July 7, 2019 at 5:16 am #26026
From Ars Technica (reprint from 2015):
No, a “checklist error” did not almost derail the first moon landing
From the archives: The cause of Apollo 11’s landing alarms is a lot more complicated.
Last week was the forty-sixth anniversary of the Apollo 11 moon landing—the first of the six crewed landings on our nearest celestial neighbor. In the years between 1969 and 1972, 12 human beings walked on the surface of the moon: Neil Armstrong, Buzz Aldrin, Pete Conrad, Al Bean, Alan Shepard, Ed Mitchell, Dave Scott, Jim Irwin, John Young, Charlie Duke, Jack Schmitt, and Gene Cernan. Each Apollo landing by necessity leapfrogged the previous by some notable amount, because even as Apollo 11 was preparing to lift off it was obvious that the money wasn’t coming and Project Apollo might be the only chance to visit the moon—perhaps for a long, long time.
Even though Apollo 10’s “dress rehearsal” had taken NASA through all but the final phase of the lunar landing two months before, there were still a large number of unknowns in play when Neil Armstrong and Buzz Aldrin separated Eagle from Columbia, leaving Michael Collins to watch his crewmates descend to the lunar surface—perhaps to stay there forever.
And as it turned out, the first landing on the moon almost did encounter disaster. Shortly after Eagle entered one of the most complicated stages of the descent, the guidance computer began throwing off alarms—very serious alarms, of a type no one in mission control or on the spacecraft was immediately familiar with. Back at MOCR2 in Houston, the burden to determine whether or not the alarms were benign—and therefore the decision to determine whether to abort the landing, blow the Eagle in half, and make an emergency burn to try to make it back up to Columbia—fell on the shoulders of two people: guidance controller Steve Bales and backroom guidance specialist Jack Garman.
“You can not operate in this room unless you believe that you are Superman, and whatever happens, you’re capable of solving the problem.” – Gene Kranz
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