Dust Devils on Titan

Brian Jackson, Ralph D. Lorenz, Jason W. Barnes, and Michelle Szurgot

Summarized by Lisette Melendez

What data were used? In 2019, NASA announced a brand-new mission: Dragonfly. The objective? To visit Titan, the largest moon of Saturn and the only place in our universe (besides Earth) where distinct evidence of surface liquid has been discovered. Titan’s environment is very similar to that of very early Earth, with a nitrogen-rich atmosphere and volcanic activity. By studying Titan’s chemistry, scientists can discover more about the origin of life itself. It’s a very exciting mission, but it’s important for scientists to prepare for all the different obstacles the rotorcraft will encounter on Titan’s surface, including hazardous weather phenomena like dust devils.

We’ve learned more about weather patterns on Titan through NASA’s Cassini spacecraft, which orbited Saturn from 2004 to 2017. This study focuses on how dust storms are identified on other celestial bodies and what implications they hold for the Dragonfly mission. Cassini identified three regional dust storms within the equator near the “Shangri-La” dune fields that were chosen as Dragonfly’s landing spot. The study of these dust storms in Titan’s unique environment (with clouds and rain of methane!) can help us learn more about how they operate and life dust in the first place. This study also draws from observations by the Huygens probe for information on Titan’s temperatures and atmosphere.

Methods: In order to determine the weather conditions necessary for a dust storm on Titan, scientists need data on various atmospheric circumstances, such as temperature, elevation, and pressure. By analyzing the images and observations collected by Cassini and Huygens and combining these findings with data collected by observing dust devils here on Earth, scientists were able to model the surface conditions that were suitable for dust devil formation as well as the size of these storms. The study focused on dust devils on the equator because that’s where we have the most data available about Titan’s weather conditions.

Results: Many of the atmosphere conditions identified on Titan are favorable for the formation of dust devils. On Earth, dust devils are generally hindered by the presence of liquid because the increased particle cohesion (i.e., how sticky the particles are to one another) prevents wind from being able to lift the dust particles. Observations show that the equator of Titan is very arid and dry, with methane downpours only occurring in areas once every 10 Earth years. By looking at surface humidity levels measured by Huygens, it shows that the surface is too dry for even cloud formation. The abundance of dunes and dust storms provides further evidence that Titan has the ideal environment for dust devils.

However, there are some surface conditions on Titan that may reduce the occurrence of dust devils, including the possibility of insufficient wind speeds. Additional work is required to model typical speeds on Titan’s surface.

Why is this study important? This study is important because it helps predict the occurrence of dust devils on Titan when Dragonfly is scheduled to arrive in 2034. This study outlines what remains unknown about the formation of dust devils and how Dragonfly presents the opportunity to study wind-related phenomena in a novel environment.

The big picture: After analyzing the environment on the surface of Titan based on the data currently available, it is concluded that the dust devils will most likely not pose a threat to the Dragonfly rovercraft (since they are too slow in the given conditions). Nevertheless, the mission can provide crucial insight to the creation of dust devils and how frequently they occur on other celestial bodies. Dragonfly provides us the opportunity to learn so much more about extraterrestrial worlds, and we’re all very excited for its departure!

Citation: Jackson, B., Lorenz, R. D., Barnes, J.W., & Szurgot, M. (2020). Dust devils on Titan. Journal of Geophysical Research: Planets, 125, e2019JE006238. https://doi.org/10.1029/2019JE006238

