For Astronaut Neil Armstrong, at the controls of the frail, spidery craft, a crisis in flight was nothing new. In 1966 he had subdued the wildly gyrating Gemini 8 when one of its thrusters stuck. More recently, he had ejected safely from the "flying bedstead," a 752 jet-powered lunar-landing training vehicle, just before it crashed. Now he would need all the coolness and skill acquired during 500 earthbound hours in simulators and during years test-flying the X-15 and other experimental aircraft for the National Aeronautics and Space Administration.

The problem was not completely unexpected. Shortly after Armstrong and his companion, Edwin (Buzz) Aldrin, had begun their powered dive for the lunar surface ten minutes earlier, they had checked against landmarks such as crater Maskelyne (below) and discovered that they were going to land some distance beyond their intended target.

And there were other complications. Communications with earth had been blacking out at intervals. These failures had heightened an already palpable tension in the control room in Houston. This unprecedented landing was the trickiest, most dangerous part of the flight. Without information and help from the ground, Eagle might have to abandon its attempt.

Moreover, the spacecraft's all-important computer had repeatedly flashed the danger signals "1201" and "1202," warning of an overload. If continued, it would interfere with the computer's job of calculating altitude and speed, and neither autopilot nor astronaut could guide Eagle to a safe landing.

Eagle's Descent Fuel Runs Low

Armstrong revealed nothing to the ground controllers about the crater ahead. Indeed, he said nothing at all; he was much too busy. The men back on earth, a quarter of a million miles away, heard only the clipped, deadpan voice of Aldrin, reading off the instruments.

"Hang tight; we're go. 2,000 feet."