Powered Descent Initiation (PDI) is a term used during the
Apollo program Moon landing
A Moon landing is the arrival of a spacecraft on the surface of the Moon. This includes both crewed and robotic missions. The first human-made object to touch the Moon was the Soviet Union's Luna 2, on 13 September 1959.
The United S ...
missions to describe the maneuver of the
Apollo Lunar Module as it descended from
lunar orbit to a
rocket-powered landing.
"''Eagle'' was GO to ignite its descent engine, and
Armstrong Armstrong may refer to:
Places
* Armstrong Creek (disambiguation), various places
Antarctica
* Armstrong Reef, Biscoe Islands
Argentina
* Armstrong, Santa Fe
Australia
* Armstrong, Victoria
Canada
* Armstrong, British Columbia
* Armstrong ...
and
Aldrin
Aldrin is an organochlorine insecticide that was widely used until the 1990s, when it was banned in most countries. Aldrin is a member of the so-called "classic organochlorines" (COC) group of pesticides. COCs enjoyed a very sharp rise in popular ...
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."
[Moon Shot The Inside Story of America's Race to the Moon, Alan Shepard/Deke Slayton Page 17 First Edition]
References
{{reflist
Spaceflight concepts