Curiosity Detects Unusually High Methane Levels


June 23, 2019

This image was taken by the left Navcam on NASA's Curiosity Mars rover on June 18, 2019, the 2,440th Martian day, or sol, of the mission. It shows part of "Teal Ridge," which the rover has been studying within a region called the "clay-bearing unit." Credits: NASA/JPL-Caltech

This image was taken by the left Navcam on NASA’s Curiosity Mars rover on June 18, 2019, the 2,440th Martian day, or sol, of the mission. It shows part of “Teal Ridge,” which the rover has been studying within a region called the “clay-bearing unit.” Credits: NASA/JPL-Caltech

This week, NASA’s Curiosity Mars rover found a surprising result: the largest amount of methane ever measured during the mission — about 21 parts per billion units by volume (ppbv). One ppbv means that if you take a volume of air on Mars, one billionth of the volume of air is methane.

The finding came from the rover’s Sample Analysis at Mars (SAM) tunable laser spectrometer. It’s exciting because microbial life is an important source of methane on Earth, but methane can also be created through interactions between rocks and water.

Curiosity doesn’t have instruments that can definitively say what the source of the methane is, or even if it’s coming from a local source within Gale Crater or elsewhere on the planet.

“With our current measurements, we have no way of telling if the methane source is biology or geology, or even ancient or modern,” said SAM Principal Investigator Paul Mahaffy of NASA’s Goddard Spaceflight Center in Greenbelt, Maryland.

The Curiosity team has detected methane many times over the course of the mission. Previous papers have documented how background levels of the gas seem to rise and fall seasonally. They’ve also noted sudden spikes of methane, but the science team knows very little about how long these transient plumes last or why they’re different from the seasonal patterns.

The SAM team organized a different experiment for this weekend to gather more information on what might be a transient plume. Whatever they find — even if it’s an absence of methane — will add context to the recent measurement.

Curiosity’s scientists need time to analyze these clues and conduct many more methane observations. They also need time to collaborate with other science teams, including those with the European Space Agency’s Trace Gas Orbiter, which has been in its science orbit for a little over a year without detecting any methane. Combining observations from the surface and from orbit could help scientists locate sources of the gas on the planet and understand how long it lasts in the Martian atmosphere. That might explain why the Trace Gas Orbiter’s and Curiosity’s methane observations have been so different.

For more information about Curiosity, visit:

45 thoughts on “Curiosity Detects Unusually High Methane Levels

    • That’s what I was thinking. It is an extremely common gas in the solar. So, while it may indicate a set of microbes having munched on bio-matter, it doesn’t prove much.

    • Titan is very far from the sun and methane will freeze and settle as a liquid. No cows or chemcal process below the crust.
      That means the source must be external. Methane from the solar wind, leftover supernova gas in the local fluff, or from Saturn itself. (The rings came from somewhere)
      It makes sense that all the outer moons of Jupiter and Saturn would be covered in ice, if our solar system passed through an intergalactic cloud like we see between us and the center of our own galaxy.
      Mars would be covered in ice like Europa (The melting ice on the Martian poles is all that is left to melt). That would explain the frozen methane, that has been detected, is exposed seasonally from the Martian poles as the ice melts.
      It also would explain on earth, how our ocean levels can rise 400 feet in a short time. The earths atmosphere would burn from a massive galactic gas cloud. The methane and ammonia would be converted, by our oxygen, into water causing one of many ice ages. The frozen mastodons suddenly under 100 feet of ice in Siberia for 10,000 years with summer butter cups in their mouths.
      Earth’s thick atmosphere would get thin as the rain turns into snow covering the planet in ice. (Noah’s flood?)

      Using my million dollar analogy to put these big numbers into perspective so every day people can understand how small the numbers are. Earth’s methane levels at 1.8 ppm is like a $1.80 cents out of 1 million dollars. (100 stacks of $100 dollar bills, 100 bills high)
      21 ppb on Mars is like putting the million in a suitcase, 1000 times. “100 suitcases,10 suitcases high” opening one up and pulling out “21 bucks”. It’s amazing they can detect levels that low. I wonder what the margin of error is?

      • Perhaps you were joking, but in case you were serious: the use of the term “cloud” for interstellar gas aggregations is misleading you. Such clouds do not–unlike earthly clouds–contain any significant density of water, nor of anything else for that matter, except in the case of those clouds that are collapsing into stars. Interstellar clouds are mostly composed of Hydrogen (atomic and ionized, and sometimes molecular), Helium, dust, and sparser amounts of other ions and molecules. Density ranges from 100 molecules/ cubic centimeter up to 10^6 molecules/ cc (again, except in the immediate vicinity of a newly forming star). 10^6 molecules/ cc is a bit more than the density of the vacuum near the Moon (the Moon’s “atmosphere”). I daresay the Earth could safely pass through such a “cloud” without any discernible effect, save that the stars would dim a bit.

        • “except in the case of those clouds that are collapsing into stars.”

          Exactly HOW does this happen? Last time I check, the Second Law of Thermodynamics precludes this. Interstellar gas collapsing to form a star is going from a less ordered state to a more ordered state. How does this happen?

  1. Did someone forget to take out the bung from the TGO, the one with the’Remove before flight’ tag on it? Dafter things have happened before.

  2. I’d just like to know why none of the NASA probes on Mars nor the next one(s) are designed to actually test for life? They have never repeated the analyses carried out in the 1970s by the Viking landers which gave a positive result for life; later interpreted to be some weird Martian chemistry instead.

    Is NASA just too afraid that if they don’t find traces of life their funding will be cut? Sounds a bit like another topic they spend megabucks endlessly examining doesn’t it!

