Wednesday November 20, 2019
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Mars Once had Salt Lakes Similar to the Ones on Earth

Since then, its geological terrains have recorded the history of Mars, and studies have shown Gale Crater reveals signs that liquid water was present

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Mars, Salt, Lakes
Gale Crater was formed about 3.6 billion years ago when a meteor hit Mars. Pixabay

Mars once had salt lakes similar to the ones on Earth and has gone through wet and dry periods, according to a new study.

The researchers from Texas A&M University College in the US examined Mars’ geological terrains from Gale Crater, an immense 95-mile-wide rocky basin that is being explored by the NASA Curiosity rover since 2012 as part of the MSL (Mars Science Laboratory) mission, according to the study published in the journal Nature Geoscience.

The results show that the lake, which was present in Gale Crater over three billion years ago underwent a drying episode, potentially linked to the global drying of Mars.

Gale Crater was formed about 3.6 billion years ago when a meteor hit Mars.

Mars, Salt, Lakes

The researchers from Texas A&M University College in the US examined Mars’ geological terrains from Gale Crater, an immense 95-mile-wide rocky basin that is being explored by the NASA Curiosity rover since 2012. Pixabay

“Since then, its geological terrains have recorded the history of Mars, and studies have shown Gale Crater reveals signs that liquid water was present over its history, which is a key ingredient of microbial life as we know it,” said study co-author Marion Nachon from Texas A&M University.

“During these drying periods, salt ponds eventually formed. It is difficult to say exactly how large these ponds were, but the lake in Gale Crater was present for long periods of time – from at least hundreds of years to perhaps tens of thousands of years,” Nachon said.

According to the researchers, Mars probably became drier over time, and the planet lost its planetary magnetic field, which left the atmosphere exposed to be stripped by solar wind and radiation over millions of years.

“With the atmosphere becoming thinner, the pressure at the surface became lesser, and the conditions for liquid water to be stable at the surface were not fulfilled anymore, so liquid water became unsustainable and evaporated,” Nachon said.

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The salt ponds on Mars are believed to be similar to some found on Earth, especially those in a region called Altiplano, which is near the Bolivia-Peru border.

Nachon said that the Altiplano is an arid, high-altitude plateau where rivers and streams from mountain ranges “do not flow to the sea but lead to closed basins, similar to what used to happen at Gale Crater on Mars.

“This hydrology creates lakes with water levels heavily influenced by climate. During the arid periods Altiplano lakes become shallow due to evaporation, and some even dry up entirely,” she said.

Nachon added that the study shows that the ancient lake in Gale Crater underwent at least one episode of drying before “recovering.”

Mars, Salt, Lakes
The results show that the lake, which was present in Gale Crater over three billion years ago underwent a drying episode, potentially linked to the global drying of Mars. Pixabay

It’s also possible that the lake was segmented into separate ponds, where some of the ponds could have undergone more evaporation.

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These results indicate a past Mars climate that fluctuated between wetter and drier periods, the researchers said. (IANS)

Next Story

Plant that Invade Lakes across Georgia and Southeast, Contributing to Deaths of Eagles and Other Birds

Scientists have been studying the issue after bald eagle carcasses were being found at a man-made lake in Arkansa

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Plant, Lakes, Georgia
An American Bald Eagle catches a fish at Occoquan River in Virginia. (Photo: Diaa Bekheet). VOA

Researchers have been trying to learn more about a plant that has invaded lakes across Georgia and the Southeast, contributing to the deaths of eagles and other birds.

The hydrilla has helped to cause the deaths of American bald eagles and thousands of other water birds over the past 25 years, scientists say.

The plant isn’t killing the birds directly, but is providing a home for a new kind of cyanobacteria that produces a lethal toxin, The Athens Banner-Herald reported.

Scientists have been studying the issue after bald eagle carcasses were being found at a man-made lake in Arkansas. An increasing number of afflicted birds then began showing up in Arkansas, Georgia, and other states across the South.

Plant, Lakes, Georgia
The hydrilla has helped to cause the deaths of American bald eagles and thousands of other water birds over the past 25 years, scientists say. Pixabay

There were reports of injuries — the loss of motor control in eagles and in a water bird called the coot. Their symptoms included wings that twitch but don’t flap, and difficultly maintaining balance.

Necropsies found that the affected eagles and coots showed peculiar lesions that made their brains look like sponges, the Athens newspaper reported.

Wildlife scientists had a name — Avian Vacuolar Myelinopathy, or AVM — but lacked crucial details on what was causing it.

The problem has been especially acute at Thurmond Lake, a man-made reservoir on the Savannah River between Georgia and South Carolina, the newspaper reported.

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University of Georgia professor Susan Wilde saw patterns. The lakes where eagles were dying of AVM are man-made, and they had been heavily invaded by hydrilla. The coots were eating the hydrilla, and the eagles found easy prey in the disabled coots.

Wilde’s hypothesis: The coots could be ingesting some neurotoxin associated with the plants, then passing on the toxin when the eagles ate them. Wilde also found that a previously unknown kind of cyanobacteria was growing on the underside of the spreading hydrilla leaves. That could be producing lethal toxins.

In 2014, nearly two decades after the neurological disease first showed up, Wilde and her colleagues had a name for the cyanobacteria: Aetokthonos Hydrillicola, or eagle-killer. They’d also isolated the toxin it produces.

Plant, Lakes, Georgia
The plant isn’t killing the birds directly, but is providing a home for a new kind of cyanobacteria that produces a lethal toxin, The Athens Banner-Herald reported. Pixabay

On Thurmond Lake, more than 105 AVM eagle deaths have been confirmed so far, and scientists believe the death toll is higher since many animal carcasses are never found.

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Lake managers are trying strategies to beat back the plant invader and its toxic companion. They’ve had some success stocking Thurmond and other lakes with a kind of sterile grass-eating carp to gnaw away at the hydrilla, combined with sowing native water plants. Lake managers are also using chemical killers on the plants, though that carries its own set of environmental risks. (VOA)