Mars Can't be Terraformed? Not enough Gravity to hold Hydrogen?

[Ichingcarpenter]

I was surfing the net on terraforming planets and came upon this. What do you guys think?......'Does it hold 'water'? pun intended.



Why Mars can't be terraformed

Mars is too small.
As we can see from Equation 1, Mars will need additional gravity to hold Hydrogen in it's atmosphere.
Equation 2 can be used to determine how much additional mass is needed.










The Math..

http://www.terraformers.org.au/escape.html


The site:

http://www.terraformers.org.au/whymars.html




Meanwhile the Mars Rover took this photo that NASA
just released:

[LiberalArkie]

1. Love it

[izquierdista]

2. A little empirical

One has to question how they calculated their fudge factor k. To do the calculation from first principles, you just need to know the temperature of the planet, not necessarily the luminosity of the star (although the two are highly correlated). From the temperature, you calculate the mean velocity of the gas molecules in the atmosphere and compare that to the escape velocity for the planet. If the mean velocity exceeds the escape velocity, the planet is going to that component of the atmosphere over time.

Then again, such calculations as these don't account for any mechanism to add atmosphere, such as gases brought in by comets, meteors and asteroids crashing into the planet.

[Ichingcarpenter]

3. What keeps hydrogen from escaping earth?

It seems that would be a problem here.
I know the main problem with Mars terraforming is its lack of a magnetic field. However, I hadn't heard of this argument before about the gravity and mass of Mars.

Anyway thanks for your input.

[tabatha]

7. Helium and hydrogen escape earth.

This is why the gas giant planets have significant amounts of hydrogen and helium, which escape on Earth.

http://en.wikipedia.org/wiki/Atmospheric_escape

Hydrogen in water does not.

[izquierdista]

9. Good reference

They should mention that hydrogen is chemically sequestered into heavier molecules, which is why you don't have much H2 floating off into space. But as for helium, once it escapes from underground where it was generated by radioactive decay, it's got pretty clear sailing off into the solar system.

[qazplm]

4. haven't we always known that it was going to be a continual process

that Mars gravity and lack of a magnetic field means that we will have to occasionally and continuously replenish certain gases to maintain a suitable environment?

[Ichingcarpenter]

5. The Gravity/hydrogen problem is not mentioned

in the wikipedia article

http://en.wikipedia.org/wiki/Terraforming_of_Mars

[qazplm]

17. maybe not that specific issue

but it's well known that Mars lost its atmosphere for various reasons and thus it can't permanently maintain a new atmosphere (unless we are going to add mass and give it a magnetic field)...

thus over thousands of years or longer, we'd have to keep renewing the atmosphere somehow to keep it livable.

[laconicsax]

6. I wouldn't trust anything on that site.

Venus has a high surface temperature and pressure. This is due to the high concentration of Carbon dioxide (CO2) gas. When all CO2 gas is removed, Venus will be colder than Earth by 35 K. The highly reflective SO2 in the upper atmosphere will precipitate within a few years, warming the planet by a few Kelvin. CO2 is dissociated, the Carbon stored and the Oxygen released. The atmosphere will then be mostly O2 with a small portion of N2. Venus is then relocated to an orbit between Earth and Mars. H2 is then imported from the gas giants and released directly into the atmosphere from space. H2 will react with atmospheric O2 producing water that will rain down across the planet. Water is a greenhouse gas and Venus will warm again until it is slightly cooler than Earth. After a hydrosphere is established the excess atmosphere is then seperated into its constituents. Each constituent is liquified and stored under pressure for later use or incremental release. The planet is now ready for colonisation!

They call this "difficult, but possible."

[Ichingcarpenter]

8. OK.... that's what I thought

I didn't read the venus bit ..lol
Anyway back to my sci/fi adventure.

