Hardware

SpaceX for the Falcon 9 uses Linux and x86 processors on three redundant computers

A few days ago we all marveled at the liftoff of SpaceX's Falcon 9 that powered the Crew Dragon capsule with two NASA astronauts. Recently, data on the software and hardware used for the rocket has also been released by SpaceX. Through this and employee data, the Falcon 9 has been known to use simplified Linux and x86 processors.

It seems that the most cutting-edge rocket in the world today is based on a specific Linux distribution quite reduced. In addition, to run and control all systems and sensors, three duplicate computers based on dual-core x86 processors are used. Which is really interesting data.

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SpaceX on the Falcon 9 uses Linux and x86 processors

These processors do not have dedicated or special elements, they would be quite ordinary chips. In addition, they do not have special protections against radiation, since the first stage of the Falcon 9 is hardly in outer space. The redundancy of the systems would be more than sufficient and saves a lot of costs.

Unfortunately it has not been revealed specifically which processor they are using. This ISS uses the Intel 80386SX 20MHz processor with multiplexer and demultiplexer to control it. Additionally for daily work HP ZBook laptops with Debian, Scientific Linux or Windows 10 are used. Linux systems are used as remote terminals for C&C MDM and Windows for viewing emails, browsing and entertainment.

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Regarding the software for the flight control of the Falcon 9, it would have been written in C / C ++, a language that Elon Musk masters. This software runs in parallel on the three installed computers. Three redundant computers to give reliability to multiple backups. Each result of each computer is compared with that of the other systems and if they match, the command is validated and executed.

Custom designed software

All the specific software for on-board systems, a rocket simulator, flight control diagnostic tools, communication software and even flight analysis software has been developed by 35 engineers. The flight control software and equipment has been tested in a simulator prior to launch. Within the simulations, various veiling conditions and emergency situations have been tested.

The Crew Dragon capsule makes use of a flight software based on Linux and C ++. The graphical interface used for astronauts is a Chromium-based JavaScritp. Everything is managed by a touch screen, but in case of failure, there is a keyboard that allows you to control the ship.

Why three processors? This is because, as explained in StackExchange Space Exploration, SpaceX uses an Actor-Judge system to provide security through redundancy. In this system, each time a decision is made, it is compared with the results of the other cores. If there is any disagreement, the decision is discarded and the process restarts. It is only when each processor gets the same response that a command is sent to the PowerPC microcontrollers.

These controllers, which make the decisions for the rocket motors and fins on the network, get three commands from each of the x86 processors. If all three command strings are identical, then the microcontroller executes the command, but if one of the three is incorrect, the controller follows the last correct instruction above. If things go completely wrong, the Falcon 9 ignores commands from the failing chip.

Indicates ZDNet

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Roberto Solé

Director of Contents and Writing of this same website, technician in renewable energy generation systems and low voltage electrical technician. I work in front of a PC, in my free time I am in front of a PC and when I leave the house I am glued to the screen of my smartphone. Every morning when I wake up I walk across the Stargate to make some coffee and start watching YouTube videos. I once saw a dragon ... or was it a Dragonite?
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