Image copyright Science Photo Library

Researchers have found evidence of an existing body of liquid water on Mars.

What they believe to be a lake sits under the planet's south polar ice cap, and is about 20km (12 miles) across.

Previous research found possible signs of intermittent liquid water flowing on the martian surface, but this is the first sign of a persistent body of water on the planet in the present day.

Lake beds like those explored by Nasa's Curiosity rover show water was present on the surface of Mars in the past.

However, the planet's climate has since cooled due to its thin atmosphere, leaving most of its water locked up in ice.

The result is exciting because scientists have long searched for signs of present-day liquid water on Mars, but these have come up empty or yielded ambiguous findings.

It will also interest those studying the possibilities for life beyond Earth - though it does not yet raise the stakes in the search for biology.

Read more about Mars exploration

Image copyright TAS

The discovery was made using Marsis, a radar instrument on board the European Space Agency's (Esa) Mars Express orbiter.

Image copyright NASA/JPL/Malin Space Science Systems Image caption The proposed lake sits beneath ice near the south pole of Mars

"It's probably not a very large lake," said Prof Roberto Orosei from the Italian National Institute for Astrophysics, who led the study.

Marsis wasn't able to determine how thick the layer of water might be, but the research team estimate that it is a minimum of one metre.

"This really qualifies this as a body of water. A lake, not some kind of meltwater filling some space between rock and ice, as happens in certain glaciers on Earth," Prof Orosei added.

Image copyright ESA/INAF Image caption Artists' impression: Mars Express probing the planet's surface. Marsis radar results above.

How was it found?

Radar instruments like Marsis examine the surface and immediate subsurface of the planet by sending out a signal and examining what is bounced back.

The continuous white line at the top of the radar results above marks the beginning of the South Polar Layered Deposit; a filo pastry-like accumulation of water ice and dust.

Beneath this, researchers spotted something unusual 1.5km under the ice.

"In light blue you can see where the reflections from the bottom are stronger than surface reflection. This is something that is to us the tell tale sign of the presence of water," says Prof Orosei.

Image copyright USGS Astrogeology Science Center, Arizona State Un Image caption Artists' impression: Marsis data shows an area of high reflectivity (dark blue) which is thought to be water

What does this mean for life?

Nothing definitive. Yet.

Dr Manish Patel from the Open University explained: "We have long since known that the surface of Mars is inhospitable to life as we know it, so the search for life on Mars is now in the subsurface.

"This is where we get sufficient protection from harmful radiation, and the pressure and temperature rise to more favourable levels. Most importantly, this allows liquid water, essential for life."

This principle of following the water is key to astrobiology - the study of potential life beyond Earth.

So while the findings suggest water is present, they don't confirm anything further.

"We are not closer to actually detecting life," Dr Patel told BBC News, "but what this finding does is give us the location of where to look on Mars. It is like a treasure map - except in this case, there will be lots of 'X's marking the spots."

Image copyright Science Photo Library Image caption Astrobiologists study extreme environments like salt lakes on Earth to understand how life might survive on Mars

The water's temperature and chemistry could also pose a problem for any potential martian organisms.

In order to remain liquid in such cold conditions (the research team estimate between -10 and -30 Celsius where it meets the ice above), the water likely has a great many salts dissolved in it.

"It's plausible that the water may be an extremely cold, concentrated brine, which would be pretty challenging for life," explained Dr Claire Cousins, an astrobiologist from the University of St Andrews, UK.

What next?

While its existence provides a tantalising prospect for those interested in the possibility of past or present life on Mars, the lake's characteristics must first be verified by further research.

"What needs to be done now," explained Dr Matt Balme from the Open University, "is for the measurements to be repeated elsewhere to look for similar signals, and, if possible, for all other explanation to be examined and - hopefully - ruled out.

"Maybe this could even be the trigger for an ambitious new Mars mission to drill into this buried water-pocket - like has been done for sub-glacial lakes in Antarctica on Earth," he added.

Image copyright Science Photo Library Image caption The area has been compared to Lake Vostok, which lies 4km beneath the Antarctic ice

Scientists have previously claimed to find bacterial life in the buried depths of Antarctica's Lake Vostok, but drilling on Mars would make for an ambitious project indeed.

"Getting there and acquiring the final evidence that this is indeed a lake will not be an easy task," said Prof Orosei.

