Speaker
Description
Waseda University and Science Tokyo are jointly developing GRAPHIUM, a 65 kg small satellite scheduled for launch in 2027. Its primary instrument, INSPIRE, is a box-type hybrid Compton camera operating in pinhole mode from 30 to 200 keV and Compton mode from 200 keV to 3 MeV. It achieves an angular resolution of 7.0°and an energy resolution of 7.5% at 662 keV, with an expected sensitivity comparable to COMPTEL. Its wide field of view, covering about one-quarter of the sky, enables the detection of unpredictable transient gamma-ray sources such as gamma-ray bursts. Observations of kilonovae from neutron star mergers could provide new insights into the origins of heavy-element nucleosynthesis. INSPIRE features a highly agile attitude control system, enabling rapid and flexible pointing toward targets including solar flares, active galactic nuclei (AGNs), and the Galactic center. A full-scale engineering model (EM) equivalent to the flight model was developed, and imaging tests using various radioactive sources were conducted. We also implemented a method for extracting individual spectra from multiple sources within the same field of view using Compton imaging, and successfully demonstrated its feasibility with the EM. To validate its mechanical robustness, vibration tests simulating Falcon 9 launch conditions were conducted using a partially equipped EM with mass-equivalent dummies. No performance degradation was observed before and after the tests, confirming structural integrity under launch conditions.
