欧洲一些国家正在研究各种航天飞机方案,如法国宇航公司提出的ARES-S技术验证方案和德国的“不死鸟”。日本除集中发展“希望”X小型航天飞机外,日本宇宙科学研究所对用于未来太空旅游的称为“观光丸”的单级入轨运载器样机进行了一系列的亚音速低空试飞。此外,印度也在研究称为“艾斯塔”的航天飞机 Several countries in Europe are studying a variety of spacecraft programs, such as the ARES-S technical verification program proposed by the French Aerospace Corporation and the German “Phenix.” In addition to the concentrated development of Japan’s “Hope”X small space shuttle, Japan’s Institute of Space Research conducted a series of low-altitude subsonic low-altitude test flights on a single-stage orbiting carrier prototype called “tourist pill” for future space tourism. In addition, India is also studying a space shuttle called “Esta”.