"It will require flying a robot there which is capable of drilling through 1.5km of ice. This will certainly require some technological developments that at the moment are not available."

The findings were reported in Science.

Follow Mary on Twitter.</s>The subglacial lake on Mars was found by the European Space Agency's Mars Express and measures 12.4 miles in length

Scientists have just published a new study which has confirmed that the first known liquid water has been found on Mars, with a lake lurking 0.93 miles beneath the ice cap at the Red Planet’s south pole and extending 12.4 miles in length

As Science Magazine report, the lake on Mars is believed to be very similar to pools of water that can also be found beneath the ice of Antarctica and Greenland. And, just like the subglacial lakes here on Earth, it is certainly feasible that life may also be found in the one just discovered on the Red Planet.

As Imperial College London geophysicist Martin Siegert enthusiastically explained, “It will open up a very interesting area of science on Mars.”

It is believed that billions of years ago there may have been a plentiful supply of water on Mars, back when its atmosphere was much different than it is today, and old lake beds, river channels and floodplains are still fully visible on the planet’s surface.

The device that can be credited for the new discovery of the liquid lake on the Red Planet is called the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument (MARSIS), and was held on the orbiter known as the Mars Express, which was deployed by the European Space Agency.

Robert Orosei, who led the new research which has shown that liquid water still exists on Mars in the form of a subglacial lake, noted that studielectric permittivity allowed scientists to locate this body of water.

According to Physics World, it is not known at this time whether the liquid water lake that was detected on the Red Planet is a shallow layer lake or whether it is a deep lake. However, the Norwegian Polar Institute’s Anja Diez has commented that there are certainly similarities between the lake on Mars and our subglacial lakes here on Earth, and explained that scientists will be keeping an open mind on the subject until they have obtained further data.

Excitingly, future missions to Mars will be equipped with high-frequency radar, which means that we will be able to get a much better picture of the ground ice on the Red Planet and everything that lurks beneath it.

The new study on the liquid water lake that was found on the south pole of Mars has been published in the journal Science.</s>A massive underground lake has been detected for the first time on Mars, raising the possibility that more water -- and maybe even life -- exists there, international astronomers said Wednesday.

Located under a layer of Martian ice, the lake is about 12 miles (20 kilometers) wide, said the report led by Italian researchers in the US journal Science.

It is the largest body of liquid water ever found on the Red Planet.

"This is a stunning result that suggests water on Mars is not a temporary trickle like previous discoveries but a persistent body of water that provides the conditions for life for extended periods of time," said Alan Duffy, an associate professor at Swinburne University in Australia, who was not involved in the study.

Mars is now cold, barren and dry but used to be warm and wet. It was home to plenty of liquid water and lakes at least 3.6 billion years ago.

Scientists are eager to find signs of contemporary water, because such discoveries are key to unlocking the mystery of whether life ever formed on Mars in its ancient past, or if it might persist today.

Being able to access water sources could also help humans survive on a future crewed mission to Earth's neighboring planet.

This particular lake, however, would not be drinkable, and lies almost a mile deep (1.5 kilometers) beneath the icy surface in a harsh and frigid environment.

Whether microbial forms of life lie within is a matter of debate.

Some experts are skeptical of the possibility since the lake is so cold and briny, and mixed with a heavy dose of dissolved Martian salts and minerals.

The temperature is likely below the freezing point of pure water, but can remain liquid due to the presence of magnesium, calcium, and sodium.

"This is a discovery of extraordinary significance, and is bound to heighten speculation about the presence of living organisms on the Red Planet," said Fred Watson, of the Australian Astronomical Observatory.

"Caution needs to be exercised, however, as the concentration of salts needed to keep the water liquid could be fatal for any microbial life similar to Earth's," added Watson, who was not involved in the research.

Radar detection



The discovery was made using radar instruments on board the European Space Agency's Mars Express orbiter, which launched in 2003.

The tool is called the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS), and was designed to find subsurface water by sending radar pulses that penetrate the surface and ice caps.

MARSIS "then measures how the radio waves propagate and reflect back to the spacecraft," said the study.

These reflections "provide scientists with information about what lies beneath the surface."

Lead author Roberto Orosei of the Istituto Nazionale di Astrofisica in Bologna, Italy surveyed a region called Planum Australe, located in the southern ice cap of Mars, from May 2012 until December 2015.

