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Thread: Apollo 11 Moon landing 50 years ago

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    Administrator lpetrich's Avatar
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    Apollo 11 Moon landing 50 years ago

    Fifty years ago, on July 20, 1969, 20:17:40 UTC (4:17:40 pm EDT), the first human space travelers landed on another celestial body.

    They were Neil Alden Armstrong and Edwin Eugene "Buzz" Aldrin, landing in "Eagle", the lunar module of their spacecraft. The third member of the Apollo 11 crew, Michael Collins, stayed aboard "Columbia", the command-service module of their spacecraft, orbiting the Moon.

    The Apollo 11 astronauts started on their way on 13:32:00 UTC (9:32:00 EDT), with them and their spacecraft being launched atop a Saturn V rocket, the most powerful rocket ever successfully flown. The rocket stood some 363 ft / 110 m tall and weighed some 3000 metric tons when fully loaded. Most of that was fuel and oxidizer; its empty mass was about 180 mt.

    The first stage of the Saturn V fired for about 3 minutes, then the second stage for 6 minutes, and then the third stage for a few minutes. The Apollo spacecraft stayed attached to the third stage, and the combination made 1 1/2 orbits at an altitude of 100 nautical miles (185 kilometers, 605,000 feet). The third stage then fired again, sending the combination off toward the Moon. Thirty minutes later, the Columbia separated itself from the third stage, turned around, docked with the lunar module, and backed away from the third stage. That stage then went around the Moon and ended up in a heliocentric orbit.

    The command module was conical, and it was attached at its base to the cylindrical service model. At the other end of the service module was a rocket nozzle. The lunar module was boxy-looking with four landing-gear legs attached, each leg with a pad on its end. In the Apollo 9 mission, the command module got the call sign Gumdrop and the lunar module Spider, from their appearances.

    On July 19 at 17:21:50 UTC, the Columbia-Eagle combination went behind the Moon and the service module fired its engine, getting the combination into lunar orbit. Nearly a day later, on July 20 at 12:52:00 UTC, Armstrong and Aldrin entered Eagle, and at 17:44:00 UTC, Eagle separated from Columbia. After some inspection maneuvers, Armstrong exclaimed "The Eagle has wings!"

    The Eagle was soon on its way, and as it approached the Moon's surface, the two astronauts found a flat area to land in, avoiding some boulders and some craters. At 20:17:40 UTC, they landed. "Houston, Tranquility Base here. The Eagle has landed." radioed back Armstrong. A Mission Control guy responded "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."

    Two and a half hours later, the two astronauts prepared for exiting Eagle and walking on the Moon. The preparations took three and a half hours, longer than expected, and on July 21, 02:39:33 UT, after depressurizing the Eagle, they opened its side hatch. At 02:51, Armstrong exited the Eagle's interior, and he climbed down the nearby landing-gear leg. At 02:56:15, Armstrong stepped onto the Moon's surface, and after noting that its dust was "very fine-grained" and "almost like a powder", he announced "That's one small step for (a) man, one giant leap for mankind."

    A video camera caught this event and the lunar module broadcast it back to NASA's Deep Space Network. From there, the broadcast was forwarded to TV stations all over the world, and an estimated 600 million people watched that event. I didn't, sad to say, and I don't recall paying much attention to the Apollo missions in my childhood.

    Seven minutes later, Armstrong collected a sample and put it into a thigh pocket in his spacesuit. That was in case they had to abort their EVA, in this case, visiting the Moon's surface. When Aldrin joined Armstrong, he described the Moon's surface as "Magnificent desolation."

    The two astronauts placed the video camera on a tripod on the Moon's surface, they placed a seismometer, a retroreflector, and a flag there, they took still pictures with a Hasselblad film camera, and they collected several rocks and soil samples. President Richard Nixon called in to congratulate them.

    Aldrin returned to Eagle first, then they got their film and samples into Eagle, and then Armstrong returned to Eagle. They left their Hasselblad camera behind, along with spacesuit overshoes and backpacks and some other stuff, to save weight. They closed the Eagle's side hatch at 05:11:13, pressurized it, and got some sleep.

    During this time, Collins was all alone, but he didn't feel lonely.

    At 17:54:00 UTC, Armstrong and Aldrin departed from the Moon's surface in the Eagle's ascent stage, the upper half of the lunar module. The lower half, the descent stage, was left behind on the Moon. Eagle met Columbia at 21:24:05 UTC and the two spacecraft docked at 21:35:00. Armstrong and Aldrin returned to Columbia with their film and samples, and at 23:41:31, they and Collins jettisoned Eagle.

