NASA astronaut Sunita “Suni” Williams will retire in December 2025 after nearly three decades of service. A veteran of three space missions, she logged 608 days in orbit, led the ISS twice, and set records that continue to shape human spaceflight and future Artemis missions.NASA astronaut Sunita “Suni” Williams will retire in December 2025 after nearly three decades of service. A veteran of three space missions, she logged 608 days in orbit, led the ISS twice, and set records that continue to shape human spaceflight and future Artemis missions.