A total of 29 sets of radar samplings showed a "very sharp change in its associated radar signal," allowing scientists to map the outlines of the lake.

"The radar profile of this area is similar to that of lakes of liquid water found beneath the Antarctic and Greenland ice sheets on Earth, suggesting that there is a subglacial lake at this location on Mars," said the report.

"This is the first body of water it has detected, so it is very exciting," David Stillman, a senior research scientist in the Department of Space Studies at Southwest Research Institute in Texas, told AFP in an email.

However, Stillman, who was not involved in the research, said another spacecraft, or other instruments, need to be able to confirm the discovery.

He noted that a higher-frequency radar instrument made by the Italian space agency, SHARAD, on board the Mars Reconnaissance Orbiter launched in 2005, has been unable to detect subsurface water.

"It is strange that SHARAD cannot confirm this discovery. In fact, SHARAD cannot penetrate through the ice here and no one understands why it can't," Stillman said.

"This suggests that something strange is going on here. Thus, I'm skeptical about this discovery."

But researchers are excited about the potential for future finds, because if liquid water could be found at Mars' south pole, it might be elsewhere too.

"There's nothing special about this location other than the MARSIS radar on the Mars Express spacecraft is most sensitive to that region meaning there are likely similar water deposits below the ground all across Mars," said Duffy.</s>
• Scientists from the National Institute for Astrophysics in Bologna may have found a lake of liquid water on Mars.
• Satellite data suggests the water might lie underneath the surface of a polar ice cap.
• The researchers used radar to probe the ice cap, and their new study suggests the potential lake could be 20 kilometers long.

We’ve heard it before – there may be a major source of water on Mars, in ice sheets that lie just under the red planet’s. But according to a new study published in the journal Science, liquid water may exist there, too.

Researchers from the National Institute for Astrophysics in Bologna in Italy used a radar tool on the European Space Agency’s Mars Express satellite to probe the planet’s ice caps. They believe three years’ worth of data indicates there could be a lake of liquid water under the caps that stretches 20 kilometers across.

The team, led by Roberto Orosei, said this may be the first time scientists have found liquid water that can remain in a liquid state for a prolonged period of time, rather than freezing. Elsewhere on the red planet, it is too cold for water to remain a liquid – Mars’ average temperature is -81 degrees Fahrenheit (-62 degrees Celsius).

“If these researchers are right, this is the first time we’ve found evidence of a large water body on Mars,” Cassie Stuurman, a geophysicist at the University of Texas who found signs of an enormous Martian ice deposit in 2016, told the AP.

In their paper, the researchers suggested that the lake could lie about 1.5 kilometers below the ice cap’s surface. But they are not yet certain whether there is really a lake there or how deep it could be. Until a human expedition or more sophisticated Rovers can investigate the polar region further, we won’t know for sure. But for now, liquid water seems to be the most likely explanation for what researchers observed.

“I really have no other explanation,” Orosei told the AP.

Radar detection has proved unreliable for gathering information about Mars in the past. But after reprogramming the radar tool on the Mars Express satellite – called the Mars Advanced Radar for Subsurface and Ionosphere Sounding, or MARSIS – radar pulses were able to penetrate the surface of the ice caps.

The tool measured how radio waves traveled and behaved when traveling through Mars’ ice caps, then the satellite beamed that information to Earth. This gave the team an idea of the composition under the ice caps.

Time was also not on the researchers’ side, however. They had to wait for the satellite to be in the right place to observe the caps at night time, a position that has only occurred 30 times in three years.

Liquid water would have major implications for life on Mars and future human settlements

Orosei told New Scientist that a combination of calcium, magnesium, and sodium salts on Mars can lower water’s freezing point, which might explain the possibility of a liquid lake.

If it exists, there’s also hope that the water could potentially host life.

“It is not a place where life would be expected to have an easy time, but it is possible based upon terrestrial analogues,” Orosei told New Scientist. The analogues he’s referring to are places on Earth that researchers have used to mimic Mars environments to test conditions in which microbes could survive.

Finding a source of liquid water on Mars would also be exciting for the prospect that the red planet could one day host a human settlement. Both Elon Musk and NASA have released plans to send humans to Mars, maybe as soon as the 2030s.

