Terraforming Mars

[CraigD]

is there more potential energy in hydrogen peroxide HO+H=H2O

per volumetric ratio?

A simple way to compare the relative energies of various reactions is by comparing the molecular masses of their components. This gives us mass 2H +O -H2O = 0.0000407 AMU

H2O2 +2H -2H2O = 0.0000274 AMU

So the energy density of hydrogen fuel + hydrogen peroxide oxidizer ([ce]2H +H2O2 \to 2H2O[/ce]) is about 67% that of hydrogen fuel + oxygen ([ce]2H +O \to H2O[/ce]).

 

Hydrogen peroxide is also a monopropellant ([ce]H2O2 \to H2O + O[/ce]) Since

H2O +O -H2O2 = 0.0000133 AMU

It’s has about 49% of the energy density of [ce]H + H2O2[/ce] bipropellant.

 

Energy density is usually the ration of available energy to mass of a fuel. It can be converted to an energy/volume ratio by using the combined average density of the fuel and oxidizer by the formula

[math]d = \frac{m_1 +m_2}{\frac{m_1}{d_1}+\frac{m_2}{d_2}}[/math]

For [ce]2H + O[/ce], this gives about 425 g/L, for [ce]2H + H2O2[/ce], about 693. [ce]2H + H2O2[/ce] monopropellant has density 1440 g/L. So, despite lower energy/mass ratios, the energy/volume ratios are:

2H +O -H2O = 100%

H2O2 +2H -2H2O = 111%

H2O +O -H2O2 = 110%

 

So in an application where compactness is important (eg: a road car) lower energy density fuels like hydrogen peroxide may be preferable to ones like hydrogen+oxygen. Hydrogen peroxide also is liquid at room temperature, so much simpler to use.

[belovelife]

so if you used hydrogen peroxide in a vehicle

as the "gas"

you would still need a hydrogen fuel cell?

[harmonSmith]

interesting

[CraigD]

so if you used hydrogen peroxide in a vehicle

as the "gas"

you would still need a hydrogen fuel cell?

You could use hydrogen peroxide ([ce]H2O2[/ce]) to power an engine. It’s exhaust would consist mostly of hot (about 600 C) [ce]H2O[/ce] and [ce]O[/ce]. Though very clean, this high-temperature exhaust would react with other compounds found in air to produce some of the same pollutants (eg: nitrogen oxides) as petroleum-burning engines. Also, unreacted [ce]H2O2[/ce] could be present in the exhaust. Without an effective exhaust treatment system, an [ce]H2O2[/ce] powered vehicle would, I suspect, be pretty hazardous to anyone breathing in its vicinity. “High test” (that is, concentrated enough to react to do work) [ce]H2O2[/ce] is also scary stuff to handle, as it reacts violently with such materials as human skin, and if it comes into uncontrolled contact with materials it could easily be spilled on, can react violently enough to be considered explosive.

 

In short, it needs to be handled much more carefully than gasoline or diesel, and is only potentially environmentally cleaner.

 

Hydrogen peroxide also has a low energy density (about 2.7 MJ/kg) compared to fuels such as gasoline (46.4) or hydrogen (143). This is due in part to it containing its own oxidizer, where these other fuels get oxygen from the air, 2.7 MJ/kg is a pretty low energy density for applications like autos, closer to that obtainable from good batteries than from ordinary fuels.

 

In short, hydrogen peroxide doesn’t seem a good alternative car/truck/airplane fuel. :thumbs_do

 

Hydrogen fuel cell exhaust is almost nothing but [ce]H2O[/ce], making it almost certainly the cleanest power source available - you actually can, and Apollo astronauts did, drink its condensed exhaust water! However, they remain terribly expensive to make and easy to ruin, while compressed gas or liquid hydrogen is difficult and expensive to handle - simply keeping it from escaping before it can be used is a challenge.

 

In short, despite optimistic projections from policy makers and auto manufacturers, the feasibility of fuel-cell powered cars is far from assured. :(

[Moontanman]

I used to fly model rockets powered by liquid freon, the vapor pressure was used to make a reaction rocket. I've often thought that a H2O2 powered rocket would be pretty cool, built along the same lines as the freon rocket. The mono propellant H2O2 does need a catalyst, platinum I think, in the nozzel, does anyone know how much thrust to weight the peroxide would provide compared to a freon type rocket or a solid fuel model rocket?

[CraigD]

does anyone know how much thrust to weight the peroxide would provide compared to a freon type rocket or a solid fuel model rocket?

According to reports from companies building them (see previous wikipedia links) [ce]H + H2O2[/ce] bipropellant rockets have specific impulse slightly less [ce]H + O[/ce], and slightly better than kerosene. As a monopropellant, [ce]H2O2[/ce] has about half the energy density of [ce]H + H2O2[/ce] bipropellant. The best solid fuel rockets have about half the [math]I_{sp}[/math] of liquid fuel ones, so as a rough guess, I’d say peroxide monopropellant would be roughly comparable to solid fuel.

