In the hilly regions of the Pacific Rim, the difference between 30 meters and 90 meters (98 feet and 295 feet) could mean life or death.

NIMA, a secretive governmental body, wants to keep the most detailed maps from the Shuttle Radar Topography Mission out of the hands of the public.

"Research is a public forum," said Charles Rubin, a professor of geological sciences at Central Washington University who hopes to use detailed topographical maps of areas near fault lines to study earthquake hazards. "If it has implications for society, that's something policy makers and the public should beable to evaluate."

"It's an extra layer of detail which won't make a wit of difference for Joe Sixpack planning his estate development, or an engineer laying the next superhighway," a NIMA spokesman said. "But it does have an application, and gives an informational edge, in a military context."

Just ask Dr. Jeffrey Weissel, a researcher of landslides at Columbia University's Lamont-Doherty Earth Observatory.

Weissel hopes to use highly detailed 30-meter resolution data from an upcoming shuttle mission to better understand the danger of landslides in New Zealand, New Guinea and Taiwan.

But Weissel might be in for a disappointment: he, and other researchers who study landslides, volcanoes, earthquakes and other aspects of Earth science, might never get a hold of the 30-meter data from the mission.

The detailed data, which show the altitude of objects as close together as 30 meters, will be enough to make a stunning and complete topographical map of these regions that could be used by authorities to better prepare for natural disasters, as well as give overall insight into the study of landslides. But elevation data also are important in battlefield planning, and can be used to set courses for missiles.

The National Imagery and Mapping Agency (NIMA), a secretive governmental body that provides maps for the military and civilian intelligence agencies -- and which is co-sponsoring the mission with NASA -- wants to keep the most detailed data out of the hands of the public.

According to NIMA, if the data are made available to foreign powers, it could compromise certain U.S. strategic military advantages.

Instead, the agency, is offering data that are three times less detailed. NIMA says the 30-meter information has limited use outside a military context, while scientists say the 90-meter data being offered would significantly weaken their ability to carry out their research.

It's this conflict between national security and research that has some in the scientific community crying foul.

"Research is a public forum," said Charles Rubin, a professor of geological sciences at Central Washington University who hopes to use detailed topographical maps of areas near fault lines to study earthquake hazards. "If it has implications for society, that's something policymakers and the public should be able to evaluate."

The project is called the Shuttle Radar Topography Mission, and involves two antennas attached to the space shuttle in slightly different positions that transmit radar signals to the surface of the Earth. The differences in the waves that bounce back can be used to calculate the surface elevation.

In 176 orbits of Earth, the shuttle, which is set to be launched at the end of January, will take elevation data for about 80 percent of the Earth's land mass. In a year's time, scientists will have developed the most accurate and complete topographical map of the Earth.

NASA is providing some of the technology for the mission, while NIMA is contributing around $200 million. An agreement between the two bodies reached during the summer of 1996 stipulates that the Department of Defense will have control over the mission's raw data -- the key to the most highly detailed maps.

According to NIMA spokesman Eric Berryman, NIMA will grant access to the 30-meter global data on a case-by-case basis for certain humanitarian purposes. Additionally, 30-meter data of the United States will also be released, he said.

Images with detailed 30-meter resolution, he said, have limited use outside a military context.

"It's an extra layer of detail which won't make a wit of difference for Joe Sixpack planning his estate development, or an engineer laying the next superhighway," he said. "But it does have an application, and gives an informational edge, in a military context."

According to scientists, however, the difference between the low- and high-resolution data will make a world of difference.

"There's a great deal of difference between a 90-meter estimate of slope and 30-meter," said Weissel, the researcher at Columbia who studies landslides. "You could miss the slope entirely."

The topography of Papua New Guinea [source: Columbia University]

Rubin, the earthquake researcher, says that lower-resolution maps are useful for studying faults in a large region, but that the study of individual fault lines requires much more detailed images.

"If I'm looking at large scale processes in the Himalayas, the 90-meter data works fine," he said. "Eventually, you have to come down to individual faults. That's kind of the bread and butter for human suffering."

And Dr. Victor Baker, the head of the department of hydrology and water resources at the University of Arizona, says that his research in the flow of rocks, boulders, and other debris along waterways -- factors that were responsible, he says, for fatalities in Central America during Hurricane Mitch -- will be hindered if the high-resolution data is withheld from public view.

"The more refined [the view], the more you can discover." Baker said. "The processes for debris flow are not well understood."

The debate over public and scientific access to high-resolution images of Earth expanded recently with the launch of privately owned satellites like Ikonos, owned by Space Imaging Inc., which from its orbit can see objects as small as 1 meter (3.2 feet). Previously secret and highly sensitive imagery will soon be available for purchase by anyone with an internet connection.

But the conflict over government imagery, like that which will come from the topography mission, continues.

Negotiations on the topic of public access to the topographic data gathered by government agencies continue between NASA, whose information is usually distributed freely, and NIMA, a part of the secretive U.S. intelligence community.

Dr. Ernie Paylor, the program scientist for the topology mission and one of the negotiators, says most scientists who are part of NASA's science team for the mission will likely have some access to the high-resolution data. Concerns remain, he said, over the nationality of some of the scientists, and the areas of the world for which information is requested.

Even those who receive the high-resolution data, however, will most likely be kept from reprinting those data sets in their published work. They will, Paylor said, be able to publish the conclusions of their investigations.

"This is a very complicated and complex subject," Paylor said. "We've been talking about this for almost a year now, and we're finally getting close."

Meanwhile, the scientists -- Weissel, Rubin and Baker, each of whom is part of the SRTM science team -- say they understand the national security concerns, but hope that, in the end, politics will not overly inhibit the progression of science, and especially their own research.

"It partly plays out as international politics," Baker said. "I'm just a scientist trying to figure out the hazards."