ASTRO-H

JAXA ASTRO-H, also known as Hitomi, was a satellite mission launched by the Japan Aerospace Exploration Agency (JAXA) on February 17, 2016. The mission aimed to study the universe in the X-ray and gamma-ray bands to better understand the behavior of black holes, active galactic nuclei, and other high-energy astrophysical phenomena. In this article, we will explore the background, purpose, implementation, cost, and achievements of the JAXA ASTRO-H mission in detail.

Background

The study of the universe in the X-ray and gamma-ray bands has been an essential area of astrophysics since the launch of the first X-ray astronomy satellite, Uhuru, in 1970. The X-ray and gamma-ray spectra provide a unique view of the universe, revealing the most energetic processes and phenomena such as black holes, neutron stars, supernovae, and active galactic nuclei (AGNs).

JAXA has been active in the field of X-ray and gamma-ray astronomy since the launch of its first mission, Tenma, in 1983. Since then, JAXA has launched several successful missions, including ASCA, Suzaku, and NuSTAR, which have significantly contributed to our understanding of the universe's high-energy phenomena. ASTRO-H, also known as Hitomi, was the latest mission launched by JAXA to continue this legacy.

Purpose

The JAXA ASTRO-H mission had several scientific objectives, including:

Studying the behavior of black holes: ASTRO-H aimed to observe the strong gravity of black holes, which distort and bend the light emitted by matter falling into them. The observations were expected to help us better understand the nature of black holes and their role in the evolution of galaxies.

Observing AGNs: ASTRO-H aimed to study the emission from AGNs, which are believed to be powered by supermassive black holes at the centers of galaxies. The observations were expected to help us better understand the growth and evolution of galaxies.

Studying the hot intergalactic medium: ASTRO-H aimed to study the hot intergalactic medium, which is the gas that fills the space between galaxies. The observations were expected to help us better understand the distribution and evolution of matter in the universe.

Studying the high-energy emission from supernovae: ASTRO-H aimed to study the high-energy emission from supernovae, which are explosive events that mark the death of stars. The observations were expected to help us better understand the physics of these events and their role in the evolution of galaxies.

Implementation

The JAXA ASTRO-H mission was implemented using a satellite that was launched into space on February 17, 2016, by the H-IIA launch vehicle. The satellite was designed to operate in a low-Earth orbit, at an altitude of about 580 kilometers.

The satellite had four scientific instruments onboard, which included a Soft X-ray Spectrometer (SXS), a Soft X-ray Imager (SXI), a Hard X-ray Imager (HXI), and a Soft Gamma-ray Detector (SGD). The SXS and SXI were designed to observe the soft X-ray band (0.3-12 keV), while the HXI and SGD were designed to observe the hard X-ray (5-80 keV) and soft gamma-ray (40-600 keV) bands, respectively.

The mission was planned to last for at least three years, during which the satellite would observe the universe in the X-ray and gamma-ray bands, collect data, and transmit it back to Earth for analysis.

Cost

The JAXA ASTRO-H mission had an estimated cost of about 31 billion yen, which is roughly equivalent to 280 million USD. The cost of the mission included the design, development, and launch of the satellite, as well as the cost of operating it in space for the planned duration of the mission.

Achievements

Unfortunately, the JAXA ASTRO-H mission did not achieve all of its scientific objectives due to a malfunction that occurred shortly after the satellite's launch. The malfunction was traced back to an issue with the satellite's attitude control system, which caused it to spin and lose communication with Earth.

Despite this setback, the mission did manage to collect some valuable data before the malfunction occurred. The Soft X-ray Spectrometer (SXS) onboard the satellite was able to obtain high-resolution spectra of several celestial objects, including the Perseus Cluster, a galaxy cluster located about 240 million light-years away from Earth. The spectra obtained by the SXS provided valuable insights into the behavior of black holes, including their gravitational effects on the surrounding matter.

The JAXA ASTRO-H mission also made significant contributions to the field of X-ray and gamma-ray astronomy through its innovative technology and instrumentation. The Soft X-ray Spectrometer (SXS) onboard the satellite was the first instrument of its kind to achieve high spectral resolution in the soft X-ray band, which enabled scientists to study the behavior of black holes and other high-energy phenomena with unprecedented detail.

In conclusion, the JAXA ASTRO-H mission was an ambitious project aimed at studying the universe in the X-ray and gamma-ray bands to better understand the behavior of black holes, active galactic nuclei, and other high-energy astrophysical phenomena. Despite its setback, the mission made significant contributions to the field of X-ray and gamma-ray astronomy through its innovative technology and instrumentation, providing valuable insights into the nature of the universe and its most energetic phenomena.