    • How do you test for life? The Viking landers proved that soil chemistry is tricky. Photos showed no sign of plants or animals.

      Testing for methane at least provides look at a largish area, and finding variations in its concentration will be a big help in deciding what to look for in future missions.

      • Few if any scientists expect to find eukaryotic multicellular organisms on Mars, such as plants, animals or fingi. But small unicellular microbes are a different Petri dish of prokaryotes.

        Bacteria and methanogenic archaea arose on Earth before 3.5 Ga, so they might well have done so on a wet Mars, too. Once started, life is hard to eradicate. Subterranean life is massive on our planet, so could have survived on Mars after it lost most of its surface liquid water.

        Finding it however may require landings by humans or probes large enough to borrow at least meters into the crust at promising sites.

    • I believe that NSA will never admit they found life on Mars unless they are 100% sure ten times over because the ramifications of such an announcement will be , well, biblical.

    • Alastair

      It didn’t give a positive test result for life, it gave a controversial positive measurement of methane.

      The result was disputed and defended for decades. It may have been just such a plume measurement they speculate about today.

      The stalwart defender of the positive measurement (I believe he designed the instrument) never gave up. And he is now proven right, at least in terms of confirming the gas is present.

      The most likely source is natural gas which forms naturally from water and rocks at depths of more than 30 km on Earth. In weaker gravity it would be deeper.

      • It’s too bad they don’t have a mass spectrometer about Curiosity. They can be very small these days, and one would not have taken up much room.

        With that, they could have measured the C-12/C-13 ratio of the methane. From that, one could probably deduce whether the methane is biological or not. Biological methane is depleted in naturally-occurring C-13.

        Inorganic methane production requires water, carbonate, a reducing environment usually consisting of metallic iron, and heat. Those conditions typically require depth.

        Methane typically is not something produced near the surface, except biologically.

        • Know what your underlying assumptions are.
          That C-12 preference assumes an Earthly biome enzymatic preference for C-12.

          • Joel, I understand that. Any biological system anywhere will select for C-12 just because of the kinetic isotope effect.

      • Crispin in Waterloo but really in Johor
        June 24, 2019 at 8:35 am

        Yes, I totally agree that any methane is probably abiotic. However, my point is that NASA is really scared that they will find no signs of life (past or present) so they are constantly dumbing down their instruments.

        They need to get real…it’s almost 40 years since those wonderful probes were launched and they still haven’t checked the results on the ground! Surely that should have been a priority. I would certainly prioritise it over earthquake and thermal measurements.

        As you obviously know as a geologist if you get a geochem anomaly you go back and resample as a priority.

    • My limited facts off the cuff theory is the large blue “dunes” that have been imaged are a life form. The recent meteor strike that hit mars and turned up dark “soil” hit some of these and released methane. Now I am pretty sure if I actually looked at location of strike and rover odds are 50/50 not even in same hemisphere. 😉 But hey it’s a fun theory.

  3. “One ppbv means that if you take a volume of air on Mars, one billionth of the volume of air is methane.”

    Chemistry shoots itself in the foot with moles, umpteen volume units, and the somewhat confusing definition given above of ppbv. Chemistry should have enlisted physicists to define its units:

    1 ppbv means 1 molecule out of a billion.

    • Compare one part per billion in dollars – in pennies!
      You open your door in a parking lot and see a shiny Lincoln head penny. Your Lucky penny!
      Drive out to the country and you see a beautiful lake in a valley – about a mile across to the far side and drive of 14 miles along the valley shoreline – that is around 8,900 acres on the surface. – Close to the 8,969 acres it would take to find One Hundred Billion Pennies or One Billion Dollars in Lincoln pennies.

    • It was invented by Joseph Gay-Lussac, who was recognized as both a chemist and physicist.

      It’s straightforward to create various gas mixtures by volume.

    • 1 ppbv means 1 molecule out of a billion per unit volume.

      1 molecule out of a billion, itself, is a mole ratio.

      One mole is the number of molecules (Avogadro’s number) that produce an atomic (or molecular) weight in grams. Mole as a unit is both rational and very convenient.

      Chemistry uses the same SI volume units as Physics.

  4. So Mars has CO2 and methane which is some 23 or more time as potent as CO2 as a green house gas, but shows no sign of over heating. Huh.

    • Of course not. What’s on Mars is natural. What’s on Earth is human caused. Nature knows the difference and responds accordingly. /s

    • Yup, on one of the pseudoscience posts promoting the back radiation hypothesis over the last month I equated that Mars’ temperature is within 99.7% of its estimated S-B equated temperature – or in other words the 500+ pascals of CO2 on Mars along with traces of methane are not showing signs of the mythical GHG back radiation.

    • mars has a small GHE. but its atmosphere is too thin. basic textbook planetary physics.

      • Mars has 8.9 more total CO2 in its atmosphere than does the Earth, and, because of its smaller size, 54 times more CO2 per unit surface area than does the Earth. From an optical standpoint, Mars’ atmosphere is very, very thick.

  5. The boyz at JPL need to recruit some real scientists from GISS to help them solve this. They’ll have Mars methane at 400 ppm and Venus surface temps in no time with a few quick and easy homogenizations and infills. Then they can apply for all sorts of grants to study the imminent Mars climate crisis.

  6. Methane has also been detected in volcanic gasses on Earth. This means that either an hapless heifer was cast into a volcanic cauldron by a chanting shaman, or it is a component of the Earht’s crust and mantle. Diamonds , after all, originate from some 600 km within the mantle, as does oxygen.

  7. So they finally found the methane Thomas Gold was drilling for with other people’s money at the impact crater in Sweden.

  8. With that amount of methane and the GWP factor (25) Mars would soon be overheated. We must act fast to prevent this catastrofic climate change.

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