 

[math]I_{sp}[/math] and energy density aren’t the same as thrust to weight, but for rough comparisons, I think they're OK.

 

The energy density of peroxide monopropellant is about 5 times greater than the best compressed gas, so it would, I think, blow away all your Freon rockets (hopefully not literally ;)).

[Eclipse Now]

Hi all,

I'm loving this thread but just had to respond to something back on page 4. Will continue with the Mars stuff after this rant. :singer:

 

TO Chief Seattle:

What went wrong Chief Seattle? Religion and overpopulated cities ("civilization") went wrong, and took everyone with it. People in cities have more opportunity to find mates, so they overpopulated and expanded to other areas. They were forbidden by their religion to control population by any means but war. As they crossed the oceans and landed on other people's homelands their cross was held high and millions fell beneath it. When you believe your religion makes you superior to all others you can denigrate the "unclean" and treat them as less than human - with sanctity. No guilt was felt because "God was on their side". Americans still worship this same god, never asking if he was immature then and has grown wiser now. It is still believed he was and is perfect.

 

Pffft, do bacteria suffer from "religion"? Or the deer on St Matthew Island?

http://dieoff.org/page80.htm

 

 

It seems Agent Smith was wrong. Man is not a virus because he grows and grows until his environment is destroyed, other mammals also occasionally reach a certain "saturation" of their environment and then destroy it. Indeed, I would say that all individual species primed with the right growth conditions would grow until they exhausted their nutrients and then experience "dieoff"... it's just that sometimes nature finds an optimal mode of species interaction, called the food web, that enables certain energy flows. In a certain balance we call it an ecosystem.

 

In an artificial environment, we call it a petri dish. In our case, with our bigger brains, we call it "over-consumption" or "environmental degradation" but it's not necessarily involved with religion. I know atheists with enormous families and religious couples with no kids.

[belovelife]

 

ok so thi is salt water@-75degrees f

 

and it moves up

very strange

 

(from the mars pheonix lander)

[Eclipse Now]

To the Moderators, can this thread please be split at the Panspermia leap-off point, and we continue discussing Mars? Please? If there's another post on viruses falling from the sky or epistemology (how we know stuff for sure) I might just turn on "Invasion of the body Snatchers" out of spite.:singer:

 

Please let us know soon, as I'd love to ask some Mars questions. Cheers.

[Eclipse Now]

Would a "thick enough" atmosphere protect us from the solar radiation on Mars?

[Moontanman]

Would a "thick enough" atmosphere protect us from the solar radiation on Mars?

 

Yes, our own magnetic field does indeed protect us from radiation but it's role in stopping our atmosphere from sputtering off into space is more important. Our own atmosphere is the equivalent to several inches of lead in stopping radiation. If we didn't have our atmosphere the really very weak terrestrial magnetic field would be better than nothing but it wouldn't protect us from high energy cosmic rays and other very energetic radiation from space, nor would it protect us from things like X-rays, UV, or Gamma rays. These forms of radiation would end life on Earth just as surely as the charged particles from the Sun. Venus, which has no significant magnetic field, is a case in point, it's atmosphere, mostly CO2, is around 1300 psi or 90 times Earth atmospheric pressure. If the Earth's CO2 were released we would have just as much CO2 but many times as much water as Venus. lack of a magnetic field allows the suns energetic particles to strip away the hydrogen from water and from Venus and leaves Venus bereft of hydrogen which would mean no life even if there was lots of atmosphere.

[Eclipse Now]

So how much mass would we lose each year from the atmosphere? I guess the Kim Stanley Robison scenario is that life will find a way.... (as in, Mankind will keep generating atmosphere to compensate for what is lost).

Earth has lots of atmosphere.... so I'm imagining that generating this would take a long time? However, Kim Stanley Robinson (KSR from now on) seems to imagine that we can do it from introducing various life forms, from mining, from "concentrated solar guns" (like giant magnifying glasses) floating across Mars burning up regolith, to robot controlled asteroids being broken up in the atmosphere, to subsurface water being released.

 

If we can miraculously create an atmosphere on Mars to support life in the first place, then surely it is no great feat to maintain that atmosphere even if it is losing a good fraction each year?

 

Sure, Earth has lots of atmosphere.... Making a comparable amount means making (or releasing) 5 million billion tons of atmosphere...

 

The average mass of the atmosphere is about 5 quadrillion metric tons or 1/1,200,000 the mass of Earth. According to the National Center for Atmospheric Research, "The total mean mass of the atmosphere is 5.1480 × 1018 kg with an annual range due to water vapor of 1.2 or 1.5 × 1015 kg depending on whether surface pressure or water vapor data are used; somewhat smaller than the previous estimate. The mean mass of water vapor is estimated as 1.27 × 1016 kg and the dry air mass as 5.1352 ±0.0003 × 1018 kg."

