For the first time, we can measure the human footprint on Antarctica



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The Casey Station is part of Australia’s permanent outpost in Antarctica.
Shaun Brooks, Author provided

Shaun Brooks, University of Tasmania and Julia Jabour, University of Tasmania

Most people picture Antarctica as a frozen continent of wilderness, but people have been living – and building – there for decades. Now, for the first time, we can reveal the human footprint across the entire continent.

Our research, published today in the journal Nature Sustainability, found that while buildings and disturbance cover a small portion of the whole continent, it has an outsized impact on Antartica’s ecosystem.




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Our data show 76% of buildings in Antarctica are within just 0.06% of the continent: the ice-free areas within 5km of the coast. This coastal fringe is particularly important as it provides access to the Southern Ocean for penguins and seals, as well as providing a typically wetter climate suitable for plant life.

A hard question to answer

How much land we collectively impact with infrastructure in Antarctica has been a question raised for decades, but until now has been difficult to answer. The good news is it’s a relatively small area. The bigger issue is where it is. Together with our colleagues Dana Bergstrom and John van den Hoff, we have made the first measurement of the “footprint” of buildings and disturbed ice-free ground across Antarctica.

This equates to more than 390,000 square metres of buildings on the icy continent, with a further 5,200,000m² of disturbance just to ice-free land. To put it another way, there is more than 1,100m² of disturbed ground per person in Antarctica at its most populated in summer. This is caused primarily by the 30 nations with infrastructure in Antarctica, along with some presence from the tourism industry.

Figure Building footprint density.
Nature Sustainability

It has taken until now to find the extent of our impact because of difficulty in gathering the data. Because so many countries are active in Antarctica, getting them to provide data on their infrastructure has been very slow. As two-thirds of research stations were built before the adoption of the Protocol on Environmental Protection to the Antarctic Treaty, they did not require environmental impact assessments or monitoring, so it is quite likely many of the operators do not have accessible data on their footprints. In addition, due to the inherent difficulty in accessing Antarctica, and the vast distances between each station, it is not possible to conduct field measurements on a continental scale.

To address these problems, our team took an established approach to measuring a single station’s footprint, and applied it to 158 locations across the continent using satellite imagery. The majority of images used were freely sourced from Google Earth, enabled by continually increasing improvements in resolution and coverage.

This process took hours of painstaking “digitisation” – where the spatially accurate images of buildings and disturbed ground were manually mapped within a computer program to create the data.

Davis Station, one of Australia’s three permanent research outposts in Antartica. Researchers used Google Earth images to map the footprint of human infrastructure across the continent.
Shaun Brooks, Author provided

Interestingly, one of the most difficult sites was the United States’ Amundsen-Scott Station. As this station is located on the geographic South Pole, very few satellites pass overhead. This problem was eventually solved by trawling through thousands of aerial images produced by NASA’s Operation IceBridge, where we found their aircraft had flown over the station in 2010. After capturing these data, we then compared our measurements against existing known building sizes and found our accuracy was within 2%.

Unlike buildings, we didn’t have measurements to compare for disturbed ground such as roadways, airstrips, quarries and the like. We believe we have produced a significant underestimate, due to factors including snow cover and insufficient image resolution obscuring smaller features such as walking tracks.




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Location, location, location

After mapping the footprint of buildings and ground disturbance our data has yielded some interesting results. For practical reasons, most stations in Antarctica are located within the small ice-free areas spread across the continent, particularly around the coast. In addition to being attractive to us, these areas are essential for much of Antarctica’s biodiversity by providing nesting sites for seabirds and penguins, substrate for mosses, lichens, and two vascular plants, and habitat for the continent’s invertebrate species.

Adelie penguins need ice-free areas to access the ocean.
Shaun Brooks, Author provided

Another interesting finding from these data is what they tell us about wilderness on the continent. Although the current footprint covers a very small fraction of the more than 12 million square kilometres of Antarctica, we found disturbance is present in more than half of all large ice-free areas along the coast. Furthermore, by using the building data we captured, along with existing work by Rupert Summerson, we were also able to estimate the visual footprint, which amounts to an area similar in size to the total ice-free land across the whole continent.

The release of this research is timely, with significant increases in infrastructure proposed for Antarctica. Currently there are new stations proposed by several nations, major rebuilding projects of existing stations underway (including the US’s McMurdo and New Zealand’s Scott Base), and Italy is building a new runway in ice-free areas.

Australia has proposed Antarctica’s first concrete runway, which if built would be the continent’s largest.




