ASTROH

ASTRO-H, also known as Hitomi, was a Japanese X-ray astronomy satellite developed by the Japan Aerospace Exploration Agency (JAXA) with international collaboration, including NASA. ASTRO-H stands for Advanced Satellite for High Energy Astrophysics. The mission aimed to perform high-resolution spectroscopy and broad-band imaging of high-energy phenomena such as clusters of galaxies, accreting black holes, and supernova remnants.

The spacecraft carried four instruments: the Soft X-ray Spectrometer (SXS), a microcalorimeter-based spectrometer for high-resolution X-ray spectroscopy; the Soft X-ray Imager (SXI); the Hard X-ray Imager (HXI); and the Soft Gamma-ray Detector (SGD). Together they covered roughly 0.3 to 600 keV, enabling detailed spectral measurements and imaging across a wide energy range.

ASTRO-H was launched on February 17, 2016, by an H-IIA rocket from Tanegashima Space Center and placed into low Earth orbit. The mission began science operations, but on March 26, 2016, the spacecraft lost attitude control and could not maintain pointing, ending the mission prematurely. JAXA declared Hitomi non-operational; the satellite remained in orbit but no further observations were possible.

Although short-lived, ASTRO-H represented a significant advancement in X-ray astronomy through its multi-instrument, high-resolution approach. Its loss led to the XRISM project (X-ray Imaging and Spectroscopy Mission), a joint JAXA–NASA effort to continue Hitomi’s goals. XRISM, launched in 2023, carries a Resolve microcalorimeter and an Xtend imager and seeks to restore high-resolution X-ray spectroscopy capabilities for the field.