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McKitten Since: Jul, 2012
#26: Aug 27th 2012 at 11:03:18 AM

One more possibility: If a moon is tidally locked, an orbit around the planet can also keep a vehicle in a fixed position relative to the moon's surface. evil grin

kassyopeia from terrae nullius Since: Nov, 2010
#27: Aug 27th 2012 at 1:23:17 PM

Ah, yes, I meant to mention Lagrangian points. The ones closest to the planet, L1 and L2, are technically unstable, but that would obviously be of no concern for a craft with interstellar capabilities. Thanks for picking up the slack! smile

Soon the Cold One took flight, yielded Goddess and field to the victor: The Lord of the Light.
breadloaf Since: Oct, 2010
#28: Aug 28th 2012 at 10:14:48 PM

For the detection range, there was much maths happening for that one too and thus why I just said 1 AU for a 300 K temperature object about the size of a dreadnought but with zero ability to discern it beyond a heat point. For discerning the actual shape of the object it's 300 000 km or less.

I think the term "stealth in space" is simply misleading because it's just a misunderstanding of what detection means. All detection is just a matter of range and the cost of that range.

So anyway, we have some potential moons used for mining and I'm not sure if we know what's on those moons? I also think keeping industry strictly in space would be more profitable than splitting anything between a gravity well and having to "elevator" goods to and from orbit. Even with a space elevator it's still like say.. I dunno, $1/kg to lift.

McKitten Since: Jul, 2012
#29: Aug 29th 2012 at 1:32:31 AM

Well, whatever that math was, it has to be wrong, because we routinely find objects that are smaller and colder than that, at distances greater than 1 AU.

kassyopeia from terrae nullius Since: Nov, 2010
#30: Aug 29th 2012 at 4:03:24 AM

[up][up], [up] Which "dreadnought" class are you guys talking about, the historical navy vessel or the Star Wars starship or something else?

Soon the Cold One took flight, yielded Goddess and field to the victor: The Lord of the Light.
McKitten Since: Jul, 2012
#31: Aug 29th 2012 at 5:08:37 AM

Hm yes, good point. I suppose the wooden iterations of the HMS Dreadnought would be pretty undetectable in space.

breadloaf Since: Oct, 2010
#32: Aug 29th 2012 at 9:53:14 PM

Which things being detected are you talking about? The Wide-Field Infrared detector can't see asteroids beyond an AU. But it can be used to scan for stars in space on the infrared spectrum because stars are much hotter.

McKitten Since: Jul, 2012
#33: Aug 30th 2012 at 3:06:49 AM

Of course it can. Even the Asteroid belt is over one AU distant, (if only a little more) where the WISE mission found thousands of new asteroids. Note the "new", instruments have been good enough to find asteroids there for decades. Asteroids are also quite routinelz found as far awaz as Jupiters orbit (also started before WISE).

kassyopeia from terrae nullius Since: Nov, 2010
#34: Aug 30th 2012 at 4:03:24 AM

Excerpt from a 'pedia list of apparent magnitudes, {additions mine}:

[...]
28.20 - Halley's Comet {diameter ~11 km} in 2003 when it was 28AU from the Sun
31.50 - Faintest objects observable in visible light with Hubble Space Telescope
35.00 - Sedna {diameter ~1,000 km} at aphelion (900 AU)
[...]

Brightness by reflection of sunlight (and, analogously, heat output due to absorption of sunlight) scales as diameter^2/distance^4. That is, according to this data, Hubble's detection limit is on the order of ~3 metres at 1 AU, ~30 metres at 3 AU (asteroid belt), ~300 metres at 10 AU (Saturn). Below 3 metres or so, we no longer call chunks of rock "asteroids" but "meteoroids". However, there are a lot more small chunks of rock than there are big chunks of rock; therefore, a typical asteroid has a size very near that lower limit. In other words, an argument about whether or not we can "see asteroids beyond an AU" is really really silly, because "asteroids" covers such a wide range of sizes.

edited 30th Aug '12 4:22:44 AM by kassyopeia

Soon the Cold One took flight, yielded Goddess and field to the victor: The Lord of the Light.
McKitten Since: Jul, 2012
#35: Aug 30th 2012 at 4:48:55 AM

Well, assuming we're still within the parameters of the OP, so we're talking a 1-2km in size, but very hot object.

kassyopeia from terrae nullius Since: Nov, 2010
#36: Aug 30th 2012 at 6:46:09 AM

I thought we were talking about "dreadnoughts" now, whatever those are. tongue

Soon the Cold One took flight, yielded Goddess and field to the victor: The Lord of the Light.
McKitten Since: Jul, 2012
#37: Aug 30th 2012 at 9:13:26 AM

A series of wooden ships of the line in the royal navy in the 15th to 17th century. (and lately, a submarine)

You're welcome. :p

edited 30th Aug '12 9:13:46 AM by McKitten

TuefelHundenIV Night Clerk of the Apocalypse from Doomsday Facility Corner Store. Since: Aug, 2009 Relationship Status: I'd need a PowerPoint presentation
Night Clerk of the Apocalypse
#38: Sep 1st 2012 at 3:09:59 PM

-looks at the math and nose starts bleeding-

That is a lot of math.

Who watches the watchmen?
breadloaf Since: Oct, 2010
#39: Sep 2nd 2012 at 1:38:31 PM

I think Hubble's range is much better than WISE but WISE can find objects which are only spewing radiation in the IR range (thus able to find a zillion new things). The asteroids it finds are in the main belt which is around 1 AU to 2 AU (or something like that), those are about 300 K.

The "dreadnought" discussed was a cubic area of something like 300 m x 100 m x 100 m for the purposes of calculations (and then morphed into a sphere because that was easier to calculate).

The mission says it will find "Detect most Main Belt asteroids larger than 3 km". Of course that being a function of temperature and size, it would vary.

On the topic of asteroid mining, I found some idea of gravitationally towing asteroids about, but that is a many years-long operation. However, the main benefit is that it doesn't really need much human intervention or fuel.

One could also presumably just plant a mobile refinery into an asteroid since asteroids are basically like surface strip mining. The materials are right there.

Usually, I think, the main difference is just how much it would cost to mine a planet versus an asteroid. If you arrived at Sol System by space in the first place, there's no terrestrial settlement for you to haul the materials to in-system. Everything is being shipped off somewhere else. So, I think maybe asteroid mining might have better cost-benefit.

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