But there are huge barriers to any colonization efforts, such as growing enough food and recycling waste. Pre-delivered supplies and habitats could sustain human life on the barren surface for a year or two, some experts say, but long term colonization is a different matter. Researchers have even highlighted concerns about how reproduction would work on Mars, should a self-sustaining settlement ever arise there, since life in space has dramatic effects on people’s health.

Despite all these challenges, it’s exciting that there could be an underground reservoir of water on Mars. Perhaps it could be tapped as a resource, or maybe it harbors undiscovered clues about alien life.

Plus, as Orosei said in a statement, this discovery may be a clue that Mars has other hidden bodies of water that are still waiting to be found.

“This is just one small study area; it is an exciting prospect to think there could be more of these underground pockets of water elsewhere, yet to be discovered,” he said.</s>Mars may have been a watery and temperate place in the distant past, but it’s been a giant dustball for many eons. That doesn’t mean there aren’t interesting things on the planet and even the potential for life. Liquid water may be largely absent on the surface, but a stunning new analysis from the European Space Agency (ESA) says there’s plenty of it in a vast underground lake near the planet’s south pole.

This analysis comes from data collected by the venerable Mars Express orbiter, which has studied the red planet for nearly 15 years. This spacecraft carries an instrument called the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument (MARSIS). It was the first-ever radar sounder brought to another planet, but the team was unable to determine if it detected water on Mars until now.

Scientists working on the project have developed new techniques to generate higher-resolution images of what lurks beneath the surface of Mars. After processing and reprocessing data from 2012 to 2015, the researchers believe they’ve detected a large subsurface lake. The unnamed body of water is near the south pole of the planet. This isn’t as strange as you might think; after all, Antarctica has hundreds of subsurface lakes like Lake Vostok.

The radar data from Mars Express shows water packed between layers of ice and dust spanning about 20 kilometers (12.4 miles) at a depth of 1.5 kilometers (0.9 miles). If this body of water is anything like Earth’s Antarctic lakes, it is kept liquid by two processes. First, the water is probably very high in salt content. Salt based on magnesium, calcium, or sodium can interfere with the bonding of water molecules to form a brine. This lowers the freezing temperature dramatically. Brine lakes on Earth can remain liquid at temperatures as low as 8.6 degrees Fahrenheit (-13 degrees Celsius). In addition, pressure from the layers of ice and dust above the lake can also lower the freezing point.

The truly remarkable thing here is the Mars Express data only covered a swath of the planet about 200 kilometers (124 miles) across. There could be similar deposits in other places around the planet just waiting to be found. It’s not even outlandish to think there could be living organisms in these bodies of water. On Earth, we have found living microorganisms in Antarctic lakes. Future Mars missions will include more powerful radar systems that could reveal these hidden worlds in greater detail.</s>A huge 20km-wide lake of liquid water lies beneath the southern ice cap of Mars, scientists have learned. (AAP Video) NO ARCHIVING AAP VIDEO BEYOND 48 HOUR NEWS USAGE

A MASSIVE underground lake has been detected for the first time on Mars, raising hopes that more water — and maybe even life — exists there, international astronomers said Wednesday.

Located under a layer of Martian ice, the lake is about 20 kilometres wide, said the report in the US journal Science.

It is the largest body of liquid water ever found on the Red Planet.

“Water is there. We have no more doubt,” co-author Enrico Flamini, the Italian space agency’s Mars Express mission manager, told a press conference.

Mars is now cold, barren and dry but it used to be warm and wet. It was home to plenty of liquid water and lakes at least 3.6 billion years ago.

Scientists are eager to find signs of contemporary water, because such discoveries are key to unlocking the mystery of whether life ever formed on Mars in its ancient past, and whether it might persist today.

“This is a stunning result that suggests water on Mars is not a temporary trickle like previous discoveries but a persistent body of water that provides the conditions for life for extended periods of time,” said Alan Duffy, an associate professor at Swinburne University in Australia, who was not involved in the study.

Being able to access water sources could also help humans survive on a future crewed mission to Earth’s neighbouring planet, with NASA aiming to send explorers in the 2030s.

This particular lake, however, would be neither swimmable nor drinkable, and it lies around 1.6 kilometres beneath the icy surface in a harsh and frigid environment.

Whether microbial forms of life could lie within is a matter of debate. Some experts are sceptical of the possibility since the lake is so cold and briny, mixed with a heavy dose of dissolved Martian salts and minerals.

