  XRISM is an X-ray astronomical mission by the JAXA, NASA, ESA and other
international participants, that is planned for launch in 2022 (Japanese fiscal
year), to quickly restore high-resolution X-ray spectroscopy of astrophysical
objects. To enhance the scientific outputs of the mission, the Science
Operations Team (SOT) is structured independently from the instrument teams and
the Mission Operations Team. The responsibilities of the SOT are divided into
four categories: 1) guest observer program and data distributions, 2)
distribution of analysis software and the calibration database, 3) guest
observer support activities, and 4) performance verification and optimization
activities. As the first step, lessons on the science operations learned from
past Japanese X-ray missions are reviewed, and 15 kinds of lessons are
identified. Among them, a) the importance of early preparation of the
operations from the ground stage, b) construction of an independent team for
science operations separate from the instrument development, and c) operations
with well-defined duties by appointed members are recognized as key lessons.
Then, the team structure and the task division between the mission and science
operations are defined; the tasks are shared among Japan, US, and Europe and
are performed by three centers, the SOC, SDC, and ESAC, respectively. The SOC
is designed to perform tasks close to the spacecraft operations, such as
spacecraft planning, quick-look health checks, pre-pipeline processing, etc.,
and the SDC covers tasks regarding data calibration processing, maintenance of
analysis tools, etc. The data-archive and user-support activities are covered
both by the SOC and SDC. Finally, the science-operations tasks and tools are
defined and prepared before launch.
