This remains an important field of scientific investigation and many foundational discoveries were made at EISCAT previously. EISCAT 3D offers incredible new sensing opportunities for HF heating experiments.

The EISCAT Heating facility is an infrastructure of vital importance for our continued research about the fundamental physics of our near-earth space, and our understanding of the interaction between radio-waves and plasma. The combination of the EISCAT/EISCAT_3D radars with groundbased diagnostic tools as for example the optical ALIS_4D facility capable of 3D reconstruction of radio-induced optical emissions. The space-related infrastructures in the region would benefit a quite a bit from an upgraded modern reliable heating facility. The investment for this is small related to what is already invested in scientific infrastructures in the region. Without this investment many scientific objectives of instrumentation in the region would remain unresolved and the scientific capabilities of already existing infrastructures reduced.

Although my direct involvements with EISCAT have been small, I have had the privilege to be a close observer of all its developments over the past 50 years. It has been, and remains, a wonderful example of scientific work in ionospheric physics. So I fully support future operation of the heating facility as a tool for advancing our understanding of the ionosphere, not least because it will do great science in conjunction with EISCAT_3D.