From: marsh@panix.com   
      
   On Thu, 18 Mar 2021, JF Mezei wrote:   
      
   > Does the SLS core stage tank use the same foam as for the Shuttle's   
   > ET? Would all the post-Columbia research and refinements still be   
   > considered to be "current" or would much progress have been made   
   > since resulting in new significantly different foam formulation?   
      
   For what is the foam used?   
      
   > In terms of the Shuttle ET, it was mostly smooth except for perhaps 1/5   
   > that had ridges on the surface. What was the purpose/reason for only   
   > that portion having ridges? SLS doesn't appear to have such a zone.   
   >   
   > Does the foam have an expiry date? Since SLS has been delayed and   
   > delayed and delayed, I wonder if at one point they would have to ditch   
   > the tank/core because the foam has started to decompose?   
      
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