Humans have dreamed of spaceflight since ancient times. The Chinese used rockets for ceremonial and military purposes centuries ago, but in the second half of the 20th century, the first rockets were developed to open space to human exploration.
The earliest practical work on rocket engines designed for spaceflight occurred simultaneously during the early 20th century in three countries: in Russia, by Konstantin Tsiolkovski; in the United States, by Robert Goddard; and in Germany, by Hermann Oberth.
The first U.S. satellite, Explorer 1, went into orbit on January 31,1958. In 1961, Alan Shepard became the first American to fly into space. On February 20,1962, John Glenn's historic flight made him the first American to orbit Earth.
"Landing a man on the moon and returning him safely to Earth within a decade" was a national goal set by President John F. Kennedy in 1961. On July 20,1969, Neil Armstrong took "a giant step for mankind" as he stepped onto the moon. Six Apollo missions were made to explore the moon between 1969 and 1972.
By the early 1970s orbiting communications and navigation satellites were in everyday use, and the Mariner spacecraft was orbiting and mapping the surface of Mars. By the end of the decade, the Voyager spacecraft sent back detailed images of Jupiter and Saturn, their rings, and their moons.

Q1: what is the general idea of the passage?

A. The specific achievements of American astronauts in the space race

B.The significant milestones and progress in human space exploration during the 20th century

C.The development of rocket technology in three different countries

D.The contributions of Chinese rockets to modern space exploration