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Water on Mars: discovery of three buried lakes intrigues scientists

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An image of Mars

Scientists have long thought that there could be water trapped beneath the surface of Mars.Credit: Steve Lee, Univ. Colorado/Jim Bell, Cornell Univ./Mike Wolff, SSI/NASA

Two years ago, planetary scientists reported the discovery of a large saltwater lake under the ice at Mars’s south pole, a finding that was met with excitement and some scepticism. Now, researchers say they’ve confirmed the presence of that lake — and found three more.

The discovery, reported on 28 September in Nature Astronomy1, was made using radar data from the European Space Agency’s (ESA) orbiting Mars Express spacecraft. It follows the detection of a single subsurface lake in the same region in 2018 — which, if confirmed, would be the first body of liquid water ever detected on the red planet and a possible habitat for life. But that finding was based on just 29 observations made from 2012 to 2015, and many researchers said they needed more evidence to support the claim. The latest study used a broader data set comprising 134 observations from between 2012 and 2019.

“We identified the same body of water, but we also found three other bodies of water around the main one,” says planetary scientist Elena Pettinelli at the University of Rome, who is one of the paper’s co-authors. “It’s a complex system.”

The team used a radar instrument on Mars Express called the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) to probe the planet’s southern polar region. MARSIS sends out radio waves that bounce off layers of material in the planet’s surface and subsurface. The way the signal is reflected back indicates the kind of material that is present at a particular location — rock, ice or water, for example. A similar method is used to identify subsurface glacial lakes on Earth. The team detected some areas of high reflectivity that they say indicate bodies of liquid water trapped under more than one kilometre of Martian ice.

The lakes are spread over about 75,000 square kilometres — an area roughly one-fifth the size of Germany. The largest, central lake measures 30 kilometres across, and is surrounded by three smaller lakes, each a few kilometres wide.

Salty lakes

On the surface of Mars, the low pressure that results from the planet’s lack of a substantial atmosphere makes liquid water impossible. But scientists have long thought that there could be water trapped under Mars’s surface, perhaps a remnant of when the planet once had seas and lakes billions of years ago. If such reservoirs exist, they could be potential habitats for Martian life. On Earth, life is able to survive in subglacial lakes in places such as Antarctica.

But the amount of salt present could pose problems. It’s thought that any underground lakes on Mars must have a reasonably high salt content for the water to remain liquid. Although this far beneath the surface there may be a small amount of heat from the interior of Mars, this alone would not be enough to melt the ice into water. “From a thermal point of view it has to be salty,” says Pettinelli.

Lakes with a salt content about five times that of seawater can support life, but as you approach 20 times that of seawater life is no longer present, says John Priscu, an environmental scientist at Montana State University.

“There’s not much active life in these briny pools in Antarctica,” says Priscu, whose group studies microbiology in icy environments. “They’re just pickled. And that might be the case [on Mars].”

Heated debate

The presence of the Martian lakes themselves is also still debated. After the 2018 discovery, researchers raised concerns such as the lack of an adequate heat source to turn the ice into water. And although the latest finding supports the 2018 observation and involves much more data, not everyone is yet convinced that the regions identified are liquid water.

“If the bright material really is liquid water, I think it’s more likely to represent some sort of slush or sludge,” says Mike Sori, a planetary geophysicist at from Purdue University, in West Lafayette, Indiana.

Jack Holt, a planetarty scientist at the University of Arizonasays that while he thinks the latest data are fine, he isn’t sure about the interpretation. “I do not think there are lakes,” says Holt, who is on the science team for the Mars Shallow Radar sounder (SHARAD) on NASA’s Mars Reconnaissance Orbiter (MRO). “There is not enough heat flow to support a brine here, even under the ice cap.”

A Chinese mission that is on its way to Mars might offer one way to check the claims. The Tianwen-1 mission will enter orbit in February 2021, and as well as deploying a rover onto the surface, the orbiter will carry a suite of scientific instruments. These include radar equipment that could be used to make similar observations. “Its capabilities are similar to MARSIS and SHARAD,” says David Flannery from the Queensland University of Technology.

For the time being, the prospect that these lakes are remnants of Mars’s wet past remains an exciting possibility. “There may have been a lot of water on Mars,” says Pettinelli. “And if there was water, there was the possibility of life.”

Source:- Nature.com

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Ice loss to add 0.4C to global temperatures: Study – The Jakarta Post – Jakarta Post

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The loss of billions of tons of ice from Earth’s frozen spaces is likely to increase global temperatures by an additional 0.4 degrees Celsius, according to research Tuesday highlighting the danger of a “vicious circle” of warming.

Arctic summer sea ice levels have declined by more than 10 percent each decade since the late 1970s and mountain glaciers have shed roughly 250 billion tons of ice annually over the last century.

