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32-461: In July 2018, scientists reported the discovery, based on MARSIS radar studies, of a subglacial lake on Mars , 1.5 km (0.93 mi) below the southern polar ice cap , and extending sideways about 20 km (12 mi), the first known stable body of water on the planet. Planum Australe is partially covered by a permanent polar ice cap composed of frozen water and carbon dioxide about 3 km thick. A seasonal ice cap forms on top of

64-587: A 40 m dipole antenna for MARSIS to work; a less crucial 7-meter-long monopole antenna was deployed on June 17. The radar booms were originally scheduled to be deployed in April 2004, but this was delayed out of fear that the deployment could damage the spacecraft through a whiplash effect. Due to the delay it was decided to split the four-week commissioning phase in two parts, with two weeks running up to July 4 and another two weeks in December 2005. The deployment of

96-571: A crucial role as a keystone species by regulating phytoplankton and bacterioplankton levels. The Artemia species also serves as an intermediate host for helminth parasites that affect migratory water birds like flamingos, grebes, gulls, shorebirds, and ducks. Vertebrates in saline lakes include certain fish and bird species, though they are sensitive to fluctuations in salinity. Many saline lakes are also alkaline, which imposes physiological challenges for fish, especially in managing nitrogenous waste excretion. Fish species vary by lake; for instance,

128-423: A high content of carbonate is sometimes termed a soda lake . Salt lakes are classified according to salinity levels. The formation of these lakes is influenced by processes such as evaporation and deposition. Salt lakes face serious conservation challenges due to climate change, pollution and water diversion. The primary method of classification for salt lakes involves assessing the chemical composition of

160-710: Is a hyposaline lake. Mesosaline lakes have a salinity level ranging from 3 to 35 g/L. An example of a mesosaline lake is Redberry Lake in Saskatchewan, Canada . Hypersaline lakes possess salinities greater than 35 g/L, often reaching levels that can exceed 200 g/L. The extreme salinity levels create harsh conditions that limit the diversity of life, primarily supporting specialized organisms such as halophilic bacteria and certain species of brine shrimp . These lakes can have high concentrations of sodium salts and minerals, such as lithium, making such lakes vulnerable to mining interests. Hypersaline lakes can be found in

192-445: Is a landlocked body of water that has a concentration of salts (typically sodium chloride ) and other dissolved minerals significantly higher than most lakes (often defined as at least three grams of salt per liter). In some cases, salt lakes have a higher concentration of salt than sea water ; such lakes can also be termed hypersaline lake , and may also be pink lakes on account of their color. An alkalic salt lake that has

224-641: Is dissected by canyons Promethei Chasma , Ultimum Chasma , Chasma Australe and Australe Sulci . It is theorised that these canyons were created by katabatic wind . The largest crater in Planum Australe is McMurdo Crater . The seasonal frosting and defrosting of the southern ice cap results in the formation of spider-like radial channels carved on 1 meter thick ice by sunlight. Then, sublimed CO 2 (and probably water) increase pressure in their interior, producing geyser-like eruptions of cold fluids often mixed with dark basaltic sand or mud. This process

256-501: Is not limited to the Aral Sea; salt lakes around the world are shrinking due to excessive water diversion, dam construction, pollution, urbanization, and rising temperatures associated with climate change. The resulting declines cause severe disruptions to local ecosystems and biodiversity, degrades the environment, threatens economic stability, and displaces communities dependent on these lakes for resources and livelihood. In Utah, if

288-646: Is operated by the European Space Agency , is operational and orbits Mars as an instrument for the ESA's Mars Express exploration mission. The MARSIS Principal Investigator is Giovanni Picardi from the University of Rome "La Sapienza", Italy. It features ground-penetrating radar capabilities, which uses synthetic aperture technique and a secondary receiving antenna to isolate subsurface reflections. MARSIS identified buried basins on Mars. MARSIS

320-409: Is rapid, observed happening in the space of a few days, weeks or months, a growth rate rather unusual in geology – especially for Mars. The Mars Geyser Hopper lander is a concept mission that would investigate the geysers of Mars. In September 2020, scientists confirmed the existence of several large saltwater lakes under the ice in the south polar region of the planet Mars . According to one of

