GREENBELT -- Jerry Von Ahn flew low over the barren red landscape yesterday, plotting a course that his mission's Mars Rover could follow in exploring the terrain around the landing site.
His low-flying craft dipped into the valleys and pulled up abruptly to clear the steep Martian hills as the pale sun cast long, dark shadows over the rocks.
When he reached the base station, the operator reset the virtual reality display and showed him how he did. As Mr. Von Ahn watched through his optical headset, the Mars Rover cruised past the first flag easily, like a Jeep traversing rolling farmland. Then the ground craft ventured onto terrain that was too steep. It tipped over.
"Congratulations, you have just killed the Mars Rover," read the message flashing across the computer monitors at the Digital Equipment Corp. display. "Not only have you wasted hundreds of training hours, but also billions of taxpayer dollars. You need more training."
Mr. Von Ahn, a manager with RMS Technologies at the Goddard Space Center in Greenbelt, didn't seem dismayed. "That was great, really, really wonderful. It was almost like being there," he said.
The simulation of travel on the Martian surface was one of three virtual reality demonstrations presented yesterday as Woburn, Mass.-based DEC showed off its latest technologies. The program Mr. Von Ahn viewed, created for the National Aeronautics and Space Administration, is being used to train astronauts for an eventual manned flight to Mars, DEC officials said.
In rough terms, virtual reality is a technology that uses computers to generate a simulated three-dimensional environment in which the scenery shifts as the viewer's perspective changes.
Beyond that, there's little agreement on a definition, said A. J. Michalewicz, the DEC computer technology consultant who oversees the company's advanced-technology efforts. "Everyone has their own understanding of what virtual reality is," he said.
While the technology has been portrayed in movies and on television in fanciful terms, virtual reality is actually "right around the corner," Mr. Michalewicz said. "It's in its infancy, but there's a lot of good work that's happening now."
Mars training aside, most of the uses being devised for virtual reality are down-to-earth business applications, Mr. Michalewicz said. For instance, he said, Boeing Co. was using virtual reality displays to give prospective buyers "tours" of the interior of its new 777 jetliner even before it had built a plane.
A second display at DEC's regional headquarters in Greenbelt yesterday showed how virtual reality can let a viewer navigate around the three-dimensional interior of an office building -- choosing which corridors to follow, poking in and out of offices and viewing the lobby's atrium from different levels. That particular application was devised for U.S. Army anti-terrorist training so that troops planning to storm a building could study its interior before launching an assault.
A third, more abstract program called "Virtual Portfolio Manager," used a symbolic landscape to represent trends in the global stock market. Under the concept, a trader ofthe future would use the program to spot global opportunities faster than is possible now.
Mr. Michalewicz said that virtual reality has been around for decades but that it has been hampered by a lack of affordable computer power. Virtual reality is a ravenous consumer of processing power because the entire geometrics have to be recalculated 30 times a second when the picture is in motion, he said.
Only within the last year or so have the prices of microprocessors that are powerful enough, such as DEC's Alpha, come down enough to make virtual reality cost-effective, Mr. Michalewicz said.
For now, most virtual reality displays are handicapped by graphics that can readily be discerned as computer drawings. But by the end of the decade, virtual reality environments will achieve photographic quality, he said. In addition, DEC is working on head-mounted displays that will weigh only a few ounces, he said.