The temperature is likely below the freezing point of pure water, but the lake can remain liquid due to the presence of magnesium, calcium and sodium.

“This is a discovery of extraordinary significance, and is bound to heighten speculation about the presence of living organisms on the Red Planet,” said Fred Watson of the Australian Astronomical Observatory.

“Caution needs to be exercised, however, as the concentration of salts needed to keep the water liquid could be fatal for any microbial life similar to Earth’s,” added Watson, who was not involved in the research.

The discovery was made using a radar instrument on board the European Space Agency’s Mars Express orbiter, which launched in 2003.

The tool is called the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS), and was designed to find subsurface water by sending radar pulses that penetrate the surface and ice caps.

MARSIS “then measures how the radio waves propagate and reflect back to the spacecraft,” said the study.

These reflections “provide scientists with information about what lies beneath the surface.”

A team of researchers led by Roberto Orosei of the National Institute for Astrophysics in Bologna, Italy, surveyed a region called Planum Australe, located in the southern ice cap of Mars, from May 2012 until December 2015.

A total of 29 sets of radar samplings showed a “very sharp change in its associated radar signal,” allowing scientists to map the outlines of the lake.

“The radar profile of this area is similar to that of lakes of liquid water found beneath the Antarctic and Greenland ice sheets on Earth, suggesting that there is a subglacial lake at this location on Mars,” said the report.

Researchers said they are not sure how far down it goes, but that it may be around three feet</s>TAMPA-A massive underground lake has been detected for the first time on Mars, raising the possibility that more water - and maybe even life - exists there, international astronomers said Wednesday.

Located under a layer of Martian ice, the lake is about 12 miles (20 kilometers) wide, said the report led by Italian researchers in the US journal Science.

It is the largest body of liquid water ever found on the Red Planet. "Water is there. We have no more doubt," co-author Enrico Flamini, the Italian space agency's Mars Express mission manager, told a press conference.

Mars is now cold, barren and dry but used to be warm and wet. It was home to plenty of liquid water and lakes at least 3.6 billion years ago.

Scientists are eager to find signs of contemporary water, because such discoveries are key to unlocking the mystery of whether life ever formed on Mars in its ancient past, or if it might persist today.

"This is a stunning result that suggests water on Mars is not a temporary trickle like previous discoveries but a persistent body of water that provides the conditions for life for extended periods of time," said Alan Duffy, an associate professor at Swinburne University in Australia, who was not involved in the study.

Being able to access water sources could also help humans survive on a future crewed mission to Earth's neighboring planet.

This particular lake, however, would be neither swimmable nor drinkable, and lies almost a mile deep (1.5 kilometers) beneath the icy surface in a harsh and frigid environment.

Whether microbial forms of life could lie within is a matter of debate. Some experts are skeptical of the possibility since the lake is so cold and briny, and mixed with a heavy dose of dissolved Martian salts and minerals.

The temperature is likely below the freezing point of pure water, but can remain liquid due to the presence of magnesium, calcium, and sodium.

"This is a discovery of extraordinary significance, and is bound to heighten speculation about the presence of living organisms on the Red Planet," said Fred Watson of the Australian Astronomical Observatory.

"Caution needs to be exercised, however, as the concentration of salts needed to keep the water liquid could be fatal for any microbial life similar to Earth's," added Watson, who was not involved in the research.

The discovery was made using a radar instrument on board the European Space Agency's Mars Express orbiter, which launched in 2003.

The tool is called the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS), and was designed to find subsurface water by sending radar pulses that penetrate the surface and ice caps.

MARSIS "then measures how the radio waves propagate and reflect back to the spacecraft," said the study.

These reflections "provide scientists with information about what lies beneath the surface."

A team of researchers led by Roberto Orosei of the Istituto Nazionale di Astrofisica in Bologna, Italy, surveyed a region called Planum Australe, located in the southern ice cap of Mars, from May 2012 until December 2015.

A total of 29 sets of radar samplings showed a "very sharp change in its associated radar signal," allowing scientists to map the outlines of the lake.

"The radar profile of this area is similar to that of lakes of liquid water found beneath the Antarctic and Greenland ice sheets on Earth, suggesting that there is a subglacial lake at this location on Mars," said the report.

Researchers said they are not sure how far down it goes, but may be around three feet (one meter) deep.