352-720: The McMurdo Dry Valleys in Antarctica, where salinity can reach ≈440‰. Salt lakes form through complex chemical, geological, and biological processes, influenced by environmental conditions like high evaporation rates and restricted water outflow. As water carrying dissolved minerals ( sodium , potassium , and magnesium ) enters these basins, it gradually evaporates, concentrating these minerals until they precipitate as salt deposits. Then, specific ions interact under controlled temperatures, which leads to solid-solution formation and salt crystal deposition within

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384-474: The Great Salt Lake is not conserved, the state could face potential economic and public health crises, with consequences for air quality, local agriculture, and wildlife. According to “Utah’s Great Salt Lake Strike Team”, in order increase the lake's level within the next 30 years, see average inflows must increase by 472,00 acre-feet per year, which is about a 33% increase in the amount that has reached

416-458: The Martian polar caps provided a store of CO 2 much larger than the atmospheric reservoir. However it is now thought that both polar caps are made mostly of water ice. Both poles have a thin seasonal covering of CO 2 , while in addition the southern pole has a permanent residual CO 2 cap, about 8 to 10 metres thick, that lies on top of the water ice. Perhaps the key argument that the bulk of

448-489: The Salton Sea is home to species such as carp, striped mullet, humpback sucker, and rainbow trout. Stratification in salt lakes occurs as a result of the unique chemical and environmental processes that cause water to separate into layers based on density . In these lakes, high rates of evaporation often concentrate salts, leading to denser, saltier water sinking to the lake's bottom, while fresher water remains nearer

480-407: The booms was a critical and highly complex task, requiring effective inter-agency cooperation between ESA, NASA, industry partners, and public Universities. MARSIS transmits a series of modulated chirps at frequencies between 1.8 and 5.0 MHz in subsurface sounding mode, with a 1 MHz bandwidth. It also emits chirps sweeping between 0.1 and 5.4 MHz when ionosphere sounding. Depending on

512-522: The geographical south pole. The presence of two massive impact basins in the western hemisphere – Hellas Planitia and Argyre Planitia – creates an immobile area of low pressure over the permanent ice cap. The resulting weather patterns produce fluffy white snow which has a high albedo . This is in contrast to the black ice that forms in the eastern part of the polar region, which receives little snow. There are two distinct subregions in Planum Australe – Australe Lingula and Promethei Lingula . It

544-464: The ice cap. The most reflective part of the ice cap is approximately 85% dry ice and 15% water ice. The second part, where the ice cap forms steep slopes at the boundary with the surrounding plain, is almost exclusively water ice. Finally, the ice cap is surrounded by permafrost fields that extend for tens of kilometres north away from the scarps. The centre of the permanent ice cap is not located at 90°S but rather approximately 150 kilometres north of

576-418: The ice is water is that CO 2 ice isn't mechanically strong enough to make a 3 km thick ice cap stable over long periods of time. Recent evidence from SHARAD ice penetrating radar has revealed a massive subsurface CO 2 ice deposit approximately equal to 80% of the current atmosphere, or 4–5 mbar, stored in Planum Australe. Data from ESA 's Mars Express indicates that there are three main parts to

608-479: The lack of vertical mixing. Extremophiles , including specific bacteria and archaea , inhabit the hypersaline and oxygen-deficient zones at lower depths. Bacteria and archaea, for example, rely on alternative metabolic processes that do not depend on oxygen. These microorganisms play a critical role in nutrient cycling within salt lakes, as they break down organic material and release by-products that support other microbial communities. Due to limited biodiversity,

640-400: The lake bed. This cycle of evaporation and deposition is the main process to the unique saline environment that characterizes a salt lake. Environmental factors further shape the composition and formation of salt lakes. Seasonal variations in temperature and evaporation drive mineral saturation and promote salt crystallization . In dry regions, water loss during warmer seasons concentrates

672-428: The lake in recent years. Water conservation is viewed as being the most cost-effective and practical strategy to save salt lakes like the Great Salt Lake. Implementing strong water management policies, improving community awareness, and ensuring the return of water flow to these lakes are additional ways that may restore ecological balance. Other proposed methods of maintaining lake levels include cloud seeding and

