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HOPE-X (H-II Orbiting Plane-Experiment)

The National Space Development Agency of Japan (NASDA) began studying the development of a small crewless space shuttle in 1987. The original parameters called for a 20,000 kg vehicle that would be lifted by the H-2 booster and would land by remote control in Japan or Australia.

HOPE-X (H-II Orbiting Plane-Experiment) was to be the end result of a series of experiments: the Orbital Re-entry Experiment (OREX) completed in 1994, the Hypersonic Flight Experiment (HYFLEX) and the Automatic Landing Experiment (ALFLEX) both completed in 1996, and finally the High Speed Flight Demonstration (HSFD) which was planned for early 2002. Hope-X planned to validate the technologies developed by the previous experiments (OREX, HYFLEX and ALFLEX and the HSFD) over a complete flight from orbit to landing.

The Orbital Re-Entry Flight Experiment (OREX), which was conducted in 1994, evaluated autonomous de-orbit technologies and vehicle thermal protection systems and materials to protect from aerodynamic heating during high-speed atmospheric re-entry. The Automatic Landing Flight Experiment (ALFLEX) performed demonstrations for the automatic landing of a re-entry vehicle. The ALFLEX vehicle is based on a 37% scale 1992 HOPE design. The ALFLEX flight tests were conducted at the Woomera Airfield in Australia from July to August of 1996.

Japan’s National Space Development Agency (NASDA) experienced a setback 12 February 1996 when one of its prototypes for a small, robotic spacecraft landed in the ocean and sank. The Japanese officials had anticipated the ocean landing immediately after the launch of the Hyflex shuttle from an island in southern Japan. In spite of the loss of its shuttle, NASDA did not consider the exercise an entire failure. The HYFLEX had launched successfully, separated from its rocket at a height of 70 miles (113 kilometers), and then returned to Earth 19 minutes later, as planned.

The problem occurred when the craft splashed into the ocean, and a rope connecting the 1-ton (900-kilogram or 0.9-tonne) shuttle to its flotation device broke, causing it to sink. NASDA reported that it had intended to collect data during the flight to test the shuttle’s fitness for reentry, but had been unable to procure much of the information needed. Japan had manufactured the US$37 million HYFLEX shuttle domestically, planning the exercise as a part of its effort to bolster its fledgling space program.

The High Speed Flight Demonstration (HSFD) project consisted of two flight experiment campaigns, Phase I and Phase II. The Phase I flight experiment concluded in November 2002 after three successful flights, and the first Phase II flight was performed in July 2003 in collaboration with Centre National d'Etudes Spatiales of France (CNES). The configuration of both demonstrators is based on a 25% scaled HOPE-X configuration, for which much aerodynamic data has already been obtained.

For the experiment, HOPE-X was to be launched by an H-II rocket and is expected to demonstrate de-orbit, lift, transonic flight, and autonomous landing. As well as being designed for transportation between the Earth and orbit, the vehicle is designed to be able to carry out experiments and to make observations on orbit.

In addition to lofting larger GEO satellites, the H-II was designed specifically to accommodate the proposed HOPE (H-II Orbiting Plane) spacecraft. HOPE was to have a launch mass of approximately 10 metric tons, a length of 11.5 m, and a wing-span of 8.6 m. Originally viewed as a major logistical vehicle for the Japanese Experiment Module of the Freedom Space Station, HOPE was initially to be an unmanned spacecraft with a one-metric-ton payload capacity which could service the new International Space Station after the turn of the century. The maiden flight of a NASDA HOPE demonstration vehicle (HOPE-X) is tentatively scheduled for 1999.

A 20-metric-ton version of HOPE, possibly manned with a 3-3.5 metric ton payload capacity, was also considered. Such a vehicle would be 16 m long with a wing-span of 12.3 m. To support the larger HOPE, the H-II launch vehicle would require additional strap-on boosters (up to six solid boosters or a combination of solids and liquids). However, preliminary engineering analyses suggested that the new H-2D would still not be able to insert the larger HOPE directly into orbit, requiring HOPE to burn up to four metric tons of propellants to enter LEO. Meanwhile, studies of other reusable spacecraft, including single stage-to-orbit concepts, were underway in the 1990s(References 149-152).

The design for the Hope-X shows a 49-square meter delta wing and two vertical tails on its 13.4 meter-long fuselage. The main structure will be made of a conventional aluminum alloy strengthened with ceramic tiles and flexible thermal insulation. The Hope-X was to be launched by the H-2A rocket and will enter low earth orbit and climb to an altitude of 200 km powered by its own Orbital Maneuvering System after separation. After one revolution, it will de-orbit and re-enter into the atmosphere where the reaction control system will control the flight path and attitude. The mission should be completed in approximately two hours.

Although launched by an expendable launcher, H-IIA, HOPE-X itself is designed to have the capability of re-flight. It also has enough cross-range capability to approach the target landing site and lands on a runway like an airplane. The vehicle lands as a traditional airplane on an island in the Pacific Ocean. HOPE-X would make one orbit flight after launched from Tanegashima Space Center on top of a single stage version of an H-IIA launcher and will land on a runway on Christmas Island in the Central Pacific Ocean Budget constraints forced NASDA to postpone Hope-X’s first launch originally planned for 2001. Although the HOPE-X flight experiment had been planned for 2004, it was decided to review the R&D scenario of reusable space transportation technologies, and so the implementation of this experiment was suspended.

Following on from the HOPE-X project, the Future Space Transportation Research Centre has been considering conceptual future space transportation systems building on the HOPE-X development studies. One of these concepts a lifting body re-entry vehicle, which aims to reduce the vehicle's mass by minimising the wings and generating lift using the shape of the body itself. Compared to a winged body configuration, a lifting body re-entry vehicle is a wingless blunt shape and so has inferior flight performance within the atmosphere, but is thought to have advantages in terms of lower aerodynamic heating during re-entry and greater payload capacity.

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