Studies on weightlessness in a primate in the Biosatellite 3 experiment

Area of Science:

• Space biology
• Physiology
• Neuroscience

Background:

• The Biosatellite 3 mission aimed to study the physiological effects of prolonged spaceflight on a pigtail macaque.
• Understanding these effects is crucial for future human space exploration.

Purpose of the Study:

• To investigate the impact of weightlessness on central nervous, cardiovascular, and metabolic functions in a pigtail macaque.
• To analyze sleep-wake cycles, physiological rhythms, and fluid balance during spaceflight.

Main Methods:

• A male pigtail macaque (Macaca nemestrina) was flown in Earth orbit for 8.8 days.
• Comprehensive pre- and post-flight assessments included metabolic function, bone density, and urine analysis.
• In-flight monitoring focused on central nervous and cardiovascular functions, sleep states, and physiological rhythms.

Main Results:

• The macaque exhibited desynchronosis, with physiological rhythms (pCO2, temperature, heart rate) exceeding 24 hours.
• Sleep patterns were fragmented and brief, resembling those of individuals with high cervical cord transection.
• Weightlessness induced immediate increases in central venous pressure, leading to dehydration and electrolyte imbalances, with a 20% body weight loss.

Conclusions:

• Spaceflight significantly disrupts physiological regulation, including circadian rhythms and sleep architecture, in non-human primates.
• Weightlessness-induced fluid shifts and dehydration pose serious risks, potentially leading to severe cardiovascular events like ventricular fibrillation.
• Findings underscore the need for countermeasures to mitigate adverse health effects during long-duration space missions.