Solar System

[harry]

G'day

Solar System: Planets compared to Earth mass and distance

Planet Mass Distance (AU)

Mecury 0.055-------------------0.4
Venus 0.815-------------------0.7
Earth 1.0----------------------1.0
Mars 0.1----------------------1.5

ASTEROID BELT ------------------------2.3 to 3.3 Here we have large dwarf planets millions of small to large rocks.

Ceres ------------------------2.7 Dia 1000km
Hygiena -------------------------to come
Vesta --------------------------to come


Jupiter 318 -----------------------5.2
Saturn 95 ------------------------9.5
Uranus 14-------------------------19.6
Neptune 17-------------------------30

Kuiper Belt ------------------------------------30 to 50 Au over 100,000 ice blocks with 50 Km radius and dwarf planets including Pluto and Charon

Pluto ------------------------------------39 Au 2200 Km dia
Chevron -----------------------------------39 Au ??????? to come

Outer solar system
Eris -------------------------------------68 AU 2400 Km Dia
Sedna -------------------------------------68 AU 2000 Km Dia


It's amazing how man can search the stars and keep on finding star bodies out there. Not to mention over 170 moons.

Note the mass of MARS: How can it hold an atmosphere with such little mass?

[neufer]

Note the mass of MARS: How can it hold an atmosphere with such little mass?

It can't (except for heavy CO₂)

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Surface pressure: 	0.006–0.010  (earth) atmospheres
....................................
Carbon dioxide    95.72% 
Nitrogen           2.7% 
Argon              1.6% 

[Orca]

Temperature is another issue. Take Titan for example. Titan has a thick, mostly nitrogen atmosphere even though it's much smaller than Earth. It's easier for a planet or moon to hold on to an atmosphere when the temperature is so low because the gas particles are less energetic.

[neufer]

Temperature is another issue. Take Titan for example. Titan has a thick, mostly nitrogen atmosphere even though it's much smaller than Earth. It's easier for a planet or moon to hold on to an atmosphere when the temperature is so low because the gas particles are less energetic.

Still, it should still be easier for gases to leave Titan than for gases to leave Mars
based upon "escape velocity index" = [ Escape velocity / Sqrt(Temperature) ]

However, gases that escape Titan simply go into orbit around Saturn and are recovered by Titan.
(Titan gases are also protected from the solar wind by Saturn's magnetic field.)

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Mars: Escape velocity index: 307
Escape velocity 	5027 m/s
Surface temp. (max)  268 K
............................................
Titan: Escape velocity index: 272
Escape velocity 	2639 m/s
Temperature 	93.7 K

Total escape velocity index: >511
Total escape velocity  >4947 m/s
Temperature 	93.7 K

[harry]

G'day

Sorry, I meant an atmosphere such as Earth.

[makc]

I meant an atmosphere such as Earth.

you mean, how could it be made to support an athmosphere such as Earth one, while being much less than Earth? well, that's a good question for terraforming device designers it either should constantly generate it from planet ice core or build some kind of shield around the planet.

[orin stepanek]

I believe if we ever colonise Mars; we would have to keep some type of bubble shelter to hold in life support. Keep it under wrap; so to speak.

Orin

[Orca]

I really don't think that terraforming Mars is worth serious consideration.

Even if you could find a way to introduce enough gasses to thicken the atmosphere - which you probably can't - Mars does not have a magnetic field, so what ever gas you introduce would bleed away into space over time. A constant flow of replacement gas is even more fanciful than introducing any significant change to its atmosphere in the first place.

I think that in all likelihood "Martians" will never be more than colonists and they'll survive by spending most of their time underground.

[BMAONE23]

I have to agree. I don't believe that Mars would be gravitationally capable of sustaining planet wide oxygen-nitrogen atmospheric pressure capable sustaining life on our terms. Titan has a fair atmospheric pressure but this is due to both the cold conditions and the gasses that comprise it. I think that the most likely candidate for terraforming would be Venus but you would have to start with a massive CO2 scrub to lower both temperature and pressure.

[Chris Peterson]

I have to agree. I don't believe that Mars would be gravitationally capable of sustaining planet wide oxygen-nitrogen atmospheric pressure capable sustaining life on our terms.

Mars, with a surface gravity nearly 40% of the Earth's, is very capable of supporting an oxygen-nitrogen atmosphere. There are good indications that it had a much denser atmosphere during its first billion years or so. There is abundant oxygen, and probably water on Mars to effectively terraform it. Key to the process is inserting sufficient water vapor, and the lack of a magnetic field probably means that water (or at least, its hydrogen component) would be lost to space at a much higher rate than occurs on Earth. But the amount of water present, and its rate of loss, is still sufficient for millions of years of a warmer, denser atmosphere.

There are a variety of good reasons to doubt that we'd ever attempt terraforming Mars (or Venus, for that matter- a much more difficult planet to deal with), but I think terraforming Mars is almost entirely an engineering problem, not something with physics working hard against it.

