Human dependability and knowledge management in spacecraft operations — Successes and lessons learned from 12 years in-flight experience on Mars Express and Rosetta

For long-duration missions such as Mars Express and Rosetta, operating at considerable distances from Earth and with complex and highly variable mission profiles, issues of automation, the retention of knowledge and experience, and the potential human risk factor are especially relevant. Maximising the benefits of a “human in-the-loop” are increasingly seen as fundamental to on-going mission success. This paper presents a summary of these benefits, the experiences gained and the lessons learned. In section 4 of the paper specific case studies are presented, illustrating for both missions the significance of human involvement. This facilitated for Mars Express: (i) more efficient use of limited resources on the spacecraft; (ii) safer and more robust routine operations (as a reaction to critical on-board anomalies); (iii) the resolution of potentially significant scientific losses to the mission; and (iv) the realisation of a science return after mitigating risk during the encounter with Comet Siding Spring. Complementary case studies are also presented for Rosetta. In section 5, the principal lessons learned from the two missions are reviewed. These lessons encompass the experiences and knowledge gathered during extensive simulations and training campaigns, as well as years of in-flight experience. It is shown how a continually evolving mission profile (due, for example, to changes in science requirements, anomalies on the spacecraft or complex and changing mission phases), and on-going staff turnover, have led to significant challenges in knowledge retention and dissemination. Experience gained in the implementation of control-room automation is specifically highlighted — a concept introduced partly as a proof of concept, but also as a complement to (and extension of) automation implemented within the Mission Planning System. The relevance of the above experiences to the future evolution of the Mars Express mission is presented in section 6. This mission will have to manage a number of future challenges: (i) safely automating end-to-end spacecraft operations from planning and scheduling to spacecraft commanding; (ii) increasingly automating the verification process wherever possible and utilising the human resources where they are most valuable to the process; (iii) conducting safe operations within increasingly constraining power/thermal conditions; (iv) ensuring that knowledge and expertise can be retained in future years, after the Rosetta mission has ended. To summarise, the longevity and success of such complex missions could not have been achieved without the resourcefulness and adaptability offered by the human operator in the loop. The primary challenge for the remaining years of the Mars Express mission is therefore how to build on this knowledge and expertise for the benefit of the mission, whilst also encouraging and fostering a more institutionalised approach to knowledge capture and dissemination for the missions to come.