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India Today
20-05-2025
- Science
- India Today
Study casts doubt on water flows as cause of streaks on Martian slopes
Images taken of Mars from orbit dating back as far as the 1970s have captured curious dark streaks running down the sides of cliffs and crater walls that some scientists have construed as possible evidence of flows of liquid water, suggesting that the planet harbors environments suitable for living organisms.A new study casts doubt on that interpretation. Examining about 500,000 of these sinewy features spotted in satellite images, the researchers concluded they were created probably through dry processes that left the superficial appearance of liquid flows, underscoring the view of Mars as a desert planet currently inhospitable to life - at least on its data indicated that formation of these streaks is driven by the accumulation of fine-grain dust from the Martian atmosphere on sloped terrain that is then knocked down the slopes by triggers such as wind gusts, meteorite impacts and marsquakes."The tiny dust particles can create flow-like patterns without liquid. This phenomenon occurs because extremely fine dust can behave similarly to a liquid when disturbed - flowing, branching and creating finger-like patterns as it moves downslope," said Adomas Valantinas, a postdoctoral researcher in planetary sciences at Brown University and co-leader of the study published on Monday in the journal Nature Communications."It's similar to how dry sand can flow like water when poured. But on Mars, the ultra-fine particles and low gravity enhance these fluid-like properties, creating features that might be mistaken for water flows when they're actually just dry material in motion," Valantinas study examined about 87,000 satellite images - including those obtained between 2006 and 2020 by a camera aboard NASA's Mars Reconnaissance Orbiter - of slope streaks, which form suddenly and fade over a period of years. They average roughly 1,970-2,540 feet (600-775 meters) long, sometimes branching out and going around slope streaks were concentrated mostly in the northern hemisphere, particularly in three major clusters: at the plains of Elysium Planitia, the highlands of Arabia Terra and the vast Tharsis volcanic plateau including the Olympus Mons volcano, towering about three times higher than Mount researchers said limitations in the resolution of the satellite images mean they account for only a fraction of slope streaks. They estimated the actual number at up to two is considered an essential ingredient for life. Mars billions of years ago was wetter and warmer than it is today. The question remains whether Mars has any liquid water on its surface when temperatures seasonally can edge above the freezing remains possible that small amounts of water - perhaps sourced from buried ice, subsurface aquifers or abnormally humid air - could mix with enough salt in the ground to create a flow even on the frigid Martian surface. That raises the possibility that the slope streaks, if caused by wet conditions, could be habitable it is very difficult for liquid water to exist on the Martian surface, due to the low temperature and the low atmospheric pressure. But brines - very salty water - might potentially be able to exist for short periods of time," said planetary geomorphologist and study co-leader Valentin Bickel of the University of Bern in the massive volume of images, the researchers employed an advanced machine-learning method, looking for correlations involving temperature patterns, atmospheric dust deposition, meteorite impacts, the nature of the terrain and other factors. The geostatistical analysis found that slope streaks often appear in the dustiest regions and correlate with wind patterns, while some form near the sites of fresh impacts and researchers also studied shorter-lived features called recurring slope lineae, or RSL, seen primarily in the Martian southern highlands. These grow in the summer and fade the following winter. The data suggested that these also were associated with dry processes such as dust devils - whirlwinds of dust - and analysis found that both types of features were not typically associated with factors indicative of a liquid or frost origin such as high surface temperature fluctuations, high humidity or specific slope orientations."It all comes back to habitability and the search for life," Bickel said. "If slope streaks and RSL would really be driven by liquid water or brines, they could create a niche for life. However, if they are not tied to wet processes, this allows us to focus our attention on other, more promising locations."Must Watch
BBC News
24-04-2025
- Science
- BBC News
Iceberg tracks found off UK coast could shed light on Antarctica
Icebergs as large as cities, potentially tens of kilometres wide, once roved the coasts of the UK, according to found distinctive scratch marks left by the drifting icebergs as they gouged deep tracks into the North Sea floor more than 18,000 years the first hard evidence that the ice sheet formerly covering Britain and Ireland produced such large findings could provide vital clues in understanding how climate change is affecting Antarctica today. The scientists searched for fingerprints of giant icebergs using very detailed 3D seismic data, collected by oil and gas companies or wind turbine projects doing ocean is a bit like doing an MRI scan of the sediment layers beneath the present-day seafloor, going back millions of researchers found deep, comb-like grooves, interpreted to have been created by the keels of large icebergs that broke off the British-Irish ice sheet more than 18,000 years of these scratch marks are as close as 90 miles (145km) to Scotland's present-day east coast. "We found [evidence of] these gigantic tabular icebergs, which basically means the shape of a table, with incredibly wide and flat tops," said James Kirkham, marine geophysicist at the British Antarctic Survey and lead author of the new study, published in the journal Nature Communications."These have not been seen before and it shows definitively that the UK had ice shelves, because that's the only way to produce these gigantic tabular icebergs."Ice shelves are floating platforms of ice where glaciers extend out into the ocean. By analysing the size of the grooves, the scientists estimate that these icebergs could be five to tens of kilometres wide and 50-180m thick, although it's difficult to be means they would have covered an area roughly as big as medium-sized UK cities like Norwich or Cambridge. The icebergs are comparable in size to some of the smaller icebergs found off present-day Antarctica, such as blocks that calved from the Larsen B ice shelf in Kirkham described seeing such an iceberg when working in Antarctica two years ago."Those of us working on this paper were standing together, gazing out onto this iceberg and thinking, 'Wow, that's probably a similar size iceberg to what was found off the shore of Scotland 18,000 years ago, staring us at us right in front of us in Antarctica today.'" Clues for Antarctica? Hundreds of ice shelves surround about three-quarters of today's Antarctic ice sheet, helping to hold back its vast glaciers. But if ice shelves are lost, the glaciers behind can speed up, depositing more and more ice into the ocean and raising sea levels worldwide. Exactly how this plays out, though, is "one of the largest sources of uncertainty in our models of sea level rise", Dr Kirkham told BBC partly because scientists have only been able to use satellites for a few decades to observe about 10 cases of ice shelves collapsing - hence the desire to look for examples further back in ice shelf setting is the same, but the researchers say their findings from the former British-Irish ice sheet could help understand how Antarctica might respond to today's rapidly warming looking at the changing scratch marks on the seafloor, the researchers discovered an abrupt shift in Britain's icebergs about 18,000 years ago, a time when the planet was gradually warming from a very cold period. The occasional production of giant bergs ceased. Instead, smaller ones were produced much more indicates that the ice shelves suddenly disintegrated; without these massive floating platforms, such large icebergs could no longer be it's potentially important because this coincides with the time when the glaciers behind began to retreat faster and faster. The crucial, but unresolved, question is whether the disintegration of Britain's former ice shelves was merely a symptom of a quickly melting ice sheet - or whether the loss of these shelves directly triggered the runaway retreat of this chicken-and-egg dilemma, as Dr Kirkham put it, would shed light on how serious the impacts of losing today's Antarctic ice shelves might be."These ocean records are fascinating and have implications for Antarctica, as they illustrate the fundamental role of ice shelves in buttressing [holding back] the flow of continental ice into the ocean," said Prof Eric Rignot, glaciologist at the University of California, Irvine, who was not involved in the study."But the argument that the collapse of ice shelves triggered ice sheet collapse is only part of the story; the main forcing is warmer air temperature and warmer ocean temperature," he argued. Graphics by Erwan Rivault
