ISS Uses 3 Lighting Modes and UTC to Override 16 Daily Sunrises
Updated
Updated · spacedaily.com · Jul 31
ISS Uses 3 Lighting Modes and UTC to Override 16 Daily Sunrises
1 articles · Updated · spacedaily.com · Jul 31
Summary
The ISS runs crew life on a 24-hour UTC schedule rather than its 90-to-93-minute orbit, separating the station’s 16 daily sunrises from astronauts’ working day and bedtime.
NASA reinforced that clock with solid-state lighting that shifts from 6500K alertness light to 4500K general light and 2700K pre-sleep light, giving the body timed cues that windows alone cannot provide.
Crew routines still include Cupola viewing and night photography, but fatigue guidance limits bright, blue-rich light in the 2 hours before sleep and uses crew-quarter darkness, eye masks and glasses to protect rest.
Sleep remains a constraint: a 2014 study found ISS astronauts averaged 6.09 hours a night, and newer research says dockings, spacewalks and other operational events can still force split or shifted sleep schedules.
That makes circadian lighting a model for longer missions, as lunar and Mars crews will also need engineered day-night cycles when natural sunlight no longer provides a usable clock.