Return to the Red Planet

National Aeronautic and Space Administration

Long gone are the days when space missions were conducted by radio waves and onboard computer memory was limited to storing merely a few hundred words.

Space exploration technology has evolved to the point that NASA can now provide near-real-time 3-D views of neighboring planets via the Internet.

Since Jan. 4, NASA has treated billions of online viewers to spectacular images of Mars, courtesy of Spirit, the latest Mars Exploration Rover to land on the Red Planet. And with a second rover, Opportunity, in flight to Mars and expected to land near the planet's south pole Jan. 24, NASA plans to keep the images flowing.

"It's going far, far better than I had hoped," said Mark Adler, mission manager for the Mars Exploration Rovers program at the Jet Propulsion Laboratory in California. "Everything's going really well."

After flying more than 300 million miles and navigating a tricky landing, Spirit has used its two scientific panoramic cameras to transmit some of the best images ever captured of Mars.

Donna Shirley, a former manager of the rovers program who worked on the 1997 Pathfinder mission, marvels at the ability of Spirit's technology to generate high-

resolution images.

Spirit "has a camera so good it's like being there yourself with 20/20 vision," said Shirley, who is the director of Experience Science Fiction, a Seattle museum opening this summer.

The onboard technological force behind Spirit is VxWorks a real-time operating system made by Wind River Systems Inc. This system controls all mission-critical tasks, such as trajectory, descent and ground operations control, data collection and Mars/Earth communication relay.

Spirit's operating system is embedded in an old IBM Corp. RAD 6000 computer that Adler said resembles a desktop model from the mid-1990s. Running at 20 MHz and radiation-hardened to survive the mission, the computer contains 128M of memory, with 256M of flash memory for storing images.

This onboard computer is nearly

identical to the one on the Pathfinder rover, Adler said. Spirit was designed to maximize the capabilities of this system and was given additional memory for image storing.

Despite not being considered a state-of-the-art onboard system, it is still a vast improvement from past NASA missions.

Shirley said the 1973 Mariner 10 Venus/Mercury mission had a flight control system that was limited to 512 words of onboard memory and that Pathfinder was the first Mars rover with a hazard-avoidance system.

NASA has benefited from technological advances made in the land systems used by mission control. Engineers operating on Sun Microsystems Inc. stations with Solaris software can process larger amounts of data than ever before, Adler said.

The high-speed processors allow NASA officials to ensure that software programs on Spirit work before the rovers roll off the lander to validate all systems on the ground before being sent up to Spirit. To accomplish this task, officials test full-scale duplicates of the rovers and use computer simulation programs.