Scientists have been looking for liquid water on Mars for decades. Now, Italian researchers claim they have found a whole underground lake near the south pole. The next question to answer – is there life in the water?
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Mars has a 20-kilometer (12.4-mile) wide lake some 1.5 kilometers underneath its surface, according to a study published in the US Science magazine on Wednesday and conducted by a team led by Roberto Orosei from the National Institute of Astrophysics in Bologna.
The spectacular find ends decades-long debate on the existence of liquid water on Mars. Liquid water is a key condition for life as it exists on Earth.
Astronomers have long known that Mars used to have rivers and oceans of liquid water billions of years ago, based on, among other things, flowing patterns on the planet's surface. More recent discoveries confirmed the presence of ice in its polar regions and water vapors in the planet's thin atmosphere.
NASA's Phoenix module also registered snow and, possibly, water droplets falling in 2008. There are also hints that small amounts of liquid water could temporary build up in a thin layer below the Mars' surface.
The latest find, however, relies on radar information gathered by the Mars Express mission by the European Space Agency (ESA). The data shows a region of a uniform radar signature close to the south pole of Mars, which the Italian researchers claim to be a hidden lake.
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.
Mars - marked by water
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"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.
Too cold for a swim
Scientists believe the lake consists of liquid water, despite having an estimated temperature of –68 degrees Celsius (-90.4 Fahrenheit). This is possible if the lake has a large content of salt which significantly changes the freezing point.
NASA's rover Perseverance has landed on Mars
Perseverance is NASA's fifth Mars rover and its biggest and heaviest to date. Its mission on the Red Planet has started this Thursday.
Image: NASA/JPL-Caltech
A new rover for the red planet
NASA's Mars 2020 Perseverance rover (shown in artist's illustration) is the most sophisticated rover NASA has ever sent to Mars. Ingenuity, a technology experiment, will be the first aircraft to attempt controlled flight on another planet. Perseverance touched down at Mars' Jezero Crater on February 18, 2021 at about 20:57 UTC with Ingenuity attached to its belly.
Image: NASA/JPL-Caltech
Everything prepared
NASA engineers loaded the Mars rover Perseverance onto an Atlas V rocket at the start of July 2020. The rocket took off on July 30 from Cape Canaveral, Florida. The rover arrived at the orbit around Mars in early February 2021.
Image: NASA
Presentation in a clean room
This is how Perseverance looked when it was presented to the public in 2019. The rover will support NASA's Curiosity rover, the most modern rover until Perseverance came along. The new rover weighs a little over a ton — 100 kg (220 pounds) more than its predecessor. And at 3 meters (10 ft) long, it's also 10 centimeters longer as well.
Image: NASA/JPL-Caltech
More performance
Perseverance can be loaded with more research instruments and sensors than its predecessor. And its gripper arm, with its cameras and tools, is stronger, too. The rover can collect samples from Mars. It's got 23 cameras and many other instruments. One mission is to test whether it's possible to extract oxygen from Martian rock. But, hey, what's that standing next to the rover on the ground?
Image: NASA/JPL-Caltech
A small drone
That's right! Perseverance has a helicopter onboard. That's never happened on a planetary mission before. The helicopter is completely new territory for its developers. It will be the first time they're able to experience and collect data from flight in atmospheric conditions that are different from those on Earth, and in a gravity that is about a third of our own.
Image: NASA/Cory Huston
The robotic giant
Curiosity is the largest and most modern of all Mars rovers currently deployed. It landed on August 6, 2012, and has since traveled more than 21 kilometers (13 miles). It is much more than just a rover. Its official name is "Mars Science Laboratory," and it really is a complete lab on wheels.
Image: picture-alliance/dpa/Nasa/Jpl-Caltech/Msss
What's in it?
For example, it contains a special spectrometer, which can analyze chemical compounds from a distance with the help of a laser; a complete meteorological station that can measure temperature, atmospheric pressure, radiation, humidity and wind speed; and most importantly, a chemistry lab that can run detailed analyses of organic compounds and is always on the hunt for traces of alien life.
Image: NASA/JPL-Caltech/MSSS
Not just scratching the surface
Curiosity has shown that life would theoretically be possible on Mars. But it hasn't discovered any life, yet. The robot's arm is equipped with a full power drill. Here, it's taking a sample in "Yellowknife Bay" inside the Gale Crater.
Image: NASA/JPL-Caltech
Off to the lab!
The Mars dust is processed by a large number of instruments. First, it's filtered and separated into different-sized particles. Then, those get sorted and sent off to different analytical laboratory machines.
Image: picture alliance/AP Photo/NASA
A tiny predecessor
Curiosity's predecessors were much smaller. On July 4, 1997, the small Mars rover Sojourner left its first tire tracks behind in the dust of the red planet. It was the first time a mobile robot had been left to its own devices there, equipped with an X-ray spectrometer to conduct chemical analyses and with optical cameras.
Image: NASA/JPL
Size comparison
Three rover generations. (The tiny one up front is Sojourner.) At 10.6 kilograms (23 pounds), it's not much bigger than a toy car. Its top speed: 1 centimeter per second. Opportunity weighs 185 kilograms — roughly the equivalent of an electric wheelchair. Curiosity is as big as a small car, at 900 kilograms. The big ones travel up to 4 or 5 centimeters per second.
Image: NASA/JPL-Caltech
Almost four months of duty
Sojourner travelled about 100 meters during its lifetime and delivered data and pictures until September 27, 1997. This is one of the last pictures of it, taken nine days before the radio connection broke down. Sojourner probably died because the battery did not survive the cold nights.
Image: NASA/JPL
Paving the way for tomorrow's technology
Without the experience of Sojourner, newer rovers could have hardly been envisaged. In 2004, NASA landed two robots of the same model on Mars: Spirit and Opportunity. Spirit survived for six years, travelling a distance of 7.7 kilometers. The robot climbed mountains, took soil samples and withstood winter and sandstorms. Its sibling, Opportunity, lost contact on February 13, 2019.
Image: picture alliance/dpa
Lots of gadgets
Opportunity passed the marathon distance of 42 kilometers back in 2015, and to this day, it has covered much more ground than Curiosity. It can take ground probes with its arm. It has three different spectrometers and even a 3D camera. It was last operating in "Perseverance Valley," an appropriate workplace for the sturdy robot, before being incapacitated by a sandstorm.
Image: picture-alliance/dpa
The red planet's landscapes
This panorama was taken by Curiosity's mast camera. The most modern of the rovers will stay in service as long as possible — hopefully at least another five years. The Martian landscape looks familiar somehow, not unlike some deserts here on Earth. Should we give in to our wanderlust, then — or would it be better leave Mars to the robots?
Image: Reuters
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The team lead by Orosei now speculates about the presence of life in the lake, comparing to similar locations on Earth, which are found below Antarctic and Greenland. Researchers have found life in an underground lake in the Arctic, dubbed Lake Whillands, but only on microbe-level.
Martian birthday for Curiosity
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Separately, NASA's Curiosity rover found "organic materials" on Mars last month. While the presence of organic molecules does not prove life, it points towards a "habitable environment" on the neighboring planet.
Currently, NASA is working on a mission to send humans to an asteroid near Mars in 2025 and land a human team on the planet sometime in the 2030s.