What is the coldest body in our Solar system?

[m1omg]

And we should walk and build a base on Mercury in the sunless craters - then you will not fry and due to the almost no thermal conductivity 'cos of no atmosphere even not freeze.There might be even frozen water in that craters.That will make a fully self-sustainable colony and a great source of metals.

[jamini]

According to this temperature calculator, http://www.astro.indiana.edu/~gsimon...perature1.html , the temperature of Sedna assuming it's albedo is 0.2, is only 9 Kelvin , which confirm Celestia number.

Eris is 29 K cold, but this is +20 K temperature difference.

From 97 AU the Sun is still relatively bright.
From 1000 AU, however, it have 1/2 the brightness of the full moon.
And according to Wikipedia, temperature on Sedna never rises above 30 K even in it's perihelion.
I guess that Sedna is the coldest (discovered) body in our Solar system.

Thanks, that is more what I was looking for and your guess may very well be correct. However in order to derive the temperatures precisely, we would need to consider the bodies' mean distances from the Sun; heat absorption/retention properties; atmospheric considerations; reflective radiation and other thermodynamic parameters.

[jamini]

And we should walk and build a base on Mercury in the sunless craters - then you will not fry and due to the almost no thermal conductivity 'cos of no atmosphere even not freeze.There might be even frozen water in that craters.That will make a fully self-sustainable colony and a great source of metals.

Some day perhaps we will. Although personally I feel that many other celestial bodies offer less hostile conditions that would prove more conducive to colonization.

,

[m1omg]

Some day perhaps we will. Although personally I feel that many other celestial bodies offer less hostile conditions that would prove more conducive to colonization.

,

But the amouts of metal on Mercury...and in cold crater there will be no worse than on cold crater on the Moon.
Most planets in universe are probably barren and terraforming takes millenias....we must adopt ALL places

[neilzero]

We SHOULD adopt MANY places. All is one of those words that scream exceptions. If miminal amounts of ionizing radiation fall in the polar crators of Mercury, I would rate it 3d or 4 th as most practical for an off Earth habitat or outpost with near term technological advances. In my opinion, massive advances are needed to build an O'Neal colony or a scaled down "deep Space 9" Neil

[Noclevername]

In my opinion, massive advances are needed to build an O'Neal colony or a scaled down "deep Space 9" Neil

What advances (besides access to space itself!) would be needed?

[baric]

We SHOULD adopt MANY places. All is one of those words that scream exceptions. If miminal amounts of ionizing radiation fall in the polar crators of Mercury, I would rate it 3d or 4 th as most practical for an off Earth habitat or outpost with near term technological advances.

Good luck finding any sane person that would want to live on a Mercury colony for any extended amount of time.

Human nature will inevitably be a greater roadblock to colonization than technology.

[m1omg]

Why not if an artifactal enviroment will be created...
I am one of them.

[m1omg]

And why?On Mercury there is no uglier enviroment than on the Moon

[m1omg]

My opinion - first space colonies will be probably big rotating habitats (creating artifactal "illusion" of gravity) with big greenhouses inside and also with cities.
A much nicer place to live than on Mercury..

[neilzero]

Let's try an optimistic time line for not very big rotating human habitats in space.
2008 access to space costs one dollar per pound = $2.20 per kilogram = $2200 per metric ton.
2012 we complete a sphere with a radius of ten meters; surface area = 4 pi r squared = 1257 square meters. About one ton per square meter of shielding will mean only slightly higher cancer risk than typical of Earth's surface = $2,764,608 for transportation from Earth to to the construction site in space. We haven't done this before, so total cost, perhaps ten billion dollars for the shell of the sphere with attachment flanges to connect interior stuctures. Perhaps another ten billion dollars for interior structure and supplies for the first ten years. 100 people are possible, but ten is realistic for sort of spacious long term accomodations. My house is almost 500 cubic meters for mostly two people, plus we have a yard around the house.
A similar 2nd unit will cost perhaps five billion dollars, if we made few mistake on the first unit, otherwise we may want to try different designs for each of the first ten units at about ten billion dollars each. The units can be tethered together in pairs about two kilometers apart, to provide artificial gravity.
By 2099 and somewhat larger unit 11 we may have a a moon base and/or asteroid base which can supply some of the materials for construction at competitve prices, but the total cost to 2099 may be one million times a million dollars to accomodate a few hundred humans, most of whom work long hours in space. Neil

[Noclevername]

By 2099 and somewhat larger unit 11 we may have a a moon base and/or asteroid base which can supply some of the materials for construction at competitve prices, but the total cost to 2099 may be one million times a million dollars to accomodate a few hundred humans, most of whom work long hours in space. Neil

2099 for asteroid mining? That sounds very pessimistic, considering that there are companies working on that problem now. It need not requre a manned base, for loose "rubble" asteroids an automated scoop can pick up or grind off material, and there are engineers working on automated systems for processing materials in space.

[neilzero]

I agree the first astreroid mining may occur by 2020, but when will an asteroid be making big deliveries to the construction site of something like deep space 9 or an O'Neal colony? Unless the proven quality is excellent, the contractors will often choose to pay double for construction materials from Earth, made to tight specifications. We are just beginning to build structures on Earth with dimenions of about one kilometer. With 1g of artifical gravity, the engineering will be very critical of the materials.
Odds are good, humans will suffer another major setback in the next few decades, comparable to the great depression of the 30's or WW2 of the 40's. If not, we could have asteroid mining and fabricated colonies if a few decades. Neil

[Ilya]

The radiation isn't from Jupiter, its from particles trapped in its magnetic field (like the Van Allen Belts around Earth), I don't think its directional enough that you could hide behind a moon.

It is SOMEWHAT directional. As Jupiter spins, its magnetic field spins and charged particles are carried along. Since all Jupiter's moons orbit slower than the planet rotates, the magnetic field hits them from behind. Thus a moon's leading hemisphere gets less radiation than the trailing one. Still enough to kill you, though.

[neilzero]

Is it lots more difficult to keep the astronaught at 300 degrees k if the frozen surface is zero k verse 9 k in a high vacuum? Neil

[Ilya]

Good luck finding any sane person that would want to live on a Mercury colony for any extended amount of time.

Why not if an artifactal enviroment will be created...
I am one of them.

For the same reason very few people want to live in Siberia for any extended amount of time.

Soviet government needed to "staff" (for lack of better word) mining, logging and fishing towns in Siberia, since there was only so much it could do with prisoners. Moscow attracted the settlers by paying then 2-3 times more than they would get for the same job in more benign climates, and by ensuring the consumer goods were same price as in the rest of USSR (i.e. subsidized transportation costs). This worked until USSR collapsed and subsidies dried up. Then everyone who could, fled from Siberia back to warmer places. Without high salaries the place is intolerable.

This could be due to overall lousiness of Soviet (and immediate post-Soviet) distribution of consumer goods, but population of Canada follows same pattern. Generally, people do not want live in places where you need an airlock for a foyer.

[mugaliens]

If you have good heating in your spacesuit, you will not freeze.

Wrong.

Vaccuum is an excellent insulator.

Being in the presense of cold fluids/gases would require extraordinary heating abilities to counter the cold conducted by the adjacent gases.