Past 50 years and next 50 years of space activity

抄録

Author's experience in space engineering was first reviewed. The past 50 years activities include launch vehicles, satellites in commercial and educational areas, space debris, deep space exploration, on-orbit servicing and other advanced systems. Although some of the tasks provided outputs to serve actual space systems, most of other tasks originated or proposed failed to go into real programs. Discontinuation of original proposal is very common in actual space programs. Successful programs also often go through a series of alternations due to engineering, economic or political reasons, and the established systems not necessarily represent ideal ones that have been envisioned in the original thinking. Some remarks from this view point are stated to look into future space endeavors, perhaps in next 50 years.