When is the earliest time for an American spaceship to take off?

Manned Space Flight From 196 1 to the end of 1984, the United States has carried out five manned space flights and completed 46 manned space flights, costing about 50 billion US dollars. 1959 In April, NASA selected the first batch of astronauts and began training at Langley Research Center. 1961May, A.B. Sheppard, the first American astronaut, completed his first in-orbit flight in the Mercury spacecraft. Johnson Space Center was established in September, 196 1. Its task is to design and manufacture manned spacecraft and select and train astronauts. In 1960s, project mercury (see Mercury spacecraft), Gemini project (see Gemini spacecraft) and Apollo project were realized. Through the first two plans, the problems of manned flight and return were solved, and the technologies of spacecraft orbital maneuver, rendezvous and docking and astronaut extravehicular activities were tested, which laid the foundation for the implementation of Apollo plan. 1July 1969 to1February 1972, six Apollo spacecraft completed their voyage to the moon, and 12 astronauts made scientific investigations on the surface of the moon, bringing back 368 kilograms of lunar soil and rock samples. The Apollo project cost about $25.5 billion. Later, due to the limited practical value, the funds were cut, the number of flights was reduced, and the plan was ended ahead of schedule. In the 1970s, the United States focused on two projects: the Skylab project and the Space Shuttle project. Skylab (Figure 2) was transformed into an experimental space station by using the third stage shell of Saturn V rocket. During the period of 1973 ~ 1974, as the base of space activities, three groups of astronauts went to Apollo spacecraft to carry out experiments in biology, astronomy, earth resources investigation and production technology. The space shuttle was developed in 1972. It was first tested in April and put into use in June. In addition, in July 1975, the United States and the Soviet Union cooperated in the docking flight of Apollo-Soyuz. A serious accident occurred in manned space activities in the United States:1967 65438+1On October 29th, an Apollo spacecraft caught fire during ground test at Kennedy Space Center, and three astronauts were killed.