Powered Descent Initiation (PDI) is a term used during the Apollo Moon landing missions to describe the maneuver of the Apollo Lunar Module as it descended from lunar orbit to landing.
"Eagle was GO to ignite its descent engine, and Armstrong and Aldrin locked their eyes to the glowing numbers displayed before them. They were almost at an invisible junction of height, speed, range, and time when everything would join together for commitment. When the instruments told them that they were 192 miles from their projected landing site, and were precisely 50,174 radar~measured feet above the long shadows of the moon, they would unleash decelerating thrust and begin slowing their speed for the touchdown.....this was it. PDI. Powered Descent Initiate."
Famous quotes containing the words descent and/or initiate:
“My life has been one long descent into respectability.”
—Mandy Rice-Davies (b. 1944)
“The need to become a separate self is as urgent as the yearning to merge forever. And as long as we, not our mother, initiate parting, and as long as our mother remains reliably there, it seems possible to risk, and even to revel in, standing alone.”
—Judith Viorst (20th century)