ROS 2 CCSDS Communication Bridge

This package implements a ROS 2-to-CCSDS communication bridge that simulates space-to-ground telemetry and telecommand communication using the CCSDS standard. It allows ROS 2 topics to be encoded as CCSDS packets, transmitted over a Starlink-style relay server, and decoded on the ground side to forward to tools like Open MCT.

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System Overview

The communication pipeline consists of two main parts:

1. bridge.launch.py – Uplink from Space Station (Flight Segment)

• Encodes ROS 2 topics into CCSDS telemetry packets
• Sends packets over WebSocket to a Starlink relay server

2. ground_station.launch.py – Downlink to Ground Station

• Receives CCSDS packets from the relay server
• Decodes them into native ROS 2 messages
• Forwards them to other systems (e.g. Open MCT dashboard)

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📁 Folder Structure

demo\_ros\_ccsds\_bridge/
├── config/
│   └── bridge.yaml                   # APID and topic mappings
├── demo\_ros\_ccsds\_bridge/
│   ├── ground/                       # Ground-side receiver and decoder
│   ├── space\_station/               # Space-side encoder and bridge
│   └── **init**.py
├── launch/
│   ├── bridge.launch.py             # Launches space → relay node
│   └── ground\_station.launch.py     # Launches ground ← relay node

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Configuration File

Edit the bridge.yaml config to define which ROS 2 topics are bridged and how they're mapped to CCSDS APIDs:

- ros_topic_name: "/o2_storage"
  ros_type_name: "std_msgs/msg/Float64"
  packet_apid: 44
  communication_type: "TM"  # "TM" = Telemetry

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How to Run

Prerequisites

• ROS 2 (Humble or later)
• websockets Python package (pip install websockets)
• spacepackets for CCSDS encoding

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1. Launch the Bridge (Space Segment)

This sends CCSDS packets from ROS 2 topics to the relay:

ros2 launch demo_ros_ccsds_bridge bridge.launch.py

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3. Launch the Ground Station

This receives CCSDS packets, decodes them, and republishes to ROS:

ros2 launch demo_ros_ccsds_bridge ground_station.launch.py

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How It Works

Encoding Path (bridge.launch.py)

1. Reads topic-to-APID mappings from bridge.yaml
2. Subscribes to each ROS 2 topic
3. Encodes messages into CCSDS packets
4. Sends them over WebSocket to the relay server

Relay Server

• Accepts WebSocket clients from space and ground
• Forwards packets transparently between them

Decoding Path (ground_station.launch.py)

1. Receives packets from the relay server
2. Parses CCSDS headers to extract APID and payload
3. Converts payload into a ROS 2 message and republishes

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Testing

You can echo and publish to topics like:

ros2 topic pub /o2_storage std_msgs/msg/Float64 "data: 18.5"
ros2 topic echo /o2_storage  # On ground side

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Telemetry Forwarding to Open MCT (Need to add)

On the ground, decoded topics can be visualized by running:

npm start  # From the openmct-ros plugin directory

And configuring it to receive topics from WebSocket output like:

{
  "topic": "/o2_storage",
  "value": 18.5,
  "timestamp": 1754424273.52
}

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📚 Reference

• CCSDS Packet Specification: https://public.ccsds.org
• WebSocket Docs: https://websockets.readthedocs.io
• Open MCT: https://nasa.github.io/openmct/
• spacepackets Python Library: https://github.com/robamu-org/python-spacepackets

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🛠️ Future Improvements

• Support for Telecommand (TC) encoding and decoding
• Packet error injection for testing fault tolerance
• Add encryption layer for secure transmission
• Add support for CFDP and USLP

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👨‍🚀 Authors

Developed as part of the Space Station OS project.

Bridging ROS 2 space systems with real-world ground communication standards.