Satellites and computers have revolutionized the ancient art of surveying, and Utah is at the forefront in putting the new technology to work.
Utah is the first state in which the Bureau of Land Management has signed an agreement with counties to tie their surveys into a national mapping network, using the new system. A new data base called the Land Information System is expected to be set up, using the mapping data along with information about mining and other resources.The library of information is expected to enhance the ability of land administrators to manage the public domain.
"It's a major effort nationally within the BLM," said Donald A. Buhler, the agency's land surveyor for Utah. The BLM wil spend $150 million developing the Land Information System.
To show how the Global Positioning System works, Buhler and a team of experts set up a tall, spindly antenna over the Salt Lake Base and Meridian Post. They erected the antenna and booted up their computer for display only. But the measurement was actually performed this way recently, when the post's location was checked by satellite.
Six satellites orbiting 11,000 miles above the earth beam signals constantly. They are intercepted by temporary receivers like the one set up over the post.
A laptop computer interprets signals from four or five of the satellites, depending on which ones are in the line of sight at the time a position is being figured.
Six Air Force satellites are in use. They're to be joined by a new one, expected to be launched on Jan. 13. Eventually, 24 will be there, in six orbital planes.
With data from four or five satellites and two separate antennas, the system "can get it down to a couple of inches - an inch or less," said Buhler, technically a geodesist for the BLM's Cadastral Survey.
He and BLM land surveyor Milbert Krohn demonstrated how the computer outlines the satellites' orbits.
"It gives us an accurate latitude and longitude, in such an efficient manner now that we're able to make our maps in a much more accurate manner," Buhler said.> First priority for using the satellite system are places with high property or natural resource values - where it's important to know exactly on whose land that gold mine is located. It can pinpoint the ownership of valuable timber tracts on national forests, or oil, gas, minerals and coal on BLM land.
Eventually, blind people may carry backpacks with radios that will be able to tell them exactly where they are on city streets. Or hikers can find out their precise locations.
In the past, surveyors always worried about the weather. Strong winds would make their instruments shake so badly they either had to put up tents around them or give up looking through the telescopes. Heat waves or car exhausts distorted the view, giving false readings.
The new radio system ends all that. Although severe storms can damage data, the computers have safeguards built in to throw out suspect signals.
While the atmosphere can bend radio waves too, as long as several satellites are used at the same time, the distortions cancel each other out, Krohn said.
The whole state is expected to be surveyed using the new Global Positioning System by the end of the century. But it's already helped in establishing boundaries for valuable claims in Uintah County, according to a BLM release.
Also, it has been useful in Washington County to calculate the positions of crucial surveying markers.
"The Salt Lake County Surveyor's Office hopes to someday have enough money to purchase this sort of thing," said Carl Larsen, Salt Lake County surveyor.
At least two setups, antennas and computers, are needed for precise data. They cost about $32,000 a set.
"Nationally, with the Forest Service we've incorporated some data into our maps that was generated in this manner," said Robert Nutter, a cartographic technician with the U.S. Forest Service's Geometronics Service Center, 2222 W. 23rd South.
Wealthy yachters use the satellites today for navigation.
The BLM is considering setting up three permanent stations in Utah that would broadcast satellite-corrected location information 24 hours a day. One could be in Salt Lake City, another in Cedar City, the third in Moab.