What’s going on with methane on Mars?

This week, Madeline discusses a critical component of her research into how methane is vertically distributed in the martian atmosphere. Read on for some details about the present state of the ongoing debate about Methane on Mars.
(Image source: https://mars.nasa.gov/system/feature_items/images/6037_msl_banner.jpg)

by Madeline Walters

On Earth, we’ve often heard of methane being produced as a result of living beings-microbes that help with livestock digestion. Though when we found methane on Mars, we were puzzled by its origins. Are there microbes helping the digestion of Martian cattle? Most signs point to no, however, we are still unsure of what may be producing the gas on Mars. Besides biogenic sources, methane can also be produced by geological processes, so being able to identify the sources of methane is a tricky yet interesting problem.

The issue with identifying the sources of methane is finding the methane in the first place. Since landing in Gale Crater in 2012, the Tunable Laser Spectrometer (TLS) instrument onboard NASA’s Curiosity rover detected background levels and a few higher spikes of methane from the surface, however, ESA’s ExoMars Trace Gas Orbiter (TGO) wasn’t able to detect any methane from higher up in the sunlit atmosphere. 

TLS lead scientist Chris Webster [1] comments: "When the Trace Gas Orbiter came on board in 2016, I was fully expecting the orbiter team to report that there's a small amount of methane everywhere on Mars, but when the European team announced that it saw no methane, I was definitely shocked." 

The results were certainly unexpected after other detections of methane from other instruments, leading to new questions about whether the detections from TLS perhaps originated from the rover itself. Some scientists suggested the rover detected methane after crushing rocks, or perhaps wheel degradation, not willing to rule out any possibilities. However, the Planetary Fourier Spectrometer onboard the Mars Express (MEx) spacecraft observed higher levels of methane in 2013, after Curiosity also reported a methane spike, bringing back the question of how to make sense of these detections.

So why are some instruments reporting methane while others aren’t? This is something that is puzzling scientists almost as much as the source of the gas itself. Because of the conflicting reports of detection from different instruments, the key is observing how methane diffuses through the atmosphere at different times of day and through different seasons to see if perhaps the reports of methane from different instruments can still make sense.

Moores et al. [2] suggests a small amount of methane seeps out of the ground continuously such that during the day, it mixes well with the atmosphere, which results in very low levels of methane further up. Meanwhile at night, the methane can build up near the surface from the lack of convection. From this approach, we can make sense of both the ExoMars and Curiosity observations. While this could explain the discrepancies in methane detection from different instruments, we still have yet to determine the origin of the gas itself and if that origin perhaps can explain how the gas is being destroyed much quicker than it should. Because solar radiation and oxidation should be destroying the produced methane after a lengthy 300 years, the excess methane buildup should be detectable by TGO. This points to some destruction or sequestration mechanism that is getting rid of the methane quicker than expected such that the detected amounts make sense. 

"We need to determine whether there's a faster destruction mechanism than normal to fully reconcile the data sets from the rover and the orbiter," says Webster. 

One possible explanation for this is the gas’ reaction with the surface components. A chemical compound called perchlorate, which has been detected by Mars landers, may be acting as a sink for methane due to oxidation reactions [3]. When exposed to ultraviolet radiation from the sun, perchlorate accelerates the destruction of methane-from over 300 years to just days or hours. However, scientists are still exploring this possibility and as of right now, there’s still no way to be sure this is the reaction responsible for the gas’ quick destruction. While there are still many questions surrounding Martian methane, we are getting closer to explaining the mysteries of the gas.

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References:

[1] https://www.jpl.nasa.gov/news/first-you-see-it-then-you-dont-scientists-closer-to-explaining-mars -methane-mystery
[2] Moores, J. E., King, P. L., Smith, C. L., Martinez, G. M., Newman, C. E., Guzewich, S. D., et al. (2019). The methane diurnal variation and microseepage flux at Gale crater, Mars as constrained by the ExoMars Trace Gas Orbiter and Curiosity observations. Geophysical Research Letters, 46, 9430– 9438. https://doi.org/10.1029/2019GL083800
[3] Zhang, Xu & Berkinsky, David & Markus, Charles & Chitturi, Sathya & Grieman, Fred & Okumura, Mitchio & Luo, Yangcheng & Yung, Yuk & Sander, Stanley. (2021). Reaction of Methane and UV-activated Perchlorate: Relevance to Heterogeneous Loss of Methane in the Atmosphere of Mars. Icarus. 376. 114832. http://dx.doi.org/10.1016/j.icarus.2021.114832.

More conference talk. Suddenly stuck at home? Make the best of it!

We had all hoped to be in person at this year's DPS, however, the hybrid nature of the conference meant that any students who had last minute disruptions could still attend virtually. It's really nice to be able to accommodate these sorts of situations and, while the online experience is not the same as the in-person experience, it means that someone who has made arrangements and already paid their registration can still get some value out of the conference, perhaps even more value than they had expected as our new PhD student Elisa Dong attests below. For more on the picture above, see the Caption at the bottom of the article.

 by Elisa Dong

New PhD student (Elisa) checking in with the usual readers of this blog. This week I've been invited to discuss whatever I so desire on the blog. I happened to be writing something for my own blog on attending conferences. Here are a series of mostly serious tips for attending conferences remotely, when the format is hybrid and all your friends are attending in person. The backdrop for this conference was DPS, on which Conor has recently posted. A lot of these tips have been test-run during the pandemic where I attended AGU online.