"This is the first body of water it has detected, so it is very exciting," David Stillman, a senior research scientist in the Department of Space Studies at Southwest Research Institute in Texas, told AFP in an email.

However, Stillman, who was not involved in the research, said another spacecraft, or other instruments, need to be able to confirm the discovery.

He noted that a higher-frequency radar instrument made by the Italian space agency, SHARAD, on board the Mars Reconnaissance Orbiter launched in 2005, has been unable to detect subsurface water.

"It is strange that SHARAD cannot confirm this discovery. In fact, SHARAD cannot penetrate through the ice here and no one understands why it can't," Stillman said.

"This suggests that something strange is going on here. Thus, I'm skeptical about this discovery."

But researchers are excited about the potential for future finds, because if liquid water could be found at Mars' south pole, it might be elsewhere too.

"There's nothing special about this location other than the MARSIS radar on the Mars Express spacecraft is most sensitive to that region meaning there are likely similar water deposits below the ground all across Mars," said Duffy.

Red planet and ‘blood moon’ pair up to dazzle skygazers

PARIS - The longest “blood moon” eclipse this century will coincide with Mars’ closest approach in 15 years to offer skygazers a thrilling astronomical double bill on Friday, astronomers say. For about half the world, the moon will be partly or fully in Earth’s shadow from 1714 to 2328 GMT - six hours and 14 minutes in all. The period of complete eclipse - known as “totality”, when the moon appears darkest - will last from 1930 to 2113 GMT. “Totality will last for 103 minutes, making it the longest eclipse of the 21st century!” said the Royal Astronomical Society in London. At the same time, Mars will hover near the moon in the night sky, easily visible with the naked eye. Our neighbouring planet will appear unusually large and bright, a mere 57.7 million kilometres (35.9 million miles) from Earth on its elliptical orbit around the sun. “We have a rare and interesting conjunction of phenomena,” Pascal Descamps, an astronomer with the Paris Observatory, told AFP. “We should have a coppery red tint on the moon with Mars the ‘Red Planet’ just next to it, very bright and with a slight orange hue itself.”

Amateur astronomers in the southern hemisphere will be best-placed to enjoy the spectacle, especially those in southern Africa, Australia, India and Madagascar, though it will also be partly visible in Europe and South America.

A total lunar eclipse happens when Earth takes position in a straight line between the moon and sun, blotting out the direct sunlight that normally makes our satellite glow whitish-yellow.

The moon travels to a similar position every month, but the tilt of its orbit means it normally passes above or below the Earth’s shadow - so most months we have a full moon without an eclipse.

When the three celestial bodies are perfectly lined up, however, the Earth’s atmosphere scatters blue light from the sun while refracting or bending red light onto the moon, usually giving it a rosy blush.

This is what gives the phenomenon the name “blood moon”, though Mark Bailey of the Armagh Observatory in Northern Ireland said the colour can vary greatly. It depends partly on “how cloudy or transparent those parts of the Earth’s atmosphere are which enable sunlight to reach the moon”, he told AFP. “During a very dark eclipse the moon may be almost invisible.

“Less dark eclipses may show the moon as dark grey or brown... as rust-coloured, brick-red, or, if very bright, copper-red or orange.”

The long duration of this eclipse is partly due to the fact that the moon will make a near-central passage through Earth’s umbra - the darkest, most central part of the shadow. Our constant companion will also be at the farthest point on its orbit from Earth, making its movement across the sky slower from our perspective, thus spending longer in the dark.

NASA, meanwhile, has called out social media hoaxers claiming that Mars will appear as big as the moon during the eclipse. “If that were true, we’d be in big trouble given the gravitational pulls on Earth, Mars, and our moon!” the NASA website states.

Mars will more likely appear as a very bright star, and viewers will need no protective eye gear.

“All you have to do is dress warmly and go outside!” the Royal Astronomical Society advises.

“If you want a close-up view of the moon as it turns red, a pair of binoculars is helpful.”

“All eclipses are spectacular,” the society’s Robert Massey added. “In the middle of a lunar eclipse it can look as if a red planet has taken up residence near the Earth - they are both eerie and beautiful and I’ll certainly be looking out for it!”</s>A lake of liquid water has been detected by radar beneath the southern polar ice cap of Mars, according to a new study by Italian researchers from the Italian Space Agency, published Wednesday in the journal Science.

