PAVING THE WAY

NASA’S Pioneer program, which ran for two decades from 1958 to 1978, involved a series of custom-built spacecraft designed to test out various aspects of spaceflight beyond Earth orbit. Two of these spacecraft, Pioneers 10 and 11, acted as pathfinders for the Voyager project, with both having a focus on spaceflight engineering as much as planetary research.

Pioneer 10 was launched in March 1972, reaching the asteroid belt – the first spacecraft to do so – in July that year. It crossed it unscathed, since it isn’t as hazardous as it’s often portrayed in fiction, and reached Jupiter in December 1973, capturing the first close-up images of its atmosphere and moons. As it passed by, Pioneer 10 used the slingshot effect of Jupiter’s gravity to boost it onto an interstellar trajectory. It was the first spacecraft to employ a ‘gravity assist’ manoeuvre of this type, and the first to acquire escape velocity from the Solar System.

Around a year after its predecessor, Pioneer 11 followed in its footsteps – but with an added twist. As well as acquiring escape velocity, the boost it received from Jupiter put it on course for a flyby of Saturn, which took place in September 1979.