 

Yet you seem to be suggesting Mars would be losing the water molecules that we had released back into the atmosphere? That's a problem for long term maintenance! Could automated robot asteroid ships constantly aerobraking bring in the ice asteroid atmospheric mass we needed? Or would we have fusion reactors that would artificially generate a field? (Heck, if we could do that surely we'd be sucking mass out of the sun and generating our own planets from scratch as in the Peter F Hamilton "Night's Dawn" trilogy where some alien species made their own planets. Or as in Stephen Baxter's "Time Ships" where the Morlocks drew material from the sun to make a Dyson sphere!)

[Moontanman]

As we can see on Venus most of the atmosphere will stay, it's the hydrogen that we would loose. mars with it's weak gravity would loose hydrogen faster than Venus or the Earth. This would still be a long term, many millions of years, problem. I would have to agree that by the time we can do engineering on the scales we are talking about We will be able to do much more than Terra-form Mars, huge orbiting free space colonies than can travel between stars to me seem more likely than terraforming a planet which would take many thousands if not hundreds of thousands of years any way you look at it. .

[Eclipse Now]

I've been harping on about the incremental changes in industrial systems brought about by small advances in individual technologies having larger Cascading Adaptive Systems advantages. In simpler terms: progress can have surprising effects.

 

The figure of hundreds of thousands of years to terraform Mars has been tossed about. What about 100?

 

From the Mars Society.

 

Mars Papers — The Mars Society

 

Terraforming Mars With (Largely) Self Reproducing Robots

In: On To Mars 2, edited by Zubrin, RM, and Crossman, F. Collector's Guide Publishing Inc.

 

Abstract:

There are various schemes to provide Mars with a CO 2 atmosphere by causing the evaporation of the dry ice at the South Pole and in the regolith. Although no one knows how much is available from these sources, getting it to vaporize may not be too difficult and a reasonably thick atmosphere may be attainable in a hundred years or so. (1,2)

 

Other terraformers suggest the use of nanobots, tiny self reproducing robots that will rip the CO 2 apart physically. But nanotechnology is so far in the future that no one can really guess its capabilities or limitations. We do not need nanobots, only robots able to reproduce themselves. Presumably such machines will be roughly man-sized, not microscopic. Nor need they be able to reproduce every part of themselves, just the heavy parts. Light parts -- e.g. computer chips -- can easily be brought from earth. Even today a chip weighs half a gram, and two million of them weigh only a ton, so we can transport the brains for a robot army in a small space probe. Once there are many robots on Mars they can make solar panels or reflectors enough to cover the planet, and the power can be used to run cracking plants to split the CO 2

 

We can today build robots for mining and assembly, and will soon be able to make largely-self-replicating robots that can increase their numbers to any desired level at little cost to us. Cheap robot armies give us a powerful new tool for terraforming whose uses have barely been touched on here. Others should consider the possibilities that this idea opens up. For Mars we should have sufficient capabilities in fifty years, though it could be more or less. But surely we will have macrobots before nanobots, and whether it takes fifty years or a hundred and fifty we will have them, and be able to turn Mars' CO 2 to O 2 in a few decades. We should therefore abandon the idea that it will take a hundred millennia to terraform Mars, and turn our thoughts to a livable O 2 atmosphere in a century or less.

[Eclipse Now]

Sounds like we are going to have to solve this atmosphere leaking thing one day as it's happening here on earth! If hydrogen escape is the means by which water leaves planets, we need to fix this!

 

Our Planet's Leaky Atmosphere: Scientific American

 

our earth 3 billion years ago, today, and 3 billion years in the future....

[Eclipse Now]

Check this out... the future may include radiation resistant plants for terraforming Mars?

 

Slashdot | Radiation-Resistant Plants Could Be Used In Space

[Eclipse Now]

Now the problem of earth slowly losing its atmosphere over the next few billion years is caused by particles that are super-accelerated by the solar wind.

 

I'm now going to ask something very silly, but I'm not suggesting it is practical with today's technologies OK? So we don't need to raise issues of cost, energy and materials involved, but just assume for now that some future SCI-FI like technology solves all that for us.

 

What if we could place a huge glass 'window' between a planet and the sun, a window of glass or plastic that stopped the solar wind but allowed the sun's light and heat through.

 

Would this solve our planet's atmospheric leak, and also help towards terraforming Mars if we did the same there? Because without the solar wind blowing the Martian atmosphere away, surely gravity would take over and Mars would have a longer atmospheric lifespan if we terraformed it.

 

So, what do we think about our nano-plastic, self healing, bad radiation blocking planet sized mirror parked in space between our favourite planets and the Sun? Could this even help terraform Venus? (And I can't remember Kim Stanley Robinson's super-engineering scheme for getting Venus spinning again).