Evidence was gathered by the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument, also known as MARSIS, on the European Space Agency’s Mars Express spacecraft.

Between May 2012 and December 2015, MARSIS was used to survey the Planum Australe region, which is in the southern ice cap of Mars. It sent radar pulses through the surface and polar ice caps and measured how the radio waves reflected back to Mars Express.

Those pulses reflected 29 sets of radar samples that created a map of drastic change in signal almost a mile below the surface. It stretched about 12.5 miles across and looked very similar to lakes that are found beneath Greenland and Antarctic ice sheets on Earth. The radar reflected the feature’s brightness, signaling that it’s water.

“We interpret this feature as a stable body of liquid water on Mars,” the authors wrote in the study.

The study authors ruled out any other causes for this brightness, apart from water-rich sediments.

“This is just one small study area; it is an exciting prospect to think there could be more of these underground pockets of water elsewhere, yet to be discovered,” said Roberto Orosei in a statement. Orosei is the lead study author and principal investigator of the MARSIS experiment.

Previously, there has been some suggestions about water on Mars, like droplets of water condensing on the Phoenix lander or as the possible cause of recurring slope lineae, which are seasonal dark streaks on Martian slopes. But there hasn’t been evidence of stable bodies of water until now, the researchers said. However, the presence of liquid water at the base of Martian polar caps was first hypothesized in a study 31 years ago.

Given its location beneath the polar ice cap, the water is expected to be below the freezing point of water. But salts like magnesium, calcium and sodium already found on Mars could help the water to form a brine, which would lower the melting point to allow the lake to remain liquid.

On Earth, lakes exist below the Antarctic ice sheet even though the mean annual temperature is around negative 76 degrees Fahrenheit. Brine lakes on Earth can remain liquid at 8.6 degrees Fahrenheit, according to the study. In comparison, salty ocean water freezes at 28.4 degrees Fahrenheit, according to the National Oceanic and Atmospheric Administration.

Much like our own ice sheets, the polar ice caps change depending on the climate and act as archives for what has happened in the past. Learning more about these caps can reveal Mars’ climate history.

“The long duration of Mars Express, and the exhausting effort made by the radar team to overcome many analytical challenges, enabled this much-awaited result, demonstrating that the mission and its payload still have a great science potential,” said Dmitri Titov in a statement, Mars Express project scientist. “This thrilling discovery is a highlight for planetary science and will contribute to our understanding of the evolution of Mars, the history of water on our neighbor planet and its habitability.”

But how reliable are these detections?

Outside experts have not been able to confirm these findings with other radar detections, like SHARAD, the Shallow Radar sounder onboard the Mars Reconnaissance Orbiter.

“We don’t see the same reflector with SHARAD, not even when we recently summed together [thousands] of observations to create CATSCAN-like 3-D views of both polar caps,” Nathaniel Putzig, Mars Reconnaissance Orbiter SHARAD deputy team leader and senior scientist at the Planetary Science Institute, said in an email.

“We’re hoping to carry out that same imaging process with the MARSIS data next. I’m excited to see how the 3-D imaging will clarify the view of this detection and whether we will find similar ones elsewhere beneath the polar caps.”</s>A lake of liquid water has been detected by radar beneath the southern polar ice cap of Mars, according to a new study by Italian researchers from the Italian Space Agency, published Wednesday in the journal Science.

Evidence was gathered by the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument, also known as MARSIS, on the European Space Agency’s Mars Express spacecraft.

Between May 2012 and December 2015, MARSIS was used to survey the Planum Australe region, which is in the southern ice cap of Mars. It sent radar pulses through the surface and polar ice caps and measured how the radio waves reflected back to Mars Express.

Those pulses reflected 29 sets of radar samples that created a map of drastic change in signal almost a mile below the surface. It stretched about 12.5 miles across and looked very similar to lakes that are found beneath Greenland and Antarctic ice sheets on Earth. The radar reflected the feature’s brightness, signaling that it’s water.

“We interpret this feature as a stable body of liquid water on Mars,” the authors wrote in the study.

The study authors ruled out any other causes for this brightness.

