New Mars Forums

The loss rate is *minimal*. As in, takes aeons to be substantial. Both Venus and Mars are mostly protected from the Solar Wind by the induced ionosphere fields on both planets.

However, an artificial field might help protect people on Mars from Solar storms. That's a good thing. But nothing to do with stopping atmosphere from blowing away.

Water ice frost in the old Viking pictures. Or is there more recent pictures you guys are discussing.

TmCom seems to be smoking something pretty potent. Oxygen and plant life? What the??

The thinness of the Martian atmosphere has been known since 1964 - even before the flyby of Mariner 4. Astronomers measured it from Earth. Until that time most couldn't accept the idea the atmosphere was almost all CO2 - most assumed the CO2 was a minor component and there was a lot of N2. But once they measured the atmosphere with just about every probe since 1965, the thin atmosphere has been confirmed every time, by every probe. To imagine anything else is just *nuts*.

Back in the mid 1970s, one model for Titan's atmosphere was ~21 bars of N2, with a surface temperature of ~200 K. That's about what it'd take to "greenhouse effect" the place. More methane, thanks to photolytic polymerisation, would mean a stronger anti-greenhouse effect (AGE).

Supplying more radiant energy from the Sun, via a concentrating soletta, would puff the atmosphere up. Presently the troposphere finishes where the temperature drops to about ~70 K at the ~0.1 bar level. Increasing the troposphere equilibrium temperature probably won't lead to too much extra loss from the exosphere, because the mesosphere is already a warmish ~170 K. However I don't think we can push as high as Earth-like temperatures without crazy photochemical effects making the smog even more of a problem.

To be honest, terraforming Titan seems bit of a fool's errand, since it's liable to turn into an ammoniated swamp if the sub-surface ocean breaks through. Warming the place to ~200 K might allow some more interesting biochemistry, but that presumes there's nothing interesting there already. We'll need to check out the bubble rafts in the polar lakes to make sure we're not destroying some unique cryo-chemistry.

Insulated clothes should work just fine. As for "instantly freeze solid" that's total bunkum. Nothing is that cold. Human bodies put out 100 W or so of heat, and aren't going to lose it quick enough to freeze instantly.

The atmosphere loss for all planets from the present day Solar Wind is negligible. Mars -if given an Earth normal surface pressure - would also have a much lower cosmic ray flux due to the mass of the atmospheric column being higher to have the same weight on the surface, and its gradient is much lower thus cosmic ray fragments would decay more before reaching the ground. Especially muons.

Nice idea Tom. One fly in the ointment is that there's nothing strong enough in existence to make it, aside from stable nuclear matter. And we don't (yet) know how to make that. Another problem is that 150 km isn't tall enough to retain air. Needs to be higher or have a magnetically retained ionosphere to provide the counter pressure at such altitudes.

Bzzt... Wrong. Compression would make it maybe 500 km deeper than the 1 bar level.

Tom, that's a ridiculous waste of resources and energy. What's the point? Even removing the atmosphere of Venus doesn't require that much energy input. Why sequester 10,000 atmospheres of N2 & O2 in such a fashion?

Hi All

Just trawlling through the archive. Found Karov's odd idea of "terraforming" Venus under a helium blanket. Liquid CO2 is all very well, but it suffers from the fact that the lowest CO2 partial pressure compatible with its liquid phase not evaporating away is ~5.2 bar. CO2's critical point is just 31 C and over 72 bar. Thus decent temperatures mean the atmosphere is full of evaporating CO2 - bad news for colonists.

I'm guessing Karov realised the mistake and dropped the idea.

Hi All

Firstly, the surface escape velocity of Ceres is about equal to the thermal speeds of breathable air, so its atmosphere will leak away. But a mass of air won't just explode freely into space - if its pressure is higher than ambient and its path-length is small, then the gas does work against itself and cools as it expands. So the air traps itself a bit.

Secondly the gravity declines as fast as the volume of individual layers of air increases - meaning the effective weight is constant at all altitudes in an isothermal atmosphere without rigid rotation. Factor in an adiabatic cooling profile and that means the atmosphere thins quite a bit at altitude. The maximum altitude is Ceres' Hill Sphere at 77,400 km radius. Beyond that and the gas is orbitting the Sun, not controlled by Ceres' gravity, but it should thin out to solar wind density before then.

But the solar wind wouldn't need to do much work to scrape away the outer layers. Unlike places like Earth, Venus or even Mars. I would say an atmosphere on Ceres would be marginally stable - it might stick around, or it might not. If we began with an isodense layer then let it freely expand, then it would cool significantly, perhaps creating a cold trap sufficient to keep some air down... if it wasn't for the damned Sun heating it up again *sigh*

Hi All

These discussions always seem to turn into a game of "who can tell the biggest whopper"...

To get to the core we want something heavy, but abundant - the recent suggestion of 100,000 tons of molten iron was pretty good. Should melt and shove its way to the core quite well, perhaps even more so on Mars or the Moon.

As for re-energising the Core, just how much heat do we want to add? Suppose we gather a massive deuterium bomb together, wrapped in something nice and explosive - but stable until we get up to ~ 10 GPa pressure. Then set it off - the high ambient pressure would help start and sustain the deuterium fusion, and the deuterium reaction produces a neutron and helium-3, thus heating the iron core via neutron absorption.

As for energy on Venus, the average temperature is more like ~ 630 K when you integrate over the whole of the atmosphere. Carbon dioxide's heat capacity changes substantially over the temperature range of Venus' atmosphere, but roughly 500 GJ per sq. metre is stored in it. That's 2.3 x 10^26 J total, much of which is extractable if we shade the planet. Most would be released in the early phases of cooling, at higher temperatures. If we made the atmosphere over-turn rapidly the energy could be captured via a global thermovoltaic collector. Roughly 2.3 billion kg energy equivalent in extreme, half that with collection system losses.

For comparison Earth's rotational energy is 4.26 x 10^29 J (4.73 trillion kg energy), while it's orbital energy is 2.65 x 10^33 J (29.4 quadrillion kg energy.) Earth's binding energy is roughly ~ 75 MJ per kg (over 4.4 x 10^32 J) - about twice the homogeneous mass binding energy because of the dense core.

As for making antimatter, very intense lasers can cause pair-production, which could be separated via intense magnetic fields. According to one review article I read the researchers aren't far off the energy density needed for electron/positron production, though that's 3 orders of magnitude short of making proton/anti-proton mixes. Positrons would be handy for all sorts of things, including igniting big fusion bombs...