    On July 22 at 04:55:42 UTC, the Columbia left lunar orbit and started its trip back to the Earth. The next day, each of the three astronauts did a broadcast. The day after, on July 24 at 16:21:12 UTC, the astronauts jettisoned the Columbia's service module and got into position for hitting the Earth's atmosphere at around 11 km/s / 40,000 km/h / 25,000 mph. When they did so, at 16:35:05, they lost radio contact from the glowing ionized air around them, and they felt an acceleration of some 6 Earth gravities (g's). At 16:44:06, Columbia deployed its two drogue parachutes, two initial ones. A few minutes later, it deployed its three main ones, and at 16:50:35, it hit the ocean.

    The Columbia command module landed close to the center of the Pacific Ocean, and its landing local time was 5:50:35. It soon turned upside down, but the astronauts turned on some inflatable balloons, and those got it back to its correct orientation. The aircraft carrier Hornet was nearby as a floating operations base, and a recovery crew departed from there in helicopters to pick up the astronauts and the Columbia. The astronauts were brought back in plastic isolation overgarments, and then to an isolation trailer aboard the Hornet. The recovery crew also picked up the Columbia and the samples and film that were aboard it. The three astronauts spent about 3 weeks in quarantine before they were released.

    The only part of the Saturn-Apollo rocket that returned was the Columbia command module. It weighed in at about 5.6 mt, only 1/500 the departure mass.

    The Apollo-spacecraft parts:
    • Command Module: 5.56 mt
    • Service Module: 6.11 mt / 24.52 mt
    • Command-Service Module: 11.67 mt / 30.08 mt
    • Ascent Stage: 2.15 mt / 4.70 mt
    • Descent Stage: 2.13 mt / 10.33 mt
    • Lunar Module: 4.28 mt / 15.03 mt
    • Apollo Spacecraft: 15.95 mt / 45.08 mt

    Their habitable volume:
    • Command module: living space 218 cu ft / 6.2 m^3, pressurized 366 cu ft / 10.4 m^3
    • Ascent stage: living space 160 cu ft / 4.5 m^3, pressurized 235 cu ft / 6.7 m^3


    Apollo 11, Apollo 11 Timeline

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    I watched this happen with my 80 year old grandfather. He’d been born when the horse and buggy was still the primary means of transportation. He was old enough to recall reading about the Wright brothers first flight. I think he was as excited as I was. I recall looking up at the moon, and saying I was sure I could see the contrails of the command module. I passed out on their sofa, and then recall my grandfather waking me up just in time to see Armstrong descend the ladder and take the first step on the moon. I’ve never stopped being in awe of that moment.

    SLD

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    Administrator lpetrich's Avatar
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    The Apollo command module had a cabin volume and a mass roughly comparable to a minivan with its seats in place inside it. Imagine you and two other people being stuck in one for a week with nothing but vacuum outside of it. The lunar module's ascent stage had a somewhat smaller cabin volume.


    The Apollo missions were an attempt to technologically outdo the Soviet Union, and those missions succeeded in that purpose. The Soviet Union had a similar Moon effort, but it never got very far. The SU needed a big booster rocket comparable to the Saturn V for that effort, and for that purpose, it developed its N-1 rocket. But the N-1 failed in all four of its test flights, while the Saturn V flew successfully in all of its 13 flights.

    However, the Apollo missions succeeded in other ways.

    How did the Moon form? | 5 things we learnt from the Apollo Moon Landings - YouTube by Dr. Becky

    1. The Distance to the Moon.

    The Apollo 11 crew placed a retroreflector on the Moon, a set of mirrors arranged to bounce light back to its source. The Apollo 14 and 15 crews also did so, giving three. One gets the distance to the Moon by aiming a laser at a r-r with a telescope, and then using a telescope to see the returned light. The travel time of the laser light gives the Moon's distance.

    The Moon is moving away from the Earth at about 3.8 cm/year. Extrapolated into the past, this means that the Moon must have started some 1.5 billion years ago. But both the Earth and the Moon have rocks older than that, so the relative tidal drag must now be higher than in much of the past.

    2. The Structure inside the Moon.

    The Apollo 11 crew put a seismometer on the Moon, as their successors also did. It picked up Moon tremors or moonquakes, and since they travel through the Moon's interior, they probe it. Doing for the Moon what has long been done for the Earth, one finds that the Moon has an iron core about 1/4 its radius, while the Earth's iron core is about 1/2 its radius.

