From 1974 he was Acting Director General of ESRO .
From 1974 he oversaw the transition of the two previous organisations ESRO and ELDO to form the European Space Agency ( ESA ) in 1975 .
From 1974 he was Acting Director General of ESRO , and oversaw the transition of the two previous organisations ESRO and ELDO to form the European Space Agency ( ESA ) in 1975 .