Curiosity Finds A Region of Ancient Dried Mud. It Could Have Been an Oasis Billions of Year Ago

What happened to Mars? If Mars and Earth were once similar, as scientists think, what happened to all the water? Did there used to be enough to support life?

Thanks to the Mars Science Laboratory (MSL) Curiosity, we’re getting a better picture of ancient Mars and what it went through billions of years ago. A new study published in Nature Geoscience says that Mars likely underwent alternating periods of wet and dry, before becoming the frigid, dry desert it is now. Or at least, Gale Crater did.

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New layers of water ice have been found beneath Mars’ North Pole

One of the most profound similarities between Earth and Mars, one which makes it a popular target for research and exploration, is the presence of water ice on its surface (mainly in the form of its polar ice caps). But perhaps even more interesting is the presence of glaciers beneath the surface, which is something scientists have speculated about long before their presence was confirmed.

These caches of subsurface water could tell us a great deal about Martian history, and could even be an invaluable resource if humans ever choose to make Mars their home someday. According to a recent study by a pair of scientists from the Universities of Texas at Austin and Arizona, there are also layers of ice beneath the northern polar ice cap that could be the largest reservoir of water on the planet.

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Rivers on Mars Flowed for More Than a Billion Years

A photo of a preserved river channel on Mars. The color is overlaid to show elevation, with blue being low and yellow being high elevation. Image Credit: NASA/JPL/Univ. Arizona/UChicago

The ancient climate of Mars is a mystery to scientists. Even with all we’ve learned about Mars, it’s still difficult to explain how lakes and rivers existed. A new study shows that Martian rivers were swollen with runoff and that they flowed far later into the planet’s history than previously thought.

The question is, how did the Martian climate create these conditions?

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Planetary Scientists Continue to Puzzle Over the Mysterious Slope Streaks on Mars. Liquid? Sand? What’s Causing Them?

Since they were first observed in the 1970s by the Viking missions, the slope streaks that periodically appear along slopes on Mars have continued to intrigue scientists. After years of study, scientists still aren’t sure exactly what causes them. While some believe that “wet” mechanisms are the culprit, others think they are the result of “dry” mechanisms.

Luckily, improvements in high-resolution sensors and imaging capabilities – as well as improved understanding of Mars’ seasonal cycles – is bringing us closer to an answer. Using a terrestrial analog from Bolivia, a research team from Sweden recently conducted a study that explored the mechanisms for streak formation and suggest that wet mechanisms appear to account for more, which could have serious implications for future missions to Mars.

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Lakes on Mars Filled up so Quickly They Would Overflow Catastrophically Carving Canyons Within Weeks

Roughly 4.2 billion years ago, Mars was a much different place than it is today. It’s atmosphere was thicker and warmer and its surface much wetter. Unfortunately, the planet’s atmosphere was stripped away by solar wind over the next 500 million years, causing the surface to become so cold and dry that it makes Antarctica look balmy by comparison!

As a result, most of Mars’ water is currently locked away in its polar ice caps. But billions of years ago, water still flowed freely across the surface, forming ancient rivers and lakes. In fact, new research led by The University of Texas at Austin indicates that sometimes these lakes would fill so fast that they would overflow, causing massive floods that had a drastic impact on the surface.

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Planetary Scientists Have Chosen a Few Landing Sites for the Mars 2020 Rover

In the summer of 2020, NASA’s Mars 2020 rover will launch from Cape Canaveral and commence its journey towards the Red Planet. Once it arrives on the Martian surface, the rover will begin building on the foundation established by the Opportunity and Curiosity rovers. This will include collecting samples of Martian soil to learn more about the planet’s past and determine if life ever existed there (and still does).

Up until now, though, NASA has been uncertain as to where the rover will be landing. For the past few years, the choice has been narrowed down to three approved sites, with a fourth added earlier this year for good measure. And after three days of intense debate at the recent fourth Landing Site Workshop, scientists from NASA’s Mars Exploration Program held a non-binding vote that has brought them closer to selecting a landing site.

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There Might be Enough Oxygen Below the Surface of Mars to Support Life

The possibility that life could exist on Mars has captured the imagination of researchers, scientists and writers for over a century. Ever since Giovanni Schiaparelli (and later, Percival Lowell) spotted what they believed were “Martian Canals” in the 19th century, humans have dreamed of one day sending emissaries to the Red Planet in the hopes of finding a civilization and meeting the native Martians.

While the Mariner and Viking programs of the 1960s and 70s shattered the notion of a Martian civilization, multiple lines of evidence have since emerged that indicate how life could have once existed on Mars. Thanks to a new study, which indicates that Mars may have enough oxygen gas locked away beneath its surface to support aerobic organisms, the theory that life could still exist there has been given another boost.

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Was This Huge River Delta on Mars the Place Where its Oceans Finally Disappeared?

For some time, scientists have known that Mars was once a much warmer and wetter environment than it is today. However, between 4.2 and 3.7 billion years ago, its atmosphere was slowly stripped away, which turned the surface into the cold and desiccated place we know today. Even after multiple missions have confirmed the presence of ancient lake beds and rivers, there are still unanswered questions about how much water Mars once had.

