Open Source Python Implementation of Ccsds File Delivery Protocol to Support File-Based Operations

The Consultative Committee for Space Data Systems (CCSDS) File Delivery Protocol (CFDP) enables reliable file transfer across space communication links that experience interruptions and delays, supporting diverse transfer modes with minimal human intervention. This paper presents an open-source Python library implementing CFDP, following guidelines from the CCSDS Blue Book. To date, this library is the only fully functional CFDP implementation in Python and is among the first open-source versions available. Developed in Python 3, with compatibility for MicroPython for low-power applications, the library supports both Class 1 (unreliable) and Class 2 (reliable) file transfers, using Zero Message Queue (ZMQ), CCSDS Space Packet Protocol, and User Datagram Protocol (UDP) for transport and network layers. An extendable virtual file store is included to support various data storage options. Full CCSDS compliance has been validated through cross-testing with the European Space Agency (ESA) CFDP implementation. A graphical user interface (GUI) enhances usability for nontechnical users, supplementing the command-line interface. This open-source CFDP library is ideal for space and terrestrial file transfers and is increasingly valuable for file-based operations in space missions.