Over two weeks at the beginning of June 2018, localised dust storms combined and spread to form an impenetrable blanket of dust that hid almost the entire planet’s surface. The global dust storm, which coincided with Mars’s equinox and lasted until mid-September, proved fatal to NASA’s solar-powered Opportunity rover.

Streeter and colleagues from The Open University, NASA and the Russian Academy of Sciences examined the effects of the event on the martian atmosphere by combining data from a Mars Global Climate Model with observations from the European Space Agency/Roscosmos ExoMars Trace Gas Orbiter and NASA’s Mars Reconnaissance Orbiter missions.

Dr Streeter said: “This was a perfect opportunity to investigate how global dust storms impact the atmosphere at the martian poles, which are surrounded by powerful jets of wind in winter. Since the last global storm in 2007, several new missions and instruments have arrived in Mars orbit, so the 2018 event was the most-observed to date.”

Previous research has shown that high levels of dust in the atmosphere can have significant effects on polar temperatures and winds. The vortices at the winter poles also affect temperatures and the transport of air, dust, water and chemicals, so their disruption could mean substantial changes in the martian atmosphere.

The team found that the 2018 storm had profoundly different effects in each hemisphere. At the south pole, where the vortex was almost destroyed, temperatures rose and wind speeds fell dramatically. While the vortex may have already been starting to decay due to the onset of spring, the dust storm appears to have had a decisive effect in ending winter early.

The northern polar vortex, by contrast, remained stable and the onset of autumn followed its usual pattern. However, the normally elliptical northern vortex was changed by the storm to become more symmetrical. The researchers link this to the high dust content in the atmosphere suppressing atmospheric waves caused by the extreme topography in the northern hemisphere, which has volcanoes over twice as tall as Mount Everest and craters as deep as terrestrial mountains.

Dr Streeter added: “Global dust storms at equinox may enhance transport into the southern pole due to the diminished vortex, while the more robust northern vortex continues to act as an effective barrier. If this pattern for global dust storms holds over the course of the thousands of years that Mars maintains this particular axial tilt, it has implications for how dust is deposited at the north and south poles and our understanding of the planet’s climate history.”

Video: https://www.youtube.com/watch?v=tCawZig5fCg

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Materials provided by Royal Astronomical Society. Note: Content may be edited for style and length.

The cratered surface of our nearest planetary neighbour has a long and complex history, and searching for rocks amidst more rocks may seem like a futile activity. Despite this, Martian rovers statistically have a significantly higher ‘find per mile’ success rate than dedicated meteorite hunts on Earth: for every kilometre travelled by a Mars rover, approximately one meteorite is found, even though the rovers have not been specifically looking for them up till now.

However, as part of the European Space Agency’s upcoming ExoMars mission, the next rover — named Rosalind Franklin, after the chemist best known for her pioneering work on DNA — will drill down into the Martian surface to sample the soil, analyse its composition and search for evidence of past or present life buried underground.

Meteorites are important pieces of evidence that can help us understand this story; once a meteorite lands on a planet, it is subjected to the same atmospheric conditions as the rest of the surface. Chemical and physical weathering can provide information on climate weathering rates and water-rock interactions, meteorite sizes and distribution can help to infer information about the density of the atmosphere, and stony meteorites could be a potential delivery mechanism for organic materials to Mars.

“Meteorites act as a witness plate across geological time,” said Sara Motaghian, the PhD student at the NHM and Imperial College London who is carrying out the work. “Generally, the surfaces of Mars we are exploring are incredibly ancient, meaning there have been billions of years for the surface to accumulate these meteorites and lock in information from across Mars’ past.”

The team are looking in particular at the use of multispectral imaging with the PanCam instrument, hoping to be able to highlight features in images that could be associated with meteorites as the rover moves across the surface. They are also investigating the possibility of using pattern recognition techniques to distinguish features such as Widmanstätten patterns, which can be revealed by extreme weathering.

The launch of the ExoMars rover was originally scheduled for 2020, however was delayed until 2022 due to technical issues and growing concerns over the coronavirus pandemic. Once the rover reaches Mars in 2023, the team hope that their work will allow meteorites on the surface to be studied for longer by the Rosalind Franklin rover before it drives on, helping to build a more complete understanding of the Martian surface and its history, if any, of life.

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Materials provided by Royal Astronomical Society. Note: Content may be edited for style and length.

“Neighboring communities can be impacted very differently after a natural catastrophic event,” said Dr. Ali Mostafavi, associate professor in the Zachry Department of Civil and Environmental Engineering and director of the Urban Resilience.AI Lab. “And so, we need to identify which areas can recover faster than others and which areas are impacted more than others so that we can allocate more resources to areas that need them more.”

The researchers have reported their findings in Interface, a publication of The Royal Society.

The metric that is conventionally used to quantify how communities bounce back from nature-caused setbacks is called resilience and is defined as the ability of a community to return to its pre-disaster state. And so, to measure resilience, factors like the accessibility and distribution of resources, connection between residents within a community and the level of community preparedness for an unforeseen disaster are critical.

The standard way of obtaining data needed to estimate resilience is through surveys. The questions considered, among many others, are how and to what extent businesses or households were affected by the natural disaster and the stage of recovery. However, Mostafavi said these survey-based methods, although extremely useful, take a long time to conduct, with the results of the survey becoming available many months after the disaster.

“For federal agencies allocating funds, recovery information is actually needed in a faster and more near real-time fashion for communities that are trailing in the recovery process,” said Mostafavi. “The solution, we thought, was to look for emerging sources of data other than surveys that could provide more granular insights into community recovery at a scale not previously investigated.”

Mostafavi and his collaborators turned to community-level big data, particularly the information collected by companies that keep track of visits to locations within a perimeter from anonymized cell phone data. In particular, the researchers partnered with a company called SafeGraph to obtain location data for the people in Harris County, Texas, around the time of Hurricane Harvey. As a first step, they determined “points of interest” corresponding to the locations of establishments, like hospitals, gas stations and stores, that might experience a change in visitor traffic due to the hurricane.

Next, the researchers mined the big data and obtained the number of visits to each point of interest before and during the hurricane. For different communities in Harris County, they calculated the time taken for the visits to return to the pre-disaster level and the general resilience, that is, the combined resilience of each point of interest based on the percent change in the number of visits due to the hurricane.

Their analysis revealed that communities that had low resilience also experienced more flooding. However, their results also showed that the level of impact did not necessarily correlate with recovery.

“It’s intuitive to assume, for example, that businesses impacted more will have slower recovery, which actually wasn’t the case,” said Mostafavi. “There were places where visits dropped significantly, but they recovered fast. But then others that were impacted less but took longer to recover, which indicated the importance of both time and general resilience in evaluating a community’s recovery.”

The researchers also noted that another important finding was that the areas that are in close proximity to those that had flooding are also impacted, suggesting that the spatial reach of flooding goes beyond flooded areas.

“Although we focused on Hurricane Harvey for this study, our framework is applicable for any other natural disaster as well,” said Mostafavi. “But as a next step, we’d like to create an intelligent dashboard that would display the rate of recovery and impacts in different areas in near real time and also predict the likelihood of future access disruption and recovery patterns after a heavy downpour.”

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Materials provided by Texas A&M University. Original written by Vandana Suresh. Note: Content may be edited for style and length.