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Ernst Stuhlinger, physicist and space scientist, was one of the most talented of the 118 German rocket scientists who surrendered to the Americans in 1945, shortly before the end of the Second World War.

The Americans brought the group to Fort Bliss, Texas, as part of the secret Operation Paperclip, to use their considerable skills in rocket science to establish and develop the United States space programme. In 1950 the group was moved to the US Army’s Redstone Arsenal, Huntsville, Alabama.

A close colleague of the famous Wernher von Braun, both in Germany during the war and in America afterwards, Stuhlinger made a crucial contribution to the American attempts to keep ahead of the Soviet Union in the postwar space race.

Working quietly behind the scenes, Stuhlinger became the director of science at the Marshall Space Flight Centre, Huntsville, that was part of the US National Aeronautics and Space Administration (Nasa). A number of generations of rockets were developed by the von Braun team at the Marshall Centre, the most powerful of which was Saturn 5, which took American astronauts to the Moon in the Apollo programme. Stuhlinger worked on the guidance and navigation systems for the spacecraft.

On October 4, 1957, the Soviet Union launched Sputnik 1 using the R-7 launch vehicle, the first man-made object to orbit the Earth, as part of the International Geophysical Year. The satellite was 58cm (23in) in diameter and weighed 83.6kg (183lb).

Sputnik 1, which soon became widely known by its “beep, beep, beep” sound transmissions, surprised the world. America, reeling from the spectacular failure to launch two of its Vanguard satellites, was exceedingly shocked and humiliated. To catch up with the Soviet Union it began a crash programme — the space race was born within the Soviet-American Cold War.

In its frenzy to catch up with the Soviet scientists, the US Army Ballistic Missile Agency (ABMA), which included the Braun group, and the Jet Propulsion Laboratory (JPL) in California were ordered to get the Explorer 1 satellite into orbit as quickly as possible. The US Explorer programme had been proposed earlier by the ABMA.

Together with JPL, ABMA built Explorer 1 in 84 days and launched it on January 31, 1958. By then, however, the Soviet Union had launched a second satellite, Sputnik 2, on November 3, 1957. On December 6, 1957, the spectacular televised failure of the launch of another Vanguard satellite deepened American concern over the country’s performance in the space race.

Stuhlinger’s expertise was critical to the effort to launch Explorer 1. The rocket used for the launch was a hybrid — combining the technology used by the Germans for their V-2 rockets with American upper stages. The second stage of the rocket had to be fired at precisely the right time if the satellite was to achieve orbit.

There was so much pressure to launch the satellite quickly that Stuhlinger worked in his garage at home. In a matter of hours, he came up with an ingenious and unsophisticated timing device.

On March 17, 1958, Vanguard 1 became the second artificial satellite successfully launched into Earth orbit by the United States. The first solar-powered satellite, it was only 152mm (6in) in diameter and weighed just 1.4kg (3lb). The Soviet President, Nikita Khrushchev, described it contemptuously as “the grapefruit satellite”.

Stuhlinger was born in Niederrimbach, Germany, in 1913. In 1936 he was awarded a PhD in physics by the University of Tübingen. Between 1936 and 1941 he was an assistant professor in the physics department of the Berlin Institute of Technology, continuing his research into cosmic rays and nuclear physics.

He was then called up into the German Army and, as a private, was sent to the Russian front. He was wounded at the Battle of Moscow and managed to survive the Battle of Stalingrad. In 1943 he was sent to work with von Braun at the German rocket centre, working at the centre for the Research and Development of Missile Guidance and Control Systems, Peenemünde. His job was to improve the guidance system of the V-2 rocket, which was used to bombard London towards the end of the war.

By 1946 he was working on the research and development of guided missiles at Fort Bliss. Between 1956 and 1960 he was the Director of the Research Projects Laboratory at the US Army Ballistic Missile Agency in Redstone Arsenal.

In the 1950s he developed designs for solar-powered spacecraft. The best of these used ion thrusters that ionized either caesium or rubidium vapour (by removing electrons from atoms of the vapour) and then accelerated the positively charged ions through electrodes in the form of grids to propel the spacecraft.

Between 1960 and 1968 he was the director of the Space Sciences Laboratory at the Marshall Space Flight Centre. In 1968 he became the associate director for science at the Centre. He retired in 1975 to become an adjunct professor and senior research scientist at the University of Alabama, Huntsville.

Stuhlinger wrote a number of publications on electric propulsion, including the classic textbook Ion Propulsion for Space Flight, published in 1964. In 2005 the Electric Rocket Propulsion Society awarded him its medal for Outstanding Achievement in Electric Propulsion.

He became an American citizen on April 14, 1955.

His wife, two sons and a daughter survive him.

Ernst Stuhlinger, physicist and space scientist, was born on December 19, 1913. He died on May 25, 2008, aged 94