The Planetary Science Summer School (PSSS) prepares the next generation of scientists and engineers to participate in future solar system exploration missions. Since 1999, over 650 post-graduate and early career participants learned the development process for a robotic planetary exploration mission concept, working with mentors from JPL’s advanced project design team Team X. Students select, design, and develop a hypothesis-driven science mission concept from the Planetary Science Decadal Survey, under guidelines of the NASA New Frontiers Announcement of Opportunity. PSSS bridges participants’ knowledge gained in graduate and PostDoc positions through a 3-month authentic, immersive, “breakthrough” experience. PSSS was adapted in 2020 to: progressively refine mission concepts through a step-wise increase in Concept Maturity Levels; conduct the final culminating week virtually versus onsite at JPL, due to Covid-19 concerns; and organize an additional heliophysics science mission concept development experience. 10 weeks of preparatory webinars are normally done remotely, with the final week at JPL where students collaborate with Team X in the final mission design and present it to a review board. Team X communication tools and operational practices that enabled mission studies during the pandemic also permitted live, one-on-one coaching aspects of PSSS in a virtual environment. Time zone-accommodations, direct work with science mentors outside of working hours, daily debriefings, and student ownership of their own collaborative tools and processes, Feedback data is collected by weekly assignment progress, daily check-ins during virtual culminating week, and post-experience surveys of students and mentors. While students in the first session expressed general disappointment in lack of in-person experience, they understood the necessity and rated the session highly, on par with previous years. Results from the complete data from all 3 summer sessions will be presented. Link: go.nasa.gov/missiondesignschools.