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Atmosphere
Revised 7 Jun 2022
Human beings require not only oxygen and water to stay alive but also an optimal atmospheric environment to thrive.
The design parameters for a pressurized environment cannot be overlooked.
In order to drive to an interesting location for exploration, a pressurized rover is needed to protect the prospectors from the harsh outside Mars environment while providing the cabin comfort to travel from point A to point B.
Similar, when performing Extravehicular Activities (EVAs) outside on the surface of Mars, settlers need to don EVA suits which have Portable Life Support System (PLSS) with miniaturized tanks of O2 attached.
| Tiers | Description | mb | kPa | psi |
|---|---|---|---|---|
| 0. | Earth Sea Level | 1013 | 101.3 | 14.7 |
| 1. | Zubrin's Human 1 | 340 | 34 | 4.93 |
| 2. | NASA's EMU | 296 | 29.6 | 4.3 |
| 3. | Zubrin's Human 2 | 170 | 17 | 2.47 |
| 4. | Automated Plants only | 68 | 6.8 | 1 |
In Robert Zubrin's How to Live On Mars, he suggested just 2 tiers of habitable atmosphere for human beings.
In a foreseeable future, settlers would be confined to living inside a pressure dome unless advances in the area of genetics provide ways to augment our body to adapt to the ambient environment of Mars.
One research question is, what types of tasks may be carried out most comfortably or effectively under what regime of operating pressure ?
At the Earth's sea level, the atmospheric pressure is 101.3 kPa or 14.7 psi. Most human beings are born, live and die breathing at an atmosphere with 20.9% content of oxygen.
In mars-sim, a (Tier 1) atmosphere of 34 kPa or 4.93 psi is chosen for settlement living having a higher composition of oxygen at 58.8%.
Similarly, mars-sim's greenhouses operates at this pressure level.
On the other hand, NASA's Extravehicular Mobility Unit (EMU) (another name for the space suit) consists of PLSS that maintains a (Tier 2) pressurized 29.6 kPa or 4.3 psi environment with nearly 100% oxygen for breathing and ventilation.
However, in mars-sim, both inside a rover or an EVA suit, an less expensive (Tier 3) low pressurized environment of 17 kPa or 2.47 psi is adopted for more optimal use of resources.
In future, automated farming can make use of the least expensive (Tier 4) pressure of 6.8 kPa or 1 psi as the design specification for growing food crop. Human beings, however, would need to don a pressure suit to be able to enter this super low pressure environment.
See the quick description of the U.S.'s Spacesuit Models of Historical Significance