Andrzej Jeziorski/SINGAPORE

Japan has radically revamped its H-2 Orbiting Plane-Experimental (HOPE-X) space shuttle project, turning it into a more ambitious, fully reuseable space transportation system.

HOPE-X has been criticised, with opponents saying it represents no progress beyond technology already used in the 20-year-old US Space Shuttle. HOPE-X funding was suspended in January, when the Japanese Government decided to focus on developing the H-2A expendable launcher following two launch failures of the H-2 rocket.

The new reuseable launch vehicle (RLV) project merges HOPE-X work done by the National Space Development Agency (NASDA) and the National Aerospace Laboratory (NAL)with two other programmes facing uncertain futures - the NAL Supersonic Transport (SST) and the Hypersonic Transport Propulsion System Research (HYPR) engine.

The new orbiter will be transported into the upper atmosphere in "piggy-back" fashion by a hypersonic transport (HST), which would take off horizontally from an airstrip, powered by air-breathing engines. Once separated from its first stage, the orbiter would use its own rocket engines to boost itself into orbit while the HST returns for a conventional landing.

Officials from NALand the National Space Development Agency (NASDA) are pushing for funding in Japan's 2001 budget.

According to sources close to the programme, the hypersonic carrier aircraft will incorporate elements from current SST research and the HYPR programme, which was completed in March last year. The current design envisages a 65m (213ft) long HST with a 30m wing span and a 140t take-off weight, not including the shuttle. The shuttle will be 39m long, with a 17m wing span and a 130t take-of weight, including an 8t payload.

The first phase will run from 2001 to 2005, covering four elements: research and development on reuseable rocket engines for the orbiter; aerodynamic development of the shuttle, including scaled demonstrator flights; development of an experimental HST airframe; and development of the air-breathing powerplants, which could be variable cycle engines like the turbojet/ramjet HYPR.

The second phase, from 2006 to 2010 would involve the integration of powerplant and airframe developments, leading to a full-scale, experimental shuttle with reuseable rocket engines, and a sub-scale HST demonstrator. The final phase, after 2010, would involve the development of the full-scale, two-stage, reuseable launch vehicle.

Source: Flight International