Education
Gaastra attended the Rijks Lyceum in Heerenveen and began his studies in history at the University of Leiden in 1965, receiving his doctorate in March 1972.
Gaastra attended the Rijks Lyceum in Heerenveen and began his studies in history at the University of Leiden in 1965, receiving his doctorate in March 1972.
In 1972-1973, he began working as a researcher with the Nederlandse Organisatie voor Zuiver Wetenschappelijk Oonderzoek on Dutch-Asiatic Shipping. In 1973-1974, he taught history in Haarlem, then in March 1974, the University of Leiden appointed him as a university docent. In 2004, he succeeded Jaap R. Bruijn, as Professor of Maritime History.
Gaastra retired from this post at the University of Leiden in June 2010 and was succeeded by Hendrik J. den Heijer, a specialist in the history of the Dutch West India Company.