July 8, 2008

NASA-Funded Study to Improve Image Access

By The Associated Press

SIOUX FALLS, S.D. (AP) - A new South Dakota State University project hopes to give Internet users better access to satellite information and images collected by a data center near Sioux Falls.

Professor David Roy of SDSU's Geographic Information Science Center of Excellence is heading the five-year effort, funded with a $3.29 million grant from the National Aeronautics and Space Administration.

The project is a collaboration with the U.S. Geological Survey through its Center for Earth Resources Observations and Science, the main federal repository for satellite images.

The view would be similar to what a Web surfer would see on Google Earth, but it'd be closer to real-time because the images would be regularly updated.

"The image of the whole United States will be updated as the data is sent," Roy said. "That's what we're gunning for."

Many of the land images gathered at EROS are beamed down by the Landsats, a pair of workhorse satellites operating long past their prime.

Landsat 5, launched in 1984, continues to transmit detailed images of the ground surface more than 20 years past its scheduled mission end, while younger sibling Landsat 7 has been putting in more than four years of overtime.

They work in tandem to take mid-resolution pictures that help document forest fires, droughts, hurricanes, tsunamis and other calamities.

The project team hopes to take Landsat 7 observations every 16 days for all the contiguous United States and Alaska for a seven- year period and make the images easily available. It would also make the data associated with those images more accessible.

NASA launched the first Landsat satellite in 1972, and the orbiters have been sending images back to EROS ever since. Engineers have worked through many anomalies to keep the grizzled veterans taking snapshots.

Landsat 7's scan line corrector, which compensates for the satellite's forward motion, failed in 2003, leaving zigzag gaps in some of the images.

There's also an issue with cloud cover, as an average of 35 percent of Landsat data is obscured by clouds.

"When you've got clouds, the satellite can't see the surface through the clouds," Roy said.

The SDSU project will try to fill some of the gaps using data from another satellite system called MODIS.

Roy, who worked with MODIS during his time at the NASA Goddard Space Flight Center in Maryland, said the satellite operates in the same orbit as Landsat 7 but has a different spatial resolution. With a Landsat image, the smallest part of the picture corresponds to 30 meters on the ground.

"With MODIS it corresponds to 500 meters, but the thing about MODIS is we get it every day," Roy said.

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