Friday, November 18, 2005

Global Warming on Mars

The debate is on, is global warming a fact or is it fiction? If it is a fact are humans to blame or is it just a natural cycle of the planet? You can find people with opinions all over this subject but one thing is certain, if global warming is a fact and if man is to blame that sure does not explain why mars seems to be undergoing similar global warming! Let’s take a closer look…

Scientists have suspected in recent years that Mars might be undergoing some sort of global warming. New data points to the possibility it is emerging from an ice age. NASA's Mars Odyssey orbiter has been surveying the planet for nearly a full Martian year now, and it has spotted seasonal changes like the advance and retreat of polar ice. It's also gathering data of a possible longer trend. There appears to be too much frozen water at low-latitude regions -- away from the frigid poles -- given the current climate of Mars. The situation is not in equilibrium, said William Feldman of the Los Alamos National Laboratory.

"One explanation could be that Mars is just coming out of an ice age," Feldman said. "In some low-latitude areas, the ice has already dissipated. In others, that process is slower and hasn't reached an equilibrium yet. Those areas are like the patches of snow you sometimes see persisting in protected spots long after the last snowfall of the winter." Frozen water makes up as much as 10 percent of the top 3 feet (1 meter) of surface material in some regions close to the equator. Dust deposits may be covering and insulating the lingering ice, Feldman said.

Feldman is the lead scientist for an Odyssey instrument that assesses water content indirectly through measurements of neutron emissions. He and other Odyssey scientists described their recent findings today at the fall meeting of the American Geophysical Union in San Francisco.

"Odyssey is giving us indications of recent global climate change in Mars," said Jeffrey Plaut, project scientist for the mission at NASA's Jet Propulsion Laboratory.

High latitude regions of Mars have layers with differing ice content within the top 20 inches (half-meter) or so of the surface, researchers conclude from mapping of hydrogen abundance based on gamma-ray emissions.

"A model that fits the data has three layers near the surface," said William Boynton of the University of Arizona, Tucson, team leader for the gamma-ray spectrometer instrument on Odyssey. "The very top layer would be dry, with no ice. The next layer would contain ice in the pore spaces between grains of soil. Beneath that would be a very ice-rich layer, 60 to nearly 100 percent water ice."

Boynton interprets the iciest layer as a deposit of snow or frost, mixed with a little windblown dust, from an era when the climate was colder than nowadays. The middle layer could be the result of changes brought in a warmer era, when ice down to a certain depth dissipated into the atmosphere. The dust left behind collapsed into a soil layer with limited pore space for returning ice.

More study is needed to determine for sure what's going on.

Other Odyssey instruments are providing other pieces of the puzzle. Images from the orbiter's camera system have been combined into the highest resolution complete map ever made of Mars' south polar region.

"We can now accurately count craters in the layered materials of the polar regions to get an idea how old they are," said Phil Christensen of Arizona State University, Tempe, principal investigator for the camera system.

Temperature information from the camera system's infrared imaging has produced a surprise about dark patches that dot bright expanses of seasonal carbon-dioxide ice.

"Those dark features look like places where the ice has gone away, but thermal infrared maps show that even the dark areas have temperatures so low they must be carbon-dioxide ice." Christensen said. "One possibility is that the ice is clear in these areas and we're seeing down through the ice to features underneath."

While it is theoretically possible for human and animal activities to affect the climate on Earth, the main factor causing fluctuations in temperatures on this planet, as on Mars, must be variability in energy output from the Sun. The Mars Global Surveyor data suggests what I think would be a relatively simple experiment: Why not place thermometers in a few locations on Mars, equipped with radio transmitters that would send temperature data to Earth or to a spacecraft? You'd have to take into account the two planets' different atmospheres, of course; the atmosphere on Mars is thin, but consists almost entirely of carbon dioxide. In time--it would take more than a few years' observations, obviously--such an experiment would settle once and for all the question whether human activities are making a significant contribution to climate variations on Earth.
I don't think the experiment would be very hard to conduct. The main catch I can see is that figuring out how to account for the planets' different atmospheres might recreate
the debates that are now going on about how to properly model the Earth's weather system.
For one thing, there are easier ways to measure the variation in energy output from the Sun directly. For another, calculating overall temperature changes on Mars would take
more than a handful of thermometers; how, exactly, to do it would replicate one of the major debates now going on over temperature changes on Earth.

Still, it seems to me that even a rough estimate of the extent to which increasing solar output is raising temperatures on Mars would be a useful reality check on the "global warming" claims being made here on Earth.

Greenhouse gases may be a problem on Earth, but what about the idea of injecting them into the Martian atmosphere, could it make Mars a second home for the human race?

A team of researchers has proposed injecting synthetic "super" greenhouse gases into the planet's atmosphere to raise its temperature and melt its polar ice caps to provide conditions suitable for biological life.

While the researchers aren't the first to propose the use of greenhouse gases in terraforming Mars, they developed a detailed approach that could be initiated by human visitors to the Red Planet.

"Bringing life to Mars and studying its growth would contribute to our understanding of evolution, and the ability of life to adapt and proliferate on other worlds," says Margarita Marinova, the study's lead author. "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 approach developed by Marinova and colleagues involves artificially created greenhouse gases nearly 10,000 times more effective than carbon dioxide. Using a computer model of the Martian atmosphere, the researchers analyzed four of the best candidate gases individually and in combination.

Focusing on fluorine-based gases, which are composed of elements readily available on the Martian surface, they found that a compound called octafluoropropane produced the greatest warming alone and even more warming in combination with several similar gases.

Adding about 300 parts per million of the gas mixture in the current Martian atmosphere, the researchers say, could spark a runaway greenhouse effect that causes the evaporation of carbon dioxide on the Martian surface. This in turn would lead to further melting, temperature increases, enhanced atmospheric pressure and a thicker atmosphere.

While it could take centuries or even millennia before Mars became hospitable to life, astronauts could create the fluorine gases on a manned mission to the planet because the raw materials exist on Mars. This makes the proposal the most feasible yet for raising temperatures and increasing atmospheric pressure on the planet, or so the researchers conclude.

Anyway it seems that we not only live on a weird world but also in a weird Solar System! That’s cool!

I’m Average Joe


NotApp said...

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