'We can lose three [computers] and still ride through: Inside the 8-CPU brain of NASAs Artemis II that votes on every move

Date:
Fri, 17 Apr 2026 21:50:00 +0000

Description:
NASAs Orion spacecraft uses eight synchronized processors and layered redundancy to maintain operations in deep space, where hardware failures cannot be repaired.

FULL STORY ======================================================================Copy link Facebook X Whatsapp Reddit Pinterest Flipboard Threads Email Share this article 0 Join the conversation Follow us Add us as a preferred source on Google Newsletter Tech Radar Pro Are you a pro? Subscribe to our newsletter Sign up to the TechRadar Pro newsletter to get all the top news, opinion, features and guidance your business needs to succeed! Become a Member in Seconds Unlock instant access to exclusive member features. Contact me with news and offers from other Future brands Receive email from us on behalf of our trusted partners or sponsors By submitting your information you agree to the Terms & Conditions and Privacy Policy and are aged 16 or over. You are
now subscribed Your newsletter sign-up was successful Join the club Get full access to premium articles, exclusive features and a growing list of member rewards. Explore An account already exists for this email address, please log in. Subscribe to our newsletter The Orion spacecraft uses eight processors running identical instructions simultaneously A fail-safe design prevents faulty computers from sending incorrect commands Triple redundant memory corrects single-bit errors automatically on access The NASA Artemis II
mission relies on a computing system built to remain operational under
extreme conditions and hardware faults.

Unlike the Apollo program, where onboard computers handled limited functions, the Orion spacecraft manages life support, navigation, and communication through integrated flight software. The Orion capsule carries one of the most fault-tolerant computer systems ever built for spaceflight, operating 250,000 miles from Earth, where no repairs are possible. Article continues below You may like Even the Artemis II astronauts aren't immune to Microsoft software glitches You can buy the same memory card used during the Artemis II mission on Amazon Artemis II will use laser beam tech to send '4K video from the
Moon' From Apollo's limits to Orion's full system control Apollo astronauts relied on a 1MHz computer with just 4 kilobytes of memory, but today's spacecrafts need much more, considering the distance.

The Orion spacecraft uses two vehicle management computers, each containing two flight control modules.

Each module consists of a pair of processors that continuously check each other's outputs, resulting in 8 processors executing the same instructions simultaneously.

If a processor produces an incorrect result, the paired design detects the mismatch immediately and prevents the output from being used. Are you a pro? Subscribe to our newsletter Sign up to the TechRadar Pro newsletter to get
all the top news, opinion, features and guidance your business needs to succeed! Contact me with news and offers from other Future brands Receive email from us on behalf of our trusted partners or sponsors By submitting
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"We still architect to cover for hardware failures," said Nate Uitenbroek, Software Integration and Verification Lead in NASA's Orion Program.

"Along with physically redundant wires, we have logically redundant network planes. We have redundant flight computers."

Instead of relying on majority voting, the system selects outputs from available modules based on a defined priority order. What to read next The first iPhone 17 Pro Max photos sent from the Artemis II mission NASA unveils its playlist of wake-up call songs for the Artemis II crew Artemis II astronaut snaps stunning Moon photo with an iPhone 17 Pro Max

The system is designed to tolerate rapid failures during flight. Uitenbroek stated, "We can lose three FCMs in 22 seconds and still ride through safely
on the last FCM A faulty computer will fail silently, rather than transmit
the wrong answer."

Failed modules are reset and re-synchronized, allowing them to rejoin the system during the mission.

Orion uses a time-triggered Ethernet network that distributes a shared time reference throughout the system - so if a module fails to meet its execution deadline, it is automatically isolated, reset, and re-synchronized before returning to operation.

The computing system includes triple-redundant memory capable of correcting single-bit errors during every read operation.

Network interfaces use dual communication lanes that are continuously
compared to detect inconsistencies, while the overall network is replicated across three independent planes.

Orion carries a separate Backup Flight Software system that operates on different hardware and software, running continuously in the background.

"It is intentionally different to ensure that a common mode software failure in the primary flight software isn't also implemented incorrectly on the backup," Uitenbroek said.

The spacecraft also includes procedures for full power loss scenarios, allowing systems to restart, stabilize, and re-establish communication once power is restored.

The system is overengineered by any commercial standard, but deep space
offers no second chances.

Whether all 8 processors will perform as designed under real radiation conditions remains untested, and the backup software has never faced an
actual emergency.

Still, for a mission where the nearest hardware store is 250,000 miles away, this architecture makes a brutal kind of sense.

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