You are cordially invited to join the first OPENS international science workshop hosted by JAXA/ISAS, fully online on September 29-30, 2025. Two-day sessions of 2.5 hours each will allow international scientists and engineers to join the meeting from all regions worldwide in major time zones.

Background:
The outer planet region of the Solar System offers us natural laboratories for planetary formation and evolution, references for comparative study with exoplanetary systems, and the search for a second genesis in the ocean worlds.
　Yet, the outer planet region beyond Mars remains a destination only for legacy space agencies with large launch capabilities, RTG technology, multi-billion-dollar budgets, and multi-generational commitments. In addition, recent advances in telescopic observations of the outer planets from the Earth's vicinity provide more frequent and shorter turnaround scientific outcomes than decade-long spacecraft missions.
　As an innovative solution, JAXA/ISAS has introduced a program concept called OPENS (Outer Planet Exploration by Novel Small Spacecraft) and recently selected "OPENS-0" as the first mission for a newly created "Eco and Fast" small-class category.
　In the OPENS program concept, the OPENS-0 technology verification and operational lessons will be applied to subsequent missions for other outer planet destinations through various flight opportunities, such as a solo rendezvous mission, a sample return mission combined with a larger orbital transfer vehicle, and daughtership provision for an international flagship mission. Consequently, we aim to realize a higher frequency of outer planet exploration at less cost.

Scopes:
　Aiming to be launched in the late 2020s, the OPENS-0 is an engineering demonstration mission of key enabling technologies for a 100-kg class spacecraft to independently explore the outer planet region, e.g., Saturn's ring flyby. Inevitably, the spacecraft is limited in its resources and operational capabilities compared to legacy spacecraft. Thus, the OPENS-0 is designed to maximize its scientific output by employing "multi-purpose" instruments such as optical navigation cameras for observing zodiacal light, main belt asteroid morphology, and Saturn's ring structure. It is also planned to use the ultra-stable oscillator and deep space transponder for radio occultation of the solar flare, the planetary atmospheres, and Saturn's ring, as well as the PVDF-layered MLI for micrometeoroid flux at 1-10 AU heliocentric distance and dust structure in the vicinity of Saturn's ring.
　This workshop is aimed at the following three scopes.
(1) The workshop will present the mission concept and its potential scientific opportunities of the OPENS-0 to the international science community at the earliest stage of the mission formulation.
(2) The solicited talks will review outcomes from the cruising science investigations conducted by past and present deep space missions to provide lessons learned and remaining scientific challenges for the OPENS-0 mission.
(3) The OPENS-0 team will identify potential candidates for the future OPENS-0 international science team among the participants who express their interest in joining the mission.