"That's where I poked around before finally settling on my Garmin eTrex Vista," Durda said. "It's a great little unit that cost me about $240 by the time I got all the special promotion discounts."

Durda said the unit is very easy to use and Garmin updates the software for the unit occasionally with new features.

"You just download the new software from the Garmin web site and uplink it to the unit via the serial interface," he said. "I really like the interface with the various versions of topographic map software on my laptop. I've connected the unit to the laptop for real-time moving-map display of where I'm at while driving [or] shooting instrument approaches while flying."

Durda said the GPS unit has been helpful in making note of geological sampling of sites, particularly in doing research on the Cretaceous-Tertiary (KT) boundary -- the KT border line separating the age of the reptiles and the age of the mammals.

"It's great," he said. "You grab a sample, click the 'mark waypoint' option on the GPS unit, and later download all the waypoints to [the] topographic map software to mark and label all the samples sites."

Durda has heard of people mowing corn mazes based on precise GPS navigation of pre-planned design maps.

A more serious and related use, he said, is in precise application of fertilizers and pesticides on large farms. Farmers can use satellite multispectral image data showing the health of their crops and build up field maps of the best places to apply fertilizers or pesticides in various concentrations. Their tractors and application hardware are then programmed and linked with GPS data to appropriately apply the materials as they drive around the field.

As Durda puts it, "Better crop yield to feed a hungry world all brought to you by space technology."