But experts say that as more detailed maps become necessary, relief agencies have to use information from higher-resolution, privately owned satellites. NASA satellites are equippped to take images of larger areas, such as the entire flood zone in Myanmar. In contrast, commercial satellites can zero-in on a particular village or building.
"The most detailed maps will probably come from commercial sources," said Lars Bromley, a project director who runs the geospatial technologies and human rights program at the American Association for the Advancement of Science. "You're able to see individual structures. You can count how many houses. You can see foot trails up to official roads."
Bromley added, "The broader issue is how big was this [cyclone], who did it hit? Your standard weather satellite would show cloud formation, where this thing went and who it might have affected."
Higher resolution images show, in detail, areas that were underwater after the cyclone, he said.
Bromley has been watching satellite images of Myanmar for a while. Last year, he published a paper comparing satellite images with reports of genocide, made by international human rights groups.
Direct Relief International, a Santa Barbara, Calif.-based medical relief organization, used satellite images from the U.N., the Navy and Google Earth, according to agency spokesman Jim Prosser.
"We're using satellite imagery to map out affected areas ... so we know how to effectively funnel material and financial aid to those affected," Prosser said. "Also, we're looking at displaced people, so we're able to be flexible to changes in population."
Although the group uses satellite imagery regularly, last month Google approached Direct Relief International to participate in a program designed to allow nonprofits to take advantage of Google Earth.
The group's online map of Myanmar shows that the coastal areas and much of the capital of Yangon are flooded. The group plans to ship medicine to the country on a Thai Airways flight on Friday.
DigitalGlobe, a six-year-old company that owns the satellite that supports the maps on Google Earth, regularly works with nonprofits during natural disasters.
"Once an event like this happens, we look at when our satellites will be passing over the region," said DigitalGlobe spokesman Chuck Herring. "We do a lot of work, understanding as best we can from people on the ground, where the hardest hit areas have been," to know what images to capture.
Satellites can also go where planes can't, said Val Webb of GeoEye, another commercial satellite operator.
The satellites were helpful "especially during Sept. 11, when airspace [was] blocked off," Webb said. "Airplanes couldn't go over, but our satellites still did."
But even the clearest, most detailed satellite image in the world won't save Myanmar.
"We can do a heck of a lot with the planning," said Bromley. "But if no one gets on the ground in there, it won't be useful, in the relief sense; it would only be useful in the academic sense."