I seem to be on a space jag lately. My last blog entry, about the TubeSat, talked about an affordable option to put a small satellite in low Earth orbit. According to a NASA document I found, low Earth orbit's environment is "fairly benign with a typical dose rate of about 0.1 krad/year." However, communication satellites, among others, prefer a geosynchronous orbit where the satellite appears to be over a fixed location on the Earth. That means the satellite must have a rotation speed of 1 revolution per day and the speed is a function of the satellite's height. So a geosynchronous satellite orbits at 36,000 km (compared to 500 km for the International Space Station in low Earth orbit, for example). At 36,000 km the radiation does is about 10 krad/year -- quite a bit more than a lower satellite will endure. For a 10 year mission, that adds up to 100 krad of exposure. Earlier this month Xilinx announced a radiation hardened version of the Virtex-5 FPGA which claims immunity to 700 krad. Xilinx claims that a combination of techniques make the new member of the Virtex family robust enough to use standard IP even in harsh radiation environments like geosynchronous orbit. Granted, not everyone has this problem. But if you do design for high radiation environments, its probably worth a look.

August 01, 2010
URL:http://www.drdobbs.com/embedded-systems/space-fpgas/228701718

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