ASTRO-H (also known as NeXT for New X-ray Telescope) is an X-ray astronomy satellite commissioned by the Japan Aerospace Exploration Agency (JAXA) for studying extremely energetic processes in the universe. The space observatory is 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. It is planned to be launched in February 2016 into a low Earth orbit altitude of 575 km (357 mi). It will be launched from the Tanegashima Space Center on board an H-IIA rocket.
The objective of ASTRO-H is to explore the structure and evolution of universe
- Understand the extreme conditions in the universe
- Explore the diverse phenomena of non/thermal universe
- Elucidate dark matter and dark energy
These objectives will be achieved with the following observational capabilities:
- Imaging and spectroscopic observations with a hard X-ray telescope
- Spectroscopic observations with an extremely high energy resolution of the micro-calorimeter
- The most sensitive wideband observation over an energy range from 0.3 to 600 keV
- Soft X-ray Telescope (SXT-S, SXT-I)
- Soft X-ray Spectrometer (SXS), 0.4-12 keV, for high-resolution X-ray spectroscopy
- Soft X-ray Imager (SXI), 0.3-12 keV
- Hard X-ray Telescope (HXT)
- Hard X-ray Imager (HXI), energy range: 5-80 keV 
- Soft Gamma-ray Detector (SGD), 60-600 keV
ASTRO-H has been built by an international collaboration led by JAXA with over 70 contributing institutions in Japan, the US, Canada, and Europe.
NASA is providing the High-Resolution Soft X-Ray Spectrometer (SXS). The Netherlands Institute for Space Research (SRON) is providing the filter-wheel and calibration source for the spectrometer. The Canadian Space Agency (CSA) is providing the Canadian Astro-H Metrology System (CAMS), which is a laser alignment system that will be used to measure the distortions in the extendible optical bench.
With a mass of 2,400 kilograms (5,300 lb), ASTRO-H will be the heaviest Japanese astronomy mission so far. When its telescope is extended, the satellite is 14 m (46 ft) in length.