“A Giant Leap For Mankind”… 45 Years Ago Man Landed on the Moon
45 years ago today Neil Armstrong’s booted foot, pressed firmly in the lunar soil, symbolized the stunning success of man’s highest adventure. The achievement of man’s first step on the moon came on the evening of 20th July, 1969 and realized the ambitious goal set by the late President John F. Kennedy some eight years previously.
Commander Neil A. Armstrong, Command Module Pilot Edwin “Buzz” E. Aldrin, Jr. and Lunar Module Pilot Michael Collins blasted off on the 44 ton Apollo 11 / Saturn V SA-506 rocket assembly on 16 July 1969 at 13:32:00 UTC. Apollo 11 landed the first humans on the moon some four days later at 20:18 UTC and Armstrong became the first to step onto the lunar surface six hours later on 21st July at 02:56 UTC. Armstrong spent approximately two and a half hours outside the spacecraft, Aldrin slightly less, and together they collected 47.5 pounds of lunar material to bring back to Earth.
While this was happening, Collins piloted the command spacecraft alone in lunar orbit until Armstrong and Aldrin returned to it.
The moon landing almost didn’t happen though as the astronauts were rapidly running out of fuel. As the descent began, Armstrong and Aldrin found that they were passing landmarks on the surface four seconds early and reported that they were “long” meaning they would land miles west of their target point.
Five minutes into the descent burn, and 6,000 feet (1,800 m) above the surface of the Moon, the LM navigation and guidance computer distracted the crew with the first of several unexpected “1202” and “1201” program alarms. Inside the Mission Control Center in Houston, Texas, a message was relayed to the crew that it was safe to continue the descent.
When Armstrong again looked outside, he saw that the computer’s landing target was in a boulder-strewn area just north and east of a 300-meter (980 ft) diameter crater (later determined to be “West crater,” named for its location in the western part of the originally planned landing ellipse). Armstrong took semi-automatic control and, with Aldrin calling out altitude and velocity data, they landed at precisely 20:17:40 UTC with about 25 seconds of fuel left.
Apollo 11 landed with less fuel than other missions, and the astronauts encountered a premature low fuel warning. This was later found to be the result of greater propellant ‘slosh’ than expected, uncovering a fuel sensor. On subsequent missions, extra anti-slosh baffles were added to the tanks to prevent this.
Throughout the descent Aldrin had called out navigation data to Armstrong, who was busy piloting the Lunar Module. A few moments before the landing, a light informed Aldrin that at least one of the 67-inch (170 cm) probes hanging from Eagle’s footpads had touched the surface, and he said “Contact light!” Three seconds later, Eagle landed and Armstrong said “Shutdown.” Aldrin immediately said “Okay, engine stop. ACA – out of detent.” Armstrong acknowledged “Out of detent. Auto” and Aldrin continued “Mode control – both auto. Descent engine command override off. Engine arm – off. 413 is in.”
Charles Duke, acting as CAPCOM during the landing phase, acknowledged their landing by saying “We copy you down, Eagle.”
Armstrong acknowledged Aldrin’s completion of the post landing checklist with “Engine arm is off,” before responding to Duke with the words, “Houston, Tranquility Base here. The Eagle has landed.” Armstrong’s unrehearsed change of call sign from “Eagle” to “Tranquility Base” emphasized to listeners that landing was complete and successful. Duke mispronounced his reply as he expressed the relief at Mission Control: “Roger, Twan– Tranquility, we copy you on the ground. You got a bunch of guys about to turn blue. We’re breathing again. Thanks a lot.”
The event was broadcast on live TV to a worldwide audience approaching 600 million people. The images flickered onto, by modern standards, tiny television sets and at first, were blurry and a little bewildering. Finally, they started to make sense as the eerie silhouette of Neil Armstrong descended down to the moon surface.
People in 47 countries watched events unfold as a $400,000, seven pound camera specially designed for the hostile vacuum of space sent the images back to Earth. This was no mean feat in itself as the images of Buzz Aldrin’s leap, the flag planting ceremony and the lunar material gathering passed through a fixed focus lens fitted to the camera and were then transformed into electrical impulses. The impulses were then amplified a hundred times and beamed directly to Earth. At Parkes, New South Wales, Australia, a 210 foot diameter radio telescope gathered the signal which was then converted to a conventional TV image and sent, via microwave and satellite, off to Houston, which instantly rebroadcast to the world.
An amazing achievement and we can only wonder what the world would look like today if this hadn’t happened and that man hadn’t set off to explore the planet around him.
