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karov

Member

From: Bulgaria

Registered: 2004-06-03

Posts: 953

Venus + magnesium

http://www.spacedaily.com/reports/Mercu … t_999.html

Mg from wiki: "and the eighth most abundant element in the Earth's crust[2] and ninth in the known universe as a whole.[3][4] Magnesium is the fourth most common element in the Earth as a whole (behind iron, oxygen and silicon), making up 13% of the planet's mass and a large fraction of the planet's mantle."

I do not know how rich are the outer layers of Mercury, BUT I remind here that there was long time ago the idea to "extinguish" the excessive Venusian atmosphere with reactive metals.:

Mine magnesium and aluminum by solar-powered self-replicating automated factories on Mercury, and "sniper" Venus by solar-powered catapults with metal ingots, bullets, flakes ...

The metal would react with the CO2 into metalic oxides and sooth ( carbon ) , both solid under high pressure and temperature, which solid residue would precipitate on surface.

MgO the chemical formula of magnesia tells us that each Mg atom would take 1 Oxigen with it. Two Mg atoms to turn to ashes a molecule of CO2.

Molar mass of Mg approx. 24
Molar mass of MgO approx. 40
Molar mass of CO2 approx. 44

Of 4.8x10exp20 kg total mass of the atmosphere of Venus, 27% are carbon by mass. Or...:

... after the magnesium bombardment commences just step aside and wait several decades ( and about 200 000 000 000 000 000 tonnes of Mg delivered ) in order to get a 3-4 bars almost pure Nitrogen atmosphere around Venus and giant masses of magnesia-sooth on surface ... and you have ( pretty much indeed ) way more handable place to terraform and settle.

add water, stir well, wait the sediments to settle, infect with photosynthesizing organisms ...

If the Mercurian rocks of interest are, say, 10% Mg by mass, then "only" 1 000 000 000 km3 of rock must be processed en situ.

With surface area of 75 000 000 000 000 m2 and approx. surface density of 2000 kg/m3 one has to scrape off only 4-5 miles down from the whole surface.

The resulting 90% slag / scoria / dross from the Mg refinement would consist of iron, oxigen, alumina, silica ... ... which with their shear mass of 1 800 000 000 000 000 000 tonnes and areal density of about 30 tonnes per m2 are enough for construction of 600 000 000 000 000 000 m2 of habitat area or 600 BILLION SQUARE KILOMETRES or 1200 TIMES the total planetary surface of the Earth, or 4000 TIMES the land area of Earth!!!!

Thus the project "mine Mg from Mercury to solidify the nasty atmosphere of Venus" would bring only 0.03% "profit" as terraformed Venus, the major objective and the rest of 99.97% would come from utilizing the waste products of the project.

Void

Member

Registered: 2011-12-29

Posts: 7,836

Re: Venus + magnesium

Perhaps it is OK, due to the lack of current activity if I should suggest an optional deviation from that plan.

I have considered a "First Step" to neutralize the PH of Venus and make it more machine friendly.

A second step would be to reduce or eliminate the cloud cover, letting a large part of the heat potential out.

Metals inserted into the atmosphere would most likely move the PH towards neutral.  I expect it would take less metals than to dissapear the whole atmosphere into metal compounds.

It might be a perference if the Sulphuric Acid reacting with metals would leave behind some H20, but that may not be a subsidiary feature of such a process.

At any rate if you can dump metals into the atmosphere of Venus, perhaps not just Magnesium, but other metals, and Silicon.

I have speculated on a shell in the atmosphere previously, where below it is the bulk of the CO2, and also >3/4 ths of the Nitrogen.

Above the shell, Nitrogen at 58%, and if obtainable 42% Oxygen.  (500 MB?, about right for Venus with Times 2 sunlight?)

I am aware that Venus has ferocious winds.

However such a shell would "Float" on a layer of mostly CO2 like the surface of a waterbed.  Should it bulge, the weight of the bulge would draw it back down, because the above layer is approximately 1/2 as dense as what is below.  The shell would also need to be lighter than the mix below, which requires hollows with a light gas.

The sequence of building might be:
1) Get rid of the acid PH.
2) Get rid of most of the clouds.
3) Wait for the turbulence from this change to settle down.
4) Floating habitats, and high temperature robots on the surface.
5) Perhaps the Hall weather machine?  Refelctive bots?
6) More cooling if 5 is available.
7) Have a robotic system build a shell,  hives of very small robots. 
8) Begin separating the atmosphere above from that below.
9) Thicken the shell.
10) Habitate the surface of the shell.

It is all far fetched, but not the most far fetched ever mentioned here.

After all that either export atmosphere by some means, or indeed continue to import metals from Mercury, and reduce the volume of the atmosphere.  The falling materials of course would have to be fashioned into shell materials, or pushed under the shell.

If I remember, you like shell worlds also.

I can also say that if this was done, then the "Shell" could generally be highly reflective, and would have only 1/2 bar of atmosphere above it which would help cooling, the lower layers below the shell would eventually cool more.  Of course that would then require that the shell adjust it's size, so it's not all that easy, but I am guessing you are enterained a little bit by my response.

