One of the toughest challenges for the Mars mission teams remotely conducting the experiments from Earth is to visualize a rover's position on the planet relative to objects in the Martian environment. A tool developed at Ames Research Center called Viz uses two-dimensional images a rover returns to display a three-dimensional picture, putting the teams virtually in the Martian environment.

"The idea is to put the scientist, as much as possible, on Mars," says Viz project lead Larry Edwards.

Using a keyboard and mouse, teams can drive the rover around a reconstructed Martian surface to interactively explore and plan experiments. With Viz the teams can virtually travel across the surface to pick science targets, and select the safest, most efficient path.

Viz and similar virtual reality tools are essential to controlling planetary rovers and for conducting science on Mars, says MER and Mars Pathfinder mission scientist Michael Sims. "In order to drive a rover one must know the context within which the rover sits and in order to understand a scientific measurement you must know the context of where that measurement was made."

Viz is primarily used by science planning teams. With Viz teams can measure the rock surface areas and the distances between the rocks with clicks of a mouse. With the topographical information that Viz provides and the software's ability to pour virtual water into depressions, scientists can hypothesize what natural forces, such as ancient water or lava flow, might have shaped the planet.

Within the virtual Marscape, the software predicts when and where on Mars the sun will cast shadows on the rover and land surfaces so that mission planners can capture good images and other data. With Viz scientists can pan and tilt the camera to preview an image before the scientists send the real rover over to take a shot.

At a software laboratory at Ames' Computational Sciences Division, Edwards faces a computer monitor while wearing what resemble safety goggles. The goggles are stereo glasses that produce a 3-D image from the rover's 2-D stereo pictures. The effect is a lot like that of the old blue and red 3-D movie glasses, but better. "They really reveal the subtle and sometimes not-so-subtle variations in the terrain that you don't always pick up in a two-dimensional image," he says.

For example, during a mission field test in an Earth desert a couple of years ago scientists using two-dimensional photos spotted what looked like a ground depression between the rover and a rock the scientists wanted the rover to examine. Viz clearly showed the potential for danger. "In 3-D it was quite a sharp drop off," says Edwards. "It showed them they probably wanted to take another path."

Years before that, in 1997, the Viz predecessor called MarsMap provided the Mars Pathfinder teams with virtual exploration. Sims recalls that MarsMap proved critical as teams navigated Pathfinder's Sojourner rover up against a large rock. "The overhang was obvious in the Ames 3-D virtual reality models but almost unnoticeable in the direct 2-D images traditionally used for navigation."

With the latest MER version of the Viz, its developers made the software adaptable to other NASA missions. Viz now supports network communications so that two or more people in different locations can communicate through Viz. The team plans to play a role in the next Mars rover mission, Edwards says, the 2009 Mars Science Laboratory (MSL), which calls for onboard autonomy and remote operations.

"With network capability, one thing for the future might be to have some real remote collaborative capability for scientists at different institutions to work in the Viz environment," he says. In 2009, Viz might also help the MSL rover's autonomy software figure out on its own the best, safest route for reaching science targets the teams select. "One way might be to visualize the route."