Transient post-glacial processes on Mars: Geomorphologic evidence for a paraglacial period

by: Erica R. Jawin, James W. Head, David R. Marchant 

Summarized by: Lisette Melendez

What data were used? Mars, just like Earth, goes through a cycle of glaciation and deglaciation. The rise and fall of glaciers on Mars is influenced primarily by the planet’s obliquity, or the tilt of its axis. During times of higher obliquity, the planet’s tilt is greater, hence its poles are exposed to more sunlight and the glaciers leave the poles and travel towards the middle of the planet. As the cycle continues and the tilt is lower, the glaciers leave the midlatitudes and migrate towards the poles once again. The period of time where environments are adjusting to deglaciation is known as a paraglacial period, and it comes with a group of identifying features that are well studied here on Earth. This study applies what we’ve learned about the kinds of geologic features that are left behind by glaciers on Earth to the environment on Mars. The area that is left behind by a glacier is known as a glacial deposit. By analyzing images of craters on Mars taken by cameras aboard the Mars Reconnaissance Orbiter, scientists are able to find evidence of paraglacial periods and how long they last on Mars.

Methods:  After choosing a crater in the midlatitudes of Mars, the scientists began breaking down the features found in the images of the crater and mapping out the terrain, as shown in Figure 1. Glaciers leave behind special signatures in the rocks on Earth (e.g., here are some Time Scavengers posts about glacial geology on Earth: glaciers in Connecticut River Valley and glaciers in the Bay of Fundy), and the objective was to identify these same features on Mars. In order to further understand the processes that were occurring in the crater on Mars, analyses of places with the same climate and geologic features on Earth were used! The climate on Mars is arid and freezing, similar to the McMurdo Dry Valleys in Antarctica.

Results: Several geologic features that, when found together, are indicative of glaciers migrating away were found in this crater on Mars. Some of these features include ridges becoming increasingly deformed as one looks further downslope, as shown in Figure 2, where the ridges of the glacial deposits in Antarctica are more deformed at the bottom of the picture. Spoon-like holes, called spatulate depressions, were also found on both the Antarctic glacial deposits and the Martian crater, formed by ice weathering away. As glaciers retreat, they often leave behind steep slopes in their wake. These slopes are unstable, and over time, sediment flows downward and builds up on the sides to stabilize the slope, as shown in Figure 3. Gullies, which are a geologic feature formed by the path that the sediment took to travel downward, and the resulting triangular piles of sediment can be found both in the crater on Mars and on Earth, shown side by side in Figure 4.

Why is this study important? This study is important because it increases our understanding of the time frames of climate cycles on Mars, and also highlights the similarities and differences between Mars and Earth. On Earth, paraglacial periods are relatively short, and the features left behind are likely to be eroded away by rainfall, rivers, and vegetation. These features are better preserved on Mars, an extremely cold and dry planet that doesn’t have the same erosive forces.

The big picture:  Understanding the formation of geologic features on Earth is essential to uncovering the geologic history of the rest of our planets. This study showed that several features that form after a glacier migrates away can be found both on Earth and on Mars. The key difference is the time frame: on Earth, the paraglacial period is relatively rapid, while on Mars, it takes place on the scale of millions of years. 

Citation:mJawin, E. R., Head, J. W. & Marchant, D. R. Transient post-glacial processes on Mars: Geomorphologic evidence for a paraglacial period. Icarus 309, 187–206 (2018).

Evolution and Development at the Origin of a Phylum

by: Bradley Deline, Jeffrey R. Thompson, Nicholas S. Smith, Samuel Zamora, Imran A. Rahman, Sarah L. Sheffield, William I. Ausich, Thomas W. Kammer, and Colin D. Sumrall

Summarized by: Lisette Melendez

What data were used? In this paper, changes in the bodies of early echinoderms (the group that includes marine animals such as starfish and sea urchins!) are tracked in order to understand the trends that separate groups from the rest of the animal kingdom. The main question is: why are all the body plans so different from one another? Figure 1 shows the range of body plans for early echinoderms, but the distinction carries on even today, considering how starfish and sea cucumbers look so different from one another! In order to quantify these changes, the scientists directly studied specimens from various natural history museums, sifted through past echinoderm papers, discussed with experts in organism classification, and consulted the Treatise on Invertebrate Paleontology. Since the scientists were looking specifically at early echinoderms, we are talking about fossils that date back to the Cambrian and Ordovician periods, about 541-444 million years ago! Usually, data from fossils this old is limited because many significant characteristics are worn away with time. However, echinoderms have notable skeletons that retain a great deal of important characteristics, making their skeletons excellent indicators of evolutionary changes through time.