[Humanist_Activist]

10. I wouldn't laugh too hard, they are technically correct...

The best kind of correct. At least as far as being able to move Venus out of its current orbit. A gravitational tug would suffice, basically a smaller mass that, combined with thrust, is put in a Venusian orbit that forces it to gradually change orbit over a period of time. Given enough time and energy, it could be moved to any distance from the sun, even far past Earth. I haven't done the math, but I would gather it would take thousands of years, at the very least. Certainly not practical or economical, but physically possible.

Don't know about why they are so hung up on H2 though, Earth is not massive enough to keep it in our atmosphere, so that's a non-issue.

[laconicsax]

12. I'm not sure they meet that standard.

Last edited Tue Mar 13, 2012, 05:02 PM - Edit history (1)

Moving Venus out past Earth's orbit in the easiest way possible (your suggestion) would result in a collision between the two planets.

ETA: Does anyone understand this bit: "The high atmospheric pressure on Venus has compressed and cooled the planetary core."

[Humanist_Activist]

19. Yeah, I thought of that after I made the post.

Two ways around it, to my way of thinking, one is to increase the inclination of Venus, make its orbit fall out of the plane of orbits for all the other planets. Since your already moving it away from the Sun, why not move it up or down as well? By the time it reaches an orbit of the same period as Earth's, it would only cross Earth's at two points during its orbit. If timed correctly, it could be set up to make it impossible to collide with Earth. Both planets would have the same period, same velocity(but at two different points), and a similar ellipse.

The issue at this point is whether to move Venus beyond its orbit at that point, if it can be artificially maintained with minimal expenditure in resources, then it would probably be economical to leave it there, over time its atmosphere could be terraformed, and it should have a relatively stable atmosphere at that point. Ripe for colonization.

The other option is to not change the inclination and instead coordinate the Earth-Moon system and Venus into two new systems, if we are not only moving a Planet, why not a Moon as well? First step is to remove the Moon from Earth orbit, using a gravitational tug just like Venus, one option(and one I like, in a fanciful way) is to move it to Mars and let Mars capture it as a new satellite. The advantage to Mars would be stabilizing its axis of rotation and also may help it form a more extensive magnetic field through tidal heating of its interior.

Venus can then be moved into an orbit where both Venus and Earth capture themselves in a stable orbit, while still retaining the overall orbit between them and the sun. A binary planetary system, if you will. They will orbit around a common barycenter while that barycenter is going around the sun in Earth's old orbit.

However, this one has one huge issue, the overall affect on Earth, the problem is tides and also disruption of the tectonic plates. There may be ways to minimize the issue, but a mass almost equal to Earth's getting close enough to orbit can cause quite a bit of disruption, increase in volcanic activity and earthquakes are a possibility, and tidal effects in the ocean may be much greater than we see now with the Moon.

One way we may minimize or eliminate this possibility would be to have Venus and Earth orbit each other in a way that matches Earth's rotation and Venus's orbital period. Tidally lock Earth and Venus together, in other words. The disruption on Venus may be more intense, given that's its rotation is actually opposite than Earth's, it could experience tidal effects much more keenly than Earth, even if tidally locked to Earth's rotation.

Of course, other issues may arise, and possibly advantages to both planets, the first may be Venus may experience tidal heating, or even better, currents in its core to kickstart its magnetic field, if not, then Earth's would provide partial protection to inhabitants of Venus from the Solar Wind. But if Venus is able to kickstart its own, it may lead to some interesting effect, Auroras in differing locations on both planets as its magnetic field interacts with Earth's, etc. Of course, we would also have a full fledged planet right next door to colonize, doubling humanity's living space with very little energy requirements(relatively) to get to either planet.

Of course, we are talking about the theoretical here, if humanity decides this has to be done, I imagine it won't happen for hundreds if not thousands of years in the future. My only point is that nothing in physics, hell nothing that can't be done with current or near future tech, is impossible here.

[laconicsax]

21. Little nitpick:

Mars, being substantially smaller than Venus, wouldn't capture Venus as a moon. The best that could be hoped for would be for the two to enter into a binary system with the barycenter closer to Venus than Mars.