    3. What the solar wind is made of.

    The Apollo 11 crew placed an aluminum sheet draped from a pole on the Moon, as did their successors except for Apollo 17. This sheet was for collecting solar wind and getting some clues as to the Sun's composition. Part of it was the ratio of the two stable hydrogen isotopes, deuterium and protium (ordinary hydrogen): D/H or H(2)/H(1). Deuterium tends to be consumed rather than produced, so the deuterium we have today is almost all primordial. The Sun's deuterium fraction agrees fairly well with the fractions for some distant galaxies.

    4. What the Moon is made of.

    The Apollo 11 crew brought back with them about 22 kilograms of lunar material, and the grand total for the Apollo program is 382 kg. By comparison, the Soviet Union's automated Moon landers returned only 326 grams total, less than a thousandth as much. We have much more meteorite material, but most of it has very uncertain provenance, being similar to this or that family of asteroids. Only one asteroid has been identified as the parent object of any known meteorite: Vesta. Some meteorites are pieces of the Moon and Mars, I must note, and the Apollo missions provided chemical clues for recognizing lunar meteorites.

    The Moon does not have nearly as much geological activity as the Earth does, and many of its rocks are much older than many Earth rocks. The champion Earth rock is about 4 billion years old, while some Moon rocks from the celestial body's highlands go back about 4.4 billion years. Furthermore, the Moon's rocks are igneous ones, rocks that solidified from a liquid state. That means that the Moon must once have had a magma ocean.

    Furthermore, the isotope composition of Moon rock is close to that of Earth rock, much closer than it than most meteorite rock.

    Among the Moon rocks brought back is some olivine, and its formation indicates a magma-ocean depth of around 1000 km -- nearly the entire rock depth of that celestial body. So the entire Moon must once have been molten.

    Dr. Becky neglected to mention another composition feature: very low quantities of volatiles like water. The Moon is very dry.

    5. How the Moon was formed.

    The two main theories of where the Moon formed were (1) around the Earth and (2) elsewhere in the Solar System, and then captured by the Earth. I recall an article in Natural History magazine in the 1970's by someone who tried to argue that scientists are not very rational. That was because neither side changed its mind very much after the Apollo program.

    But a third theory was proposed back in 1948, that the Moon was formed by some big planetoid hitting the Earth and making a spew of material. Some of it went into orbit around the Earth and then condensed into the Moon. For a long time, this seemed very implausible, because it requires some bizarre cosmic accident.

    But in the 1970's, it re-emerged, and it was found to fit very well with what had been learned about the Moon from the Apollo missions. This hypothesis predicts that the Moon would mostly be baked rock without much iron -- and it was. By the mid 1980's, it had become generally accepted as the most plausible theory. It is the Giant Impact Hypothesis or the Big Splat Hypothesis, and the parent body is often called Theia.

    A book about the Big Whack is what inspired Dr. Becky to go into science -- because it was such an excellent mystery story.

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    Fair dinkum thinkum bilby's Avatar
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    Member Peez's Avatar
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    The Apollo mission landing humans on Luna was an amazing achievement, but the Soviet Lunokhod robot landing is worth remembering as well. The Soviets soft-landed a mobile robot that moved about on the surface almost 10 years before Apollo 11, and 27 years before Mars Pathfinder.

    Peez

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    Veteran Member Treedbear's Avatar
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    Quote Originally Posted by lpetrich View Post
    ...
    The Eagle was soon on its way, and as it approached the Moon's surface, the two astronauts found a flat area to land in, avoiding some boulders and some craters. At 20:17:40 UTC, they landed. "Houston, Tranquility Base here. The Eagle has landed." radioed back Armstrong. A Mission Control guy responded "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."
    ...
    Have to give every dog his due. The first words spoken from the moon were "Contact light." by Buzz Aldrin. Then came some back and forth between the two astronauts and Mission Control, and then came Armstrong with "Engine Arm is off. Houston, Tranquility Base here. The Eagle has landed." Also, as related by Aldrin, when they re-enter the LEM and were about to take a nap prior to take-off Aldrin finds a circuit breaker actuator knob lieing on the cabin floor. He looks at the CB panel and the only one missing is for Engine Arm. It gets pulled outward to turn it off. Apparently it had broken off when disarming the engine after landing. They called Mission Control to figure out what to do. Houston told them to take their nap while they worked something out. Aldrin ended up using the eraser end of a pencil to turn it on for lift-off. But it came close to meaning they were stranded.
    Last edited by Treedbear; 07-22-2019 at 06:55 PM.

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    Mazzie Daius fromderinside's Avatar
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    ... and I thought I was wacky for taking my 21 month old son out of his crib to see the landing so he could have the 'memory' of it.

