Mars suit
[2] 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.
[14] Some ideas for a Mars suits are a Heads-up display projected in the visor, built-in communications equipment, life support, and a voice-recognition assistant.
A hard-suit can use a high-pressure atmosphere, eliminating the need to pre-breathe, but without being too hard to move like a high pressure soft suit would be.
A simulated Mars suit was used for the HI-SEAS Earth-based spaceflight analog tests of the 2010s in Hawaii, USA.
[22] The most critical factors for immediate survivability and comfort on the Martian surface are to provide: sufficient pressure to prevent the boiling of body fluids; supply of oxygen and removal of carbon dioxide and water vapor for breathing; temperature control; and protection from cosmic radiation.
[24] The highest pressure, at the lowest surface elevation, the bottom of Hellas Basin, is 1.24 kilopascals (0.180 psi), about twice the average.
Thus breathing the Martian atmosphere is impossible for almost any organism; oxygen must be supplied, at a pressure in excess of the Armstrong limit.
Humans generally require supplemental oxygen at altitudes above 15,000 feet (4.6 km),[23] so the absolute minimum safe oxygen requirement is a partial pressure of 11.94 kilopascals (1.732 psi)[27] For reference, the Apollo EMU used an operating pressure of 25.5 kilopascals (3.70 psi) on the Moon.
[34] Another more traditional way to remove carbon dioxide from air is by a lithium hydroxide canister, but these need to be replaced periodically.
[35] Carbon dioxide removal systems are a standard part of habitable spacecraft designs, although their specifics vary.
[32] Space suits typically operate at low pressure to make their balloon-like structure easier to move, so astronauts must spend a long time getting the nitrogen out of their system.
There is also interest in hard suits that can handle higher internal pressures but are more flexible, so astronauts do not have to get the nitrogen out of their system before going on a spacewalk.
[39] Solar flare events can cause a lethal dose to be delivered in hours if astronauts are caught unprotected, and this is a concern of NASA for human operations in space and on the surface of Mars.
[43] A thin layer of gold on the visor plastic bubble of current space helmets shields the face from harmful parts of the Sun's spectrum.
[50] An article in the magazine Nature noted that due to the reduced gravity, the dynamics of walking on Mars would be different than on Earth.
[51] This is because people fall forward as part of their gait when moving, the motion of the center of body mass resembling that of an inverted pendulum.
[51] This data was produced by simulating Martian gravity for the duration of an aircraft following a flight profile that causes this type of acceleration.
[53] Rock climbing tests with a low-pressure IVA (intra vehicle activity) suit were conducted in Oregon, USA.
[54] Mountaineering on Mars may be needed when the terrain environments exceeds the abilities of a rover vehicle, or to access a target of interest, or simply to get home to a base.
[55] One common mountaineering need is a highly mobile short-stay shelter to use for overnight stays when climbing, such as a tent, and an equivalent for Mars might support the ability to get out of a space suit.
[57] Alternatively, a Mars suit would need to be worn on crewed unpressurized rovers to provide life support.
[58] There are several different options for an egress and entry airlock for a space suit, one of which is to repressurize the entire compartment as on the Apollo lunar lander.
