Four astronauts blasted off from Kennedy Space Center on Wednesday evening, beginning a 10-day journey around the Moon that will carry them farther from Earth than any human has ever travelled. But the true gamble of NASA's Artemis II mission won't play out in deep space. It comes down to the last minutes before splashdown, when the Orion capsule punches into Earth's atmosphere at roughly 25,000 mph.
That will mark the fastest crewed re-entry ever attempted. And the one barrier standing between the crew and temperatures of 2,760°C has already shown signs of failure.
