Roosa remained in lunar orbit , where he took photographs of the Moon and performed experiments. After liftoff from the surface and a successful docking, the mission returned to Earth, splashing down safely in the Pacific Ocean. He died of typhoid , pneumonia or paratyphoid fever 31 days into his term, becoming the first president to die in office. His death sparked a brief constitutional crisis regarding succession to the presidency. Vice President John Tyler claimed a constitutional mandate to become the new president and took the presidential oath of office, setting an important precedent for an orderly transfer of the presidency and its full powers when the previous president fails to complete the elected term. Wikipedia is hosted by the Wikimedia Foundation , a non-profit organization that also hosts a range of other projects :.