Venus is the really hard one.

Edited 01-Feb-2013 (I don't care much about the spellings, but I had the wrong N2 to O2 ratio I think).  Verbal is my one of my weakest abilities.

Last edited by Void (2013-02-01 21:37:04)

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Zo0tie

Member

Registered: 2013-07-05

Posts: 5

Re: Venus + magnesium

http://www.spacedaily.com/reports/Mercu … t_999.html
Mg from wiki: "and the eighth most abundant element in the Earth's crust[2] and ninth in the known universe as a whole.[3][4] Magnesium is the fourth most common element in the Earth as a whole (behind iron, oxygen and silicon), making up 13% of the planet's mass and a large fraction of the planet's mantle."
I do not know how rich are the outer layers of Mercury, BUT I remind here that there was long time ago the idea to "extinguish" the excessive Venusian atmosphere with reactive metals.:
Mine magnesium and aluminum by solar-powered self-replicating automated factories on Mercury, and "sniper" Venus by solar-powered catapults with metal ingots, bullets, flakes ...
The metal would react with the CO2 into metalic oxides and sooth ( carbon ) , both solid under high pressure and temperature, which solid residue would precipitate on surface.
MgO the chemical formula of magnesia tells us that each Mg atom would take 1 Oxigen with it. Two Mg atoms to turn to ashes a molecule of CO2.
Molar mass of Mg approx. 24
Molar mass of MgO approx. 40
Molar mass of CO2 approx. 44
Of 4.8x10exp20 kg total mass of the atmosphere of Venus, 27% are carbon by mass. Or...:
... after the magnesium bombardment commences just step aside and wait several decades ( and about 200 000 000 000 000 000 tonnes of Mg delivered ) in order to get a 3-4 bars almost pure Nitrogen atmosphere around Venus and giant masses of magnesia-sooth on surface ... and you have ( pretty much indeed ) way more handable place to terraform and settle.
add water, stir well, wait the sediments to settle, infect with photosynthesizing organisms ...
If the Mercurian rocks of interest are, say, 10% Mg by mass, then "only" 1 000 000 000 km3 of rock must be processed en situ.
With surface area of 75 000 000 000 000 m2 and approx. surface density of 2000 kg/m3 one has to scrape off only 4-5 miles down from the whole surface.
The resulting 90% slag / scoria / dross from the Mg refinement would consist of iron, oxigen, alumina, silica ... ... which with their shear mass of 1 800 000 000 000 000 000 tonnes and areal density of about 30 tonnes per m2 are enough for construction of 600 000 000 000 000 000 m2 of habitat area or 600 BILLION SQUARE KILOMETRES or 1200 TIMES the total planetary surface of the Earth, or 4000 TIMES the land area of Earth!!!!
Thus the project "mine Mg from Mercury to solidify the nasty atmosphere of Venus" would bring only 0.03% "profit" as terraformed Venus, the major objective and the rest of 99.97% would come from utilizing the waste products of the project.

That's not a bad idea, at least as far as terraforming ideas go. The surface of Mercury is believed to be similar to that expected from partial melts of enstatite chondrites. They tend to be high in the mineral enstatite (MgSiO3), from which they derive their name. Perhaps you could calculate the energy required to convert to magnesium to metal and the energy required to accelerate the resulting metal to a velocity to intersect the orbit of Venus.  If you assume the insolation at Mercury's orbit and assume a certain surface area for a solar cell to power everything, and assume 100% conversion you could give us a minimum timeframe within which this would be done.  Energy budget and schedule.

If you could accurately aim so that the magnesium strikes the atmosphere at an angle this could transfer momentum and speed up the Venusian day. Perhaps you could do a calculation of how much of a spin you could give.

Is the reaction of magnesium and CO2 favorable at Venus conditions?
Hmm...I guess it is.
http://chemed.chem.purdue.edu/demos/mai … /5.16.html

Last edited by Zo0tie (2013-07-15 15:06:42)

karov

Member

From: Bulgaria

Registered: 2004-06-03

Posts: 953

Re: Venus + magnesium

Zo0tie,

<<< Perhaps you could calculate the energy required to convert to magnesium to metal and the energy required to accelerate the resulting metal to a velocity to intersect the orbit of Venus.>>>

Yes, I can. But we could estimate that the temperature for chemical dissociation and separation of the Mg is negligible compared with the "temperature" of the trans-orbital velocities. So we , for the purpose of our guestimation could round-up the energy budget to dissociate Mg compounds and to send the metal over to Venus, within the orbital kinetic energy budget. How much delta-V? - 10-ish km/s? Indeed less but I'm lazy to check out.

kinetic energy = 200 000 000 000 000 000 000 kg x 10 000 m/s x 10 000 m/s / 2 Joules. = 10exp28 Joules.
momentum = 200 000 000 000 000 000 000 kg x 10 000 m/s.

