CppCon 2014

One of the more challenging aspects of developing flight software (FSW) for NASA's Spirit and Opportunity Mars Exploration Rovers (MER) and Curiosity, the Mars Science Laboratory rover was how to enable them to drive themselves safely through unknown Martian terrain. When the MER mission was approved in the year 2000, JPL researchers had already demonstrated that capability on prototype rovers [1] using software written primarily in C++ on a VxWorks realtime O/S platform with shared memory. So when asked to incorporate that capability into the MER vehicles which also relied on a similar VxWorks realtime O/S, the team concluded it would be safest and most expedient to incorporate the already field-tested C++ software. But that presented a challenge, since at that point all rover FSW development was mandated to be done mainly in the C programming language.

In this talk we present some of the challenges we faced and solutions we found in deploying C++ onto the Mars Rovers. For example, dynamic allocation was initially precluded, but development of a specialized memory allocator (using the C++ "placement new" operator) enabled us to incorporate it safely into the flight system. We will discuss what aspects of C++ were incorporated, what simulation environments aided development, describe some of the tools used to validate system behavior, and explain how our success using C++ for the implementation of autonomous navigation on MER has influenced future FSW efforts.

[1] Jeffrey Biesiadecki, Mark W. Maimone, and Jack Morrison., "The Athena SDM Rover: A Testbed for Mars Rover Mobility," June 2001 iSAIRAS conference proceedings, Montreal, Canada., june 2001.