FLOWN APOLLO 11 LUNAR MODULE LANDING SEQUENCE.
EAGLE'S LANDING SEQUENCE AND DESCRIPTION BY BUZZ ALDRIN.
Three flown sheets from the Apollo 11 LM G & N dictionary, May-July 1969, 6 pp being "PGNS-43" to "PGNS-48," 8 by 5 ½ inches, each inscribed in ink by Buzz Aldrin.
Probably the most important sheets from the most significant flight event during the Apollo 11 mission. They list events and entry commands to enable Lunar Module Eagle to descend from lunar orbit and touch down on the moon's surface. Neil Armstrong and Buzz Aldrin followed these guidance computer programs closely as they descended into history and became the first humans to land on another celestial body - the moon.
Accompanied by a Typed Letter Signed by Aldrin, which reads: "Enclosed with this letter are three sheets numbered PGNS-43/44, PGNS-45/46, and PGNS-47/48 from the Apollo 11 LM G and N Dictionary, Part No. SKB32100074-361, S/N 1001. They are part of the entire manual that was carried to the lunar surface in Lunar Module Eagle on the first lunar landing mission during July 16 to 24, 1969. These sheets are from the Primary Guidance and Navigation Section and have the exact computer procedures to perform the Power Descent Initiation (PDI) sequence which enabled Neil Armstrong and I to land on the Moon. These are the most significant pages from the entire dictionary, and from my view point, some of the most important pages available to us during the entire flight. These steps enabled the actual landing by Man on the surface of the Moon.
Sheet PGNS-43/44 has the P63 Braking Phase Program that started our descent to the surface. Neil Armstrong and I configured the flight computer for the P63 operations as listed on page PGNS-43. We had just finished the burn of Lunar Module Eagle's descent engine to put us in a lower orbit while behind the Moon. Once we were in view of the Earth and Mission Control, we reported the status of the burn which had been nearly perfect. Neil then completed the final steps of the P63 program listed on PGNS-44 up to the 'PRO' (proceed) command, where I then punched that particular button on the computer. 'IGN' (ignition) of our descent engine started and Neil verified all steps were completed at each point of time past ignition (+:05, +3:00 and +4:00). On page PGNS-43 I have inscribed: 'Used by Neil Armstrong during Eagle's landing on Apollo XI' and on page PGNS-44 I have inscribed: 'Carried to the lunar surface on Apollo XI.' I have signed both sides of this sheet.
All was going well until Neil and I saw our instrument panel flash a '1202' program alarm. We both queried Mission Control about this alarm because we had never seen it before in any simulation. After a few tense moments, Houston radioed us that we were 'GO on that alarm.' That was good news but not that reassuring when a few seconds later the same alarm occurred. The alarm coincided when I keyed the computer for information. The computer was basically telling us it had too many tasks to perform and was overloaded. About 3 minutes later an additional alarm, a '1201' flashed. Mission Control told us that it was of the same type as the '1202' and that we were still 'GO' for landing.
At about 8 and ½ minutes into the PDI sequence, Neil verified that the flight computer had initiated P64 or the Approach Phase Program. These are the steps listed on page PGNS-45. Neil was monitoring the sequence of events described on this page and the visual view out his window. He cross-checked our descent rate with the PDI descent grid from our LM Timeline Book. We had just pitched over and got our first good view of the general landing area. Neil became increasingly concerned because we were heading for a large crater surrounded by boulders. At around 500 feet above the lunar surface, Neil initiated P66 or Landing Phase Program which steps were located on pages PGNS-46 and PGNS-47. This allowed Neil to manually fly Eagle to the lunar surface with computer support. He slowed the descent rate to just a few feet per second and studied the surrounding terrain. Neil asked me about our fuel status and I indicated we had 8 percent remaining. I was then able to glance outside and began to understand why we were still flying; the craters and rocks seemed to be everywhere.
As I continued to relay our altitude and descent rate to Neil, Mission Control radioed we had '60 seconds' of fuel remaining. I made more descent data calls. Then we heard '30 seconds' ring in our headsets. Neil was almost to the surface when a haze of dust was kicked up by engine exhaust. Neil lost his ability to see the surface and had to locate something just above the dust cloud. Finally he was able to see a rock that appeared fixed in the stream of dust. This gave Neil a surface reference and he expertly nulled out a slight backward drifting motion and corrected for a small sideways drift. Just as Neil placed Eagle gently on the lunar surface, I spoke the first words from the Moon: 'CONTACT LIGHT!' This was the indicator light on our control panel that told us that Eagle had touched the lunar surface. We had only about 20 seconds of fuel remaining onboard.
We immediately called out and performed the engine stop, safety commands, and secured our attitude control equipment. Then Neil radioed the words most people remember hearing from the Moon: 'Tranquillity Base here, the Eagle has landed.' Neil and I shook hands. At the bottom of PGNS-45 I have written: 'Used by Neil Armstrong during Eagle's landing on Apollo XI' and signed that page. At the bottom of page PGNS-46, I have written: 'Carried to the lunar surface on Apollo XI' and have also signed that page.
Next we initiated the P68 or Landing Confirmation Program steps at the bottom of page PGNS-47. The most important step was to record the LAT (+NORTH), LONG (+EAST), and ALT (.01, .1nm) values from our flight computer. Since Neil had this sheet near him for reference, it was easier for me to log those values in our LM Timeline Book. It turns out that these values were the first recorded information by human hands while on the surface of the Moon. At the bottom of this page I have written: 'Used by Neil Armstrong during Eagle's landing on Apollo XI' and signed that page.
Page PGNS-48 has the P70 DPS (Descent Propulsion Section) Abort procedures. We would have used these steps if at any time during the landing sequence an emergency occurred requiring us to abort the landing and return to lunar orbit. At the bottom of this page I have written: 'Carried to the lunar surface on Apollo XI' and signed that page.
The flight plan actually had a rest period scheduled before our planned surface exploration. Needless to say, Neil and I had an abundance of energy and adrenaline surging through our bodies after this historic event and starting a rest period was the last thing on our minds. Neil asked and received concurrence from Mission Control to start the EVA activities about 5 hours early. The preparations in configuring our space suits and other equipment took a bit longer that planned but we soon began the depressurization of Eagle's cabin to allow us to open the hatch and step onto the lunar surface. At 109 hours and 24 minutes, which was 10:56 pm EDT on July 20, Neil Armstrong became the first human to step upon the Moon. He then said: 'That's one small step for a man, one giant leap for Mankind.'
Some 19 minutes after Neil's first step, I started down Eagle's ladder and set foot on the Moon. Not as well known as Neil's words but very appropriate, I spoke after stepping on the surface: 'Magnificent Desolation.' The lunar surface was indeed desolate, but had a striking beauty all its own. Gray was the dominate color, but that color changed in tone as I turned to various sun angles. Walking on the lunar surface was not difficult to get accustom to and I found the ballistic type trajectory of the surface dust kicked up by my boots fascinating to observe on this airless world. Walking and exploring on the Moon was something only eleven others experienced during the 20th century."
These sheets are originally from the collection of Apollo 11 Lunar Module Pilot Buzz Aldrin. It is doubtful that any other series of pages from the Apollo 11 flight will have greater historical importance than the present examples.