<<< If you assume the insolation at Mercury's orbit >>>

why Mercury orbit when we could use a statite solar power plant deeply at the sun, say at 1MW/m2 distance ... ?

<<< and assume a certain surface area for a solar cell to power everything, and assume 100% conversion you could give us a minimum timeframe within which this would be done.>>>

Why 100%. Indeed far less is ok - 20%, 10% ...

<<< Energy budget and schedule. >>>

You'll make me to calculate a recepie, indeed

<<< If you could accurately aim so that the magnesium strikes the atmosphere at an angle this could transfer momentum and speed up the Venusian day. Perhaps you could do a calculation of how much of a spin you could give. >>>

Indeed 10exp28 Joules is comparable with the rotational energy of the Earth, BUT magnesium flux to impart the momentum for spinning Venus faster would indeed ( I feel ) strip the atmosphere AND also, I like Venusian diurnal cycle of 2 months day and 2 months night.

Zo0tie

Member

Registered: 2013-07-05

Posts: 5

Re: Venus + magnesium

<<<But we could estimate that the temperature for chemical dissociation and separation of the Mg is negligible compared with the "temperature" of the trans-orbital velocities. So we , for the purpose of our guestimation could round-up the energy budget to dissociate Mg compounds and to send the metal over to Venus, within the orbital kinetic energy budget. How much delta-V? - 10-ish km/s? Indeed less but I'm lazy to check out. >>>
Depending on the chemical processing technology the energy demands for magnesium manufacture may vary from 1.22e+7 to 3.6e+7 J/kg.  But that's for MgCl2 which is the most common raw material available from sea water. There are processes for making magnesium directly from MgO or other magnesium compounds likely found on Mercury but I haven't found information in energy requirements.  Its probably higher which is why they're not used today.
http://www.belgeler.com/blg/lg2/electro … um-uretimi
The energy to move magnesium from Mercury to Venus orbit can be estimated based on the necessary change of total orbital energy.  If we assume circular (close despite Mercury eccentricity) orbits then it's the difference of kinetic orbital energy for a kg which can be obtained from orbital velocity of the two planets.  This gives approx 5.32e+8 J/kg.  Therefore energy of magnesium manufacture may be significant but we'll deal with that later.
The equivalent delta V required to get to Venus orbit is computed from V = SQRT(2*Energy/Mass) = 3.26e+4 m/sec or 32.6 km/sec.
You can save on energy by shooting in a very elliptic trajectory but that will require a very specific targeting solution but that will only happen when Mercury passes Venus. Since Mercury is slowly turning your Mercury based linear accelerator is going to have difficulty getting a good targeting solution. And if you miss, your magnesium cargo will drop back and probably be vaporised by the Sun.  Ultimately the total energy budget for manufacturing magnesium metal from the crust of Mercury and shooting it to Venus to reduce the CO2 levels is:

2e+20 kg of Mg * (3.6e+7 J/kg + 5.32e+8 J/kg) = 1.136e+29 Joules

Thats less than the 2.1e+29 J rotational energy of the earth so maybe if you figure out a way to keep from blowing the atmosphere away you could speed up the planet rotation.

<<< why Mercury orbit when we could use a statite solar power plant deeply at the sun, say at 1MW/m2 distance ... ?>>>

That assumes that you are going to have to either get the magnesium crust to the statite deeper into the Sun's gravity well which takes more energy or get the accumulated energy to the magnesium processing plant on Mercury. Beamed microwaves perhaps? Otherwise you're going to need a VERY long extension cord!

<<<Why 100%. Indeed far less is ok - 20%, 10% ...>>>
100% is used because we can't predict the future technological advances. Obviously no human device will ever reach 100% efficiency.  But using basic physical laws in our computations and 100% conversion effeciencies allows us to estimate the BEST we can do to achieve a specific goal.  Later if the numbers don't look too ridiculous (1,000,000 years to cool off Venus) we can refine them with realistic assumptions about future technology. Otherwise we would just mindlessly give up, wave our hands, and scream that NANOBOTS will terraform Venus, end world hunger, save us from global warming, and reduce the price of gasoline!

<<<You'll make me to calculate a recepie, indeed>>>

It's the only way to be able to realistically see which method for Terraforming Venus is the most efficient. Mass, energy, and time schedules are a critical part of of industrial planning whether you are building a statue, a city, or a new world.

<<<Indeed 10exp28 Joules is comparable with the rotational energy of the Earth, BUT magnesium flux to impart the momentum for spinning Venus faster would indeed ( I feel ) strip the atmosphere AND also, I like Venusian diurnal cycle of 2 months day and 2 months night.>>>

Many terraformer enthusiasts do. But I believe that a relatively fast spin rate is necessary to maintain convective movement of the air necessary to cool the surface. At present Venus surface receives less solar energy than the Earth due to the clouds. But lack of mixing due to the slow rotation causes a heat buildup in the lower levels of the air.  Actually it's difficult to blow away the air with collisions.  A Mars sized object hit the earth to create the Moon but here we are with plenty of air anyway.