Polar Research on Earth Assists with Mars Study
One of the IPY’s goals is to encourage scientists to share advances in different fields, including those who study other planets and, in turn, relate their own studies back to the Earth, explained James Garvin, chief scientist at NASA’s Goddard Space Flight Center.
“Obviously, the Earth’s poles matter. We live with them and they control parts of our climate destiny,” Garvin said. “But if we can compare ourselves to other poles, we may learn things about our own poles that we didn’t realize.”
By studying Mars, for instance, scientists hope to provide insight into how the Earth’s climate may change in the long term by helping understand how planets redistribute mass, changing the tilt of their rotational axis and, in turn, their climate, he said. Current data and observations suggest that the periodic redistribution of mass on Mars causes it to “wobble” on its rotational axis by tens of degrees, prompting radical climate shifts every 100,000 years or so. Scientists are still unsure whether the Earth, which is thought to change its spin axis only a few degrees, undergoes similar periodic redistributions of mass.
Even if the Earth were shown to wobble significantly on its rotational axis, Garvin cautioned that the accompanying climate changes would be “beyond the control of human influence,” since they occur over many thousands of years.
“By looking at Mars, we are asking ourselves about a new destiny — what can happen to our planet as it continues its long-term evolution,” he said.
Meanwhile, scientists who study Mars are also learning from researchers who study Earth’s poles, as the poles’ extreme climate provides an opportunity to test theories and equipment that can later be used to study the distant planet.
In August, NASA plans to launch the first of its scout missions, named Phoenix, to the Martian arctic, or north pole. The mission is a response to recent predictions that water ice may exist only centimeters below the planet’s surface near the poles.
Scientists have long been interested in the history of water on Mars because many geological formations — from soil deposits to dry river beds — on the planet’s surface suggest a wetter past. While some of this water could have escaped the planet as climactic shifts caused it to gradually lose its atmosphere, researchers predict that the majority of the water stayed on the planet, trapped underground.
“It’s all about following the water,” said Raymond Arvidson, an Earth and planetary scientist at Washington University in St. Louis and adviser to NASA’s planetary exploration program.
When it lands on Mars in June 2008, Phoenix will begin to “trench” 50-100 centimeters into the Martian soil, measuring water and other trace molecules as it digs.
Field research on Earth helped researchers predict that Phoenix will hit ice at these depths. The Antarctic Dry Valleys — considered a terrestrial analog for Mars — provided NASA scientists with a prime area to predict the depth and qualities of the Martian ice table, or the level below which ice is stable. According to Arvidson, Phoenix had to be designed with a ripper blade and rasp — rather than a scraping mechanism alone — because field experience in the Antarctic led researchers to believe that the icy soil will be “hard as concrete.”
While Phoenix will not include equipment to conduct biological experiments, recent findings of a variety of organisms in the Antarctic Dry Valleys also have bolstered hopes that the lander will provide indirect evidence for life on Mars.
Biological research in the Dry Valleys uncovered organisms living in super salty solution at temperatures as low as -50 degrees Fahrenheit. While temperatures on Mars are even more extreme than those found in the Dry Valleys, this newly discovered “pathway for life” has made researchers more optimistic that biological processes could occur on the Red Planet, according to Garvin.
Phoenix also will provide valuable meteorological information by taking the first ground measurements from a polar region on Mars. Much of what is known about the Martian climate has been deduced from observations in equatorial and mid-latitude zones and from snapshots taken over time by the various orbiters that have studied the planet.
Since Mars rotates roughly every 24 hours and has a tilt relative to its orbital axis that is comparable to the Earth, researchers have been able to adapt global circulation models developed for Earth to Mars. What researchers are lacking and hope to glean from Phoenix and successive missions is a sense of what some of the processes observed from space — such as the accumulation of dry ice, or frozen carbon dioxide in the Martian arctic every winter — look like from the ground.
Arvidson believes these meteorological observations will be of interest to Earth scientists, even though the polar processes on Mars are substantially different from those observed on our own planet.
“We’re taking a polar environment and making it much more extreme than the Earth has ever seen,” he said. These sorts of “natural planetary experiments” can be invaluable to researchers looking to understand the dynamics of polar processes on the Earth and elsewhere.
The cold, dark beyond
In addition to providing a framework for the Phoenix mission’s scientific advances, the International Polar Year may also spur future planetary exploration, said Robert Bindschadler of NASA’s Goddard Space Flight Center.
Bindschadler, who has spent decades describing the dynamics of sea ice and glaciers on Earth, said that the Antarctic ice sheet provides the perfect laboratory for “the type of rovers that would sample the polar ice caps of Mars.”
Rovers designed to run during the Antarctic winter, when there is darkness 24 hours a day and temperatures are almost as cold as on the Martian surface, could be successful prototypes of future Mars landers.
Bindschadler said he also hopes that robotic probes for burrowing through ice designed during the IPY will have applications in future planetary missions, particularly to the Jupiter’s moon Europa, which is thought to have liquid water buried underneath an ice sheet.
“During the IPY there will be explorations of lakes underneath the Antarctic Ice Sheet,” said Bindschadler. “Similar types of ice thickness, thousands of meters, will be drilled through.”
In addition, the IPY spurred new technologies for traversing icy terrain. One design, Bindschadler noted, uses a tripod mechanism that can change the length of the legs to more effectively move across an ice sheet than a vehicle on wheels.
All these advances, which are helpful in researching and understanding our own poles also are “related directly to NASA’s mission to explore icy planets in the cold, dark beyond,” Bindschadler said.