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Until now, decisions on expanding infrastructure have been without the context of how much is already present. We hope informed decisions can now be made by the international community about how much building in Antarctica is appropriate, where it should occur, and how to manage the future of the last great wilderness.The Conversation

Shaun Brooks, PhD Candidate, University of Tasmania and Julia Jabour, Leader, Ocean and Antarctic Governance Research Program, University of Tasmania

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Launching in May, the InSight mission will measure marsquakes to explore the interior of Mars



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InSight aims to figure out just how tectonically active Mars is, and how often meteorites impact it.
NASA

Katarina Miljkovic, Curtin University

When we look up at Mars in the night sky we see a red planet – largely due to its rusty surface. But what’s on the inside?

Launching in May, the next NASA space mission will study the interior of Mars.

The InSight (Interior exploration using Seismic Investigations, Geodesy and Heat Transport) spacecraft will be a stationary lander mission that measures seismic activity on Mars (often referred to as marsquakes) as well as interior heat flow.




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By listening to and probing the Martian crust and interior, the project aims to understand the formation and evolution of Mars.

The InSight mission is scheduled to launch from California in early May, with landing on Mars planned for November. The expected lifetime of the mission is at least two years.

Origins of marsquakes

The payload on board InSight includes the seismic instrument SEIS (Seismic Experiment for Interior Structure). Its task is to record seismic activity, or vibrations, of the planet.

Apart from shaking the ground while passing, seismic waves can be extremely useful in telling us about the structure of planetary interiors. Seismic waves travel at different speeds when passing through different materials. Processing their arrival time and strength via recorded seismographs is a clever way to learn about the interior structure of a planetary body – such as the crust, the next layer down (the mantle), and the core.

Seismic activity on Mars could be caused by a number of processes. For example, shallow marsquakes could originate from meteoroid strikes, and deep marsquakes could come from martian tectonic activity (the movement of tectonic plates at the surface of the planet).

It is generally believed that tectonic processes could have shaped Mars in its early evolution, similar to the Earth. However, unlike the Earth in younger ages, Mars has become largely tectonically dormant.

We think lots of meteoroids hit Mars

Considering that tectonics on Mars may not be reminiscent of what we see on our planet, we suspect that meteoroid strikes will play a major role in causing marsquakes.

On Earth, frequent and small meteoroids most often burn up in the atmosphere and appear to us as a form of “shooting star”. When a rock from space moving at supersonic speed encounters the terrestrial atmosphere, the air in front of it gets compressed extremely quickly. Temperature rises and heat builds up, so the rock starts to shine bright under the process of its destruction.




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However, on Mars we think that meteoroids may not necessarily burn up entirely upon encountering the martian atmosphere. This is simply because Mars has a less dense atmosphere than the Earth – so incoming meteoroids have a higher penetrating power. These impact events would produce seismic disturbance in the atmosphere, and also likely in the ground.

Detecting meteoroid strikes on planetary bodies began with the lunar Apollo program. Apollo missions carried seismometers to the Moon, and as a result we had a network of seismometers that operated on the Moon from 1969-77.

During its lifetime, the Apollo seismic network recorded shallow quakes produced by frequent meteoroid bombardment. Considering that the Moon does not have an atmosphere to protect its surface from the incoming meteoroids, the Apollo seismic network provided heaps of seismic data from the Moon. These impact-induced seismic moonquakes provided the first constraints about the thickness of the lunar crust as well as structure of crust and deep interior.

We’ve tried to measure Mars seismic activity before

During the lunar exploratory boom with the Apollo program, NASA also launched Vikings 1 and 2 to Mars in 1975. These became the first missions to land on Mars, and each Viking mission carried a seismometer.

While instruments on Viking have collected more data than expected, the seismometer on Viking Lander 1 did not work after landing. The seismometer on Viking Lander 2 demonstrated poor detection rates, with no quakes coming off the ground (as it had remained on the Lander).

To date, we have had no other seismic station on any extraterrestrial planetary body. This makes InSight the first-of-its-kind mission to be placed on Mars. While its design relies on proven technologies from past missions, it is ground-breaking in terms of expected science goals.

Instead of making orbital remote sensing surveys or roving on the surface similar to other rovers, InSight has a different goal to previous Martian missions.




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Why are we so interested in the subsurface of Mars?

Mars and Earth differ in size, temperature, and atmospheric composition. But similar geological features such as craters, volcanoes, or canyons can be observed on both planets. This implies that the interior of Mars may be similar to Earth’s.

It is also quite likely that there was liquid water on the surface of ancient Mars, which was the time Mars could have been very similar to Earth. So Mars could answer questions about the ancient habitability of our solar system.

Unlike potentially habitable planets orbiting distant stars, Mars is reachable within our lifetime. Discovering martian crustal properties is of great importance when it comes to planning landing missions and investigating signs of extraterrestrial habitability.

The ConversationMy role in the InSight mission is to work with the science team in analysing the data (impact-induced seismograms and any respective orbital imagery) to work out what kind of impacts had occurred during the mission lifetime.

Katarina Miljkovic, ARC DECRA fellow, Curtin University

This article was originally published on The Conversation. Read the original article.