At just after 5:00 p.m., the crew wriggled into their bright orange pressure and survival suits, and prepared for the next major milestone, at 7:33 p.m., when they separated their conical Orion command module from the cylindrical service module, which contained their main engine and their four solar panels. Then, at 7:53 p.m., when the ship was just under 76 miles above the surface of the Earth, the crew oriented their capsule rump forward, so that the heat shield at the base of the module would be the first part of the ship to encounter the atmosphere. This is when the worrying began.
What is the Artemis II heat shield made of?
As with the Apollo spacecraft, Orion’s heat shield is made principally of a material known as Avcoat, a combination of epoxy resin and silica fibers, designed to absorb the fires of reentry and slowly burn off, or ablate, carrying the reentry heat away from the capsule and crew. That’s a big job, given that the heat shield must withstand temperatures of 5,000°F, half as hot as the surface of the sun, and significantly hotter than the 3,000°F a spacecraft returning from Earth orbit endures. Unlike Apollo’s heat shields, however, Orion’s had serious R&D problems.
Read the full article here
