Editing 2909: Moon Landing Mission Profiles
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==Explanation== | ==Explanation== | ||
− | Getting astronauts to the | + | {{incomplete|Created by A MOON THAT LOOKS ESPECIALLY LARGE TONIGHT - Please change this comment when editing this page. Do NOT delete this tag too soon.}} |
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+ | Getting astronauts to the moon is hard.{{citation needed}} There are different strategies to do it. This comic reviews three mission profiles considered for the Apollo moon landings, and one which is absurd. | ||
'''{{w|Lunar Orbit Rendezvous}} (LOR)''' | '''{{w|Lunar Orbit Rendezvous}} (LOR)''' | ||
− | Description: Using a single large rocket to get | + | Description: Using a single large rocket to get a lunar orbiter and lander system into trans-lunar orbit, which can then enter lunar orbit and deploy a lander. |
Status: Chosen by the {{w|Apollo Program}} in the 1960s and 1970s. | Status: Chosen by the {{w|Apollo Program}} in the 1960s and 1970s. | ||
− | Explanation: This was the actual method used in the Apollo missions. It was efficient in terms of fuel and cost. The | + | Explanation: This was the actual method used in the Apollo missions. It was efficient in terms of fuel and cost. The spacecraft orbits the Moon and the lander separates and uses a descent-stage to safely reach the surface. |
− | After the Moon mission, the lander (ascent-stage only) ascends to dock | + | After the Moon mission, the lander (ascent-stage only) ascends to dock with the command module in lunar orbit, the crew then return to Earth in the command module (leaving the abandoned ascent stage behind, in most cases purposefully directed to impact the Moon). |
'''{{w|Earth Orbit Rendezvous}} (EOR)''' | '''{{w|Earth Orbit Rendezvous}} (EOR)''' | ||
− | Description: A large lunar-landing system is assembled in Earth orbit through several launches. Once complete, it travels to the Moon as a whole | + | Description: A large lunar-landing system is assembled in Earth orbit through several launches. Once complete, it travels to the Moon as a whole. |
Status: Rejected for requiring multiple {{w|Saturn V}} rockets per landing and potentially taking longer. | Status: Rejected for requiring multiple {{w|Saturn V}} rockets per landing and potentially taking longer. | ||
Explanation: This concept involved launching different parts of the spacecraft into Earth orbit using multiple rockets and then assembling them before heading to the Moon. It would have allowed almost arbitrarily large sizes of equipment to have reached the surface, perhaps to simplify the return journey, but with the complication of adding multiple orbital docking procedures to the project rather than most assembling and spacecraft mating being carried out prior to launch. It should be noted that Randall made a mistake on this point of the comic; the Earth Orbit Rendezvous would have required multiple launches of the {{w|Saturn IB}}, not multiple launches of the Saturn V. | Explanation: This concept involved launching different parts of the spacecraft into Earth orbit using multiple rockets and then assembling them before heading to the Moon. It would have allowed almost arbitrarily large sizes of equipment to have reached the surface, perhaps to simplify the return journey, but with the complication of adding multiple orbital docking procedures to the project rather than most assembling and spacecraft mating being carried out prior to launch. It should be noted that Randall made a mistake on this point of the comic; the Earth Orbit Rendezvous would have required multiple launches of the {{w|Saturn IB}}, not multiple launches of the Saturn V. | ||
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'''{{w|Direct Ascent}}''' | '''{{w|Direct Ascent}}''' | ||
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Status: Rejected for requiring an unreasonably large rocket. | Status: Rejected for requiring an unreasonably large rocket. | ||
− | Explanation: This was a simpler but less feasible approach, where a single huge rocket (or a particularly large rocket stack) would send the lander straight to the Moon. The inefficiency comes in taking a | + | Explanation: This was a simpler but less feasible approach, where a single huge rocket (or a particularly large rocket stack) would send the lander straight to the Moon. The inefficiency comes in taking a huge rocket down to the Moon and back up, requiring a lot more fuel than a separate lander. |
