1.
The first artificial Earth satellite, launched by the Soviet Union in 1957; its launch marked the start of the Space Race.__________________
2.
The Cold War-era competition between the United States and the Soviet Union to achieve superior spaceflight capabilities, including human spaceflight and lunar exploration.___________________
3.
The U.S. National Aeronautics and Space Administration (NASA) program in the 1960s and early 1970s designed to land humans on the Moon and return them safely to Earth.__________________
4.
NASA's first human spaceflight program (1958–1963) that aimed to put an American astronaut into low Earth orbit and study human performance in space.__________________
5.
NASA's intermediate human spaceflight program (1961–1966) that developed and tested techniques needed for lunar missions, such as long-duration flights, rendezvous, and docking.__________________
6.
The maneuver that places a spacecraft into a stable orbit around a celestial body after launch.__________________
7.
The controlled meeting of two spacecraft in orbit, a key technique practiced during Gemini to enable lunar mission assembly and transfer.__________________
8.
The physical joining of two spacecraft in orbit so crew or equipment can transfer between them.__________________
9.
The spacecraft used on Apollo missions specifically designed to land two astronauts on the Moon and return them to the command module in lunar orbit.__________________
10.
The portion of an Apollo spacecraft that housed the crew during launch, re-entry, and splashdown; it remained in lunar orbit while the LM descended to the surface.__________________
11.
Any activity performed by an astronaut outside a spacecraft, commonly called a spacewalk.__________________
12.
The automatic transmission and measurement of data from a spacecraft to ground stations, used to monitor systems and astronaut health.__________________
13.
The process of a spacecraft returning through Earth's atmosphere, requiring heat shielding to survive high temperatures and deceleration.__________________
14.
The cargo carried by a spacecraft or launch vehicle (e.g., scientific instruments, satellites, or crew modules).__________________