Tips for attending a scientific conference (when you're remotely at a hybrid event):
1.     Identify your favourite conference snacks and drinks
2.     Purchase, make, or make student-budget friendly versions of said snacks and drinks
3.     Plan chores that require at most 1 hour of your time. Preferably a bunch of 10-15 minute chores
4.     Acquire bluetooth headphones
5.     Identify some clothes for dressing up (or down)
6.     Pick a few "key" sessions you want to be awake for and some interesting ones to pad out the rest of your time.
7.     Chat with your lab mates on your preferred communication method of choice.

Let's break these down a bit. Say you were really looking forward to attending the conference in person and had already planned for those days to be away. However, you've fallen sick or some event has taken place that prevents you from attending. You might as well try to get part of the conference experience at home! While there will be significantly less mingling with others and networking opportunities will be, at best, awkward and stilted you can still delight in the little snack breaks while reflecting on the state of the field.

This brings us to tip number 1. If you've been to a conference before, what snacks did you enjoy during the breaks? Personally I like that there are usually several tea options, and sometimes the coffee is palatable. The previous conference I had attended online (planned), I had the time to order some coffee samples and pick up a variety of snacks from the asian supermarket. This time I was stuck in quarantine, so I made sure I had a kettle and a massive stock of tea bags. This covers tip number 2 as well. It doesn't have to be fancy, but having the ability to make hot drinks on demand is quite nice. It's reminiscent of downing drinks to soothe your throat in the dry, conference room air.

Tip number 3 and 4 involve keeping yourself busy. Unlike an in-person conference, there are very few things you can look at that you are unfamiliar with. You likely won't have access to the attendees (no camera facing that way, zoom only shows the speakers) so figuring out who else is at that session is out unless they speak up during Q&A. Instead, you could be getting some mundane tasks done! I personally can't look at a screen continuously, so laundry, cleaning the kitchen, organizing bookshelves, watering/trimming plants, etc. all give me breaks away from the screen, but I'm not doing anything so critical that I can't check what's on the screen if it's particularly important. Tip 4 gives you the flexibility to move around without fear of wires tangling or blasting the audio (less of an issue if you don't have roommates, but still a nice option). Earphones are also an option, but I find headphones to be a bit better with universal fitting. Also, you now have the wonderful ability to choose to go to the bathroom while still listening to the sessions.

It's all good to be perfectly cozy while stuck at home (or if you're so inclined, going outside while still plugged into the conference). A big part of the conference experience is being present though. For me, that means dressing in a slightly snappier manner than I normally might. Regardless, I would want to have a change of pace for "conference time", much like when working from home, it's helpful for me to dress up for "work hours". Dressing down could be a fun alternative to this though. After all, no one can see that you're in the goofiest of onesies. Similarly, no one will know (other than your housemates) that you attended in a full ballgown and mask. So that's tip 5.

Tip 6 is applicable to any conference you attend. There is only so much time in a day, so pick your favourite events to go to. Figure out what's relevant to your interests. Not much more to say about this one. Tip 7 is similarly applicable always. Should you find yourself longing for some company, or wanting to experience the social aspect of the conference, checking in with your lab mates or anyone else at the conference can be nice. If you're all together (remote or in person), it can be nice to schedule some hangout time outside of the planned events.

Lastly, it's always a good idea to tap out whenever you're feeling tired. No point attending a conference in your brain is on the fritz. A copy of these tips can be found on my personal blog (soon), abstract-ed.me, where I will likely keep posting silly little pseudo-articles on science and whatever catches my interest at the time.

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As an aside, for all potential incoming grads, here are the things that have happened in the last 2 months:
-        started taking my singular mandatory course (yay for transfer credits!)
-        met up the rest of the lab at an outdoors event and found out we're all equally bad at playing frisbee
-        confirmed that housing is as tricky as I thought it would be
-        ran into an old friend at the university!
-        had an impromptu zoom call with the founder of a company whose instruments I'm hoping to use in the near future (no spoilers!)
-        learned how to plug things into a breadboard and string things together with different communication protocols
-        moved some plants into the office, including my favourite "it's time to go home plant" (Fig. 1)
 

Figure 1 Caption. Here is my plant before I moved it to the office. The "it's time to go home plant" is an Oxalis triangularis. This purplish plant has a few relatives, but they are also referred to as "false shamrocks" when they are of the green variety. The sets of three leaves close up when the light begins to dim. This is usually my sign that I've been at work for too long during the summer months, and a reminder to start packing up during winter. I have been tricked in the past, as the leaves remain open with artificial lighting as well. They're generally pretty happy office/house plants, require moderate temperatures, nothing special in terms of humidity, and enjoy filtered light. They do grow rapidly outdoors, so don't plant them outside!