NASA Proposes Warming Mars

hotsauce writes "The Guardian reports a NASA scientist has proposed releasing a gas on Mars to start a global warming of the planet in order to make it more hospitable for life. No word on how much traction this has amongst geophysicists. I wonder how much simulation and testing you need before we feel safe about affecting an entire planet."

Comments

Original NASA Article from Feb/2001 with more info

[Hulkster]

Here's the original NASA article with a lot more details (no surprise!) than the Guardian ...

BTW, Edgar Rice Burroughs would approve as the author of the John Carter of Mars series of books which talked about life on the Red Planet.

Links to better articles

[FleaPlus]

As seems to be increasingly the case, I already submitted (rejected) variants of this story twice over the past week. I've pasted one of those variants below, which has links to sources far more information than the freakin' Guardian:

Greenhouse gases could breathe life into Mars

MSNBC, New Scientist and PhysOrg report on research by Margarita Marinova and others on using synthetic greenhouse gases to warm the Martian atmosphere and create the conditions for life to thrive. The study focused on fluorine-based gases (dubbed "super-greenhouse gases"), which would be non-toxic, nearly 10,000 times as effective at capturing heat as CO2, and could be made from Martian resources. The research concluded that adding 300 parts per million of these gases would lead to a feedback effect by unfreezing CO2 and water on the surface. According to Marinova, 'Since warming Mars effectively reverts it to its past, more habitable state, this would give any possibly dormant life on Mars the chance to be revived and develop further.' The feasibility and consequences of such terraforming have been debated in the past.

Also, note that contrary to the accepted submission's title, NASA hasn't done any sort of proposal of actually doing this. This is simply cool research exploring a very interesting "What-if".

The real cause: insufficient mass (of Mars)

[macklin01]

At a given temperature, a gas has a certain pressure and root mean speed (norm of velocity from its kinetic energy). (A bit of calculation can show it to be (3kT/m)^(1/2), where k is Boltzmann's constant, T is temp in Kelvin, and m the gas molecule's mass.)

If the root mean square of the gas is comparable to the escape velocity (2GM/R)^(1/2), the the majority of the gas will only stick around for a few days (if v_{esc} / v_{rms} is around 1), or maybe a few years. In fact, for the majority of the gas to be retained by the planet for several billion years, we need v_{esc} / v_{rms} around 10 or more.

It turns out that v_{esc} / v_{rms} for Mars for most gases is too low. Water, ammonia, and methane, as well as helium and hydrogen are too light to be retained for long. (Although it turns out that water is just a bit too light, so it might stick around for thousands or millions or years.) However, it does appear oxygen, nitrogen, and carbon dioxide might be just heavy enough to be retained.

This means that if there had ever been a significant amount of liquid water on Mars, it would not have stuck around long. CO2, and O2, on the other hand, have a shot. (So I guess we could design a breathable atmosphere, but water would be a problem.)

Interestingly enough, these figures change (for the worse) if temperature increases on Mars (increases the kinetic energy of the gases), so making Mars more hospitable, temperature-wise, may make it less long-term hospitable, desirable molecule-wise.

I got a lot of this info from my undergrad astronomy/astrophysics text: Introductory Astronomy and Astrophysics, 4th ed, by Zeilik and Gregory. -- Paul