Koichiro Tsuruda passed away on the morning of December 3, 2020, at the age of 83. Tsuruda was known for his outstanding contributions to magnetospheric and space physics by the developments of innovative instruments for research in very low-frequency (VLF) radio propagation and electric fields in space plasma.

After conducting VLF observations and research, Tsuruda created a new method of electric field measurement and installed it on the S-520-9 sounding rocket, the Akebono satellite, and the Geotail satellite, which was a major breakthrough in solar system plasma science research. He served as the Director of the Institute of Space and Astronautical Science (ISAS) from 2003 to 2005 and guided the Institute through a difficult period after it was integrated into the Japan Aerospace Exploration Agency.

Tsuruda had both a gentle personality and a strong resilience in his spirit, and many people loved him. He suffered from Parkinson’s disease in his later years, but he passed away peacefully at home with his family watching over him.

NASA Chief Scientist James Green issued the following statement: “As a young NASA researcher who was the deputy Project Scientist on the Global Geospace Science set of satellites, I had the pleasure of traveling to ISAS and working with the Geotail scientists where I met Dr. Tsuruda. I was already very familiar with his seminal Akebono wave papers. He was an outstanding scientist who took time to explain a number of key plasma wave concepts to me that I will never forget. We again met when he headed ISAS guiding that nations robotic space program with extensive knowledge and skill and forming long lasting relationships with NASA. He is one of our original space pioneers and will be missed.”

— Portions of text courtesy of Masato Nakamura/ISAS