||. . . GISMO to expose hidden world beneath polar ice, gauge climate change
$3 MILLION NASA GRANT FUNDS NEW RADAR INSTRUMENT
COLUMBUS , Ohio – Researchers are designing a new instrument named GISMO that could uncover parts of the planet that haven't seen the light of day for millions of years.
What it finds underneath miles of polar ice could give scientists a new perspective on global climate change.
Ken Jezek, professor of geological sciences at Ohio State University, said that GISMO's dual-antenna radar system will exploit the same physical phenomenon that creates colorful swirls on the surface of an oily puddle of water.
The technology might one day help NASA peer beneath the Martian ice caps, and reveal the frozen depths of Jupiter's ice moon Europa. The space agency just awarded Jezek's research team $3 million to build the instrument.
“The goal of this experiment is to strip away the ice sheets to reveal only what's happening underneath,” Jezek said. “That is probably the biggest unknown in glaciology today.”
As scientists try to gauge the effects of global climate change, they are beginning to look very closely at conditions beneath Earth's ice sheets, which cover roughly 15 percent of the planet.
What's happening in this invisible region – where ice meets rock, soil, and water – has a great deal of influence on how much of the ice may melt because of rising temperatures, and how much global sea level may rise as a result, Jezek explained.
Earth's poles have been covered in ice for 2.7 million years. Scientists suspect that, just as the ice surface has changed over that time, a different world has evolved underneath. Lakes of liquid water and even flowing streams may have formed, which would speed the iceflow above.
The telltale sign, Jezek said, is that some parts of the ice are moving faster than others. “There almost certainly must be water at the base of the ice lubricating it against the rock,” he said.
Confirming that hypothesis is difficult. Rough surface ice and rocks within the ice sheet obscure the view for traditional radar systems. And the regions that scientists most want to examine – the ones where the ice is flowing quickly or breaking up – are especially rough.
Jezek said that GISMO (short for Global Ice Sheet Mapping Orbiter) will get around the problem by combining radar signals reflected from the surface of the ice with signals from the base of the ice.
The two signals combine to produce an interference pattern, just like light waves interfere with each other to produce a rainbow effect on the surface of oily water. In that case, a thin layer of oil floats on the water, and light reflecting off the surface of the oil clashes with light reflecting off the surface of the water below.
Jezek's team is developing techniques that use the interference pattern to cancel out the effects of rough surface ice and rocks to reveal the base of the ice sheet. In computer simulations, the techniques create an image that resembles the rainbow on an oily puddle.
The $3 million NASA grant will enable the researchers to build the GISMO instrument. They hope to test it in an aircraft over Greenland by the end of 2006.
GISMO's design is similar to a radar system Jezek previously developed with the University of Kansas, which is also a partner on this new project.
“The Kansas radar proved that we can actually get a signal back from the base of the ice,” Jezek said. “What GISMO will demonstrate is that you can put a radar system on an aircraft or in space, effectively remove all the contaminations from the surface, and capture a pristine picture of the base.”
#Contact: Ken Jezek, (614) 292-6531; Jezek.firstname.lastname@example.org
Written by Pam Frost Gorder, (614) 292-9475; Gorder.email@example.com