set of clocks start   
   >> ticking once the SLS rocket rolls out of the VAB.   
   >   
   >I can understand SRBs which  have a "best before" date because   
   >built-already fueled.    I can understand limits on how many times you   
   >can fill/empty the tanks since going from tropical to cryo temperature   
   >cycles  impacts the metals.   
   >   
   >But to design the Orion Capsule such that it either doesn't get power   
   >from pad or didn't bother with provisions to power experiments while at   
   >pad is very strange for NASA. Same with the flight termination system   
   >whose batteries should be able to be recharged while at pad.   
      
   Two schools of thought on something like that:   
   1) If we're launching only once or twice a year, why develop all the   
   infrastructure at the pad?   
   2) On the other hand, because we plan on only launching once or twice a   
   year, it could be we're at the pad for long periods of time, so we should   
   develop the need for it.   
      
   Think of it this way too. For a variety of reasons Apple started the trend   
   of not being able to quickly/easily swap out batteries on their iPhones. For   
   one, it makes it lighter. Fewer connections, etc. For another, "well folks   
   will upgrade before the battery dies..."   
      
   Also, rechargeable batteries are a bit more complicated, adds weight,   
   potential outgassing, potential over charging, etc. So you can argue it   
   might be safer to do all that work in a separate building, not on the rocket   
   itsefl.   
      
      
      
   >   
   >The odds of delays at pad are the same whether rocket is reusable or   
   >not.  And the cost of providing pad power to these systems wouldn't be   
   >that great compared to overall cost.   
   >   
   >It is just strange that pedantic NASA wouldn't have required the rocket   
   >to be able to stand at pad without using batteries.   
   >   
   >> continue on the Shuttle even after it had been rolled out to the pad.   
   >> SLS does not have this, because why would you need to service an   
   >> *expendable* rocket?   
   >   
   >   
   >It was decided to complete preparation at the pad, and load payloads at   
   >the pad, hence the RSS for shuttle. But the shuttle itself was getting   
   >pad power and the crew compartment was fully powered and experiments,   
   >fridges etc powered by pad until a minute or two before launch.   
   >   
   >The fact that SLS can't be maintained at pad is all the more reason to   
   >allow it to be powered by the pad since changing AA or CR2032 batteries   
   >spread throughout the stack requires roll back to the VAB.   
      
   I would tend to agree. Shuttle, for all its problems WAS in theory designed   
   for quick servicing, which meant being able to do a good deal of work at the   
   pad.   
   SLS obviously wasn't.   
      
   Heck, even the Saturn V had the mobile service structure!   
      
   --   
   Greg D. Moore                   http://greenmountainsoftware.wordpress.com/   
   CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net   
   IT Disaster Response -   
   https://www.amazon.com/Disaster-Response-Lessons-Learned-Field/dp/1484221834/   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)