Rocket technology improved during World War Two. It was used to produce flying bombs.

(SOUND: V-1 bomb)

Thousands of people in Britain and Belgium died as a result of V-1 and V-2 rocket attacks. The rockets were launched from Germany. The larger V-2 rocket had the ability to hit the United States.

After the war, it became clear that the United States and the Soviet Union -- allies in wartime -- would become enemies in peacetime. So, both countries employed German scientists to help them win the race to space.

(SOUND: Radio signals from Sputnik)

The Soviets took the first step by creating Sputnik. This satellite was about the size of a basketball. It got its power from a rocket. It orbited Earth for three months.

The Soviets launched a dog named Laika on Sputnik 2 in November 1957. She survived just hours.

Within weeks, the Soviets launched another satellite into Earth orbit, Sputnik 2. It was much bigger and heavier than Sputnik 1. It also carried a passenger: a dog named Laika. Laika orbited Earth for seven days (but died after several hours.)

(MUSIC)

The United States joined the space race about three months later. It launched a satellite from Cape Canaveral, in the southeastern state of Florida. This satellite was called Explorer 1. It weighed about fourteen kilograms. Explorer One went into a higher orbit than either Sputnik. And its instruments made an important discovery. They found an area of radiation about nine hundred-sixty kilometers above Earth.