Attempting to breathe on the Moon is not possible. The primary reason is the near-total absence of an atmosphere, which makes it an uninhabitable environment for humans without specialized protection. The Moon’s surface is essentially exposed to the vacuum of space.
The Moon’s Environment
The Moon does not possess a substantial atmosphere like Earth’s; instead, it has an extremely thin layer of gases referred to as an exosphere. This exosphere is so tenuous that its particles are widely dispersed, rarely colliding with one another. It contains trace amounts of gases like helium, argon, and neon, but at incredibly low densities. To illustrate, Earth’s atmosphere at sea level contains approximately 10^19 molecules per cubic centimeter, whereas the lunar exosphere has fewer than 10^6 molecules in the same volume, effectively making it a hard vacuum. This sparsity means there is no atmospheric pressure to sustain human respiration or provide protection from solar radiation and micrometeoroid impacts.
This lunar exosphere is not stable, constantly being replenished by processes like micrometeoroid impacts vaporizing surface material and solar wind particles implanting into the lunar regolith. Despite these sources, gases are continuously lost to space due to the Moon’s weak gravitational pull. The lack of a dense atmosphere also results in extreme temperature fluctuations; sunlit areas can reach up to 127°C (260°F), while shadowed regions can plummet to -173°C (-280°F).
How Astronauts Survive
Astronauts visiting the Moon rely on sophisticated technology to survive its hostile environment, primarily through the use of a pressurized spacesuit, such as the Apollo A7L or the Extravehicular Mobility Unit (EMU). These suits are self-contained, personal spacecraft designed to provide a breathable atmosphere and protect against the vacuum and extreme temperatures. Each suit is custom-fitted to the astronaut.
A core component of these suits is the Portable Life Support System (PLSS), worn as a backpack. The PLSS supplies oxygen for breathing, removes exhaled carbon dioxide, and maintains the suit’s internal pressure. It also regulates temperature by circulating cooling water through a Liquid Cooling and Ventilation Garment worn underneath the suit. The PLSS provided life support for spacewalks lasting up to seven hours. The lunar lander also served as a pressurized habitat, offering a safe environment for astronauts when not performing extravehicular activities.
Exposure Without Protection
Being exposed to the lunar environment without the protection of a spacesuit would result in rapid and fatal consequences. The near-vacuum of space would cause the air in a person’s lungs to expand violently and rush out. Attempting to hold one’s breath would lead to severe lung damage.
Immediately following exposure, bodily fluids, such as saliva and tears, would begin to boil due to the extremely low pressure, a phenomenon known as ebullism. This boiling would also create a cooling effect as water vaporizes, potentially causing areas around the mouth and nose to freeze. Within approximately 10 to 15 seconds, a person would lose consciousness due to the lack of oxygen reaching the brain, and death would follow swiftly, likely within two minutes, primarily from suffocation and ebullism.