December 20, 2016

Researchers led by Cassie Stuurman of the University of Texas, Austin, recently used the Mars Reconnaissance Orbiter (MRO) to discover a vast deposit of ice beneath the surface of Mars. They published their findings in late November in the journal Geophysical Research Letters. To future human explorers, the ice deposit could prove more valuable than gold.

Large deposits of ice have been discovered beneath the surface of Mars, the fourth planet from the sun. Credit: NASA/JPL/Malin Space Science Systems

The MRO, launched by the United States National Aeronautics and Space Administration (NASA) in 2005, carries the highest resolution camera ever sent to Mars. The camera is capable of resolving (distinguishing) objects on the planet’s surface less than 1 meter (3 feet) across. Its high-resolution images helped identify safe landing sites for subsequent Mars landers and discovered recurring slope lineae, patterns on Martian hills and valleys likely formed by the flow of liquid water just below ground. The MRO payload also includes a high-resolution spectrometer that has mapped the occurrence of minerals formed in association with water; an instrument that measures temperatures, pressures, and dust concentrations throughout the Martian atmosphere; and ground-penetrating radar that can detect layered rocks and ice beneath the surface.

Images such as this one, showing curved depressions in Mars’s Utopia Planitia region, prompted NASA to use ground-penetrating radar aboard the Mars Reconnaissance Orbiter to check for underground ice. Credit: NASA/JPL-Caltech/Univ. of Arizona

This radar detected ice in a region called Utopia Planitia (planitia is a Latin word that can mean low plain or basin). It is the largest confirmed impact basin in the solar system, with a diameter of 2,100 miles (3,300 kilometers). An impact basin is a vast hollow created by a large asteroid or comet strike. The angular cracks and rimless pits in the Martian impact basin resemble similar surface features in Canada that mark underground ice deposits. The researchers estimate that the Martian ice deposit holds more water than North America’s Lake Superior, the largest body of fresh water on Earth. The deposit is buried beneath as little as 3 feet (1 meter) and as much as 33 feet (10 meters) of Martian soil. The deposit is not solid ice, but rather is 50 to 85 percent ice, with rock, dust, and other materials mixed in.

Billions of years ago, Mars was warmer than it is today. Oceans and streams of liquid water probably covered its surface. But the solar wind (continuous flow of particles from the sun) stripped away most of Mars’s atmosphere, causing much of the water to escape into space. Today, the surface of Mars is cold, dry, and dusty. Some water remains on Mars, however, frozen in underground deposits at the poles and other places around the planet.

The newly discovered ice deposit may have important implications for the eventual human exploration and colonization of Mars. Other such deposits exist on the planet, but most are small and found in areas with rough terrain. Mars’s poles are covered with large ice caps, but they are the coldest regions of the planet. Utopia Planitia is a large, flat basin located in the somewhat warmer mid-latitudes. Therefore, future Mars colonists may be able to land a spacecraft in Utopia Planitia and find water not far from their landing site. Such water could be used for drinking, growing crops, and creating rocket fuel for journeys back to Earth. Studying the ice could also help explain the history of Mars’s climate.

February 19, 2013

Scientists announced this week that for the first time they had found living bacteria beneath a glacier in Antarctica. A team of scientists from the Whillans Ice Stream Subglacial Access Research Drilling (WISSARD), funded by the U.S. National Science Foundation, made the find. The bacteria were discovered in Lake Whillans, which is about one-half mile (800 meters) below the West Antarctic Ice Sheet. The lake is about 5-feet (1.5-meters) deep, and scientists had to drill through the entire half mile of ice to take a sample of the lake water. After running a culture of the sample, they were able to see the bacteria under a microscope. The bacteria are members of a new ecosystem of living things that is able to survive with little light, at very cold temperatures, and under large amounts of pressure.

Lake Whillans sits at the upper tip of the Ross Ice Shelf in West Antarctica. (World Book map; map data © MapQuest.com, Inc.)

DNA testing is required for scientists to be able to identify the bacteria. Once identification has occurred, it might give scientists a better idea of what the bacteria use as food.

In addition to the excitement of finding life under Antarctic ice, scientists were also very interested in the bacteria because the conditions in Lake Whillan are not unlike some of the terrains found in outer space. For example, Jupiter’s moon, Europa, and Saturn’s moon, Enceladus, both have water that exists under ice. If the bacteria discovered under Antarctica is, for example, found to consume minerals from surrounding rock as food, a similar lifeform might be able to exist elsewhere in the solar system.

Additional World Book articles:

• Jupiter
• Europa
• Saturn
• Enceladus

March 23, 2012

The amount of ice covering the five Great Lakes in winter has decreased significantly, says a new report, and researchers warn that the loss could have a substantial impact on water quality and habitats in the region. The report, released by the American Meteorological Society (AMS), identifies an average decline of about 71 percent over the past 40 years. Measured losses vary from year to year and lake to lake. The Great Lakes are Lakes Erie, Huron, Michigan, Ontario, and Superior.

Researchers examined satellite photos and United States Coast Guard reports of ice coverage from 1979 to 2010. Lake Ontario, the smallest of the Great Lakes, showed the biggest decrease, with coverage falling by 88 percent. Coverage fell by 79 percent on Lake Superior, the largest of the lakes. The AMS also noted that only about 5 percent of the Great Lakes’ surface froze over this winter, though those data do not appear in the report. On average, the lakes have about 40 percent coverage in winter.

Together, the Great Lakes make up 18 percent of the world’s fresh surface water. Shrinking ice coverage on the lakes may speed up wintertime evaporation, leading to lower water levels and increased erosion along the shoreline. Lack of ice may also lead to an increase in algae blooms, which damage water quality.

The Great Lakes are the world's largest group of freshwater lakes. Declining levels of ice coverage may threaten the lakes and their surrounding habitats. (World Book map)

The report’s lead author, Jia Wang of the National Oceanic and Atmospheric Administration (NOAA) lab in Ann Arbor, Michigan, says the loss may be at least partly the result of climate change. Wang also noted that smaller climate patterns, such as El Nino and La Nina, may have played a role. “We are seeing the impact of global warming here in the Great Lakes,” says Wang, “but the natural variability is at least as large a factor.”

Additional World Book articles:

• Lessons from Lake Erie
• St. Lawrence Seaway
  
• Water (The water supply problem)