Yves Sillard (1936-2023) was a French engineer and senior civil servant who played a leading role in France's space and defence policy. A graduate of the École polytechnique and Sup'Aéro, he ran the Centre d'essais des Landes before serving as Director General of the French space agency CNES from 1976 to 1982, a decisive period for the Ariane programme. He later chaired the founding board of Ifremer and served as France's Délégué général pour l'armement (1989-1993). His preface to Exploration de la Terre par les satellites reflects the institutional interest in civilian remote sensing already emerging in the late 1970s.