Lovell’s first career: Wartime radar and the development of H2S

Letter from AP Rowe to Lovell, February 1945. University of Manchester Library (JBA/CS7/19/4/1945)

In February 1945, 10 months before Bernard Lovell would arrive at Jodrell Bank for the first time, A. P. Rowe, Chief Superintendent of the Telecommunications Research Establishment (TRE) writes to Lovell to assure him:

‘You must have nothing whatever on your conscience. If you never did a stroke of work for the rest of your life you would have justified your existence.’

It’s an extraordinary thought that even without Jodrell Bank Lovell’s name would have gone down in history. His wartime distinction is less well known that his work in radio astronomy, but as the UK celebrates VE Day, we’re highlighting Lovell’s work developing the H2S airborne radar system, which greatly improved the Royal Air Force’s bombing accuracy and proved decisive in the outcome of the second world war.

When war broke out in the summer of 1939 Bernard Lovell was an idealistic young physicist at the University of Manchester, researching cosmic rays under his illustrious head of department, Patrick Blackett.  He knew little about radar, and when Blackett told him to abandon his cloud chambers and report to A. P. Rowe at the Air Ministry, he had no idea what the next six years would hold for him.

Like many university scientists he became a research physicist, applying his expertise to the rapid development of war technologies, in this case, radar. After two years working on interceptors and detection systems for night fighters, Lovell was ordered to take charge of the development of a new device for night bombing. In 1941 it had become apparent that the RAF’s bombing offenses in Germany were largely unsuccessful because pilots couldn’t find their targets. The longer wavelength systems used for navigation were not precise enough to lock onto specific landmarks, so a narrower radar system, on centimetric wavelengths, was required. And fast.

Lovell was apprehensive about this new responsibility, which would see him to apply his expertise to offensive technologies for destroying rather than saving lives. But this was war and as he describes in his autobiography Astronomer By Chance: ‘those last shreds of misplaced idealism were soon to be blown out of my being by a whirlwind of activities that made the previous two years of my wartime work seem like a rest cure’.

Notably, this whirlwind involved the invention of the cavity magnetron (a high-powered vacuum tube that generates microwaves and is used now in microwave ovens); the crash of a Halifax bomber during a test flight, which tragically killed members of his team; an ultimatum from Prime Minister Winston Churchill; and many iterations of what became known as the H2S.

This precision bombing device used a rotating antenna within a cupola attached to the underside of a bomber, to build up a map of the terrain below that pilots could see on the cathode ray tube inside the cockpit. It was the first ground mapping technology ever to be used in combat. When in February 1943 the first, 10cm radar version of the H2S was brought into operation for the bombing of Hamburg, pilots marvelled at how could clearly they could see the city’s docks as ‘fingers of bright light sticking out into the dark of the Elbe’.

Lovell received many congratulations following the Hamburg offensive, but as he wrote in his diary ‘I can’t feel a bit elated, only weighed down with the vastness of things in hand and in the future’.

In 1945 as the war drew to close and this intense pressure lifted, Lovell was exhausted. The toll it had taken on him is evident in this 1945 photograph of the H2S group; he looks thin and pale and can’t seem to muster a smile. Rowe’s letter of the same month is a kind but firm order to take some time off. In July he was released and gratefully returned to the university, cosmic rays and his cloud chambers. But of course nothing was the same, war had transformed the pursuit of science and Lovell set to work applying the new radar technology to the study of the sky.

Lovell remained modest about his wartime work, with some ambivalence about being the man who led the development of the system that, according to Air Marshal Victor Tait, ‘was one of the main factors in making the Air Force so effective in the destruction of the German armed forces’. However, the work earned him an OBE in 1946, and throughout his life he received letters from the public thanking him for what he gave to wartime science, turning the fortunes of the Allied Forces and leading to the national celebrations on VE day. For some, the H2S, and not the Lovell telescope, is his greatest achievement.

You can listen to Lovell himself telling the story of his wartime work on Web of Stories here. You can also find out about our First Light Project here, which will open up more heritage stories and enable visitors to Jodrell Bank to explore the incredible stories behind the pioneering scientists that work here.