#2909: Moon Landing Mission Profiles

XKCD comic, described below.
Transcript

[Top left panel]

Lunar orbit rendezvous

Spacecraft orbits Moon, drops lander

[A big circle and a small circle, depicting the Earth and the Moon, with a line starting from the left side of the Earth curving, then straight towards the Moon, then forming an orbit around it and then descending on the Moon. A spacecraft is located at about the middle of the line.]

Chosen by the Apollo program

[Top right panel]

Earth orbit rendezvous

Large lander assembled in Earth orbit via several launches, travels to Moon

[The same circles depicting the Earth and the Moon. Two lines start from the left side of the Earth into an orbit around it, with a couple of different stages of spacecraft located in different parts of the orbit. The merged line heads straight towards the Moon to land on its left side, without orbit. A spacecraft is located around the middle of the line.]

Rejected for requiring multiple Saturn Vs per landing and potentially taking longer

[Bottom left panel]

Direct ascent

Lander launched from Earth directly to Moon

[Another big circle and small circle, depicting the Earth and the Moon again. This time, the line curves the same way as in the lunar orbit rendezvous, heads straight towards the Moon, and ends on the Moon's left side. A spacecraft is located slightly on the left, to Earth's side.]

Rejected for requiring an unreasonably large rocket

[Bottom right panel]

Lunar Earth rendezvous

Moon transits to rendezvous with spacecraft in low Earth orbit

[A big circle representing Earth and three small circles representing the Moon at different times. Starting from the right side, the small circle follows a path that curves slightly upwards. The path then straightens. Another small circle is located on the straight part. The path forms an orbit around the Earth, with another small circle on Earth's left side. Another small path leads from the left side of the Earth to the leftmost small circle.]

Rejected because I guess no one thought of it?!

(Sourced from explainxkcd.com)

Title text:If you pick a low enough orbit, it gives you a lot of freedom to use a lightweight launch vehicle such as a stepladder.


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