Operating System

Linux and Debian for CubeSats

Linux provides a stable, well-supported platform with mature tooling, strong networking, and excellent hardware support. Debian is a lightweight, long-term supported Linux distribution with reproducible package management, making it a good fit for embedded boards like the BeagleBone used in this mission. For PULSE-A, Debian enables:

  • Robust networking (SSH, SCP, SocketCAN) for development and operations

  • Package ecosystem (build tools, monitoring, scripting) for rapid iteration

  • Out of the box support for the BeagleBone Black and cFS

  • Automation via systemd, cron, and shell scripts

  • Familiar workflows for both lab work and on-orbit maintainability

Basic terminal commands

pwd                      # print current directory
ls -la                   # list files (long, including hidden)
cd /path/to-directory    # change directory
mkdir name               # create directory
cp src dst               # copy file
mv src dst               # move/rename
rm file                  # remove file
rm -r directory          # remove directory recursively
cat file                 # print file contents

Package management (Debian/Ubuntu):

sudo apt update
sudo apt upgrade
sudo apt install package-name

SSH: remote shell access

Connect to a BeagleBone or remote host:

ssh debian@[ip]

SCP: file transfer

Push a file to a remote host:

scp path/to-file debian@[ip]:~/path/to-file
scp -r path/to-directory debian@[ip]:~/path/to-directory

Pull a file from a remote host:

scp debian@[ip]:path/to-file ./
scp -r debian@[ip]:path/to-directory ./

Real-time Linux and PREEMPT-RT

Real-time means bounded, predictable response to events (low, consistent latency and jitter). The PREEMPT-RT patchset turns Linux into a fully preemptible kernel, reducing scheduling and interrupt latencies so time-sensitive tasks meet deadlines.

Why it matters for CubeSats:

  • Improves determinism for control loops, timestamping, and communication windows

  • Helps ensure consistent I/O timing on shared embedded platforms

  • Most workloads are soft real-time; enable PREEMPT-RT for subsystems that need tighter bounds

References