Six Years and 184 Tickets: The Vast Scope of the Mars Science Laboratory's Ultimate Flight Software Release

The Mars Science Laboratory (MSL) Curiosity rover has seen five full flight software upgrades since landing on Mars in August 2012. Software transitions for MSL add or replace functionality, fix bugs, and prepare for future capabilities. The penultimate full software release, R12, was installed on Curiosity in 2015, and was followed by several hot patches and one cold patch as engineers worked to address new constraints. Because each added patch increased the complexity of operating the rover, a new flight software update called R13 was proposed, which aimed to make operations more straightforward by combining the patches into a single monolithic image, and improve upon or add several capabilities to the rover's flight software. The R13 development effort kicked off in early 2017. Over the subsequent six years, the scope of R13 was expanded to include many desired capabilities and bug fixes since the last upgrade -- some of which were proposed even earlier than 2015 but were unable to be implemented in R12. Overall, the MSL Change Control Board approved 56 bug fixes and 53 new features for R13 development. Twenty-seven developers implemented these changes over a 3.5 year period. Following a 2.25 year testing campaign, R13 was approved for use in flight onboard Curiosity. In this paper, we detail the path of the R13 flight software release from its proposal in April 2016 to its approval for use in flight in September 2022.