Electronic Design

Engineering Expertise Triumphs In Mars Rovers

I'm really happy to see so much media focus on the Mars Exploration Rover program. Space exploration frequently gets buried in the back pages of the paper, while I scratch my head thinking, "Why isn't this front page news?"

Part of the reason Spirit, the first of two Rovers landing this month, is getting so much coverage is the quality of the images it has been sending back from the Red Planet. Two high-resolution color stereo cameras mounted at human-eye height deliver "you-are-there" pictures with unprecedented detail. Their narrow-angle optics provide three times the resolution of the cameras on the previous Pathfinder mission. These great photos (or even 3D images if you have red and green viewing glasses) are truly exciting.

The Spirit story resonates in the U.S. and around the world because space exploration unites earthlings like nothing else. In our divisive post-September 11 world, the ability to robotically rove another planet and beam back images to our home sphere unites us in a universe too large to be divided by ethnic or religious rifts. What's more, Spirit is the first real-life anthropomorphic robot in space. With its camera eyes, antenna tail, and robotic arms and legs, it looks a bit like a long-necked dog in space. Similar to Rover the dog, it even digs and picks up rocks! What's not to like?

Seriously, though, landing successfully on Mars is a true technological triumph. This difficult feat has been achieved just twice before, with many failed attempts in between. Congratulations to all of our readers who have played a part in the program.

In addition to the engineers at NASA, thousands of electronic designers have worked on the myriad components that came together in this triumph of electronics. I'm curious to know how many of you have contributed some piece of technology to the mission. For example, the computer in each Mars Exploration Rover runs with a 32-bit Rad 6000 microprocessor, a radiation-hardened version of the same PowerPC chip that's in my Mac.

Our continued race for electronic advancement means far more when the pieces are put together in a project of this magnitude. Spirit is real testimony to the power of the human cooperative spirit and engineering genius.

Just getting to Mars and sending back color video postcards is accomplishment enough, but the Rovers are equipped for much more, thanks to advanced scientific electronics and robotics. Essentially, the Rovers are "robotic field geologists," according to Steve Squyres of Cornell University, principal investigator for the Rovers' science instruments. "They look around with a stereo, color camera and with an infrared instrument that can classify rock types from a distance. They go to the rocks that seem most interesting. When they get to one, they reach out with a robotic arm that has a handful of tools, a microscope, two instruments for identifying what the rock is made of, and a grinder for getting to a fresh, unweathered surface inside the rock."

Squyres makes it sound simple, but powering the robot's geologic forays is an amazing display of engineering prowess. The Rover's core body, the "warm electronics box," is topped by an equipment deck populated with three antennas, a pivoting camera mast, and panels of solar cells. Unfolded on deployment, the solar cells form a total area of 14 ft2 with three layers of photovoltaics: gallium indium phosphorus, gallium arsenide, and germanium. The array, which charges lithium-ion batteries, produces nearly 900 watt-hours of energy per Martian day, though that capacity will be decreased by about a third by the end of the mission due to changes in season and dust accumulation. Because the batteries and other components aren't designed to survive Martian night temperatures as low as −157°F, radioisotope heaters using cells powered by plutonium dioxide keep the box warm.

Other tools will be key during Spirit's search for geologic clues to the hydrologic (and potentially biologic) history of Mars, too. The mini-thermal emission spectrometer determines the mineral composition of surface features from afar. With infrared observation, scientists can peer through the dusty Martian coating to look for organic molecules and minerals formed in water.

Also, the microscopic imager's micron-scale closeups of rocks and soils will help characterize sedimentary rocks to understand Mars' geologic history. A Mossbauer spectrometer determines the magnetic properties of samples using two pieces of radioactive cobalt-57. An alpha particle X-ray spectrometer further analyzes elemental makeup using curium-244 for generating radiation. A rock-abrasion tool works just like a geologist's rock hammer. And, magnet arrays collect airborne dust for instrument analysis.

If you haven't already, visit http://marsrovers.nasa.gov for a tremendous wealth of images and info. Here's hoping that this week's headlines include Spirit's twin, Opportunity, making a perfect landing as well.

TAGS: Robotics
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