The Indian ISRO space agency was going to announce the result of their first year of observations in Mars orbit - the Indian Times said - on Thursday.  But it didn't happen - seems it has been delayed! I look forward to hearing what they found - but seems that we have to wait some more.

We can't really make any deduction about what they will say, as their research is embargoed until then - they can't say anything about it. But we should hear whether or not they have detected methane from orbit so far.

Artist's rendering of India's MOM orbiting Mars.

If they have, it will add to the increasing evidence of methane forming temporarily on Mars.

If there is methane on Mars, the surprising thing is that it appears and disappears so quickly. Curiosity confirmed its presence recently.

One scientist has raises a question about whether the instrument that did the detection was contaminated by a known leakage of Earth air from its tunable laser spectrometer from methane from Earth air (which is present at 1820 ppb). 

Curiosity's tunable gas spectrometer, which has a small amount of air in its fore-optics chamber. It got there by accident, and most was pumped out when it leaked early in the mission but they kept a small amount for calibration purposes. It could overwhelm Curiosity's methane measurements - but project scientists say they have monitored it and it is no longer leaking significant amounts.

They pumped out most of it, but kept a small amount for calibration purposes. If that leaked, it would overwhelm a parts per billion detection, but the project scientists say that they are continuously monitoring it and there is no evidence of a further leak. See Mystery Methane on Mars: the Saga Continues on

If the Curiosity readings are correct - the surprise is that it varies so much, that either it is very local - or else, it is destroyed far more rapidly than you'd expect from atmospheric processes.

Occasional ten-fold spiking of methane detected by Curiosity

The conservative assumption is that it is very local.

Gilbert Levin has suggested, that if the methane is destroyed quickly - this could be the result of methanotrophs - microbes that eat methane. If Mars has methanogens that produce methane, it probably has methanotrophs that eat it as well. Methanotrophs are abundant in glacial and polar regions on Earth close to Mars conditions. Could this accelerate the process in some way?

One suggestion for a way that Mars could have methanotrophs is that they could oxidize methane through perchlorate reduction (which is first reduced to chlorite before it is used to metabolize the methane) - a process observed in terrestrial microbes.

Or they could reduce sulfate, iron and manganese. One estimate from 2011, if the atmosphere can get as rich in methane as originally thought, is that if there are methanotrophs, on an optimistic scenario if it consumes most of the methane, then there would be an average of 10,000 cells per square meter of the surface, of course concentrated in more favourable conditions. And if 1% of the levels of methane there were used to support life, they could support 1020 microbes on Mars

If we got clear evidence of large scale changes in methane levels from orbit, then this would suggest there is some unknown process going on there, possibly life, or they have to find some other explanation.

If they form locally and disperse locally, then they could be life or non life, but in either case are easier to understand.

It will be interesting if the ISRO sheds any light on this - the only experiment to date to Mars dedicated to looking for methane there.

Early calibration run from MOM, India's space probe to Mars. They will compare this reflectance map with later observations to search for methane.

They did the first stage of calibrating their instruments in spring of this year, see this post from Emily Lakdawalla. It will be interesting to see what they have discovered in the six months since then. In this topic area, null results are also interesting of course.

The ESA is planting a trace gas orbiter for 2016, with sensitivity of up to 10 parts per trillion, to many different chemicals in the Mars atmosphere, including methane. It will probably shed light on mysteries such as this and help to localize any methane sources found on the planet. 

But meanwhile, the Indian satellite in orbit, Curiosity on the ground, and measurements on Earth are the main instruments looking for methane.

So the Indian satellite - even though largely designed as a technology demo - still is also in a position to do interesting science as well, and so there's a fair bit of interest in its results.


Of course, it is important to realize that the possiblity of life on Mars doesn't stand or fall depending on the presence of methane there. I say this because in the past, as the fortunes rise and fall in the methane search, we often get news stories suggesting that if there is no methane on Mars, there is no life there. But of course you can't deduce any such thing from an absence of methane.

There are many ways there could be life on Mars without rapidly changing detectable levels of methane, or if the methane is created only by serpentization. For one thing, the life might not include methanogens.

Cyanobacteria for instance could survive on Mars using just the CO2 from the atmosphere, sunlight, and trace minerals, and they would produce oxygen. As the Mars atmosphere already has 0.146% oxygen in it, i.e. 1,460,000 parts per billion, then a parts per billion increase would hard to detect.

Or it could have methanes, but not enough of them to transform the atmosphere. If the life is slow growing and in small quantities, and for instance, most of it, say, exists in the sixteen sites with RSLs, it's effect on the atmosphere would surely be undetectable. Now that we know that the Earth went through past snowball / slushball phases when there was still life, but probably barely detectable in the atmosphere - and know about extreme Mars like environments with astonishingly small populations of microbial life, then the Lovelock argument about atmospheres in equilibrium is no longer compelling. It still would seem to give a way of positively detecting life with a high probability - but no longer gives a way to rule out the presence of life on a planet.

See Why Mars Surface Life May Leave No Traces In Its Atmosphere: Our Rovers May Need To Go Up Close To See It

Also if Mars has methanogens, it doesn't mean it doesn't have any cyanobacteria, haloarchaea, and many other suggested metabolisms, even possibly innovative solutions on Mars not yet explored on Earth.

So, this methane search is just one, very important, line of research that may turn up indirect evidence of life on Mars and give ideas of where to look for it.

For related articles, see

And other articles on my Science blog here.


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Why Mars Surface Life May Leave No Traces In Its Atmosphere: Our rovers may need to go up close to see it (Amazon)

Rhythms from Martian Sands: Did the Viking Landers find life in 1976 - or what did they find? - astonishingly, we still don't know (Amazon)

Are there Habitats for Life on Mars (Amazon)