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In reality, this was the approach imagined for the Nova C-8 rocket as an Apollo alternative. This was also the approach used in {{w|Destination Moon (comics)|Destination Moon}} from {{w|The Adventures of Tintin}}, with the fuel problem addressed by using a nuclear reactor for much of the trip—which would be a really bad idea in reality since "rockets have a tendency to explode"[https://www.youtube.com/watch?v=LHvR1fRTW8g]. Science fiction movies have frequently depicted this method of landing, either before the dawn of the actual Apollo program or (to save plot-time ''or'' by using a fictional increase in rocket capability) in more futuristic settings. | In reality, this was the approach imagined for the Nova C-8 rocket as an Apollo alternative. This was also the approach used in {{w|Destination Moon (comics)|Destination Moon}} from {{w|The Adventures of Tintin}}, with the fuel problem addressed by using a nuclear reactor for much of the trip—which would be a really bad idea in reality since "rockets have a tendency to explode"[https://www.youtube.com/watch?v=LHvR1fRTW8g]. Science fiction movies have frequently depicted this method of landing, either before the dawn of the actual Apollo program or (to save plot-time ''or'' by using a fictional increase in rocket capability) in more futuristic settings. | ||
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Status: Rejected because, humorously, "I guess no one thought of it?!" | Status: Rejected because, humorously, "I guess no one thought of it?!" | ||
− | Explanation: This is a fictional and impractical scenario. The Moon cannot | + | Explanation: This is a fictional and impractical scenario. The Moon cannot propulse itself and cannot alter its orbit to rendezvous with a spacecraft. The Moon would also break up because {{w|low Earth orbit}} is within the {{w|Roche limit}}. Astronauts would theoretically land on the Moon, but the hypothetical fragments of the Moon would make the landing impractical. This would be also bad for the Earth's climate, tides and ecosystems. |
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− | + | The title text imagines the moon coming to ''very'' low earth orbit, low enough to reach with a step ladder. There are many reasons this is wholly impractical, as well as civilization-ending. Dropping a moon on the Earth from 6 feet would likely cover the earth in about 45 km of moon matter (see [[2908: Moon Armor Index]]). If the moon somehow were put in orbit around the Earth at a height of 6 feet, the only difference is that debris would crash into you from the side at a faster velocity. | |
− | + | Given the timing and the XKCD community, this is likely an indirect reference to NASA's planned near-rectilinear halo orbit, or NRHO, for the Artemis mission: [https://www.nasa.gov/missions/artemis/lunar-near-rectilinear-halo-orbit-gateway/] | |
==Transcript== | ==Transcript== | ||
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:'''Lunar orbit rendezvous''' | :'''Lunar orbit rendezvous''' | ||
:Spacecraft orbits Moon, drops lander | :Spacecraft orbits Moon, drops lander | ||
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:Chosen by the Apollo program | :Chosen by the Apollo program | ||
− | :[Top right panel] | + | :[Top right panel] |
:'''Earth orbit rendezvous''' | :'''Earth orbit rendezvous''' | ||
:Large lander assembled in Earth orbit via several launches, travels to Moon | :Large lander assembled in Earth orbit via several launches, travels to Moon | ||
− | + | ||
:Rejected for requiring multiple Saturn Vs per landing and potentially taking longer | :Rejected for requiring multiple Saturn Vs per landing and potentially taking longer | ||
− | :[ | + | :[Lower left panel] |
:'''Direct ascent''' | :'''Direct ascent''' | ||
:Lander launched from Earth directly to Moon | :Lander launched from Earth directly to Moon | ||
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:Rejected for requiring an unreasonably large rocket | :Rejected for requiring an unreasonably large rocket | ||
− | :[ | + | :[Lower right panel] |
:'''Lunar Earth rendezvous''' | :'''Lunar Earth rendezvous''' | ||
:Moon transits to rendezvous with spacecraft in low Earth orbit | :Moon transits to rendezvous with spacecraft in low Earth orbit | ||
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:Rejected because I guess no one thought of it?! | :Rejected because I guess no one thought of it?! | ||