Methods: Once all the data was gathered, the next step was to find a way to accurately portray the changes of early echinoderm bodies through time. A morphospace, or a representation of every possible shape of echinoderms, was created, as shown in Figure 2. Four major echinoderm body plans were revealed in the graph. Three of the groups had radial symmetry (symmetry around a central part), while one was non-radial. Two of the groups were characterized by stem-like stalks that attached the echinoderm to the sea floor, while another group was mobile and free to move around. While Figure 2 shows the overall body plans of early echinoderms, this graph was further broken down into specific time intervals (each about 20 million years long) in order to study how the body plans changed over time. Figure 3 depicts how different the body plans were from one another throughout time.

Results: By studying the graphs, several important evolutionary trends can be picked out. Take, for example, Figure 3. The Cambrian was when the first major echinoderm body plans appeared, but the Ordovician was really where each body plan became more complex and different from one another, pointing to the Great Ordovician Biodiversification Event. Each body plan became more well-defined over time, and the differences between the various body plans are highlighted by the extinction of the transitional forms that connected one body plan to another. Even as evolution continued to progress, sometimes certain species would “readapt” a characteristic that they lost thousands of millions of years previously, showing how flexible evolution can really be.               

Why is this study important?  This study is important in studying the mechanisms behind the nature of the Cambrian explosion: why do all of these major animal groups start appearing and how have the groups changed over time? This study shows how fluid characteristics are throughout time, with the introduction, removal, and possibly even a re-introduction of characteristics to body plans as time progresses (this is called homoplasy). It highlights the various patterns of body types within Echinodermata and the patterns of gaining or losing characteristics over time, indicating the complexity in studying how animals change over time.

The big picture: This study helps us fill in some of the gaps in our knowledge about the Cambrian Explosion, a consequential chapter in the history of living creatures, and how animals have evolved since that point. It shows how evolution has changed the bodies of animals within the same group over time and helps us understand how some animals (like sand dollars and brittle stars) can look so different, yet be closely related to one another. 

 Citation: Deline et al., Evolution and Development at the Origin of a Phylum, Current Biology (2020), https://doi.org/10.1016/ j.cub.2020.02.054

A Qualitative Comparative Analysis of Women’s Agency and Adaptive Capacity in Climate Change Hotspots in Asia and Africa

by: Nitya Rao, Arabinda Mishra, Anjal Prakash, Chandni Singh, Ayesha Qaisrani, Prathigna Poonacha, Katharine Vincent, and Claire Bedelian

Summarized by: Lisette Melendez

What data were used? This study focused on the lives of 25 women from geographically different areas in Africa and Asia, including deserts, mountains, and deltas. Even though their cultures and livelihoods differed, they were connected by one phenomenon: climate change. Climate change is something that affects humanity as a whole, but the most severe impact will be felt by our vulnerable communities. As summers grow hotter and droughts increase, those whose livelihoods depend on natural resources will face extreme adversity in the coming years.

Methods: The focal point of the study was to investigate how a woman’s agency – or ability to make meaningful and strategic decisions – was impacted by her surroundings. During field research, each woman was interviewed and their livelihood, exposure to environmental risks (like cyclones, flooding, and storm surges), and societal standing were charted. Then, conditions like material possessions, supportive legal systems, and environmental stress were analyzed in each situation to measure the impact each had on the given woman’s life.

