Out of all the mysterious and fascinating worlds inhabiting the bewitching Wonderland that is our Solar System, the Red Planet Mars has managed to sing the most haunting of all sirens’ songs to humankind. This small, rocky, rust-colored world is our Earth’s close neighbor in space, in addition to the planet that has tantalized the imaginations of those people who seek to answer the deep question of whether or not we are alone in the Cosmos. Nevertheless, despite its allure, Mars has not shown itself to be occupied, and Earth remains the only planet that is actually known to host life. Of course, this does not mean that life isn’t out there somewhere in space–it only means that we haven’t as yet discovered it, and it apparently has not as yet discovered us. In July 2018, a team of astronomers announced that they have found evidence that deep beneath the frigid, frozen ice cap of the Martian south pole lies a hidden lake of liquid water–the first to be found pooling on the Red Planet. Life as we know it depends on the existence of liquid water.
The new discovery is based on data derived from the European Mars Express spacecraft’s radar tool named Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS). The Italian Space Agency (ASI) led the development of the MARSIS radar. NASA contributed about 50 percent of this instrument, with management of the U.S. part led by the bureau’s Jet Propulsion Laborator (JPL) in Pasadena, California.
The research paper, authored by the Italian MARSIS team, explains how a”bright spot” was discovered in radar signals approximately a mile beneath the surface of the ice cap in the Planum Australe region. This powerful radar expression was determined by the study’s authors to be liquid water. This interpretation is important because where liquid water exists, life as we understand it might also exist. The presence of liquid water suggests the possibility–though by no means the guarantee –of the existence of alien life on Mars.
“The bright spot seen in the MARSIS information is an unusual feature and extremely intriguing. It definitely warrants further study. Additional lines of evidence ought to be pursued to check the interpretation,” Dr. Jim Green commented in a July 25, 2018 JPL Press Release.
“We expect to use different tools to study it further in the future,” Dr. Green added.
One of those new tools will land on Mars late in 2018. The tool, NASA’s InSight lander will carry a heat probe that’s designed to burrow down into the Martian surface up to 15 feet. InSight was constructed by the German Aerospace Center (DLR), and it’s scheduled to provide important new data regarding just how much heat manages to escape from the Red Planet and in which the liquid water may possibly pool near its surface.
“Follow the Water” has long been one of the holy grails of NASA’s Mars program. The search for liquid water is currently the inspiration behind NASA’s exploration to the outer regions of the Solar System, where temperate ocean-moon-worlds have the capability to host delicate life forms. Even dwarf planets, such as Ceres, the largest denizen of this Main Asteroid Belt between Mars and Jupiter, may help scientists gain a fresh understanding of how water is stored in rugged”buckets” that carry water throughout our Solar System.
A Hidden Lake
The hidden Martian lake is most likely extremely cold and very salty. The hunt for other buried, hidden layers of water on Mars has intensified, and the hunt is on for other bodies of water on Mars that might be more hospitable to delicate living animals. “It’s a really exciting result: the first indication of a briny aquifer on Mars,” commented Dr. David Stillman in a July 25, 2018 Science Magazine Press Release. Dr. Stillman is a geophysicist at the Southwest Research Institute in Boulder, Colorado, who wasn’t part of this study.
The team of scientists feel that the lake is much like one of the interconnected pools situated several miles beneath the ice sheets of Antarctica and Greenland, according to Dr. Martin Siegert in the exact same Press Release. Dr. Siegert is a geophysicist at Imperial College London (U.K.), who leads a consortium planning to drill into Lake Ellsworth below the ice of West Antarctica. “It will open up a very interesting field of science on Mars,” Dr. Siegert added.
Planetary scientists generally feel that water gushed across the surface of the Red Planet billions of years ago, when it possessed a warmer and warmer setting. This water is believed to have carved gullies and channels that are still visible on Mars today. However, now low atmospheric pressures imply that any surface water will boil off. By comparison, water manages to survive frozen in polar ice caps, as well as in subsurface ice deposits. Some of these ice deposits are mapped by MARSIS.
