Not since the 1996 discovery of a controversial Martian meteorite, bearing clues of fossil microscopic life, has the planetary science community been abuzz about Mars. Last week, NASA researchers announced that they have detected methane - tons of it! - in the atmosphere of Mars.
Methane is the prime component of natural gas here on Earth, so that's why this discovery indicates that the Red Planet is alive - either biologically or geologically.
"Right now, we do not have enough information to tell whether biology or geology - or both - is producing the methane on Mars," NASA researcher Michael Mumma said in a prepared statement last week. "At northern mid-summer on Mars, methane is being released at a rate comparable to that of the massive hydrocarbon seep at Coal Oil Point in Santa Barbara, Calif."
Oddly, the Martian methane was detected not by billion-dollar U.S. and European space probes now orbiting the distant planet, but instead by old-fashioned, Earth-based observing. Astronomers used NASA's Infrared Telescope Facility atop Mauna Kea in Hawaii to make the discovery.
Finely calibrated spectrometers on the big telescopes in Hawaii were used to break down Mars' reflected light into a colorful spectrum. The spectrum's component colors were, in turn, studied in minute detail. After examining all the colors, astronomers finally isolated three spectral features - called absorption lines - that bore the fingerprints of methane gas.
So why all the buzz about methane - aka "cow gas" - a common greenhouse gas on Earth? Well, if there is Martian life producing the methane as excreta, it appears to be doing it deep below the planet's surface. Some astronomers - not all - think that deep inside the Red Planet there's liquid water at temperatures that may resemble Vermont on a balmy spring evening.
And, of course, we know that when you bring liquid water, plus energy, plus carbon together, there's a good chance for life - at least life as we know it.
What types of lifeforms could be producing Mars' methane? Most likely, any biological activity under the surface of Mars will be microscopic, although larger lifeforms might reside in deep caverns. At least for now, speculating about what Martians might look like is more science fiction than science fact.
So, don't revise your astrobiology textbook just yet. That's because there's another way to produce methane that doesn't require living organisms. And when it comes to Mars, hopes of finding extraterrestrial biology are often quenched by the local geology.
Here on Earth, some iron oxide - when it has been metamorphosed into a rock called serpentine - can produce methane gas. That's why some scientists disdain the popular term "fossil fuel" - some hydrocarbon stuff found on Earth may have been produced abiotically, not by decaying plants and animals.
Right now, Mars is outgassing 19,000 metric tons of methane from several plumes. Methane is a greenhouse gas, but the Martian variety isn't helping to trap sunlight to warm up the Red Planet's surface. The weak gravity of Mars prevents the trapping of methane in the atmosphere - it appears that most, if not all, of the precious gas is being lost to space.
Whether living things are behind it or not, with tons of methane gas above Mars there must be a lot more of it below Mars. Future astronauts might tap gas pockets for rocket fuel, even power future Martian settlements with the methane. Might Mars become the 21st century's biggest target for terrestrial oil and gas companies?
Right now, it seems that the cost of getting to Mars, extracting the methane, and returning it to Earth would be cost prohibitive. But you never know how desperate things might get on Earth. Getting at Martian natural gas would certainly be the most extreme kind of off-shore drilling.
Lou Varricchio, M.Sc., is a former NASA science writer. He is part of the NASA/JPL Solar System Ambassador program in Vermont.