Ice loss from the West Antarctic and Greenland ice sheets is accelerating and already outstripping what scientists until recently believed to be the worst-case melt scenarios.

Decades of studies have sought to quantify how Earth’s melting ice will contribute to sea level rise — Antarctica and Greenland alone contain enough frozen water to boost oceans’ height by around 60 meters.

But little research has tried to predict how ice loss will add to the already 1.0 degree C of global warming emissions from fossil fuels since the start of the Industrial Era. 

Scientists at Germany’s Potsdam Institute for Climate Impact Research (PIK) used a climate model that includes components on atmosphere, ocean, sea- and land-ice data to predict temperature change from ice loss under a variety of emissions scenarios.

They found that under current levels of atmospheric CO2 — roughly 400 parts per million — the melting of Arctic sea ice, mountain glaciers and the polar ice caps would raise temperatures by 0.4C. 

That’s on top of the 1.5C of warming our current emissions levels have rendered all but inevitable, and the safer cap on global warming aimed for in the Paris climate accord.

The main driver of temperature gain from ice loss would be due to a process known as albedo feedback, in which heat reflective bright ice is replaced by absorbent darker sea water and/or soil.

“If global ice masses shrink, this changes how much of the sunlight that hits the Earth’s surface is reflected back into space,” said lead author Nico Wunderling. 

He likened the albedo effect to wearing either white or black clothes in summer. 

“If you wear dark, you heat up more easily,”  Wunderling noted. 

This is one of Earth’s so-called climate “feedback loops”, in which increased temperatures lead to further ice loss, which in turn further increases temperatures.

Read also: If Arctic ice melt doesn’t boost sea levels, do we care?

Tipping point 

Other ways that temperatures would rise further as ice receded include increased water vapor in the atmosphere, increasing the greenhouse effects, said authors of the study published in Nature Communications.

Looking solely at Arctic sea ice — which unlike polar ice caps might be totally absent during summer months within decades — they found its melt would contribute 0.2C to global temperatures alone.

The largest ice masses in Greenland and West Antarctica, by comparison, are huge and will likely take centuries to melt fully even if emissions continue their unabated growth.

But the authors highlighted the risk that those enormous bodies of frozen water could soon reach a point of no return as temperatures creep ever higher. 

Given the unknowns surrounding ice cap tipping points, Wunderling told AFP it would be best to act in “a risk-averse” way and try to drag down emissions as soon as possible.

“With continued global warming, it becomes more and more likely that we cross tipping points -– not just in the ice-sheets, but also in other parts of the climate system,” he said.

“If the Paris Agreement is fulfilled we can avoid many of the strongest and potentially irreversible impacts on Earth’s ice masses, the global climate and humanity.”

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Arctic sea ice at record low October levels: Danish institute – Bangkok Post

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Since the 1990s, warming has been twice as fast in the Arctic, compared to the rest of the world

COPENHAGEN – Sea ice in the Arctic was at record lows for October, as unusually warm waters slowed the recovery of the ice, Danish researchers said Wednesday.

Diminishing sea ice comes as a reminder about how the Arctic is hit particularly hard by global warming.

Since the 1990s, warming has been twice as fast in the Arctic, compared to the rest of the world, as a phenomena dubbed “Arctic amplification,” causes air, ice and water to interact in a reinforcing manner.

“The October Arctic sea ice extent is going to be the lowest on record and the sea ice growth rate is slower than normal,” Rasmus Tonboe, a scientist at the Danish Meteorological Institute (DMI), told AFP, noting that the record was unequalled for at least 40 years.

According to preliminary satellite data used by the institute, sea ice surface area was at 6.5 million square kilometres (2.5 million square miles) on 27 October.

Every year, some of the ice formed in the Arctic waters melts in the summer.

It usually reaches a low point of about five million square kilometres, but then re-forms to cover about 15 million square kilometres in winter. Warmer temperatures are now reducing both the summer and winter extent of the ice.

Satellite data has been collected to monitor the ice precisely since 1979, and the trend towards a reduction is clear.

For the month of October, measurements show an 8.2 percent downward trend in ice over the last 10 years.

Already in September, researchers noted the second lowest extent of sea ice recorded in the Arctic, though not quite hitting the low levels recorded in 2012.

But warmer-than-normal sea water slowed the formation of new ice in October.

– ‘Vicious spiral’ –

Water temperatures in the eastern part of the Arctic, north of Siberia, was two to four degrees warmer than normal, and in Baffin Bay, it was one to two degrees warmer, DMI said in a statement.

The institute said this was following a trend observed in recent years, which was described as a “vicious spiral.”

“It’s a trend we’ve been seeing the past years, with a longer open water season making the sun warm the sea for a longer time, resulting in shorter winters so the ice doesn’t grow as thick as it used to,” Tonboe said.