The problem with such an arrangement is that the orbit of Earth you're would be significantly perturbed, perhaps enough to move all three planets into new orbits if not destabilize them entirely. (Similar problem with creating a binary Earth-Venus system.) Also, objects in the asteroid belt could be coaxed into new orbits significantly increasing the chances of collisions on all three planets (though I would assume that a civilization capable of precisely moving planets would have worked out an adequate defense from that).

I wonder, as an aside, what a Earth-Venus system would look like if the Moon were placed at the system barycenter as a rest-stop of sorts and whether such a system would be stable...Ooh! Or a Earth-Venus-Mars-Moon quaternary system.

[Humanist_Activist]

22. Actually, I was talking about the Moon being sent to Mars, not Venus...

Don't know if the Moon has enough mass for the barycenter to exist beyond Mars surface though, sorry I wasn't clear.

It would be interesting to wonder what it looks like, I found a program, called Orbiter, its a free flight/space simulator, but the most interesting part is this, it simulates the solar system, its gravity(each planet based on mass), temperature, atmosphere(for flight characteristics), etc. Anyways, people have made mods of it that changed the solar system around, one of which has Earth and a terraformed Venus orbiting each other around a common barycenter.

This program simulates a Newtonian universe, so while its close to ours, its not perfect, obviously the orbit of Mercury is wrong, Langrange points are extremely unstable and nothing stays there, even for a short while, etc. But its pretty damn close.

[Humanist_Activist]

11. Why would Mars have to be massive enough to hold H2 in the atmosphere?

That makes no sense, N2 yes, H2 no, Earth certainly isn't massive enough to hold it, yet we are still here, because the hydrogen that is present is in the form of bonded to other atoms to form molecules that Earth(and Mars) can hold on to.

The problem with Mars mass is related to its temperature, it couldn't retain a molten core(small mass lose heat a lot quicker), hence its magnetic field no longer extends beyond the surface of the planet. This allowed the solar wind to erode the atmosphere over time.

[laconicsax]

13. I checked, and we do have hydrogen in our atmosphere.

http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html

Very little hydrogen, but hydrogen nevertheless.

They seem to think that without H₂ in the atmosphere, you can't get any water.

You'd think that if they regard the process for terraforming Venus on the website to be doable, they'd consider importing water to Mars from elsewhere in the solar system.

[Humanist_Activist]

18. Yeah, seems silly, Mars has a lot of water, its just locked up in ice...

if the planet was given a thicker atmosphere, with a greater greenhouse effect to raise the temperature above the melting point of that water, it would melt, and lakes, rivers, possibly even an ocean(northern hemisphere) would form. Any shortage of water can be rectified by sending comets into the Martian atmosphere to break up, direct collisions may cause most of the mass of the comets to hurtle back out into space at escape velocity.

Also, as far as I'm aware of, what hydrogen is present is there due to the chemical reactions in Earth's atmosphere and volcanism and other processes.

Helium isn't present for long in Earth's atmosphere, and its not due to reactions with other elements that cause it to become undetectable, it leaves, and it is lighter than hydrogen, particularly atomic hydrogen.

[jakeXT]

14. I always thought the missing/lost magnetic field is a nail in the coffin of terraforming

[Humanist_Activist]

20. Not really a nail in the coffin, just makes thing much more difficult...

A much thicker atmosphere will provide some protection from the energized particles of the solar wind, However, they will also gradually erode away such an atmosphere(we aren't talking in decades but thousands if not millions of years). A very energy intensive solution would be large electromagnetic generators on or just below the surface of Mars, to create an artificial magnetic field, another possible solution, if not fanciful I mention in a post above, and another would be to take a lot of radioactive elements and send them down boreholes on Mars surface, to increase the level of radioactive decay in the interior(increasing heat) and possibly cause the core to become active again.

[MisterP]

15. also, colonization's a relict idea: there's a cheaper alternative:

http://en.wikipedia.org/wiki/Space_1889

[Odin2005]

16. Uh, Earth can't hold onto hydrogen, either. Stupid argument.