When Pathfinder touches down on Mars on Friday morning and the Sojourner vehicle roves around the arid surface, NASA scientists will put virtual reality to its intended use - giving the researchers the sensation that they're standing on the planet surveying the environment. But the true reality is that their shoe leather will be planted firmly on the floors of the Mars room of the Jet Propulsion Laboratory and the Ames Research Center.
The lander and Sojourner "will help us build a virtual model of the planet. We'll be observing the planet much like a field geologist surveys an area and breaks it down into individual study sites," said Daryl Rasmussen, telepresence researcher at NASA's Ames Research Center in Mountain View, California.
Virtual reality was developed by NASA 10 years ago to bridge a sizable communications gap between scientists and Mars-bound craft. Namely, scientists would issue commands to change the direction of a landing vehicle or orbiting craft only to have to wait more than a day for the directions to arrive at the vehicle and for the craft to act upon them.
The landing craft and Sojourner each will be equipped with stereo cameras that will send data to an orbiting satellite that, when it has a simultaneous line-of-sight between the Mars craft and Earth, will relay the information to researchers clad in stereo goggles and binoculars.
But even with this batch of communications and visualization technology, Rasmussen and his colleagues will be limited to sending only one command per day - perhaps two if they're lucky.
Researchers will have to be judicious in their choice of commands, but the VR Mars environment will help give Rasmussen and his colleagues a heads-up of what awaits the rover.
That heads-up is just what Rasmussen worked to achieve with his remote exploration system. As Pathfinder descends onto the Mars surface and touches down onto airbags, the stereo cameras on the lander will pan around Mars to capture a succession of 360-degree views. Once these images are relayed to Rasmussen and his colleagues, they will be able to survey the surroundings and break down the environment into study sites.
Sojourner - named for Sojourner Truth - will emerge from a flower-like casing that will peel away, petal by petal. The vehicle will pan its stereo cameras to observe its immediate surroundings and note, for example, how far the airbags spread out around it on the Mars surface and where obstacles such as rocks lie. These first observations will help the scientists direct Sojourner on a smooth path.
From this point, the directions that Rasmussen and his colleagues issue will have more to do with what they'd like to study, and which instrument they'd like Sojourner to use. Back at the observation rooms at both Ames and JPL, the researchers will have tools such as rulers to measure distances on their screens and pointers - in the form of railroad tracks - to direct Sojourner toward certain sites.
"We can lay out a track to a study site we want to observe. So if we see an area with water, we'd want to lay tracks toward that area so Sojourner could study it to see if there was once life there," Rasmussen said.
The actual operation of the scientific instruments will be part of the intelligence already loaded onto Sojourner, so scientists need only ask the rover to analyze rocks or dig in a certain spot to study the soil with the spectrometer. The craft will be able to operate the mechanical arms itself.
As Sojourner makes stops, it will leave signposts that will be visible to the scientists through the goggles. By selecting a signpost, the scientists will receive a close-up view of the study site and data that Sojourner has recorded using its instruments.
Rasmussen was confident that the mission would go off well. In a sense, he has been rehearsing for this simulated voyage for almost 10 years - perfecting his remote exploration equipment in the process. He was once called upon to use this technology to venture the seas of Greece to survey the wreckage of the Titanic's sister vessel, the Britannic.
The product of his Mars exploration practice - a simulated Mars environment from data from the Viking voyage - is currently making its way around the United States at state and county fairs. This show - the Cosmic Carnival - will make its home at the Smithsonian's Air and Space Museum this fall.