Results: With climate change leading to inconsistent rain and extreme temperatures, land becomes infertile and inadequate for farming. Men often migrate away in search of better job opportunities, and while this presents as a source of empowerment for women, with the chance of increasing their involvement in managing money, the research shows it was actually a burden. One young woman noted, ‘Men can easily migrate for work whereas we have to stay here (at home) to take care of the family’. The women were often left alone to provide food for their children and maintain the crops and pay the bills. Even in states with relief programs for floods and droughts, women were often excluded from receiving aid – reinforcing cultural norms that disadvantage women globally. The same trend can be seen in the United States right at this very moment, with up to 90% of women and minority business owners being excluded from the Paycheck Protection Program.

Environmental stress overshadowed the benefits women received from becoming a greater part in household decisions and in the workforce. Why? Because climate change has destructive consequences for the environment in which these women base their lives on. The struggle to simply survive in barren fields forces women to work harder, in poorer conditions, and for lower wages.

Why is this study important? This study provides vital information for governments to implement effective social programs for their citizens. It advances conversations about gender equality on the international stage and urges leaders to commit to gender equality when drafting important documents like the United Nations’ Sustainable Development Goals and the Sendai Framework for Disaster Risk Reduction.  

 The big picture: The negative environmental impacts of human-driven climate change are now inevitable: global temperatures will continue to rise, droughts will become more prevalent, and storms will intensify. It is important, now more than ever, to ensure that countries have the necessary social programs that can effectively help people sustainably adapt to the changing environment. Resources and adaptation strategies must be made available to the communities that are most vulnerable to fluctuating circumstances. 

Citation: Rao, N., Mishra, A., Prakash, A. et al. A qualitative comparative analysis of women’s agency and adaptive capacity in climate change hotspots in Asia and Africa. Nat. Clim. Chang. 9, 964–971 (2019). https://doi.org/10.1038/s41558-019-0638-y

Prolonged Fluvial Activity From Channel-Fan Systems on Mars

by: Gaia Stucky de Quay, Edwin S. Kite, and David P. Mayer 

Summarized by: Lisette Melendez

What data were used? In geology, there’s a basic pillar called “The Principle of Uniformitarianism”. It suggests that geologic processes almost always occur in the same manner and intensity now as they did in the past – which is why geologists can look at the rock record to learn more about Earth’s future. In the same vein, many geologic processes that occur on Earth, like landslides, volcanoes, and erosions, can be used to study the same processes on different planets!

This study focused on analyzing pictures of alluvial fans (finger-like deposits that are usually created when running water in arid or semi-arid (e.g., deserts) flows downhill onto a flat surface, as shown in Figure 1) on Mars taken by the Context Camera (CTX) on the Mars Reconnaissance Orbiter (MRO). The scientists also compared Martian alluvial fans to the ones found here on Earth using elevation data collected by the NASA Shuttle Radar Topography Mission. These alluvial fans usually mark the end of a water channel, so they can be used to study ancient water deposits on Mars.       

Methods: To study the channels of Mars, the CTX images were converted into digital elevation models, so information like width, slope, and height could be gathered from the data. The valleys on Mars were also measured for how closely they resembled a V-shape. Valleys shaped by rivers have a V-shape, while valleys shaped by other features, like glaciers, tend to have a U-shape.

After gathering all this data, the scientists desired to make an inference about the sediment on Mars, which is too small to be picked up by the camera. So, they turned to places on Earth that had alluvial fans that were very similar to the ones being studied on Mars: the Serra Geral in Brazil, the Great Escarpment in western South Africa, and the Western Ghats in India. These places were ideal parallels for the Martian surface because there’s little to no active tectonic plate movement in the area and the rocks are very well preserved over a long period of geologic time. The big difference is that instead of being placed along mountainsides or plateaus, the slopes that are being studied on Mars are usually along crater rims. 

Results: The channels studied on Mars were found to be less concave (curved inwards) and have very steep slopes, indicating a dry environment. The data on concavity and erodibility (likeliness to erode away) on the Martian alluvial fans was most similar to the data found on the South African slopes, which reinforces the idea that the environment was similarly hot and dry.

