Before the mid-20th century, most people felt travelling into space was an     1     dream. However, some scientists were determined to help     2     realise their dream to explore space. After many     3    , they succeeded in making rockets that could     4     Earth’s gravity. On 4 October 1957, the Sputnik 1 satellite was launched by the USSR and successfully orbited around Earth.    5    , the USSR focused on sending people into space, and on 12 April 1961, Yuri Gagarin became the     6     person in the world to go into space. Over eight years later, on 20 July 1969, American     7    Neil Armstrong stepped onto the moon,     8     saying, “That’s one small step for a man, one giant     9     for mankind.” Following this, many more goals were achieved. For example, America’s NASA space agency launched Voyager 1 on 5 September 1977 to study deep space, and it still transmits     10     today.