The recent discovery of methane on Mars is more than a curiousity. It could be a game changer.

For the last three decades, NASA’s Mars exploration program has been based on a single mantra: Follow the water. Where there is water, there might be life. So far, this strategy has come up empty handed. But now, NASA might have to change course and follow the methane. Methane gas, which heats up our food in our kitchen stoves, can be created by natural processes, but about 90% of the earth’s methane gas comes from living things, such as the decomposition of organic materials. So this is tantalizing evidence that perhaps some form of Martian life created this methane.

3 billion years or so ago, Mars was tropical, with lakes, rivers, perhaps even an ocean as big as the United States. Back then, you could get a sun tan on prime beach front property. And perhaps microbial life in the form of algae and plankton thrived in this lush environment. But today, Mars is a frozen desert, a bleak, sterilized, and freezing landscape with a thin atmosphere of almost pure carbon dioxide. Perhaps this methane gas was left-over from the decay of organic life billions of years ago. A more interesting hypothesis is that this methane gas comes from present-day microbial life that grows underground, perhaps heated up by volcanic activity and hot springs.

(The earth also belches large quantities of methane gas, such as off the coast of Calif., because of methane deposits on the bottom of the ocean. Some have even speculated that these belches of gas might explain the mystery of the Bermuda Triangle. Colossal bubbles of gas seeping from the floor of the Caribbean may have suffocated sailors on ships or destabilized airplanes.)

At the very least, it means that NASA may re-think where to land the next series of Mars rovers. The next mission is the Mars Science Laboratory, to be launched in 2011. Before this announcement, NASA had considered (and passed over) the Nili Fossae area for a landing site, where methane plumes have been found. Scientists may reconsider this decision in light of this discovery. By digging into the soil, or by carefully analyzing the hydrogen isotopes within the methane, scientists may settle the question of the origin of methane gas.

If it turns out to be organic in nature, it could be the most profound achievement of the entire space program, rivaling sending a man to the moon.

In the long term, even if the methane gas has been found to be of inorganic origin, there are other possible uses for it. First, it might be used to create rocket fuel. In a manned mission to Mars, the astronauts may melt the ice in the ice caps or permafrost, separate out the oxygen and hydrogen from the water, and use them for rocket fuel. If methane exists in large quantities, it might be mixed with other volatile gases to make rocket fuel, thereby saving a considerable amount of money (since it may cost upwards of several hundred thousand dollars or more to put a pound of anything on the surface of Mars).

Second, in the far future, science fiction writers have speculated that it might be possible to create an artificial Greenhouse Effect on Mars by deliberately injecting methane into the atmosphere, since methane is much more potent than carbon dioxide as a greenhouse gas. In this way, one might be able to heat up the planet to melt some of the ice caps and permafrost so that liquid water may one day freely flow on the surface of Mars. Some have speculated that we might be able to create a new Garden of Eden on Mars. The goal would be for humanity to terraform Mars so that humanity can become a “two-planet species,” i.e. to create an insurance policy in case life is threatened on earth.

Dr. Michio Kaku