Why is this study important? This study is another piece of evidence behind the idea that Mars was once full of water, before it underwent serious climate change. Understanding the history of water on Mars is crucial to understanding what conditions are necessary for life to evolve (which can help paleontologists learn about the first life on Earth, too!). It’s also interesting to note how we can learn more about planets that are millions of miles away by looking right here on Earth!

 The big picture: More than a billion years ago, water used to run freely on the surface of Mars, creating channels and alluvial fans. Scientists use images of the geologic features that remained after water was no longer on the Martian surface to learn more about the history of the Red Planet and the potential implications for human exploration. Learning more about the surface and climate of Mars is necessary for understanding the hazards and potential resources that would be encountered on a crewed mission to Mars.

Citation: Stucky de Quay, G., Kite, E. S., & Mayer, D. P. ( 2019). Prolonged fluvial activity from channel‐fan systems on Mars. Journal of Geophysical Research: Planets, 124, 3119– 3139.  https://doi.org/10.1029/2019JE006167

Deep CO2 in the end-Triassic Central Atlantic Magmatic Province

Manfredo Capriolo, Andrea Marzoli, László E. Aradi, Sara Callegaro, Jacopo Dal Corso, Robert K. Newton, Benjamin J. W. Mills, Paul D. Wignall, Omar Bartoli, Don R. Baker, Nasrrddine Youbi, Laurent Remusat, Richard Spiess, and Csaba Szabó

Summarized by Lisette Melendez. 

What data were used? 

This study investigates the large-scale volcanic activity that would eventually lead to the end-Triassic Extinction, one of the top five most devastating extinction events for life on Earth, that occurred about 201 million years ago. The volcanic eruptions took place across the globe, leading to a massive sheet of volcanic rocks known as the Central Atlantic Magmatic Province, or CAMP for short. Considering that the volcanic activity took place before the supercontinent Pangea was fully split apart, CAMP rocks can be found in North America, Africa, and Europe, as shown in Figure 1. Scientists used both intrusive (magma that crystallized underground) and extrusive (magma that cooled on the Earth’s surface) rock samples to investigate the amount of carbon dioxide, a greenhouse gas, released into the atmosphere during these catastrophic eruptions.

Methods: By analyzing the concentration of the carbon dioxide bubbles (Figure 2) trapped within the crystals that were formed during the volcanic eruptions, scientists can determine the speed and frequency of the eruptions. After collecting more than 200 samples, the concentration of carbon dioxide within the rocks was determined using microspectroscopy: a method that shows the spectra of the sample in order to identify and quantify the various compounds that are present. 

Results: Overall, there was a high volume of carbon dioxide bubbles within CAMP rocks. Since CO2 is an accelerant for magma eruptions, the volcanic activity was likely hasty and violent. The rapid rise of CO2 in the environment means CO2-removing mechanisms, like weathering, aren’t enough to balance out the excess CO2. This leads to a carbon dioxide buildup in the atmosphere, accelerating global warming and ocean acidification.

Why is this study important? The study of CO2 saturation in rocks helps us understand the role that volcanism played in the buildup of excessive greenhouse gases in the atmosphere that triggered the end-Triassic extinction. It showed that the more rapid the release of CO2 into the atmosphere is, the more severe the environmental impact.

The big picture: This study can be used as a warning for current trends, considering that the amount of CO2 emitted during the CAMP eruption roughly equals the amount of projected anthropogenic (i.e., human-caused) emissions over the 21st century. Just like in the past, the current substantial rise in CO2 is leading to a global temperature increase and a surge in ocean acidification, but we are releasing CO2 much faster than at any other time in Earth’s history. Considering that these are the same conditions that led to one of the worst biotic extinctions in Earth’s history, it is vital to encourage our governments to implement radical climate change policies in order to slow the current rise of CO2 to prevent more environmental destruction. 

Citation: Capriolo, M. et al. Deep CO2 in the end-Triassic Central Atlantic Magmatic Province. Nat Commun 11, 1670 (2020).