On our own planet, microorganisms have been found swimming in the subglacial lakes of Antarctica. These hearty little germs have been able to survive in isolation from the external Antarctica for as long as 35 million years–or more. This is because a large number of the 400 subglacial lakes which have been detected so far appear to be hydraulically tied to one another. Therefore, planetary scientists think that it is reasonable to conclude that microorganisms may swim around nearly everywhere under the Antarctic ice. Organisms, such as these, inhabiting regions generally considered to be inhospitable, are termed extremophiles. Extremophiles could be found on distant worlds dwelling in surroundings that appear to be more hostile to life.
The discovery of tiny tidbits of life swimming around in the subglacial lakes of Mars would have deep significance for humanity. This is because it will be the first life to be found on a world other than Earth. Additionally, discovery of those living tidbits would contribute to our scientific understanding of the prevalence of life in our Solar System. Ice-covered oceans are thought to slosh around beneath the frozen shells of Jupiter’s moons Europa and Ganymede, as well as Saturn’s moons Titan and Enceladus. On our planet, wherever we find liquid water, we also find life. This indicates that the discovery of geologically persistent liquid water on so many distant planetary bodies raises the intriguing possibility that aquatic life-forms may be abundant throughout our Solar System.
The amazing Italian astronomer Galileo Galilei (1564-1642) made the first telescopic observation of Mars in 1610, using his crude little”spyglass”, which was among the earliest telescopes to be used for astronomical purposes. During that same century, other astronomers also observed that the polar ice caps on Mars, using the very small telescopes of that age. These early astronomers were nonetheless able to find out the Martian rotation period, as well as its axial tilt. These observations were mostly made when Mars was at its closest approach to Earth. Improved telescopes developed in the 19th century helped astronomers map permanent albedo features, and a crude map of the Red Planet was published in 1840. This very first map of Mars was followed by a string of increasingly improved maps from 1877 on.
The imaginative tale of”little green men” inhabiting Mars started when astronomers wrongly believed they had observed the spectroscopic signature of water in its atmosphere. This captivating notion of Martian life became increasingly popular with astronomers and the general public alike, and it became particularly popular when the American astronomer Perceval Lowell (1855-1916) thought that he had detected a community of artificial canals carved by intelligent beings on the Martian surface. But these linear features were ultimately proven to be only optical illusions.
Also during the 1920s, astronomers could determine that the atmosphere of this rusty-red world harbors only tiny amounts of oxygen and water. Astronomers of that era also successfully discovered that the surface temperature of the Red Earth ranged from a really frigid -121 degrees Fahrenheit to a comfortable 45 degrees Fahrenheit.
Two decades later, in 1947, the Dutch-American astronomer Gerard Kuiper (1905-1973) demonstrated that the thin atmosphere of Mars is composed primarily of carbon dioxide which added up to roughly double the quantity found within our own planet’s atmosphere.
Mars is the fourth planet from our Sun, and like the other strong inner planets–Mercury, Venus, and Earth–it basks in the brilliant sunlight streaming out from our Star. It is famous for its reddish hue that is caused by an abundance of iron sulfide coating its surface. In addition, the surface of Mars is scarred with a high number of impact craters that appear quite similar to those observed on Earth’s Moon.
Mars has a rotational period and changing seasons like our own world. However, unlike our Earth’s large Moon (the largest moon in our Sun’s inner kingdom), Mars is orbited by a strange and intriguing duo of small potato-shaped moons.
For the last two decades, cameras in orbit around Mars have sent back to Earth numerous revealing images. These pictures show that Mars sports a surface that is dotted with tiny valleys that have been formed into slopes which bear an eerie resemblance in their form to gullies that led from gushing flooding of liquid water on our planet. The Martian gullies are thought to be relatively young geological features that are less than a few million years old–and some can even be more young than that. A few million years isn’t a lengthy time on geological time scales. These more recent observations provide planetary scientists valuable clues that great quantities of life-sustaining liquid water may still be lingering on Mars, and that this water might have been responsible for carving the surface gullies.
Even though the surface of the Red Planet is not particularly life-friendly today, there’s sufficient evidence indicating that very long ago its climate may have been such that water in its liquid phase pooled on its surface.
Mars sports two permanent polar ice caps that are composed primarily of water ice. Frozen carbon dioxide builds up as a relatively thin layer in a pole’s Martian winter. During that frigid season the poles are enshrouded in heavy blankets of relentless and continuous darkness. The cold Martian winters freeze its surface, and cause the deposition of 25-30% of the atmosphere to freeze into slabs of carbon dioxide ice (dry ice). When the poles are again swept by warm sunshine during the spring and summer, the frozen carbon dioxide sublimates. These seasonal alterations transport great quantities of water vapor and dust. This results in Earth-like frost, in addition to large cirrus clouds.
The two Martian poles display layered features, which are termed polar-layered residue . These deposits are brought on by seasonal melting and deposition of ice together with dust from the roaring Martian dust storms that sweep across the surface of Earth. Precious information regarding the past climate of Mars may become shown in these layers, which have been preserved in a type of deep freeze since early times. This has been compared to how tree ring patterns and ice core data reveal climate changes over the passing of years on Earth. Both of the Martian polar caps also show grooved features that were likely caused by winds. The grooves are also affected by the quantity of dust–in other words, the more dust there is, the darker the surface. This means that the darker the surface, the more frequent the melting. Dark surfaces absorb more light. However, there are other theories that were proposed to describe the large Martian grooves.
The south polar ice cap of Mars sports large pits, troughs and flat mesas that give it a”Swiss cheese look.” In contast, the north polar ice cap exhibits a flat surface with smaller pits than those found at the south polar ice cap–providing the north polar ice cap the appearance of”cottage cheese”, instead of”Swiss cheese.”
Hidden Liquid Water Under Ice
The radar data acquired by MARSIS provides strong evidence that there’s a pond of liquid water buried under layers of dust and ice in the south polar region of the Red Planet. Indeed, new evidence that Mars had an ancient watery past is scattered all over its surface in the form of enormous dried-out river valley networks and enormous outflow channels. These tattle-tale attributes have been clearly imaged from the spacecraft. Orbiters, together with landers and rovers, have been investigating the Martian surface for years, discovering minerals that can only form in the presence of liquid water.
Liquid water cannot exist on the Red Planet’s surface today, so astronomers are on the hunt for subsurface water.
The potential existence of water in its liquid phase on Mars (which may have provided a habitable environment for delicate forms of life) was first predicted by Dr. Stephen Clifford back in 1987. Dr. Clifford’s theory was published in a paper titled Polar Basal Melting on Mars that appeared at the Journal of Geophysical Research on August 10, 1987. Dr. Clifford is a senior scientist at the Planetary Science Institute (PSI) at Tucson, Arizona.
In reference to the recent findings of ESA’s Mars Express, published in the June 25, 2018 issue of the journal Science, Dr. Clifford mentioned:”I believe that the evidence that the paper’s authors have presented for the existence of liquid water at the base of the south polar layered deposits, in this location, is highly persuasive. It’s a finding which should be closely examined by the rest of the radar community to be sure we can rule out other alternative explanations–something I feel that the authors have already made an excellent attempt of doing.”
Whatever the extent of polar basal melting on Mars now, it was almost certainly much greater in the past, added Dr. Clifford in a July 27, 2018 PSI Press Release. Geological evidence indicates that the south polar layered deposits blanketed a region that was approximately twice as big 2 billion years ago than it is today. It follows that there was much more ice about to melt. The geothermal heat flux of Mars–that results from the decay of naturally occurring radioactive elements in the crust–is also thought to have been as much as three times greater during that early time. This would have reduced the essential thickness of polar ice for basal melting.
Dr. Clifford continued to comment:
“The work I did 30 years ago was basically a theoretical exercise that considered what we then knew about the broad network of subglacial lakes and channels which exist at the bottom of the Antarctic and Greenland ice sheets and examined its possible significance to the Martian polar caps. It is certainly gratifying that the MARSIS radar team has found evidence that demonstrates that this early theoretical work has some connection to reality.”