Thomas Kelly

Thomas Joseph Kelly, engineer: born New York 14 June 1929; married Joan Tantum (five sons, one daughter); died Cutchogue, New York 23 March 2002.

Thomas Kelly was the leader of the groundbreaking team that built the first manned spacecraft to land on another world.

Generally regarded as the "father of the lunar module", Kelly was responsible for assembling the team of engineers at the Grumman Aircraft Corporation in Bethpage, New York State, who would build the revolutionary lunar module. On six separate occasions, this flimsy but highly functional vehicle – dubbed the "spider" by the Apollo astronauts – successfully delivered two men to the surface of the Moon and safely returned them to the command module for the return trip to Earth. The lunar module also saved the lives of the three crew on board Apollo 13.

When President John F. Kennedy committed the United States to landing a man on the Moon before the end of the 1960s, very little was known about spacecraft design or the environment in which such a craft would have to operate. Even before Grumman was given the contract to develop the lunar landing craft (officially known as the Lunar Excursion Module or LEM), in November 1962, Kelly helped to develop the lunar orbit rendezvous concept that made landing on the Moon possible with the limited rocket power available at the time.

Charged with the task of building an entirely new type of spacecraft, one that would be unable to re-enter the atmosphere or bring its crew back to Earth, his Grumman team designed a two-stage lander that was optimised for operations in the vacuum of space and the one-sixth gravity of the Moon.

The descent stage was designed to deliver the entire spacecraft to the dusty surface. It also acted as a platform for the ascent stage that would lift the men back into lunar orbit in order to dock with the Command Module. Since redundancy meant extra weight, each stage was equipped with only one main engine. A failure of this engine would either cause the LEM to crash on the Moon or leave its occupants stranded a quarter of a million miles from home. Fortunately, the systems worked perfectly on every flight.

Grumman's creation comprised 12 tons of propellants surrounded by four tons of computers and operational systems encased in an eggshell-thin aluminium fuselage. Almost 23ft high and 31ft across, it contained a million parts and 40 miles of wiring.

Not surprisingly, when Kelly was promoted to be Grumman Engineering Manager in July 1966, the programme was falling behind schedule due to technical difficulties. However, the long shifts and hard work eventually paid off in March 1969 with a successful 10-day test flight of the lunar module Spider in Earth orbit. Two months later, the second LEM, called Snoopy, was flown to within a few miles of the lunar surface, preparing the way for its successor, Eagle, to deposit Neil Armstrong and Buzz Aldrin on the Sea of Tranquillity the following July.

As the experts on the LEM, Kelly and his team were regularly consulted about potential problems by Nasa managers. Within a minute of the Apollo 11 touchdown, they were asked to analyse a potentially catastrophic rise in the temperature and pressure in one of Eagle's descent stage fuel lines. Kelly quickly realised that there was probably a blockage caused by frozen fuel and reported that, if the unstable fuel was suddenly heated by the residual heat from the engine, it might explode like a mini hand grenade. Fortunately, the blockage cleared before any remedial action was necessary.

Unlucky Apollo 13 did not escape so easily. When the oxygen tanks on the Command Module exploded halfway to the Moon, the crew's lives were saved by the fact that Grumman's lunar module was still attached. Fortunately, back in 1961, even before its design had been finalised, Kelly and his fellow Grumman engineer Al Munier had envisaged the possibility that their creation might one day be required to act as a lifeboat for a stricken command module, so they changed the specifications to include more fuel and other consumables.

Kelly and hundreds of others at Grumman's Bethpage plant worked 24-hour shifts to bring Apollo 13 home. After major modifications to the command module, four more LEMs landed on the Moon, bringing the number of humans to walk on another world to 12.

"Nobody at Grumman who worked on the lunar module will ever forget it," said Kelly in a 1999 interview. "We all knew that we were part of a majestic endeavour, and that we were making history happen."

Thomas Joseph Kelly was born in Brooklyn on 14 June 1929 and raised in Bellmore, New York. In 1946, he won a Grumman Engineering Scholarship at high school, an award that eventually resulted in him working for Grumman for almost 40 years.

After working during the summer holidays as an apprentice engineer, he graduated from Cornell University in 1951 with a bachelor's degree in mechanical engineering. Kelly then joined Grumman as a propulsion engineer, first on the Rigel missile programme and then on the F-11 jet fighter programme. He obtained a master's degree in mechanical engineering from Columbia University in 1956. During his military service at Wright-Patterson Air Force Base in Ohio 1956-58, First Lieutenant Kelly was a performance engineer on prototype aircraft and the Hound Dog missile.

After a short spell as a space propulsion engineer for Lockheed's missiles and space division between 1958 and 1959, Kelly returned to Grumman as Assistant Chief of Propulsion. A year later he was made Project Engineering Leader for studies involving the proposed Apollo space programme. He soon became involved in discussions concerning the various options in transporting humans to the Moon. Eleven years later, after the heady successes of the first Moon landings, he received a master's degree in industrial management from the Massachusetts Institute of Technology.

In 1971, in recognition of his achievements, the board of directors at Grumman elected him as a company vice-president and the following year he received the Nasa Distinguished Public Service Medal for his work on Apollo. In 1991 he was elected to the National Academy of Engineering.

Kelly went on to serve as deputy director of Grumman's Space Shuttle programme and president of the Grumman Space Station Integration Division before he retired in 1992, after 38 years with the company.

His highly praised account of what he called the highlight of his career – a book entitled Moon Lander: how we developed the Apollo lunar module – was published last year.

Peter Bond