The Mars 2020 Perseverance rover relies on a variety of open source software running on Linux to carry out its groundbreaking mission on the Red Planet. Linux provides a robust, flexible, and time-tested operating system for the rover's computers, allowing it to control complex systems and operations with stability and precision.
At the heart of the rover is the RAD750 radiation-hardened single board computer, which utilizes a PowerPC 750 CPU running at 133MHz. This computer runs the VxWorks real-time operating system, which has incorporated a Linux compatibility layer in recent versions. This allows Linux software to run on the RAD750 alongside VxWorks, taking advantage of Linux's open source ecosystem while maintaining real-time determinism.
Several key software components running on Perseverance's computers are open source and Linux-based. This includes the flight software framework known as CLARAty (Coupled Layer Architecture for Robotic Autonomy). CLARAty provides interfaces for sensors, motors, power, communications, and more. It is used to develop and integrate the rover's capabilities such as autonomous navigation, robotic arm control, instrument monitoring, and surface operations.
CLARAty itself does not interface directly with hardware, but rather utilizes middleware and device drivers. Many of these drivers on Perseverance leverage functionalities from Linux and other open source software. For example, the router that handles connections between the rover and controllers on Earth utilizes Cisco's IOS XR software, which is Linux-based. Device drivers may interface sensors and instruments using SPI (Serial Peripheral Interface) or I2C, common communication protocols implemented in the Linux kernel.
The ground data processing software that supports Perseverance is also largely open source. While the rover sends back raw images and data, a complex data processing pipeline analyzes and interprets this information. Software like JPEG, HDF5, and FFmpeg handle compression and data storage, while higher-level processing relies on OpenCV and NumPy for computer vision and numerical analysis. These core Python libraries are utilized in JPL's open source analysis tools.
Network communication on Mars presents challenges due to limited bandwidth and delays. The disruption tolerant networking (DTN) protocols running on Perseverance enable storing and forwarding data through intermittent links. The DTN reference implementation uses the Bundle Protocol, which is built on Linux servers. Adaptive compression programs utilizing machine learning can optimize bandwidth usage based on link quality.
The use of open source software provides flexibility to evolve capabilities over a long-duration mission like Perseverance's. While the core real-time OS must remain static after launch to ensure reliability, Linux and other platform-independent software can be updated. As new rover technologies come online, flight software components can be developed on Earth and integrated seamlessly. Open standards also allow different science teams to build analysis tools leveraging shared libraries.
Most importantly, Linux and open source software enable transparency about how Perseverance technically works. With publicly available code, the pool of potential experts who can support and enhance these Mars missions grows significantly. As future manned missions to Mars become closer to reality, open source ensures the technical knowledge exists to bootstrap human infrastructure across interplanetary space. Just as Linux helped revolutionize technology on Earth, its role in space exploration may lead to great strides for humanity among the stars.