What computer and software is used by the Falcon 9?

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Flojo

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What computer and software is used by the Falcon 9?

I don't know if this would be public, but what CPU / Microcontrollers are used and what software do they run on the Falcon 9? Do they use an OS or is it just bare metal programming? I found some m...
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SpaceX uses an Actor-Judge system to provide triple redundancy to its rockets and spacecraft. The Falcon 9 has 3 dual core x86 processors running an instance of linux on each core. The flight software is written in C/C++ and runs in the x86 environment. For each calculation/decision, the "flight string" compares the results from both cores. If there is a inconsistency, the string is bad and doesn't send any commands. If both cores return the same response, the string sends the command to the various microcontrollers on the rocket that control things like the engines and grid fins.
The microcontrollers, running on PowerPC processors, received three commands from the three flight strings. They act as a judge to choose the correct course of actions. If all three strings are in agreement the microcontroller executes the command, but if 1 of the 3 is bad, it will go with the strings that have previously been correct. The Falcon 9 can successfully complete its mission with a single flight string.
The triple redundancy gives the system radiation tolerance without the need for expensive rad hardened components. SpaceX tests all flight software on what can be called a table rocket. They lay out all the computers and flight controllers on the Falcon 9 on a table and connect them like they would be on the actual rocket. They then run a complete simulated flight on the components, monitoring performance and potential failures.
SpaceX engineers perform what they call "Cutting the strings" where they randomly shut off a flight computer mid simulation, to see how it responds.

Dragon uses a similar triple redundant system for its flight computers.
After talking with the Dragon team at GDC2016, it appears Tesla hardware is not used. They do use some interesting software on Dragon 2. They use Chromium and JavaScript for the Dragon 2 flight interface. The actual flight computers still run on C++.
Source: Discussion with various SpaceX engineers at GDC 2015/2016
 
IIRC, the triple-redundancy thing was used in the Apollo computers as well. Obviously the hardware was a lot more primitive, but it did what it had to do.
 
Although it's a cost saving, the lack of rad hardening is going to be iffy once the spacecraft leaves the earths magnetosphere for that mars journey.

Kosmik said:
Do they call them "magi"?

Kudos to those who get the reference.
Click to expand...

Only if they are individually named melchior, balthasar and casper.
 
Mystic Twilight said:
Although it's a cost saving, the lack of rad hardening is going to be iffy once the spacecraft leaves the earths magnetosphere for that mars journey.
Click to expand...

As I understand it, crew dragon is only rated for leo. Starship is the one they want to take to the moon, and they are still exploding every second week while the plumbing is sorted out. Rad-hardening might still be a ways off.

This is one area where the original analog computers might have been better than digital computers, less chance of getting affected by radiation.
 
Interesting, i'd have thought ARM would have been in use, I guess they're not concerned about power.

www.arm.com

Radiation-Hardened Arm Chips Aim for the Stars

New research into chip radiation hardening and resiliency may temper dangerous effects of solar radiation on space electronics
www.arm.com www.arm.com

Interestingly, it seems that computers aren't as flaky as they thought in space, they've had standard windows pc's in use for non-essential stuff without issues.

For mission critical, you need hardened equipment, but for non-essential stuff, putting up with the rare crash is fine.
 
I have a related question, one that my kids thought either a bit of a weird one, or a typical dad question:

When the falcon was docking they said they are terminating the wireless communication and establishing a hard wired LAN connection via the umbilical cord.

Fine. So, my question was, would NASA use hardcoded IP addresses for the ISS & falcon or would they configure the ISS to supply a DHCP address to every other docking rockets/capsule?

There's obvious advantages to each method, so totally legit question in my mind.. not?
 
I would rather go with static DHCP IP's for existing equipment (easy to change MAC addresses should something be replaced) and DHCP on a separate VLAN for docking rockets/capsules etc.

But it causes complexities - so I have to assume they will be using a flat network to adhere to the KISS principle.
 
AntennaMan said:
As I understand it, crew dragon is only rated for leo. Starship is the one they want to take to the moon, and they are still exploding every second week while the plumbing is sorted out. Rad-hardening might still be a ways off.

This is one area where the original analog computers might have been better than digital computers, less chance of getting affected by radiation.
Click to expand...

They really need to improve technology to make a space elevator, and then move ship assembly to space.
 
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