As we observed NASA put a rover on Mars last month, it appeared as if the agency had to be employing some kind of high-tech processor in its machine. The rover is built on something much stronger than the components in devices we general civilians use. However, as NASA is technically applying a particular processor to equip the Perseverance rover, it’s not much detached from the world of consumer electronics, almost 23 years back.
The Perseverance rover is powered by a PowerPC 750 processor, which was employed in Apple’s original 1998 iMac G3, the iconic, colourful, see-through desktop. If the name PowerPC sounds familiar, it may be due to those RISC CPUs Apple applied in its computers before switching to Intel. Nevertheless, now the company is back on the RISC train with its homegrown M1 processor.
The PowerPC 750 was a single-core, 233MHz processor, and compared to the multi-core, 5.0GHz-plus frequencies modern consumer chips can attain, 233MHz is very slow. However, the 750 was the first to include dynamic branch prediction, widely used in modern processors today. The CPU architecture is making a smart guess on what instructions the CPU is going to process for improving efficiency. The more information that’s processed, the better the chip gets at forecasting what it needs to do next.
Though, there’s a major difference between the iMac’s CPU and the one inside the Perseverance rover. BAE Systems manufactures the radiation-hardened version of the PowerPC 750, dubbed RAD750, which can resist 200,000 to 1,000,000 Rads and temperatures between −55 and 125 degrees Celsius (-67 and 257 degrees Fahrenheit). Mars doesn’t have the same atmosphere type as Earth, which shields us from the sun’s rays, so one flash of sunlight and it’s all over for the Mars rover before its adventure can start. Each one costs above $200,000. That’s why some extra protection is mandatory.
If you wonder why to use a processor so old to remember when Eve 6 released its first album, then you should know that it has nothing to do with cost. Those old processors are the ideal ones for the job as they are dependable. NASA’s Orion spacecraft, for example, applied the same RAD750 processor.
Taking that into consideration, it’s sensible that NASA would opt for older technology over the new one. If you’re spending $2.7 billion to land a robot on Mars, your tech must be authentic enough to stand the test of time, down to the tiniest soldered circuits. Presently, the RAD750 empowers almost 100 satellites orbiting Earth, which includes GPS, imaging, and weather data as well as various military satellites. None of those has failed until now.