Why NASA's Next Space Suits are not Pressurized to 14.7psi - Smarter Every Day 296

Episode Overview

• This episode offers a behind-the-scenes look at NASA's preparations for the Artemis program, which aims to establish a long-term human presence on the moon.
• The core of the episode takes place at NASA's Neutral Buoyancy Laboratory (NBL), showcasing how astronauts train for lunar surface operations in a massive underwater facility.
• It breaks down the complex physics of moving in 1/6th gravity, where an astronaut's weight is reduced but their mass and inertia remain the same, creating unique challenges for stability and movement.
• The summary details the sophisticated engineering required to simulate lunar gravity, focusing on the critical alignment of an astronaut's Center of Gravity and Center of Buoyancy.
• We observe a full-duration test run where astronauts evaluate a higher-pressure spacesuit, a key decision point that trades reduced preparation time for potentially increased physical exertion.

Key Concepts

• Artemis Program vs. Apollo: The Artemis program's goal is to establish a sustainable, long-term human presence on the moon ("go back to stay"), a fundamental shift from the short-term "flags and footprints" visits of the Apollo era.
• Physics of Low-Gravity Movement: In 1/6th gravity, weight is drastically reduced, but mass and inertia are unchanged. This makes it difficult to start, stop, or change direction, making astronauts feel "sluggish" and increasing the risk of falls.
• Simulating Lunar Gravity: At the NBL, simulating the moon's gravity is more than just achieving neutral buoyancy. The primary challenge is aligning the astronaut's Center of Gravity (CG) with their Center of Buoyancy (CB) to prevent unwanted rotation and create a stable simulation for walking.
• Spacesuit Design Challenges: Modern spacesuits are pressurized, stiff enclosures that resist movement and cause significant fatigue. Key design trade-offs include balancing suit pressure (which affects pre-breathe time) with mobility and dexterity. Specific features like a mechanical bar in the gloves help maintain hand function under pressure.
• Specialized NBL Operations: To facilitate six-hour training sessions, the NBL uses a special enriched air nitrox blend (46% oxygen) that allows divers and astronauts to work for extended periods underwater without requiring lengthy decompression stops.
• Astronaut Training Protocol: Training involves performing realistic tasks like collecting rock samples and maneuvering equipment. A crucial part of the protocol is allowing astronauts to solve problems independently, such as learning to recover from a fall in the simulated low-gravity environment.

Quotes

• At 1:42 - "The Artemis program is going back to stay. People are going to live on the moon." - This quote establishes the ambitious, long-term vision of the Artemis program, distinguishing it from the temporary visits of the Apollo era.
• At 4:22 - "To get the same amount of acceleration [on the moon] requires nearly six times the tilt angle." - Quoting a lecture by Neil Armstrong, this highlights the counterintuitive physics of maneuvering in low gravity, where a much greater tilt is needed to achieve the same horizontal movement as on Earth.
• At 27:50 - "I also have to co-locate that with your center of buoyancy... otherwise you'll be too stable all the time or... it's giving me a righting moment." - An NBL expert explains the critical engineering necessity of aligning an astronaut's Center of Gravity with their Center of Buoyancy to create a stable and realistic underwater simulation.
• At 36:52 - "It all has to do with pre-breathe time. And so, that's the amount of time it takes you to get from the pressure that you're at in your space habitat or your vehicle to the pressure that you're going to be in your spacesuit." - A Test Conductor explains that the primary goal of the test is to evaluate performance at a higher suit pressure, which could save hours of preparation time before a spacewalk.
• At 1:02:22 - "I think the main reason for that is because you're using... you actually can use our bodies as they evolved." - Astronaut Jessica Meir explains why lunar simulation felt more natural and less fatiguing than zero-G EVAs, as it allows for the use of leg and core muscles for walking and stabilization.

Takeaways

• The physics of low gravity is deeply counter-intuitive; success on the lunar surface depends on astronauts retraining their brains to manage their full Earth-mass inertia despite weighing only 1/6th as much.
• Creating a realistic lunar simulation is an immense engineering challenge focused on rotational stability (aligning CG and CB), not just on reducing an astronaut's weight.
• Critical architectural decisions for Artemis, like spacesuit pressure, involve balancing operational efficiency (saving hours of pre-breathe time) against human factors like astronaut fatigue and mobility.
• Lunar surface operations represent a full-body workout that engages the legs and core, a fundamentally different physical challenge for astronauts compared to the upper-body-intensive work of zero-gravity spacewalks.