A Mashpee Middle-High School teacher and a Woods Hole scientist will both be among the women serving on panels in September when the Nantucket Maria Mitchell Association hosts a second Maria Mitchell Women of Science Symposium in Wellesley. The symposium is designed to help promote and support women and girls in the Science, Technology, Engineering and Mathematics (STEM) fields, according to an announcement of the event, and will address persisting issues that hinder women in science. Women continue to be under-represented in the sciences, the announcement said, citing a 2014 Science and Engineering Indicators report by the National Science Foundation that said women comprised just 28% of workers in science and engineering occupations in 2010. “This under-representation shortchanges the students, the field of science, and the public that benefits from scientific advancement,” organizers said. The nonprofit Maria Mitchell Association on Nantucket operates two observatories there as well as a natural science museum, an aquarium, a research center and Mitchell’s preserved historic birthplace.