Rosemary Decker is a free-lance author living in California. She is the author of Thirty-five Minutes to Mars.
Although it has been known for over a century that the easily observed Mars polar caps consist, at least partially, of water-ice, there remain many misconceptions of its nature and activity. The northern cap has been found to be almost entirely water-ice, and is much thicker than originally thought-more than half a mile thick at the permanently frozen core, which is about six degrees across, close to 600 miles. The southern cap, which is larger than the northern one at its winter maximum, melts nearly away during its short, but hot, summer. It is largely frozen carbon dioxide rather than water-ice, but planned Mars probes expect to dig for water-ice, as its presence there would be helpful to future explorers.
In addition to the snowy caps and their seasonal melting, a great supply of water (most of it frozen) has been discovered underground. In the enormous oasis region of Solis Lacus (which varies in size from time to time, but averages about 300 miles by 500 miles), Viking probe equipment detected water only a few centimeters below the surface. During a 1976 dust storm that began in a surrounding area, vast amounts of fog and moist cloud were drawn from the Solis Lacus soil by the summer heat, spreading across Solis Lacus and beyond. (The area was recently renamed Solis Planum, but perhaps “Lake of the Sun” was more appropriate.)
It was in the Solis Lacus region that the great waterspout was discovered in 1980 by Lowell astronomer Dr. Leonard Martin as he was examining Viking frames. Fortunately, the “Old Faithful” was imaged twice, at 4.5-second intervals, and the second frame shows the expansion of the rising plume of water, made clear by the changing shadow-shape.
Chances are that, like Earth, Mars has hundreds of similar hot spring eruptions. It is very unlikely that there would be only one. Here is one example among many that Mars is not a dead planet, as commonly perceived, but a live one-with the possibility of life-forms thriving in the warm, damp neighborhood of the hot spring.
Since this discovery has such exciting implications, it is unfortunate that it has received so little attention. Martin reported it promptly to NASA. His report, with the photo images, was accepted and duly published in a NASA in-house weekly that is distributed to all NASA centers. But it was never publicized outside the space agency, until researchers such as Vince di Pietro found it and gave it just recognition.
Polar Seas and Rainstorms
Water from Mars’s polar caps has some fascinating aspects. We have long been told that, due to cold and atmospheric conditions, the polar snows cannot melt into liquid water but must sublime directly to vapor. The evidence does not support this. As long ago as 1894, Lowell astronomers were noting that the dark, bluish bands which surround the shrinking polar caps looked like water. In 1896, William Pickering used a polariscope to study the widest parts of the blue bands and found that the light coming from these areas was polarized. In Mars: The Photographic Story, (1962) Dr. Earl Slipher commented, “To polarize the light it reflects is a property… of a smooth surface, such as that of water.”
This dark, bluish band has been described by NASA as dark, rough terrain.
Dr. H. P. Wilkins considered it “a shallow, temporary sea” (Mysteries of Space and Time, 1954). The band always keeps pace with the polar cap’s retreat toward the pole, and disappears as the ice cap reaches its maximum shrinkage. Before disappearing completely, the band has become a thin line, a mere thread. If Wilkins were correct, then actual melting is occurring, not merely sublimation.
Another appealing aspect of water on the green and red planet-which surprises most lay folk-is rainfall. For the past century, astronomers have observed that cloud masses moving across the planet sometimes leave dark, shadowy patches on the soil in their wake. These darkened areas fade out in hours, or in a day or two, restoring the terrain to its usual tone. The clouds that leave darkened ground are blue-white ones containing moisture, not the yellowish dust clouds. The inference is that, occasionally, rainfall does occur on Mars.
Odd Clouds and “Glass Tubes”
Then, there are the odd “W” clouds in the Tharsis region, which have been noted through most of the 20th century. These clouds always form in the same locale and consist of four stems, each several hundred miles long. Not all four are always visible at the same time; sometimes only one or two may be present. Apparently they match four of the large “canal” lines, including the Eumenides and the Ulysses, and they form over about four weeks in the Martian spring. They are not present during the mornings, but become observable in the afternoons, up until sunset. At that time, the rotation of the planet carries them out of sight, at the sunset limb. These long stems seem to consist of fog or cloud. If so, the W-shaped linear features on the ground below must be supplying the moisture. It seems that no matter how many times the notion of Martian canals is buried, it pops up again.
Among recent frames released by NASA’s Mars Global Surveyor (May 2000), there are some truly amazing ones. They reveal long, translucent tubes in eroded areas below the usual soil surface. At regular intervals along the “pipes” are whitish arched supports. This piping seems to be part of a very extensive system, most of which is out of sight, underground.
As Richard Hoagland pointed out, discussing the strange tubes on Coast to Coast AM (June 23, 2000), in all probability they were designed to carry water. Again, shades of the old canal system.
Seasons of the Red Planet
Another item Hoagland brought up was the recent discovery of a frozen lake on the Martian surface. Dubbed Lake Steadman after its discoverer, Kent Steadman, the lake is located in the Valles Marineris canyon complex. (Steadman wanted to name the lake after his father, who liked to go fly fishing.)The NASA image shows the dark lake, with its reflections of the surrounding terrain.
Very important evidence of water on Mars shows in the spring-to-summer greening of the darkish areas in the related hemisphere. This rich blue-green has been photographed in color for about half a century by a number of astronomers. Slipher, during the close oppositions of 1954 and 1956, succeeded in getting several good photos showing the green areas adjacent to the melting polar cap. One of them was published in the September 1955 National Geographic. As he stated, the blue-green turns chocolate brown in fall, and usually ochre-colored or gray in winter. (NASA remains conspicuously silent on these seasonal changes.)
Mars is peppered with countless craters-a few large, and thousands of smaller ones. A Viking orbiter photographed many that had heavy mists in their basins, shortly after sunrise, when the sun had melted frost or ice within them. Stretching out from these craters, always in the direction the prevailing wind blows, were dark streaks. In Life on Mars (1979) David Chandler commented that they appear to be plant life surviving in the path of moisture blown from the craters.
There are so many questions still to be answered: How common are hot springs on Mars? Does the frozen lake have periods of thawing in the Martian summer? What makes liquid water-rather than mere sublimation-possible at the edges of the polar caps during their springtime thaw? Of the 65,000 Mars Global Surveyor images obtained in the past few years, 27,500 have only recently been made available to the public. The plainly artificial tubes are among them. What other wonders will be discovered in this vast archive?
Just when did skilled engineers last set foot on Mars? And could a water distribution system still exist there-as Percival Lowell believed?
Stay tuned-Mars news keeps coming.
For more on Martian mysteries, see the June 2001 issue of FATE!