Proyecto Libro Azul
When Project Grudge was ordered dissolved, Project Blue Book was developed to replace it. Lt. Col. N. R. Rosengarten asked Ruppelt to take over as the new project's leader, partly because Ruppelt "had a reputation as a good organizer", and had helped get other wayward projects back on track. Though he was initially scheduled to stay with Blue Book for only a few months, when Project Grudge was reorganized in late 1951 and renamed Project Blue Book, Ruppelt (then a captain) was kept on as director.