And why would we report that here? Because Opportunity and Spirit were both in fact powered by the POWER1, or more accurately a 20MHz BAE RAD6000, a radiation-hardened version of the original IBM RISC Single Chip CPU and the indirect ancestor of the PowerPC 601. There are a lot of POWER chips in space, both with the original RAD6000 and its successor the RAD750, a radiation-hardened version of the PowerPC G3.
That's not the end of Power ISA chips on Mars, though: Curiosity, which is running a pair of RAD750s (one main and one backup, plus two SPARC accessory CPUs), is still in operation at 2,319 Mars solar days and ticking. There is also the 2001 Mars Odyssey orbiter, which is still circling the planet with its own RAD6000 and is expected to have enough propellant to continue survey operations until 2025. Curiosity's design is likely to be reused for the Mars 2020 rover, meaning possibly even more Power chips will be exploring space and doing science where it counts millions of miles from home.