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Hitomi (ASTRO-H)

Hitomi (ASTRO-H) mission graphic


Phase: Past

Launch Date: February 17, 2016

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Program(s):Astrophysics Explorers, Explorers, Missions of Opportunity

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ASTRO-H (formerly known as NeXT and renamed Hitomi) was launched on February 17, 2016 by the Japan Aerospace Exploration Agency (JAXA) into low-Earth orbit from the Tanegashima Space Center, Japan, by a JAXA H-IIA rocket.

Contact with Hitomi was lost on March 26, 2016, during observatory commissioning. Following numerous unsuccessful attempts to reestablish contact with the spacecraft, and in light of a rigorous technical investigation of the possible causes and likely impacts of the anomaly, JAXA ceased recovery attempts on April 28, 2016. For additional information on the anomaly, please see the JAXA Hitomi web page.

Hitomi was a powerful orbiting observatory developed by JAXA for studying extremely energetic processes in the universe. NASA and the JAXA/Institute of Space and Astronautical Science (ISAS) teamed up to develop a high resolution “Soft X-Ray Spectrometer” (SXS) for Hitomi. The SXS, with its unprecedented sensitivity for high-resolution x-ray spectroscopy, was designed to perform a wide variety of breakthrough science investigations. The SXS science goals included a wide range of forefront topics in astrophysics, including: testing theories of the structure formation of the universe by measuring the velocity field of x-ray-emitting gas in clusters of galaxies and the energy output from jets and winds in active galaxies; providing unique information about the origin of the elements via precise measurements of the metal abundances in the oldest galaxies; probing matter in extreme gravitational fields by obtaining time-resolved spectra of material in the vicinity of the event horizon of a black hole; and providing new insights into the explosion mechanism of supernovae by determining the chemical abundances and velocity structure in Galactic Type Ia SNR.

To carry out these investigations, the SXS employed a state-of-the-art x-ray calorimeter detector array at the focus of a high-throughput x-ray telescope. Designed to operate at extremely low temperatures, the x-ray calorimeter was able to determine the energy of each x-ray photon by measuring the heat it generated in the detector with extraordinary precision, thereby enabling high-resolution spectra to be obtained from extended astrophysical sources without degradation. The instrument utilized a multi-stage cooling system designed to maintain the ultra-low temperature of the calorimeter array for more than 3 years in space. X-rays focused onto the array of calorimeters by a highly efficient, grazing-incidence x-ray mirror provided a large collecting area. The NASA contribution to Hitomi was built at the NASA Goddard Space Flight Center in collaboration with the University of Wisconsin and the Netherlands Institute for Space Research (SRON).

Last Updated: April 29, 2016

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