[Doum]

Lets Just..

Open a wormhole between Venus atmosphere and Mars atmosphere and let the difference of pressure do the job. At 1 earth atmospheric pressure we close the link. As for water we just need to do the same but between Mars atmosphere and the Jupiter moon Europa. Just link the underground ocean of that moon.

It look like easy. Does'nt it?

[Chris Peterson]

Open a wormhole between Venus atmosphere and Mars atmosphere and let the difference of pressure do the job. At 1 earth atmospheric pressure we close the link. As for water we just need to do the same but between Mars atmosphere and the Jupiter moon Europa. Just link the underground ocean of that moon.

Well, even if you make a wormhole, you can't change fundamental laws like the conservation of energy. From Venus to Mars is "uphill"; I estimate it takes over 100 MJ per kilogram to transport anything. I don't think the paltry pressure difference between the two atmospheres in going to do that! And from Europa to Mars is pretty seriously "downhill" - you're going to have to dump a lot of energy somewhere if you don't want to ionize the water.

[Doum]

Chris,

I was joking when i make that post. And i suppose you are joking when you say uphill and downhill. Cause wormhole is supose to eliminate the distance between 2 point. So on one side you have mars and just beside you have venus (Let say a 3meter diameter wormhole). You can cross with one step from one side to the other. Dido with atmosphere and water.

Anyway the worst part is to open a wormhole, i read that it will need all the energy of the universe (So it's a science fiction idea at best). That is why i was joking when i write the post. (Also i am not sure that wormhole do exist.)

Underground city on Mars is the best shortterm solution.

[geckzilla]

I drew a picture of a city in an enormous cavern on Mars a few months ago.
http://www.geckzilla.com/art/v/139 (lower left one)
I don't like plugging my art for no reason but this time it's actually pertinent. Maybe I should do more space scenes. I've never been very good at mechanical or geometric things, though. I wonder whether there are many natural caves on Mars.

[Chris Peterson]

I was joking when i make that post. And i suppose you are joking when you say uphill and downhill. Cause wormhole is supose to eliminate the distance between 2 point. So on one side you have mars and just beside you have venus (Let say a 3meter diameter wormhole). You can cross with one step from one side to the other. Dido with atmosphere and water.

I know that your post wasn't serious. But mine was, sort of. The wormhole might eliminate the distance between two points, but it can't magically eliminate any difference in potential energy between those points... potential energy that is going to get converted to kinetic energy when something moves between. It really is uphill from Venus to Mars, and a wormhole (or teleporter, or anything like that) doesn't change that fact.

[geckzilla]

Do you mean uphill and downhill with respect to their distances from the sun?

[Chris Peterson]

Do you mean uphill and downhill with respect to their distances from the sun?

Yes. Clearly there is a significant difference in the gravitational potential energy of an object at Venus's distance from the Sun and one at Mars's distance. If you wanted to analyze this in gruesome detail (which I don't!) you'd also have to look at the difference in gravitational potential of the planets themselves (at their surfaces, or whatever height in the atmospheres you placed the wormhole ends), as well as energy differences caused by the relative motion between the two planets, which obviously changes with their orbital positions.

[Doum]

Ok, i did it for fun and its a guesstimate. So i might be completely wrong but i realy hope i am not.

For 1 Kg of venus atmosphere at 108,5 million Kmfrom the sun, the gravity effect from the sun on it is:

1,12773 e +5 N

For mars at 225 million Km the gravity effect from the sun is :

0,26224 e +5 N

Difference is 4.3 time in favor of venus. But Venus have 90 bars pressure while Mars have almost none.
_____________________________________________________________

For 1 Kg of atmosphere at 1 Km altitude. Venus gravity effect is:

32,49 e +13 N

And for Mars its:

4,28 e +13 N

Difference is 7.59 time for Venus
____________________________________________________________

Mars gravity effect compare to the "Sun gravity effect on Venus atmosphere" is 3.8 million times in favor of Mars planet. Yay!
____________________________________________________________-

So venus have 7.59 time more gravity effect on Mars then Mars on Venus. And the Sun gravity effect on Venus is negligeable compare to Mars gravity effect on venus trough a wormhole. And dont forget that Venus have 90 bars pressure compare to nothing for Mars. So i suppose that Mars will collect the gas from Venus.

As for the movement of planet, ill pass on that one. I wont calculate it. Twas fun.

Neither did i calculate the energy of 400 degre celcius gas heat and 90 bars pressure in newton. So door are still open before getting to a conclusion.

[Chris Peterson]

For 1 Kg of venus atmosphere at 108,5 million Kmfrom the sun, the gravity effect from the sun on it is...
...Difference is 4.3 time in favor of venus.

