The electrodes and sensors are connected to a digital sleep recorder that records a variety of measurements as they sleep. Mukai also will swallow a capsule containing either melatonin or a placebo as part of the sleep study. Glenn will remove and stow the Holter monitor electrodes and data recorder he has worn for the past 24 hours. The Holter monitor recorded his heart rhythm on orbit, as part of an investigation of heart rate variability during space flight. He also will process blood samples as part of the PTO experiment.
Colloids are systems of fine particles suspended in fluid.
Researchers hope to learn more about how the organization of atoms changes as they form into orderly solid structures. Duque then will deactivate these two experiments for the remainder of the mission. Discovery is orbiting the Earth every 95 minutes at an altitude of about 341 statute miles with all systems operating in excellent condition. The next STS-95 status report will be issued at approximately 6 p.m. Central time Wednesday.