The test was one of many planned to ensure that a human being could survive space flight, think clearly and perform useful functions outside the Earth's atmosphere.

The chimp, named Ham, was trained to pull levers in response to flashing lights during flight. He carried out several such operations successfully as he travelled at 5,000 mph (8,000 km/h) at a height of 155 miles (250 km) above the Earth.

Ham, named after the Holloman Aerospace Medical Centre, and originally from Cameroon in Africa, was chosen from six "astrochimps" - four female and two male - who underwent intensive training in New Mexico and Cape Canaveral in Florida.

Chimpanzees were chosen in preference to dogs - which the Russians have sent into space on several occasions - because they are more similar to humans.

Aborted mission

At 1655 GMT, the Mercury capsule with Ham on board blasted off. Almost immediately there was a hitch: the flight path was a degree higher than it should have been, and rising.

As computers reported a drop in the oxygen supply, the mission was aborted. However, partly because of the high flight angle, it had already reached 157 miles (253 km) above the Earth, higher than the planned target of 115 miles (185 km).

Ham was safe in his spacesuit throughout, and suffered no ill effects from his venture into space. In all, he travelled 155 miles (250 km) in 16.5 minutes.

For a little over six and a half minutes of the flight he experienced weightlessness, and his response times were reported to be as good in space as they were on Earth.

There was more trouble when he landed. Because of his steeper-than-expected climb, the capsule overshot its landing site in the Atlantic off Florida by some way. Ham had an uncomfortable three-hour wait before he was found.

Then when rescue helicopters finally arrived, they found the capsule on its side and sinking. It had landed with such force that the heat shield had punched two holes in the capsule.

Ham, however, took it all in his stride and when the spacecraft was opened accepted an apple and half an orange in reward.

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