在设计和研制成功一种中等尺寸的液氢火箭发动机之后,日本现在正在制造一种尺寸更大的液氢发动机。与此同时也正在研制一种单级入轨飞行器使用的液化空气火箭发动机(ALRE)。日本人已经掌握了美国空间计划所需要的动力装置基本技术方面的一些秘密,因此他们希望美国能够邀请他们共同开发空间技术。几年前日本曾参加了多国研制的V-2500发动机计划。 After designing and developing a medium-sized liquid hydrogen rocket engine, Japan is now working on a larger-size liquid hydrogen engine. At the same time, a liquefied air rocket engine (ALRE) for single-stage orbiting vehicles is being developed. The Japanese have mastered some of the secrets of the basic power plant technology required by the U.S. space program and they therefore hope that the United States will invite them to jointly develop space technology. A few years ago Japan participated in the multinational development of the V-2500 engine program.