ASTRO-H (also known as NeXT for New X-ray Telescope) is a planned X-ray astronomy satellite under development by the Japan Aerospace Exploration Agency (JAXA). It is expected to be launched in 2014 into the 550 km height orbit around earth. Launch vehicle will be the H-IIA.
With a planned weight of 2.4 t, ASTRO-H will be the heaviest Japanese astronomy mission so far. When its telescope is extended in orbit, the satellite will be 14 meters in length.