Grant died on October 11, 2026 at the age of 84. 

Grant joined NASA in the spring of 1969 as part of the team preparing for the Apollo 11 mission, and he was a critical science player throughout the Apollo era. 

Grant's obituary: https://losalamosreporter.com/2026/11/10/obituary-grant-harvey-heiken-oct-11-1942-oct-11-2026/