I would look at this in terms of energy. The solar gravitational potential energy of 1kg at Venus is 1.3e9 J, and the potential energy of 1kg at Mars is 6.1e8 J. The difference is 690 MJ, which is about how much energy it takes to lift a kilogram of mass from Venus's orbit to Mars's. That's quite a lot.

For 1 Kg of atmosphere at 1 Km altitude. Venus gravity effect is...
...Difference is 7.59 time for Venus

Here, I'd do a simple thought experiment. How far do you have to get from Venus so that you experience the same gravitational force as you would at the surface of Mars? I figure that to be about 3400 km above the surface. So let me ask this: why is it that a 3400 km long pipe from the surface up into space wouldn't drain Venus's atmosphere? After all, the difference in gravitational acceleration is the same between the two ends as between the surfaces of Venus and Mars, and the pressure difference is about the same as well. I think we can be certain that Venus's 80 bar surface pressure can't push anything through the pipe. So why should it be able to do this through a wormhole?

[BMAONE23]

Perhaps if the "Wormholes" were opened simultaneously, the energy gained from the "Downhill Run" from Europa to Mars could be utilized to drive the "Uphill Charge" from Venus to Mars

[Doum]

From Chis,
"How far do you have to get from Venus so that you experience the same gravitational force as you would at the surface of Mars? I figure that to be about 3400 km above the surface. So let me ask this: why is it that a 3400 km long pipe from the surface up into space wouldn't drain Venus's atmosphere? After all, the difference in gravitational acceleration is the same between the two ends as between the surfaces of Venus and Mars, and the pressure difference is about the same as well."

I agree on that. It's seem obvious. As the altitude increase, the gas pressure diminue in the tube till its complete vacuum (a few hundred KM in altitude you get vaccum). Then no mater how long you make the tube it wont change a thing.

But a wormhole dont have lenght. It's not a tube. So to me, its like being in a space station and you open the door. The air rush out. If you open a wormhole between the inside of the space station and the outside. The air rush out. Even if you open the other side of the wormhole far into space (million Km), the air will rush out.

Another tought experiment. Imagine a tube that start 10 meter above Venus surface and go 200 or 500 km or whatever the height into space (3400Km). Both end of the tube are open. Now instantly empty the tube of all gas and you will see a rush of gas coming from the surface of venus since the bottom tube is open to a 90 bars pressure of gas(Or 80?). The gas will get in the tube till it equalise the natural column of pressure that venus atmosphere have (That goes with the gravity planet and heat and...). Then the gas will stop getting in because the system will be in equilibrium again.

Now if we open a wormhole 10 meter above the surface of venus and the other side let say 3400 Km into space (Wormhole aint a tube.), the column of gas pressure just under the wormhole entrance on the surface of venus become Zero. So the gas start rushing into the wormhole till an equilibrium with the venus natural column of pressure is obtain. But since the exit is 3400 Km into space, the column of pressure can not be obtain and Venus atmosphere keep rushing out till nothing is left or we shutdown the wormhole.

May be the needed energy you are talking about is present in the wormhole itself and as gas pass from one side to the other the wormhole require a constant amount of energy to maintain that transfer.

[rstevenson]

Magic wands can also do amazing things.

Therein lies the problem with discussing what a wormhole can and cannot do: it can do anything at all, since it's not constrained by reality.

Rob

[apodman]

I think everyone knows this is just an exercise. Right?

---

Meanwhile, referring to contemporary commentary on Tethys, look at the Saturn system for methods of transporting material from one body to another. Saturn's moons and rings trade material like some people change underwear. As an exercise, see how large you can scale one of those existing transport mechanisms before it breaks down - with a theoretical eye to using it between Mars and Venus. I do think the plumber was right, though (**** flows more easily downhill).

[Orca]

The fact that the subject of terraforming Mars has turned into a conversation about the practicality of wormholes as transport devices sort of shows us how unlikely the prospect really is (I realize the wormhole thing was a joke and then a mental exercise. However as I understand it, though wormholes are allowed by GR they will collapse when any matter tries to pass through; sorry Deep Space Nine fans).

Introducing huge amounts of gas, probably water vapor, into Mars' atmosphere means you need a lot of water to vaporize. A lot. Transportation is just right out, unless you are talking about building a fleet of ships and moving water for hundreds or thousands of years. I can think of a few million better ways to spend our resources. So you're left with two options...the the Martian ice caps or comets.

But once again, if you vaporize the ice caps, the newly formed atmosphere will just be torn away over time by the solar wind and once that's done, well, now you're fresh out of ice caps.

And even if you were able to vaporize the caps in a short amount of time and keep an envelope of breathable air for a few thousand years, well, it's not as though you'll be strolling around the surface - taking mule trips into Valles Marineris and the like - because you'll be exposed to solar and cosmic radiation.

So what's the point?

[harry]

G'day

It's probably easier to live on Io moon of Jupiter. Lots of water and Geothermal energy and fire works for Xmas.