Since the melting ice is already in the ocean it does not directly contribute to the rise in sea levels.

But as the ice disappears sunlight “gets absorbed in the ocean, helping to further warm the Earth,” Claire Parkinson, climate scientist at NASA, told AFP in September.

Thus, with less ice reflecting sunlight, oceans are heated directly.

Over the last 40 years the Arctic has also become more of a strategic interest to world powers.

Less ice in certain areas have opened up new maritime routes, which are destined to play a larger role in international trade, meaning a larger financial stake for Arctic state actors.

The region is also estimated to house 13 percent of the world’s oil reserves and 30 percent of undiscovered natural gas deposits.

Germany’s Potsdam Institute for Climate Impact Research (PIK) said Tuesday that under current levels of atmospheric CO2 — roughly 400 parts per million — the melting of Arctic sea ice would raise global temperatures by 0.2C.

That’s on top of the 1.5C of warming our current emissions levels have rendered all but inevitable, and the safer cap on global warming aimed for in the Paris climate accord.

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Hubble telescope gives closer look at rare asteroid worth $10,000,000,000,000,000,000 – CBS News

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There’s an extremely rare metallic asteroid lurking between Mars and Jupiter, and it’s worth more than the entire global economy. Now, the Hubble Space Telescope has given us a closer look at the object, which is worth an estimated $10,000 quadrillion. 

A new study this week in The Planetary Science Journal delves deeper than ever before into the mysteries of the asteroid 16 Psyche, one of the most massive objects in the solar system’s main asteroid belt orbiting between Mars and Jupiter, about 230 million miles from Earth. It measures about 140 miles in diameter — roughly the size of Massachusetts. 

Most asteroids are made of rocks or ice. But 16 Psyche is dense and mostly made of metal, possibly the leftover core of a planet that never succeeded in forming — a so-called “protoplanet,” which had its core exposed following hit-and-run collisions that removed the body of its mantle. 

The study marks the first ultraviolet (UV) observations of the celestial object. New data reveals the asteroid may be made entirely of iron and nickel — found in the dense cores of planets.  

“We’ve seen meteorites that are mostly metal, but Psyche could be unique in that it might be an asteroid that is totally made of iron and nickel,” lead author Dr. Tracy Becker said in a statement. “Earth has a metal core, a mantle and crust. It’s possible that as a Psyche protoplanet was forming, it was struck by another object in our solar system and lost its mantle and crust.”

The massive asteroid 16 Psyche is the subject of a new study by Southwest Research Institute scientist Tracy Becker, who observed the object at ultraviolet wavelengths.

Maxar/ASU/P. Rubin/NASA/JPL-Caltech


Scientists studied the asteroid at two points in its rotation in order to view the details of both sides completely at UV wavelengths. They found the surface could be mostly iron, but warned that even a small amount of iron would dominate UV observations. 

“We were able to identify for the first time on any asteroid what we think are iron oxide ultraviolet absorption bands,” Becker said. “This is an indication that oxidation is happening on the asteroid, which could be a result of the solar wind hitting the surface.”

Solar wind is the flow of charged particles from the sun’s upper atmosphere, called the corona, throughout the solar system. It’s responsible for the tails of comets as they soar across the sky, the formations of auroras and the possible “space weathering” of Psyche. 

Researchers also said the asteroid became more and more reflective at deeper UV wavelengths, which could give some indication of its age. 

“This is something that we need to study further,” Becker said. “This could be indicative of it being exposed in space for so long. This type of UV brightening is often attributed to space weathering.”

Metal asteroids are rare, so Psyche provides researchers with an exciting opportunity to study the inside of a planet. In 2022, NASA plans to launch the unmanned spacecraft Psyche on a SpaceX Falcon Heavy rocket to study the asteroid in an attempt to understand its history and that of similar objects — the first time a mission will visit a body made entirely of metal. 

The orbiter is set to arrive at the asteroid in January 2026 to study it for nearly two years. The mission’s leader at Arizona State University estimates that the iron alone on today’s market would be worth $10,000 quadrillion — that’s a one followed by 19 zeroes. 

“What makes Psyche and the other asteroids so interesting is that they’re considered to be the building blocks of the solar system,” Becker said. “To understand what really makes up a planet and to potentially see the inside of a planet is fascinating. Once we get to Psyche, we’re really going to understand if that’s the case, even if it doesn’t turn out as we expect. Any time there’s a surprise, it’s always exciting.”

Researchers told CBS News in 2017, when the mission was confirmed, that they don’t plan to take advantage of the value of the asteroid’s composition. 

“We’re going to learn about planetary formation, but we are not going to be trying to bring any of this material back and using it for industry,” Carol Polanskey, project scientist for the Psyche mission, said at the time. 

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