Artemis: The Power of Eight Has Resolved to an Unpleasant Number
April 10, 2026
Another dinobaby post. No AI unless it is an image. This dinobaby is not Grandma Moses, just Grandpa Arnold.
The flight around the moon has generated some interesting stories. One of these is “How NASA Built Artemis II’s Fault-Tolerant Computer.” The main point of the write up struck me as:
This month’s Artemis II mission carrying a crew of four around the Moon for the first time in over 50 years is supported by one of the most fault-tolerant computer system built for spaceflight. Unlike Apollo, the Orion capsule’s computing architecture manages nearly all of the vessel’s safety-critical functions, from life support to communication routing.
The article includes snappy subheads like “The Power of Eight.” That means to those in the know “triple redundancy.” A system, fail over system B, and a third backstop system.
Thanks, Venice.ai. Good enough just like the “triple redundancy” extolled by the ACM outfit.
The article points out:
This level of redundancy is specifically scaled for the rigors of deep space.
I found this statement fascinating:
The hardware itself is also reinforced. The system employs triple-modular-redundant memory that self-corrects single-bit errors on every read. Even the network interface cards utilize two lanes of traffic that are constantly compared, ensuring that a bit flip in the communication fabric results in a fail-silent event rather than a corrupted command. The network itself is triple redundant with three separate planes, and all network switches employ self-checking strategies.
The ACM write up concludes:
As spaceflight technology has historically seeded commercial advances, Orion’s zero-tolerance architecture offers a preview of a future where mainstream computing—from autonomous vehicles to industrial grids—can achieve the same always-on resilience that’s required for the stars.
Reassuring. However, when I thought about this explanation of the power of eight, I thought about three issues:
- Microsoft Outlook ran two instances and seemed to not match the rigor described in the cited ACM article
- The toilet failed, was “fixed,” and then failed again
- The heatshield will be a binary upon reentry. I hope that the triple redundancy and power of eight works appropriately.
Net net: Consumer software, a toilet obviously not designed for the rigors of space travel, and a heat shield that either works or does not work. To narrow the power of eight seems appropriate. Some systems are operating at a power of zero. No, that’s not correct. There are diapers.
Stephen E Arnold, April 10, 2026
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[…] computing uses Triple Modular Redundant memory, storing every data value three times. When software reads a byte, the hardware performs a “best-of-three” vote, automatically correcting any single-bit error on […]