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    Administrator lpetrich's Avatar
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    List of Apollo missions - the first of them were several test flights without any astronauts, including test flights of the command-service module and the lunar module.

    The first astronauts to go on an Apollo mission were the Apollo 1 ones, and on 21 Feb 1967, all three of them lost their lives in a test on the ground. They were in the command module, and something caught fire in it.

    The first successful Apollo-astronaut flight was Apollo 7, launched on 11 October 1968. The astronauts rode in their command-service module into Earth orbit atop a Saturn 1B rocket.

    The first one to the Moon was Apollo 8, launched on 21 December 1968. The astronauts rode atop a Saturn V for that rocket's first flight with astronauts. They went to the Moon, went into orbit around it, then left orbit and came back home.

    The first test of lunar-module maneuvers was Apollo 9, launched on 3 March 1969. The astronauts practiced docking maneuvers with the lunar module in Earth orbit.

    The next test was Apollo 10, launched on 18 May 1969. The astronauts did all but the actual landing, with the lunar module coming close to the Moon's surface.

    The first landing was Apollo 11, launched on 16 July 1969. It had only one EVA, only one trip outside the lunar module.

    The second landing was Apollo 12, launched on 14 November 1969. It had two EVA's.

    A would-be landing was Apollo 13, launched on 11 April 1970. The service module suffered a major malfunction, and the crew used the lunar module as life support to get them home.

    The third landing was Apollo 14, launched on 31 January 1971. It had two EVA's, and a color-TV broadcast.

    The fourth landing was Apollo 15, launched on 26 July 1971. It had three EVA's, and the first use of a lunar rover.

    The fifth landing was Apollo 16, launched on 16 April 1972. It had three EVA's.

    The sixth and last landing was Apollo 17, launched on 7 December 1972. It had three EVA's, and the first landing of a professional geologist on the Moon.


    Apollo missions 18, 19, and 20 were canceled, though some of the hardware was reused. One of the remaining Saturn V's was used to launch the Skylab space station, and three command-service-module sets were used as shuttles to it. A fourth CSM was used in the Apollo-Soyuz Test Project.

    Skylab was a converted Saturn V third stage, and it was launched on May 14, 1973 atop the first two stages of a Saturn V rocket. It suffered a lot of damage, losing its micrometeoroid shield and one of its main solar-panel arrays. Its other one was jammed. The first mission to it was launched on May 25, 1973, and the three astronauts unjammed that solar panel, deployed it, and installed a sunshield. They stayed a month before returning home. The second Skylab mission was launched on July 28, 1973, and its astronauts stayed nearly two months. The third one was launched on November 16, 1973, and its astronauts stayed nearly three months.

    There was talk of a fourth one, but it never materialized. Also, the Space Shuttle was initially expected to be in operation soon enough to keep it from spiraling in and re-entering, but it wasn't. Skylab hit the atmosphere and was destroyed on July 11, 1979.

    The Apollo-Soyuz Test Project was jointly launched on July 15, 1975. Three American astronauts departed in a command-service module atop a Saturn IB rocket, with a docking module stowed beneath them. Two Soviet cosmonauts departed in a Soyuz spacecraft atop a Soyuz booster rocket. The Americans retrieved and docked with the docking module and the Russians then docked with it. The crewmen performed experiments, did repeated dockings, and then departed for their homes.

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    Administrator lpetrich's Avatar
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    List of missions to the Moon - quite a lot of them.

    The earliest ones had a lot of launch failures, with the first successes being flybys and impactors -- crash landings.

    1966 was a banner year for Moon missions, with the first successful landers and orbiters by both the Soviet Union and the United States. Landers came before orbiters for both nations. The two nations' orbiters returned pictures helpful for choosing Apollo landing sites, and tracking those orbiters revealed evidence of mass concentrations or "mascons" underneath the lunar maria. The mascons were from impacts early in the Moon's history, impacts that became covered by lava flows.

    Around the time of the Apollo landings, the Soviet Union also did some sample-return missions and some rover missions. The last Apollo mission was in 1972, and the last Soviet lunar mission in 1976.

    After that, it was all flybys and orbiters, with Japan, China, and India joining in. The next spacecraft to reach the surface as part of its mission was India's Moon Impact Probe, which crashed onto the Moon on 14 November 2008. The next lander was China's Chang'e 3, carrying the Yutu rover, and this combination landed on 14 December 2013. Israel entered the race with Beresheet, which attempted to land on 11 April 2019, but it crashed.

    Several Moon missions are in the works, including landers, rovers, sample returners, and crewed orbiters.

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