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704-475: The lake's chemistry, supporting only specialized microbial life adapted to extreme environments with high salinity and low oxygen levels. The restricted vertical mixing limits nutrient cycling , creating a favorable ecosystem for halophiles (salt-loving organisms) that rely on these saline conditions for stability and balance. The extreme conditions within stratified salt lakes have a profound effect on aquatic life , as oxygen levels are severely limited due to

736-548: The lake's salts. This creates a dynamic environment where seasonal shifts affect the salt lake's mineral layers, contributing to its evolving structure and composition. Groundwater rich in dissolved ions often serve as primary mineral sources that, combined with processes like evaporation and deposition, contribute to salt lake development. Salt lakes host a diverse range of animals, despite high levels of salinity acting as significant environmental constraints. Increased salinity worsens oxygen levels and thermal conditions, raising

768-456: The mode, the pulsewidth is 30, 91 or 250 μs, and the nominal Pulse repetition frequency is 130 Hz. Transmitted power is either 1.5 or 5 W. Nominal science observations began during July 2005. A 2012 paper by the MARSIS team measured a difference between the dielectric constant of the northern and southern high-latitude regions. This is evidence that the material that fills

800-505: The northern basin is a lower-density material, which could be interpreted as evidence of an ancient northern ocean. Using MARSIS data, 22 Italian scientists reported in July 2018 the discovery of a subglacial lake on Mars , 1.5 km (0.93 mi) below the southern polar ice cap , and extending horizontally about 20 km (12 mi), the first known stable body of water on Mars . Salt lake A salt lake or saline lake

832-505: The permanent one during the Martian winter, extending from 60°S southwards. It is, at the height of winter, approximately 1 meter thick. It is possible that the area of this ice cap may be shrinking due to localized climate change . Claims of more planetwide global warming based on imagery, however, ignore temperature data and global datasets. Spacecraft and microwave data indicate global average temperature is, at most, stable, and possibly cooling. In 1966, Leighton and Murray proposed that

864-503: The researchers, “We identified the same body of water [as suggested earlier in a preliminary initial detection], but we also found three other bodies of water around the main one ... It’s a complex system.” MARSIS MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) is a low frequency, pulse-limited radar sounder and altimeter developed by the University of Rome La Sapienza and Alenia Spazio (today Thales Alenia Space Italy). The Italian MARSIS instrument, which

896-417: The restrictive environment limits biodiversity , allowing only specially adapted life forms to survive, which creates unique, highly specialized ecosystems that are distinct from freshwater or less saline habitats. Salt lakes declined worldwide in recent years. The Aral Sea , once of the largest saline lakes with a surface area of 67,499 km in 1960, diminished to approximately 6,990 km in 2016. This trend

928-462: The surface. These seasonal changes influence the lake's structure, making stratification more pronounced during warmer months due to increasing evaporation, which drives separation between saline and fresher layers in the lake, leading a phenomenon known as meromixis (meromictic state), primarily prevents oxygen from penetrating the deeper layers and create the hypoxic (low oxygen) or anoxic (no oxygen) zones. This separation eventually influenced

960-482: The water within the lakes, specifically its salinity, pH , and the dominant ions present. Subsaline lakes have a salinity lower than that of seawater but higher than freshwater , typically ranging from 0.5 to 3 grams per liter (g/L). Hyposaline lakes exhibit salinities from 0.5 to 3 g/L, which allows for the presence of freshwater species along with some salt-tolerant aquatic organisms. Lake Alchichica in Mexico

992-433: The water's density and viscosity , which demands greater energy for animal movement. Despite these challenges, salt lakes support biota adapted to such conditions with specialized physiological and biochemical mechanisms. Common salt lake invertebrates include various parasites, with around 85 parasite species found in saline waters, including crustaceans and monogeneans . Among them, the filter-feeding brine shrimp plays

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1024-460: Was funded by ASI (Italy) and NASA (USA). The processor runs the real-time operating system EONIC Virtuoso. On May 4, 2005, Mars Express deployed the first of its two 20-metre-long radar booms for the MARSIS experiment. At first the boom didn't lock fully into place; however, exposing it to sunlight for a few minutes on May 10 fixed the glitch. The second 20 m boom was successfully deployed on June 14. Both 20 m booms were needed to create

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