In addition to lofting larger GEO satellites, the H-II has been designed specifically to accommodate the proposed HOPE (H-II Orbiting Plane) spacecraft. In its current configuration HOPE will 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 will initially 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, has also been 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 suggest 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, are underway (References 149-152).
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