Previously, there has been some suggestions about water on Mars, like droplets of water condensing on the Phoenix lander or as the possible cause of recurring slope lineae, which are seasonal dark streaks on Martian slopes. But there hasn’t been evidence of stable bodies of water until now, the researchers said. However, the presence of liquid water at the base of Martian polar caps was first hypothesized in a study 31 years ago.

Given its location beneath the polar ice cap, the water is expected to be below the freezing point of water. But salts like magnesium, calcium and sodium already found on Mars could help the water to form a brine, which would lower the melting point to allow the lake to remain liquid.

On Earth, lakes exist below the Antarctic ice sheet even though the mean annual temperature is around negative 76 degrees Fahrenheit. Brine lakes on Earth can remain liquid at 8.6 degrees Fahrenheit, according to the study. In comparison, salty ocean water freezes at 28.4 degrees Fahrenheit, according to the National Oceanic and Atmospheric Administration.

Much like our own ice sheets, the polar ice caps change depending on the climate and act as archives for what has happened in the past. Learning more about these caps can reveal Mars’ climate history.

But how reliable are these detections?

Outside experts have not been able to confirm these findings with other radar detections, like SHARAD, the Shallow Radar sounder onboard the Mars Reconnaissance Orbiter.

“We don’t see the same reflector with SHARAD, not even when we recently summed together [thousands] of observations to create CATSCAN-like 3-D views of both polar caps,” Nathaniel Putzig, Mars Reconnaissance Orbiter SHARAD deputy team leader and senior scientist at the Planetary Science Institute, said in an email.

“We’re hoping to carry out that same imaging process with the MARSIS data next. I’m excited to see how the 3-D imaging will clarify the view of this detection and whether we will find similar ones elsewhere beneath the polar caps.”</s>An Italian team of scientists says it has strong evidence of a subsurface lake of liquid water on Mars. It's a discovery that adds to the speculation that there could once have been life on Mars, and raises the possibility that it might be there still today, since liquid water is an essential ingredient for life.

The evidence comes from an instrument called MARSIS aboard the European Space Agency Mars Express spacecraft in orbit around the Red Planet. MARSIS is a special kind of radar called ground penetrating radar.

"Ground penetrating radars use radio signals that are capable of penetrating into the ground and then get reflections from the material under the surface," says Roberto Orosei, principal investigator on MARSIS and a planetary scientist at the Italian National Institute for Astrophysics.

Such radars are useful when searching for liquid water, "because water is a very strong radar reflector," he says.

From May of 2012 through December of 2015 the Mars Express radar mapped an area near the south pole of Mars.

When Orosei and his colleagues analyzed the data, they saw what looked like a lake of water about 12 miles in diameter and a mile below a surface layer made up of water ice and dust. There are hundreds of this of subglacial lake on Earth, mostly in Antarctica.

But Orosei and his colleagues knew better than to run right out and announce to the world they'd found liquid water on Mars. Remarkable claims that seem too good to be true frequently are.

So instead, they tried to come up with as many other explanations for what they were seeing as possible.

"After years, literally a couple of years of...discussion, debate, and let's say general head scratching, we really felt confident that any other explanation would fail," Orosei says.

Or, he adds, paraphrasing Sherlock Holmes, "Once you exclude everything that is impossible, what remains necessarily has to be the truth."

A report on the discovery of the underground lake appears in the journal, Science.

"I think this is extremely strong evidence that there is liquid water beneath the poles in this south polar layered terrain on Mars, which is extremely exciting," says Ellen Stofan, the John and Adrienne Mars Director at the Smithsonian's National Air and Space Museum. Before joining the museum, Stofan was a member of the MARSIS science team.

Stofan says finding liquid water is something scientists are extremely interested in scientifically, "because life here on Earth evolved in liquid water. It stayed in the oceans for over a billion years. And so as we go outward from the Earth, looking for evidence of life beyond Earth, we're always looking for liquid water."

Stofan says the water in the Martian underground lake is probably salty, otherwise if would freeze solid, even deep in the ground. And the salts are mostly likely made up of something called perchlorates, "which are very toxic to life here on Earth. But on Mars, who knows?"

It's not clear where the water the Italian team found is coming from, and it's not certain there are any other underground lakes to be found.

But you can bet the new results will encourage others to look.
Scientists at INAF announce the discovery of a liquid water lake beneath a polar ice cap on Mars. The discovery was made using MARSIS, a radar instrument on board the European Space Agency's Mars Express orbiter.