What are the differences and why did SpaceX prefer to use PICA?
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$\begingroup$ Interesting question! Is it possible to add a link or reference to a source supporting that SpaceX does use PICA? How do we know this is true? Thanks! $\endgroup$– uhohJan 9, 2021 at 0:17
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2$\begingroup$ When NASA invented it, the claim was that it was lighter and cheaper. I guess that worked out! $\endgroup$– Organic MarbleJan 12, 2021 at 21:51
1 Answer
PICA is less dense than other materials and enables a lighter heatshield.
Previous materials like fully-dense Carbon Phenolic (heritage entry grade Carbon Phenolic) used on more extreme missions like Pioneer Venus and the Galileo probe are propbably overkill for a LEO entry and are no longer capable of being produced:
It doesn't hurt that NASA strongly supported SpaceX in making its cargo Dragon heatshield: