Water is Found on Mars
A new analysis of pictures taken by the exploration rover Opportunity reveals what appear to be small ponds of liquid water on the surface of Mars.
The report identifies specific spots that appear to have contained liquid water two years ago, when Opportunity was exploring a crater called Endurance. It is a highly controversial claim, as many scientists believe that liquid water cannot exist on the surface of Mars today because of the planet’s thin atmosphere.
If confirmed, the existence of such ponds would significantly boost the odds that living organisms could survive on or near the surface of Mars, says physicist Ron Levin, the report’s lead author, who works in advanced image processing at the aerospace company Lockheed Martin in Arizona.
Along with fellow Lockheed engineer Daniel Lyddy, Levin used images from the Jet Propulsion Laboratory’s website. The resulting stereoscopic reconstructions, made from paired images from the Opportunity rover’s twin cameras, show bluish features that look perfectly flat. The surfaces are so smooth that the computer could not find any surface details within those areas to match up between the two images.
The imaging shows that the areas occupy the lowest parts of the terrain. They also appear transparent: some features, which Levin says may be submerged rocks or pebbles, can be seen below the plane of the smooth surface.
Smooth surface
The smoothness and transparency of the features could suggest either water or very clear ice, Levin says.
“The surface is incredibly smooth, and the edges are in a plane and all at the same altitude,” he says. “If they were ice or some other material, they’d show wear and tear over the surface, there would be rubble or sand or something.”
His report was presented at a conference of the Institute of Electrical and Electronics Engineers, and will be published later this year in the institute’s proceedings.
No signs of liquid water have been observed directly from cameras on the surface before. Reports last year pointed to the existence of gullies on crater walls where water appears to have flowed in the last few years, as shown in images taken from orbit, but those are short-lived flows, which are thought to have frozen over almost immediately.
Speedy evaporation?
Levin and other reasearchers, including JPL’s Michael Hecht, have published calculations showing the possibility of “micro-environments” where water could linger, but the idea remains controversial.
“The temperatures get plenty warm enough, but the Mars atmosphere is essentially a vacuum,” says Phil Christensen of Arizona State University, developer of the Mars rovers’ mini-Thermal Emission Spectrometers. That means any water or ice exposed on the surface evaporates or sublimes away almost instantly, he says.
But, he adds, “it is theoretically possible to get liquid water within soil, or under other very special conditions”. The question is just how special those conditions need to be, and whether they ever really are found on Mars today.
If there were absolutely no wind, says Christensen, you might build up a stagnant layer of vapour above a liquid surface, preventing it from evaporating too fast. “The problem is, there are winds on Mars… In the real world, I think it’s virtually impossible,” he told New Scientist.
Simple test
Levin disagrees. He says his analysis shows that there can be wind-free environments at certain times of day in certain protected locations. He thinks that could apply to these small depressions inside the sheltered bowl of Endurance crater, at midday in the Martian summer.
He adds that highly briny water, as is probably found on Mars, could be stable even at much lower temperatures.
Although the rover is now miles away from this site, Levin proposes a simple test that would prove the presence of liquid if similar features are found: use the rover’s drill on the surface of the flat area. If it is ice, or any solid material, the drill will leave unmistakable markings, but if it is liquid there should be no trace of the drill’s activity.
Levin’s father Gilbert was principal investigator of an experiment on the Viking Mars lander, which found evidence for life on the planet, although negative results from a separate test for organic materials led most scientists to doubt the evidence for biology.
Mars is the fourth planet from the Sun in the Solar System. The planet is named after Mars, the Roman god of war. It is also referred to as the “Red Planet” because of its reddish appearance as seen from Earth.
A terrestrial planet, Mars has a thin atmosphere and surface features reminiscent both of the impact craters of the Moon and the volcanoes, valleys, deserts and polar ice caps of Earth. It is the site of Olympus Mons, the highest known mountain in the solar system, and of Valles Marineris, the largest canyon. In addition to its geographical features, Mars’ rotational period and seasonal cycles are likewise similar to those of the Earth.
Until the first flyby of Mars by Mariner 4 in 1965, it was speculated that there might be liquid water on the planet. This was based on observations of periodic variations in light and dark patches, particularly in the polar latitudes, which looked like seas and continents, while long, dark striations were interpreted by some observers as irrigation channels for liquid water. These straight line features were later proven not to exist and were instead explained as optical illusions. Still, of all the planets in our solar system, Mars is the most likely, other than Earth, to harbor liquid water, and perhaps life.
Mars is currently host to three functional orbiting spacecraft: Mars Odyssey, Mars Express, and Mars Reconnaissance Orbiter. This is more than any planet except Earth. The surface is also home to the two Mars Exploration Rovers (Spirit and Opportunity). Geological evidence gathered by these and preceding missions suggests that Mars previously had large-scale water coverage, while observations also indicate that small geyser-like water flows have occurred in recent years. Observations by NASA’s Mars Global Surveyor show evidence that parts of the southern polar ice cap have been receding.
Mars has two moons, Phobos and Deimos, which are small and irregularly shaped. These may be captured asteroids, similar to 5261 Eureka, a Martian Trojan asteroid. Mars can be seen from Earth with the naked eye. Its apparent magnitude reaches ?2.9, a brightness surpassed only by Venus, the Moon, and the Sun, though for much of the year Jupiter may appear brighter to the naked eye than Mars.
Water is a common chemical substance that is essential to all known forms of life. In typical usage water refers only to its liquid form or state, but the substance also has the solid state, ice, and gaseous state, water vapor. About 1,460 teratonnes (Tt) of water cover 71% of Earth’s surface, with 1.6% of water below ground in aquifers and 0.001% in the air as vapor, clouds, and precipitation. Saltwater oceans hold 97% of surface water, glaciers and polar ice caps 2.4%; and other land surface water such as rivers and lakes 0.025%. Water in these forms moves perpetually through the water cycle of evaporation and transpiration, precipitation, and runoff usually reaching the sea. Winds carry water vapor over land at the same rate as runoff into the sea, about 36 Tt per year. Over land, evaporation and transpiration contribute another 71 Tt per year to the precipitation of 107 Tt per year over land. Some water is trapped for periods in ice caps, glaciers, aquifers, or lakes for varying periods, sometimes providing fresh water for life on land. Clean, fresh water is essential to human and other land-based life. In many parts of the world, it is in short supply. Many very important chemical substances, such as salts, sugars, acids, alkalis, some gases (especially oxygen) and many organic molecules dissolve in water. Outside of our planet, a significant quantity is thought to exist underground on the planet Mars, on the moons Europa and Enceladus, and on the exoplanet known as HD 209458 b.
No Comments
No comments yet.
Sorry, the comment form is closed at this time.