Author Topic: POLL: What should the volume of space around the Earth be called?  (Read 2306 times)

Offline daveklingler

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When we refer to the volume of space from LEO out through cislunar, inclusive, what term should be used?

EO? Tellurian space? Terran space? Cistellurian? Cisterran? Or something else?


Offline johnfwhitesell

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Earth sphere of influence.

Nah, what the guy below me said.
« Last Edit: 07/05/2018 04:53 PM by johnfwhitesell »

Offline RonM

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Cislunar.

Quote from: Wikipedia
Cislunar space

Earth's gravity keeps the Moon in orbit at an average distance of 384,403 km (238,857 mi). The region outside Earth's atmosphere and extending out to just beyond the Moon's orbit, including the Lagrangian points, is sometimes referred to as cislunar space.[109]

https://en.wikipedia.org/wiki/Outer_space#Cislunar_space

Offline daveklingler

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Erk. I misread the space.wikia.com definition last week and decided that I'd had a decades-long misconception. I posed the question on an NSF forum, and the lack of a response reinforced my misconception...about a misconception.

Good. I can go back to talking about cislunar infrastructure without worrying I'm not expressing myself properly. 

And thank you, Ron.
« Last Edit: 07/06/2018 12:14 AM by daveklingler »

Offline mikelepage

On some level, the pedant in me has always been annoyed by the term "cis-lunar".  Why? Because "cis" literally means "on this side". 

In what context does the space "on this side" of the moon's orbit actually matter to us more than space inside Earth's hill sphere, but on the other side of the moon's orbit?  Do we care that L1 is inside cis-lunar space, while L2 is not? L3, L4 and L5 are really more regions more than points, all of which straddle the moon's orbit.  "Cis-lunar" space invokes an arbitrary boundary (with a linguistic kludge to include the Lagrange points).  The hill sphere on the other hand, is the space in which the dominant gravitational interaction of any body, including the moon, is with Earth.

The term I've started using is "Earthspace", the region defined as within Earth's Hill Sphere.  As long as you're inside that sphere of influence and below escape velocity, you're always a few km/s and a month or so's travel away from Earth.  Once you move out of that region, your next encounter with Earth will be more than a year, or never.  That's the boundary Mars-bound astronauts will care about.

Online Johnnyhinbos

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“Ours”
John Hanzl. Author, action / adventure www.johnhanzl.com

Online Johnnyhinbos

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Oh wait, I have a better one. Closely connected to my boating life and the three mile limit...

No Dumping Zone
John Hanzl. Author, action / adventure www.johnhanzl.com

Offline Nomadd

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 In the tradition of bad science fiction movies I think it should be "Oh no, we're caught in the planet's gravitational pull" space.

Offline SweetWater

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Bob. Purely for a laugh.

Offline ChrisWilson68

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Based on just the thread title, I'd say "the universe".

Offline Coastal Ron

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Based on just the thread title, I'd say "the universe".

Obviously correct.

However if we are talking about the volume of space that is unique to Earth, I personally call it "Earth local" space.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline jcm

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Technically I think LEO out to the orbit of the Moon should all be considered cislunar space. In a recent paper I proposed that the Earth-Moon 1:4 resonance  (about 150,000 km out)  should mark the start of "deep space".
I'd call everything within that 'circumterrestrial space';  from lunar orbit to the edge of the Earth's Hill Sphere I would call translunar space.  And I would reserve 'lunar space' for the Moon's Hill sphere

So a nested view would be:

Earth-Moon System ---[   Cislunar space---- [  Circumterrestrial space  [---  LEO, MEO, HEO, GEO
                              |                              |
                              |                              |-[  Deep cislunar space                    ]
                              --[   Lunar space                                                              ]    Deep space
                              |                                                                                     ]
                              --[    Translunar space                                                      ]
                                                                                                                    ]
Rest of solar system                                                                                       ]


That's my proposal, your mileage may vary





-----------------------------

Jonathan McDowell
http://planet4589.org

Offline Eric Hedman

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I think the space around any planet should be called planetary space and the rest of stellar space around a star should be interplanetary space,  Then you would have Earth's planetary space, Mars' planetary space, Jupiter's planetary space, etc.  This would fit in convention with the space between stars in a galaxy being called interstellar space.  If you call the volume of space containing a galaxy galactic space.  Then you continue with convention of our universe being made up of galactic space and intergalactic space. The space around a moon could be called moon space or lunar space (in the case of Earth's Moon) and is part of a planet's planetary space.  Maybe each volume boundary should be the volume limits to which a small mass satellite could orbit around the body in question for more than one orbit for any inclination or eccentricity.  This would probably allow for a fairly consistent way to identify space volume boundaries for any object or group of objects in the universe. 

Offline CraigLieb

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“Local affairs”
As so capably coined by Douglas Adams in The Hitchhiker’s Guide to the Galaxy:
Script found at https://www.clivebanks.co.uk/THHGTTG/THHGTTGradio1.htm

“VOGON CAPTAIN:
[On Speakers] People of Earth your attention please. This is Prostectic Vogon Jeltz of the Galactic Hyperspace Planet Council. As you no doubt will be aware, the plans for the development of the outlying regions of the western spiral arm of the galaxy require the building of a hyperspace express route through your star system and, regrettably, your planet is one of those scheduled for demolition. The process will take slightly less than two of your Earth minutes thank you very much.

MANKIND:
[Yells of protest]

VOGON CAPTAIN:
There’s no point in acting all surprised about it. All the planning charts and demolition orders have been on display at your local planning department in Alpha Centauri for fifty of your Earth years so you’ve had plenty of time to lodge any formal complaints and its far too late to start making a fuss about it now.

MANKIND:
[Louder yells of protest]

VOGON CAPTAIN:
What do you mean you’ve never been to Alpha Centauri? Oh for heaven sake mankind it’s only four light years away you know! I’m sorry but if you can’t be bothered to take an interest in local affairs that’s your own regard. Energise the demolition beams! God I don’t know…apathetic bloody planet, I’ve no sympathy at all…
Colonize Mars!

Offline jbenton

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I think the space around any planet should be called planetary space and the rest of stellar space around a star should be interplanetary space,  Then you would have Earth's planetary space, Mars' planetary space, Jupiter's planetary space, etc.  This would fit in convention with the space between stars in a galaxy being called interstellar space.  If you call the volume of space containing a galaxy galactic space.  Then you continue with convention of our universe being made up of galactic space and intergalactic space. The space around a moon could be called moon space or lunar space (in the case of Earth's Moon) and is part of a planet's planetary space.  Maybe each volume boundary should be the volume limits to which a small mass satellite could orbit around the body in question for more than one orbit for any inclination or eccentricity.  This would probably allow for a fairly consistent way to identify space volume boundaries for any object or group of objects in the universe.

A slight amendment to that:

planetary space would be the generic for any planet, but for particular planets, perhaps we would use the accepted or proper demonym rather than simply the name for the planet. Instead of "Earth planetary space" we'd say "Terrestrial space" and "Martian space" rather than "Mars planetary space"

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