Space Transportation - mmmt_transportation.pdf - Moon Society

Dave Dietzler and Peter Kokh have been tossing about some more people-friendly names:
“The Pass” and “The Lagrange Gap”
i.e. through the “mountain ridge” between the Earth’s deep gravity well and the Moon’s shallower well.
See the illustration just below the title of this article.
Too many people have grown up with the proverbial dictum about there being no “up” and no “down” in space. For
all practical reasons, in travel between gravity well destinations, this is a misleading sophism.
It is commonplace to show Earth-Moon and Earth-Mars trajectories in a flat plane, when it would be more helpful
to show them against a gravity well map. Yes that is harder to do, like most things worth doing!
Gravity Wells Comment: Perhaps this is something we need to promote!
This should be part of our strategy of getting across to people the need to place infrastructure waystations to
enable less expensive, more heavily trafficked personnel and cargo travel between Earth and Moon: LEO, GEO, and
L1 were all bypassed by NASA because, for a low traffic operation like Apollo, it made no sense to invest in such
infrastructure, and we all now understand that this “low traffic” assumption was/is a “self-fulfilling prophecy.”
Above, how space is warped by a heavy mass “at the bottom of a gravity well.” Applies to all bodies of size: the Sun,
Earth, Moon, Mars, Jupiter, etc.
Robert A. Heinlein first noted, “once you are in Earth orbit, you are halfway to anywhere!
Gravity Wells: an animated illustration
http://www.opencourse.info/astronomy/introduction/06.motion_gravity_laws/gravity_well.gif
An illustration by our own Ken Murphy
http://www.outofthecradle.net/WordPress/wp-content/uploads/spacefarerseml1.jpg
A great YouTube Explanation
http://www.youtube.com/watch?v=VBQHtF3WhMw&feature=player_embedded
“If Earth’s gravity well is 22 steps deep, the Moon’s gravity ‘dimple’ is only 1 step deep in comparison.”
The general “terrain” of the Solar System is like a great plateau, seemingly flat, but like the Great Plains States,
gradually sloped uphill from the Sun outwards as this area is on the shoulders of the Sun’s giant gravity well.
MMM #234 - April 2010
Salvaging the Google Lunar X-Prize “Also-Rans”
By David A. Dunlop, Moon Society Director of Project Development
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