大美现在是用：PICA (Phenolic-Impregnated Carbon Ablator) ，是纳啥开发的

The heat shield on SpaceX's Dragon spacecraft is made of PICA (Phenolic-Impregnated Carbon Ablator) or PICA-X, a lightweight material designed to withstand high temperatures during re-entry.?

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The fabrication of PICA begins with the procurement of rayon, which is derived from wood pulp cellulose and is preferred over other carbon-based materials because of its low thermal conductivity. The rayon is carbonized and cast into a rigid block called FiberForm. The FiberForm is then infused with a low-density aerogel of phenolic resin that serves as the ablative material during reentry. Completed PICA billets can then be machined into tiles and installed on an aeroshell.

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