16 25 July 1969
by Hamish Lindsay
“The Lunar landing of the astronauts is more than a step in history; it is a step in evolution.”
The New York Times Editorial, July 20, 1969
Command
16 25 July 1969
by Hamish Lindsay
“The Lunar landing of the astronauts is more than a step in history; it is a step in evolution.”
The New York Times Editorial, July 20, 1969
Command Module : COLUMBIA
Commander : Neil Armstrong
Mission Fact Box:
|Launch from Pad 39A, Cape Kennedy 0932:00 USEDT 1332 :00 UT 2332:00 AEST Wednesday 16 July 1969
Earth to Moon elapsed time 73 hours 5 minutes 35 seconds
Lunar landing GET 102:45:40 2017:39 UT Sunday 20 July 1969 0617:39 AEST Monday 21 July 1969.
Lunar landing coordinates Mare Tranquillitatis at 0.67409°N, 23.47298°E (Davies et al 1987)
Commander on lunar surface GET 109:24:15 2256:15 USEDT Sunday 20 July 1969 0256:15 UT 1256:15 AEST Monday 21 July 1969
Total lunar stay time 21 hours 36 minutes 21 seconds
CM lunar orbits 30 orbits in 2 days 11 hours 30 minutes 26 seconds.
Time on the lunar surface 1 EVA totalling 2 hours 31 minutes 40 seconds
Total distance walked 1,006 metres.
Maximum distance travelled away from the LM 61 metres
Lunar samples 21.55 kilograms
Lunar photographs 339 images
Lunar lift-off GET 124:22:01 1754:00 UT Monday 21 July 1969 0354:00 AEST Tuesday 22 July 1969
Moon to Earth elapsed time 59 hours 36 minutes 52 seconds
Splashdown GET 195:18:35 1650:35 UT Thursday 24 July 1969 00250:35 AEST Friday 25 July 1969.
Total mission elapsed time 8 days 3 hours 18 minutes 35 seconds
Total distance travelled in space 1,534,832 kilometres
Site selection. Why Tranquility Base?
Science and the scientists took a back seat in choosing the first lunar landing site, as it was seen more as an operational and engineering exercise to trial all the new procedures and systems. So the operational and engineering aspects mainly dictated where the first landing would be. Thirty possible sites for the first lunar landing were originally under review by the Site Selection Board. After two years of intense analysis, which included Lunar Orbiter images and Surveyor Lander data, the choice was narrowed down to two candidates – Mare Fecunditatis or Mare Tranquillitatis.
Launch opportunities (or windows) for the chosen site and time only occurred once a month, with two windows per day. One window was a Translunar Injection over the Pacific Ocean, which used a daytime launch, and the other was over the Atlantic, which meant a night time launch (as in Apollo 17). So the first requirement by the Flight Dynamics team was for the site to be east of the lunar meridian to cater for back-up sites with suitable lighting in case the launch had to be delayed for some days. It seemed better to try a second site a few days later than wait for a whole month for the prime site to present an opportunity again. Also an easterly target was preferred because the LM would fly in from the east to land shortly after sunrise, when surface objects cast revealing shadows.
Secondly, they wanted the site to be within 5° of the lunar equator. A higher latitude site would consume more fuel, and fuel economy was one of the prime considerations for the first attempt.
A third requirement was the spacecraft was sent on a ‘free return’ translunar trajectory, so it would return back to Earth without using major manoeuvres. Finally they wanted a flat area free from sharp ridges, large boulders or awkward steep sided craters for a first attempt.
These constraints narrowed the first attempt to land on a maria near the equator, which meant either Mare Fecunditatis or Mare Tranquillitatis, with Sinus Medii as a possible back up. As Mare Fecunditatis would have provided difficulties tracking from Earth, a higher fuel consumption and the possibility of a night splashdown, it dropped out of favour.
So the choice settled on Mare Tranquillitatis, originally named by astronomers Francesco Grimaldi and Giovanni Riccioli of Bologna in 1651. Here there were two possible landing targets in the area, an easterly one near Maskelyne Crater called ALS (Apollo Landing Site)-1 and ALS-2, a bit further west. ALS-2 was only 25 kilometres southeast from Surveyor 5’s home, and Apollo 10 had made a low pass over the spot with favourable reports from Tom Stafford. ALS-2 also allowed a two-day recycle in the case of a delay to the next site Sinus Medii.
Though science did not play a major factor in the choice of the first landing site, the choice of ALS-2 made the scientists happy enough too. They felt that ALS-1 was too exotic, and for a first mission they wanted a more typical mare like ALS-2 with large subdued craters and few b