page_title: Mars suit
section_title: Pressure
hierarchical_section_title: Mars suit / Environmental design requirements / Pressure
caption_attribution_description: This is a S-1010 pressure suit for an U-2R plane. High-altitude pilots wear pressure suits as protection from cockpit depressurization. At altitudes above 63,000 feet without artificial air pressure, human blood and other fluids boil. In addition to preventing this, pressure suits also protect pilots from low temperatures at high altitudes. A coated-fabric face barrier inside this U-2 helmet divides the oxygen supply into two sections. One region covers the eyes, nose, mouth, and chin; the other compartment houses the rest of the head and is linked to the air in the interior of the suit.
context_page_description: A Mars suit or Mars space suit is a space suit for EVAs on the planet Mars. Compared to a suit designed for space-walking in the near vacuum of low Earth orbit, Mars suits have a greater focus on actual walking and a need for abrasion resistance. Mars' surface gravity is 37.8% of Earth's, approximately 2.3 times that of the Moon, so weight is a significant concern, but there are fewer thermal demands compared to open space. At the surface the suits would contend with the atmosphere of Mars, which has a pressure of about 0.6 to 1 kilopascal. On the surface, radiation exposure is a concern, especially solar flare events, which can dramatically increase the amount of radiation over a short time.
  Some of the issues a Mars suit for surface operations would face include having enough oxygen for the person as the air is mostly carbon dioxide; in addition the air is also at a much lower pressure than Earth's atmosphere at sea level. Other issues include the Martian dust, low temperatures, and radiation.
context_section_description: The atmospheric pressure on Mars varies with elevation and seasons, but there is not enough pressure to sustain life without a pressure suit. The lowest pressure the human body can tolerate, known as the Armstrong limit, is the pressure at which water boils (vaporizes) at the temperature of a human body, which is about 6.3 kilopascals (0.91 psi). The average pressure on Mars has been measured to be only about one-tenth of this, 0.61 kilopascals (0.088 psi). The highest pressure, at the lowest elevation, the bottom of Hellas Basin, is 1.24 kilopascals (0.180 psi), about twice the average. There is a seasonal variation over the Martian year (about two Earth years) as carbon dioxide (95.9% of the atmosphere) is sequentially frozen out, then sublimated back into the atmosphere when it is warmer, causing a global 0.2-kilopascal (0.029 psi) rise and fall in pressure.
  But the Martian atmosphere contains only 0.13–0.14% oxygen, compared to 20.9% of Earth's atmosphere. Thus breathing the Martian atmosphere is impossible; oxygen must be supplied, at a pressure in excess of the Armstrong limit.
caption: Partial pressure suit for high-altitude flight
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