NASA’s Orion Spacecraft is About to Face its Final Test

upstart writes:

NASA's Orion spacecraft is about to face its final test:

NASA's Artemis I mission is nearly complete, and so far Orion's daring flight far beyond the Moon has gone about as well as the space agency could hope. However, to get a passing grade, the mission must still ace its final test.

This final exam will come on Sunday, when the spacecraft starts to enter Earth's atmosphere at 12:20 pm ET (17:20 UTC). During the course of the next 20 minutes, before Orion splashes down in the Pacific Ocean off of Mexico's Baja Peninsula, it will need to slow down from a velocity of Mach 32 to, essentially, zero before dropping into the water.

This is no small feat. Orion has a mass of 9 metric tons, about the same as two or three large elephants. Its base, covered with a heat shield designed to slowly char away during passage through Earth's atmosphere, must withstand temperatures near 3,000 degrees Celsius.

There are two main elements for this reentry that NASA is aiming to test-the performance of this heat shield and of its parachute system. For the mission's planners, the heat shield is the biggest concern.

"Reentry is our priority-one objective for a reason," said Mike Sarafin, who leads the Artemis I mission management team. "There is no arcjet or aerothermal facility here on Earth capable of replicating hypersonic reentry with a heat shield the size of Orion. And this is a brand-new heat shield design. It is a safety-critical piece of equipment. It is designed to protect the spacecraft and the astronauts on board. So the heat shield needs to work. We can buy down some of that risk on the ground, but not in terms of coming back at Mach 32."

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