The space observatory was designed to extend the research conducted by the Advanced Satellite for Cosmology and Astrophysics (ASCA) by investigating the hard X-ray band above 10 keV.

[7] The spacecraft was launched on 17 February 2016 and contact was lost on 26 March 2016, due to multiple incidents with the attitude control system leading to an uncontrolled spin rate and breakup of structurally weak elements.

The inspiration of this story is that Hitomi is regarded as the "One last, but most important part", and so we wish ASTRO-H to be the essential mission to solve mysteries of the universe in X-rays.

[10][7] Hitomi was built by an international collaboration led by JAXA with over 70 contributing institutions in Japan, the United States, Canada, and Europe,[10] and over 160 scientists.

[1][10] The Netherlands Institute for Space Research (SRON) in collaboration with the University of Geneva provided the filter-wheel and calibration source for the spectrometer.

[6] Measurements by Hitomi have allowed scientists to track the motion of X-ray-emitting gas at the heart of the Perseus cluster of galaxies for the first time.

Using the Soft X-ray Spectrometer, astronomers have mapped the motion of X-ray-emitting gas in a cluster of galaxies and shown it moves at cosmically modest speeds.

[25] Initially suggested possibilities for the communication loss is that a helium gas leak, battery explosion, or stuck-open thruster caused the satellite to start rotating, rather than a catastrophic failure.

[24][31] It was determined that the chain of events that led to the spacecraft's loss began with its inertial reference unit (IRU) reporting a rotation of 21.7° per hour at 19:10 UTC on 25 March 2016, though the vehicle was actually stable.

The attitude control system attempted to use Hitomi's reaction wheels to counteract the non-existent spin, which caused the spacecraft to rotate in the opposite direction.

Because the IRU continued to report faulty data, the reaction wheels began to accumulate excessive momentum, tripping the spacecraft's computer into taking the vehicle into "safe hold" mode.

Because of this excessive rotation rate, early on 26 March 2016 several parts of the spacecraft broke away, likely including both solar arrays and the extended optical bench.

[32] However, a 27 June 2016 article from The Nikkei stated that some within the Ministry of Education, Culture, Sports, Science and Technology believed it was too early to grant funding for a Hitomi replacement.

[34] The Minister of Education, Culture, Sports, Science and Technology, Hiroshi Hase, stated during a press conference on 15 July 2016 that funding for Hitomi's successor will be allocated in the fiscal year 2017 budget request,[35] and that he intends to accept the successor mission on the condition that the investigation of Hitomi's destruction is completed and measures to prevent recurrence are done accordingly.