Hitomi

ASTRO-H, New X-ray Telescope, NeXT

Mission Profile

Hitomi (ASTRO-H, New X-ray Telescope) was JAXA's advanced X-ray astronomy satellite launched on 17 February 2016 aboard an H-IIA 202, designed to observe the universe at X-ray energies with unprecedented spectral resolution using a microcalorimeter instrument. Within weeks of launch, a series of software and command errors caused the spacecraft to spin uncontrollably, fatally shedding its solar panels and breaking apart on 26 March 2016. In its brief few days of operation, Hitomi's Soft X-ray Spectrometer obtained the first high-resolution spectrum of hot gas in a galaxy cluster, revealing gas motions far calmer than predicted by theoretical models — a discovery with profound implications for cosmological models. JAXA subsequently developed XRISM as a replacement mission to fulfill Hitomi's scientific objectives.