An advanced spacesuit for Mars has to include the helmet. Mars has gravity resulting in the same hazards as Earth. Geologists always explore the roughest terrain; that's where rocks are exposed. This leads to scaling a cliff face or climbing over broken terrain. Weight is an issue; a light-weight rover must be open like a lunar rover or ATV. Accidents can easily happen; the suit needs a crash helmet.

Wiley Post suit, 1939

Tomato Worm suit, 1940-1943

Early forms of spacesuit used a shoulder-worn helmet. Wiley Post produced the first ever pressure suit, intended for high altitude aircraft and based on deep sea diving suit.

Then the US Army developed pressure suits for military aviators. Based on the concepts of Wiley Post's work, they're helmets were also shoulder-worn; however they used a transparent bubble. Their distinctive look earned them the name Tomato Worm suits.

Mercury	G4C - Gemini	A1C - Apollo 1

NASA suits were based on military pilot suits, specifically Navy aviator suits. Mercury, Gemini, and Apollo 1 suits helmets were head-worn.

Apollo 8 and later suits returned to the shoulder-worn bubble helmet of the Tomato Worm suits.

LES	ACES

The space shuttle has a couple suits, the Extravehicular Mobility Unit (EMU) used for work in space, and a suit worn in the cabin during launch and re-entry.

The suit worn for the first 4 shuttle flight was the Launch Escape System, or LES. They weren't used for several flights, but after the Challenger accident astronauts used it again. In 1993 it was replaced by the Advanced Crew Escape Suit, ACES. Both LES and ACES are head-worn helmets.

Work at the Mars Society's analogue suites showed hazards using an ATV, one person at FMARS "hot dogged" resulting in falling off, smashing his helmet visor and tearing his PLSS. Another person at MDRS fell off, the ATV rolled over her. This demonstrates the need for a crash helmet. However, when a design based on a motorcycle helmet was suggested the response was "it looks silly". Good design is based on function, not whether it looks like a preconceived notion. But to address "looks silly", let's look at helmets seen in movies and TV shows.

closed face motorcycle helmet

A real crash helmet has already been developed and optimized. A spacesuit pressure helmet designed as an integral crash helmet will be designed like a motorcycle helmet. Existing motorcycle helmets have a breath guard to deflect breath away from the visor, to prevent fogging up. Air channels lead to either exterior vents or the chin opening. A spacesuit helmet will have a nose & mouth breathing mask like fighter pilots, but integrated into the helmet like a motorcycle breath guard. Air channels will lead to hoses at the back for an MCP spacesuit, or to ducts in the neck for a soft suit. Mercury and Gemini helmets didn't have the breath guard, but did have visor fogging problems. Apollo lunar helmets were shoulder-worn with an air duct that "washed" air across an astronaut's face. This solved the fogging problem, and "southern boys" find a breeze across the face refreshing. Those from northern cities find wind in the face annoying. With a breath guard the "face wash" effect isn't necessary; a breath guard is compatible with a head-worn helmet. The chin guard of a closed face or full helmet is much larger than science fiction. A broad chin guard has enough strength to provide crash protection.

A motorcycle helmet is made from a polycarbonate resin shell with an expanded polystyrene safety liner, then a comfort liner. The safety liner absorbs impact energy without passing it on to your head. NASA uses polycarbonate for spacesuit helmet visors. The military developed expanded polystyrene (Styrofoam) to hold nuclear bombs in a ballistic missile housing. Obviously these materials are rated for use in space.

An integral breathing mask within the helmet provides another life support backup. In case of battery failure, air movement through the CO₂ sorbent isn't possible with a traditional shoulder-worn design. A breathing mask with chest air bladder will move air through the action of breathing. A fan will blow air out of the sorbent, into an air reservoir bag made of polymer film. The bag will be located in a 1 litre polymer bottle. To prevent suction or back-pressure within the bottle, an air hose to the other side of the sorbent drains the bottle. This provides "power assist" breathing. Normally the fan fills the bag, each breath is drawn from the bag. If power fails, the bag is drained with one breath but never re-fills. Subsequent breaths pull air directly through the sorbent. One-way valves ensure air circulates; 3 valves: to helmet, to bladder, to sorbent. Pure oxygen suit gas is consumed by astronaut metabolism, converted into CO₂. That CO₂ is scrubbed out by the sorbet, reducing pressure. A pressure regulator releases oxygen from the bottle to top-up pressure. Primary life support may have electronics to actively control O₂ release, but a simple pressure regulator can operate the backup system. This permits a rebreather backup system; much more compact than an open-loop oxygen purge system yet still works with complete power failure.