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)
“I feel free as a bird. I’m in a unique position because I’m the boss. I buy what I like. I initiate things. I can experiment with all kinds of things I think the kids might be interested in. Nobody interferes. For me, it’s no chore to go to work. Most people never get to do this at any time in their lives.”
—Sarah Houghton, U.S. librarian. As quoted in Working, book 9, by Studs Terkel (1973)