DOE scientists are using the Advanced Light Source to study atmospheric reentry heat shields, including PICA [IPEE-kahl], the type currently used by NASA and SpaceX. Which of the following best describes PICA?

W) A silicone-based heating pad

X) A highly-thermally-conductive epoxy

Y) A carbon fiber that slowly ablates

Z) Titanium shingles with heat sinks
Y) A CARBON FIBER THAT SLOWLY ABLATES