Simulated shuttle egress: comparison of two Space Shuttle protective garments

Area of Science:

• Aerospace Engineering
• Human Factors in Spaceflight
• Physiological Responses to Spacecraft Environments

Background:

• Previous studies identified significant carbon dioxide (CO2) accumulation in the NASA Launch and Entry Suit (LES) helmet during simulated emergency egress.
• A high percentage of subjects (8/12) were unable to complete egress simulations in the LES due to physiological stress.

Purpose of the Study:

• To compare the Advanced Crew Escape Suit (ACES) with the LES regarding CO2 accumulation and egress walking time.
• To evaluate the performance of the new ACES design in mitigating CO2 buildup during simulated emergency egress.

Main Methods:

• Four male subjects, previously unable to complete LES egress, participated in simulated egress in the ACES.
• Simulations involved seated rest, standing, and treadmill walking (1.56 m/s, 0% grade) with G-suit inflation (1.5 psi) and 100% oxygen.
• Inspired CO2 levels and walking duration were measured throughout the simulation.

Main Results:

• The rate of CO2 accumulation was significantly lower in the ACES (0.53 %CO2/min) compared to the LES (1.07 %CO2/min).
• Egress walking time was substantially greater in the ACES (5.0 min) than in the LES (2.7 min).

Conclusions:

• Design modifications in the ACES effectively reduced the rate of CO2 accumulation.
• The ACES demonstrated improved egress walking time, indicating enhanced performance and astronaut safety over the LES.