Out-of-this-world electronics
Wow, and congratulations! That's my reaction to what the scientists and engineers at NASA have accomplished with the success of the current Mars Exploration Rovers mission. They not only managed to design, build, and test the systems while working within an extremely tight time frame, but followed through by achieving a successful landing and deployment of both rovers on the Martian surface.
The success of the current Mars Rovers mission depended on a wide assortment of electronic products�the types of products we cover every day.
Congratulations too, to all of the companies who produced products that contributed to this achievement. This was no small feat, especially considering many of the issues involved in developing and testing high-reliability electronics, as discussed in our Military/Aerospace Forum in this issue.
Since reporting on products is our stock in trade, I was curious about those that were used in the design and construction of the Mars Rover systems. Searching through press releases and on the Internet, I was able to come up with a varied�although by no means complete�list.
At the core of the rovers is a RAD6000 single-board computer provided by Information and Electronics Warfare Systems (Manassas, VA), part of BAE Systems. The 6 x 9-in. boards are running the VxWorks RTOS from Wind River (Alemeda, CA), and feature a radiation-hardened 32-bit RAD6000 microprocessor with 256 Mbytes of flash memory.
Each of the rovers is powered by two solar-charged lithium-ion battery packs manufactured by Lithion (Pawcatuck, CT), a division of Yardney Technical Products. The batteries provide power at night and aid the solar panels�manufactured by ATK Composite Optics (San Diego, CA)�during peak daytime energy usage.
As always, power management plays a critical role, and several companies have contributed in this area. Dc/dc high-reliability converter modules and MOSFET devices from International Rectifier (El Segundo, CA) are managing, maintaining, and conditioning battery power and charging systems in each Mars lander.
In addition, radiation-hardened high-performance analog semiconductor products from Intersil (Milpitas, CA)�who make single-event-hardened MOSFET drivers, PWMs, voltage regulators and references, and power supervisory circuits�are incorporated in various electronic systems on the rovers. And high-performance memory modules and A/D converters from Maxwell Technologies (San Diego, CA) are used in the power systems and communications electronics.
Of course without their motion and imaging capabilities, the rovers would be little more than stationary computers. Key to the motion-control functions on each rover are 39 motors from Maxon Motor (Burlingame, CA), which are used for driving the wheels and robot arms, for the steering mechanism, and for controlling the cameras.
Helping to control the motors for the wheels, steering, arms, cameras, and various instrumentation in the rover vehicles are radiation-tolerant Virtex FPGAs from Xilinx (San Jose, CA). Radiation-tolerant and radiation-hardened FPGAs from Actel (Mountain View, CA) are key to the operation of the multiple cameras aboard each of the rovers, as well as to the radio communications that relay the images back to the orbiters.
The 1,024 x 1,024-pixel CCD image sensors responsible for delivering the high-resolution images of the Martian surface were designed by JPL and manufactured by DALSA (Waterloo, Ontario, Canada). Located on the mast of each rover, the sensors can generate panoramic image mosaics as large as 4,000 pixels high by 24,000 pixels around.
Glass-dielectric capacitors from AVX (Myrtle Beach, SC) play a critical role in the circuits that enable the lander to open and adjust its petals, and enable it to raise the rover so that its wheels can be deployed to drive onto the Martian terrain. The capacitors' construction offers superior electrical performance, while providing environmental immunity, stability, and retraceability.
Connecting each rover's robotic arms, cameras, high-gain antenna, wheels, and sensors to the CPU are advanced flexible circuits from Dupont (Research Triangle Park, NC). The flexible laminates were key to achieving the required circuit density, small size and weight, reliability, and tolerance.
Finally, one can't ignore the EDA and development software tools that were used in various aspects of the design. For example, the CCD chip was designed using a layout editor and Spice simulator from Tanner EDA (Pasadena, CA).
The rovers' robotic arms were designed using SolidWorks' (Concord, MA) COSMOSWorks finite element analysis software, which was used to optimize the parts' balance of strength and lightness. And all of the flight software aboard the Mars Exploration Rover missions was written by JPL engineers using software development tools from Green Hills Software (Santa Barbara, CA).
R. Pell, Editor-in-Chief rpell@hearst.com
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