The Herschel Space Observatory Development, Operation and Postoperations: Lessons Learned

The Herschel Space Observatory was the fourth Cornerstone mission of ESA's Horizon 2000 programme, and a (sic)1B-class far infrared space observatory. The satellite and mission were developed over an approximately 10-year period before launch in 2009 and highly successful operation for approximately four years. A Post-Operations programme continued until 2017 (and with little resources even until 2019) in order to complete the data processing, calibration and documentation activities and to populate the Herschel Science Archive with the final data products and documentation. The Herschel Science Team, which oversaw the mission over a nearly 20-year period from late 1998 until its 61st and final meeting in late 2017, has conducted a comprehensive lessons learned review of the project from start to finish, encompassing all aspects of the endeavour - programmatics and management of the spacecraft, instrument consortia and ground segment; instrument development and testing; spacecraft implementation; ground segment and operations preparation pre-launch, in-flight operation and post-operations; science management and user support; and communications. Science is not addressed here except in general terms - this is not a scientific assessment. Focusing on generic features of the mission and its management, organisation, and technical design that have potential applications and relevance to future space projects, we have identified and assessed a number of aspects in which the Herschel experience can provide valuable lessons, both positive and negative, to aid the effective development and success of future missions, especially ones that are comparable in magnitude and complexity. We outline the main findings and conclusions of this Lessons Learned exercise.