The Chinese government is inviting scientists to help build an enormous, 1 kilometer (0.6 miles) long spacecraft that it wants to construct in orbit. The wild concept is to build a giant orbiting craft the size of 10 city blocks from components sent up by rockets one piece at a time. The concept is outlined in a [project document](//nsfc.gov.cn/publish/portal0/tab442/info81561.htm) from the National Natural Science Foundation of China (in the attachment titled “Guide for major projects of the Ministry of Mathematical Sciences”), which describes how the organization is looking for proposals for constructing an “ultra-large spacecraft with a size of one...