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Glom
2004-Dec-29, 10:05 PM
You know those cool sponge looking planets you see in cartoon scifi, where could we find one of those?

SkepticJ
2004-Dec-29, 10:12 PM
Maybe in a dry rocky environment where a plant can't send down roots to get water. The rain would soak into sponge like mass or something. Maybe in a place that gets really cold at night and the sponge layer is insulation. During the day it's really hot and the sponge layer is insulation.
Sounds like a desert.

archman
2004-Dec-29, 11:16 PM
Planets, not Plants.

SkepticJ
2004-Dec-29, 11:21 PM
Planets, not Plants.

Doh! #-o

eburacum45
2004-Dec-30, 07:52 AM
A shellworld could look a bit like a sponge; the theory is that you find a seismically quiet, small, low gravity world and excavate caverns into the interior; at the same time use the material extracted to build upwards on the surface. You end up with a planet covered with concentric shells, supported by arches and butresses (an early description of such a world is in Star Maker by Olaf Stapledon.

Pierce a few holes in the outermost shells and you have a nice sponge planet, and you could fly in to the interior of the world through the holes...

I suppose I'll have to make a model of one now- I had planned on making a few more space stations (http://tinypic.com/14a6ud)...

eburacum45
2004-Dec-30, 04:11 PM
Here is a first attempt at a spongeworld/shellworld;

http://tinypic.com/14oa5w


the outer shell layer is a concrete-like material, produced from the outer crust of the world;
the holes in this shell are open to space, and contain a caeliform oxygen atmosphere with no retaining membrane- this atmosphere would only last for a few thousand years if it were not constantly replaced.

perhaps this is a bit wasteful, but remember most of the living area of a shell world is enclosed, and perhaps the inhabitants like to camp out under the stars every so often.
There are holes leading to deeper layers here and there...

Bawheid
2004-Dec-30, 04:14 PM
Are we looking for absorbently spongy planets or bouncy spongy planets?

Kaptain K
2004-Dec-30, 07:06 PM
How about spongy planets that can reform themselves after being run through a sieve? :oops:

archman
2004-Dec-30, 09:32 PM
How about spongy planets that can reform themselves after being run through a sieve? :oops:
Dang, another popular myth! Only a few sponges can do this, but the general populations thinks it fairly universal. I have to knock that misconception down every January with my students... ooh that's not so far away.

HAVOC451
2004-Dec-31, 11:21 AM
Sponge Bob; square planet. :P

The Supreme Canuck
2004-Dec-31, 10:01 PM
Rubbery planets can be done. Just head up to the Bay of Fundy. If you see wet, red sand, you can bounce! (Not much, just kind of springy)

Gullible Jones
2004-Dec-31, 10:26 PM
Hmm... You mean like Naboo in Star Wars, where there are channels and passages going all the way down to the core?

Maybe...

(A shell-world huh? How would you reinforce the interior? Because if you didn't, you could have some pretty big sinkhols on your hands...)

Swift
2005-Jan-01, 12:05 AM
Actually, sponge planets are what you use to clean your sun/star when it has spots all over it. 8-[
Look at ours, someone left just one little spot on it.
http://www.spaceweather.com/images2004/31dec04/midi512_blank.gif

AndrewGPaul
2005-Jan-01, 03:05 PM
Here is a first attempt at a spongeworld/shellworld;

http://tinypic.com/14oa5w


the outer shell layer is a concrete-like material, produced from the outer crust of the world;
the holes in this shell are open to space, and contain a caeliform oxygen atmosphere with no retaining membrane- this atmosphere would only last for a few thousand years if it were not constantly replaced.

Why? From the description, there's no loss of mass, so the gravity should be the same; the planet should be able to retain an atmosphere as usual, no?

eburacum45
2005-Jan-02, 11:00 AM
Sorry; I didn't really explain that shellworlds are usually imagined as being made from planets and moons similar in size and gravity to our Moon; our Moon could actually keep an Earth-like atmosphere for many thousand years- which is an eyeblink compared to geological time.

But a few atmosphere filled holes open to space would represent a much lower rate of loss of precious volatiles.

The Moon would make a good shellworld; it is seismically quiet, and the low gravity would allow relatively large caverns to be excavated in safety.
Collected sunlight at the surface could be piped to light the caverns and grow crops.