Andes researchers get a lift from radar mission

A 3-D radar satellite image shows the Altos de Pica area of the Andes mountain range in northern Chile.

By Environmental News Network staff

February 18, 2000
Web posted at: 12:25 p.m. EST (1725 GMT)

Scientists from Cornell University believe data from the NASA shuttle mission now mapping the globe will help them solve some of the great mysteries of the Andes Mountains.

The majestic South American range, which rises nearly straight out of the Pacific Ocean to heights of more than 20,000 feet, boasts some of the most dramatic mountains in the world. But they are also among the least understood.

Armed with a $150,000, two-year grant from NASA, researchers from the Cornell Andes Project will carefully analyze data of the Andes gathered by the Shuttle Radar Topography Mission now in the hands of an international crew aboard space shuttle Endeavour.

Endeavour is carrying two radar antennas, one aboard the shuttle and one at the end of a 200-foot mast extending from the spacecraft. Using a technique called radar interferometry, scientists will combine signals from the two antennas to construct 3-D images of the land below.

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The radar will also supply information about the characteristics of Earth's surface. NASA plans to use the data to make detailed topographic maps of nearly the entire globe at a resolution of 30 meters (323 feet).

The Andes Project currently relies on data from European and Canadian radar satellites. While these satellites have provided the team with generally accurate information, they do not use radar interferometry and cannot accurately gather data from heavily forested or wet-weather areas such as the eastern edge of the Andes.

Scientists have a general understanding of the geologic processes that formed the Andes. Over the past 200 million years, the Nazca tectonic plate in the Pacific Ocean wedged itself underneath the western edge of the South American continental plate. The lighter continental plate lifted, crumpled and cracked open from the pressure, creating what is now the Andes, a range full of volcanoes and fault lines. These subduction processes continue today, as does the study of tectonics.

The Cornell researchers are interested in more specific information than the radar satellites have supplied. "The point is to understand topography," said professor Bryan Isacks, a member of the Andes Project team, "which is a result of tectonic processes interacting with climactic processes and erosion. These interactions are very interesting. If you understand topography, you can get a better idea of these processes ... of how mountains are built and how they are destroyed."

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"There are many puzzles that remain about the Andes," said Isacks, who heads Cornell's department of geological sciences. "There are parts of the Andes that have never been topographically mapped because of cloud cover, especially parts of the eastern side of the range. No satellite ever sees these areas from space. They are very remote and have never been surveyed on the ground. There is not even aerial photography."

For instance, said Isacks, there are large ash flows along the Andes range. While the researchers know this formation is a result of volcanic activity, they are not sure where the flows came from. Data from the SRTM could shed light on the matter, Isacks said.

The Andes Project has also identified lava fields. SRTM data will help the researchers determine the size of the eruptions and the amount of molten material that oozed out of Earth's interior as a result of subduction.

The Cornell scientists are particularly interested in an area of the range known as the altiplano. Encircled by mountain peaks, this huge plateau spreads through northern Argentina, western Bolivia and southern Peru. The altiplano, home to Lake Titicaca, the highest navigable lake in the world, is about 300 kilometers (188 miles) wide, 1,000 kilometers (625 miles) long and 3,800 meters (two miles) high.

"How this thing got raised up that way is still a fairly big mystery," Isacks said. "Being able to look at the topographic detail along the sides of it may go a long way."

The Cornell Andes Project is one of 40 scientific groups that have received grants from NASA to study SRTM data.

Copyright 2000, Environmental News Network, All Rights Reserved

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Professor Bryan Isacks
Cornell University Geological Sciences Department
Cornell Andes Project
Shuttle Radar Topography Mission

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