One of the most important unanswered questions is whether or not large seas or an ocean ever existed in the northern lowlands. According to a new study by an international team of scientists, the Hypanis Valles ancient river system is actually the remains of a river delta. The presence of this geological feature is an indication that this river system once emptied into an ancient Martian sea in Mars’ northern hemisphere.

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Underground Liquid Water Found on Mars!

According to evidence gathered by multiple robotic orbiters, rovers, and landers over the course of several decades, scientists understand that Mars was once a warmer, watery place. But between 4.2 and 3.7 billion years ago, this began to change. As Mars magnetic field disappeared, the atmosphere slowly began to be stripped away by solar wind, leaving the surface the cold and dry and making it impossible for water to exist in liquid form.

While much of the planet’s water is now concentrated in the polar ice caps, scientists have speculated some of Mars’ past water could still be located underground. Thanks to a new study by a team of Italian scientists, it has now been confirmed that liquid water still exists beneath Mars’ southern polar region. This discovery has put an end to a fifteen-year mystery and bolstered the potential for future missions to Mars.

The study, titled “Radar evidence of subglacial liquid water on Mars“, recently appeared in the journal Science. The study was led by Roberto Orosei of the National Institute of Astrophysics (INAF) in Italy, and included members from the Italian Space Agency (ASI), the ESA Center for Earth Observation (ESRIN), and multiple observatories, research institutions and universities.

Radar detection of water under the south pole of Mars. Credit: ESA/NASA/JPL/ASI/Univ. Rome

So far, robotic missions have revealed considerable evidence of past water on Mars. These include dried-out river valleys and gigantic outflow channels discovered by orbiters, and evidence of mineral-rich soils that can only form in the presence of liquid water by rovers and landers. Early evidence from the ESA’s Mars Express probe has also showed that water-ice exists at the planet’s poles and is buried in the layers interspersed with dust.

However, scientists have long suspected that liquid water could exist beneath the polar ice caps, much in the same way that liquid water is believed to underlie glaciers here on Earth. In addition, the presence of salts on Mars could further reduce the melting point of subsurface water and keep it in a liquid state, despite the sub-zero temperatures present on both the surface and underground.

For many years, data from the Mars Express’ Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument – which has been used to study the southern polar region – has remained inconclusive. Like all ground-penetrating radar, this instrument relies on radar pulses to map surface topography and determine the properties of the materials that lie beneath the surface.

Luckily, after considerable analysis, the study team was able to develop new techniques that allowed them to collect enough high-resolution data to confirm the presence of liquid water beneath the southern ice cap. As Andrea Cicchetti, the MARSIS operations manager and a co-author on the new paper, indicated:

“We’d seen hints of interesting subsurface features for years but we couldn’t reproduce the result from orbit to orbit, because the sampling rates and resolution of our data was previously too low. We had to come up with a new operating mode to bypass some onboard processing and trigger a higher sampling rate and thus improve the resolution of the footprint of our dataset: now we see things that simply were not possible before.”

Water detection under the south pole of Mars. Credit: Context map: NASA/Viking; THEMIS background: NASA/JPL-Caltech/Arizona State University; MARSIS data: ESA/NASA/JPL/ASI/Univ. Rome; R. Orosei et al 2018

What they found was that the southern polar region is made of many layers of ice and dust down to a depth of about 1.5 km over a 200 km-wide area, and featured an anomalous area measuring 20-km wide. As Roberto Orosei, the principal investigator of the MARSIS experiment and lead author of the paper, explained in a recent ESA press release:

“This subsurface anomaly on Mars has radar properties matching water or 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.”

After analyzing the properties of the reflected radar signals and taking into account the composition of the layered deposits and expected temperature profiles below the surface, the scientists concluded that the 20-km wide feature is an interface between the ice and a stable body of liquid water. For MARSIS to be able to detect such a patch of water, it would need to be at least several tens of centimeters thick.

These findings also raise the possibility of there being life on Mars, both now and in the past. This is based on research that found microbial life in Lake Vostok, which is located some 4 km (2.5 mi) below the ice in Antarctica. If life can thrive in salty, subglacial environments on Earth, then it is possible that they could survive on Mars as well. Determining if this is the case will be the purpose of existing and future missions to Mars.

The MARSIS instrument on the Mars Express is a ground penetrating radar sounder used to look for subsurface water and ice. Credit: ESA

As Dmitri Titov, one of the Mars Express project scientist, explained:

“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. 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 neighbour planet and its habitability.”

The Mars Express launched on June 2nd, 2003, and will celebrate 15 years in orbit of Mars by December 25th this year. In the coming years, it will be joined by the ESA’s ExoMars 2020 mission, NASA’s Mars 2020 Rover, and a number of other scientific experiments. These missions will pave the way for a potential crewed mission, which NASA is planning to mount by the 2030s.

If there is indeed liquid water to be found on Mars, it will go a long way towards facilitating future research and even an ongoing human presence on the surface. And if there is still life on Mars, the careful research of its ecosystems will help address the all-important question of how and when life emerged in the Solar System.

Further Reading: ESA, Science