By now you've probably heard the news about Mars: methane gas is being generated on the Red Planet, and the amount varies with season and location. There are really only two ways to make methane that we know of: geologically (volcanoes, chemical changes under the surface, and so on) and biologically (little critters basically
Mars is an interesting place, and anytime we find something new and interesting about it, it's not surprising to see the media covering it. It's also not surprising to see the scientists involved excited about it. But when that news deals with biology, well, things tend to get a little out of control.
Or, as in this case, a lot out of control.
First, what do we know?
1) A few years back (in 2004 specifically), methane was detected on Mars. However, those observations were not sensitive enough to do much more than measure the amount (10 parts per billion in the atmosphere, more or less).
2) New maps made of the Martian methane found it changes from place to place, and time to time. Methane is not stable in Mars' atmosphere: it goes away rapidly. So there must be a source of it that is making methane now, actively.
3) The easiest way to get methane is from volcanoes, but they spew out other gases, and these were not detected.
4) Another, related way is for chemical processes under the surface to create methane. However, we don't understand what is happening chemically on Mars terribly well, or beneath the surface.
5) Methane is a natural byproduct of life on Earth. Maybe that's happening on Mars as well.
That's it. That's what we know. It might be geological, it might be chemical, it might be biological. We don't know which.
Take the UK newspaper The Sun. The headline they ran? "Nasa reveals life on Mars". Incredible. The lead line was "ALIEN bugs are responsible for strong plumes of methane gas detected on Mars, it was claimed tonight."
That's simply wrong. Completely and utterly! All the scientists said they didn't know for sure. Some implied microbes were a good candidate, but none came out and said "It was alien bugs."
Sure, The Sun is a rag, best used to line bird cages (even the online version, if you can scrape enough electrons together), but it's widely read. And lest you think it was just them, then check out The Mirror, with its headline "Mars: Nasa experts to confirm there is life on Mars", or The Money Times, which had "Methane plumes indicate ‘life on Mars’". Lots of blogs ran with this idea, too.
To be fair, NASA is not blameless in this. Their press release for this was titled "DISCOVERY OF METHANE REVEALS MARS IS NOT A DEAD PLANET". Now, they are playing with the word "dead", since you can interpret that to be about geological activity, as opposed to biological. But still, that's fanning the flames they must have known would erupt. I would've hoped they had learned their lesson from the last time they pulled a PR stunt like this.
OK, so NASA goaded tabloid media into false headlines, and some ran with it (when they didn't need provocation). What's the real deal?
I'll be frank: we don't know. Methane is a very simple molecule (CH4, just four hydrogen atoms bonded to a carbon atom), and is pretty easy to produce in a number of ways. As noted above, volcanoes are probably ruled out due to the lack of any detection of other gases they usually produce.
Chemistry? Maybe. Mars is different than Earth. The laws of chemistry are the same there as here, but the chemistry going on is different. The air is thin, and mostly CO2. We know the surface chemistry of the planet is pretty different than here; the water that once flowed on its surface was probably acidic and very salty, and when it dried up left weird things like jarosite. Not only that, there appears to be perchlorate in the soil found by Phoenix, and that tends to dissolve terrestrial life. However, it's possible that CO2 could combine with water under the surface (if there's a heat source like magma) to make methane.
And what of biology? It can't be ruled out, but it cannot be ruled in either. The amount of methane detected was pretty substantial, implying a large amount of biological activity, but there has been no evidence of any life on Mars at all up to now. It's all circumstantial: ice under the surface was found by Phoenix, but near the north pole. Water used to be abundant, but no conclusive proof of extant liquid water on the surface has been found... not even temporarily (like recent flooding events). All the evidence for liquid water (like gullies in craters) could be from other sources, like clathrates.
The bottom line here is that if we want to figure out what's causing this gassy Martian eructation, we need better instrumentation at the site. I hope that NASA will equip their next landers with something that can taste the air and perhaps nail down the source of the methane.
Finally, a thought: where you get your news is just as if not more important than what that news is. When it comes to science, there are very few newspapers you can trust. When it comes to astronomy and space news, your best bet is to go to the people who know what they're talking about, and go to multiple sources to cross-check them.
And who would that be? Who got this methane story right?
Universe Today, unsurprisingly, nailed it with "Large Quantities of Methane Being Replenished on Mars". Also unsurprisingly, Emily at The Planetary Society blog has an excellent article as well. My fellow Hive Overmind blogger Carl Zimmer live blogged the press conference and produced an excellent report.
I suppose that after all this, there's one thing we know for absolute sure: methane, both chemically and journalistically, is a volatile substance.