An Outfit Suitable For Mars

[zavvy]

<b>An Outfit Suitable For Mars</b><br /><br />LINK<br /><br />The gas-pressurized space suits used by astronauts for space walks and moon landings would never work on Mars. That's the consensus, at least among astrobiologists and simulation experts at the Eighth International Mars Society Convention, which took place 11-14 August in Boulder, Colorado. <br /><br />A solution, they say, may lie with an old idea.<br /><br />The Mechanical Counter Pressure (MCP) suit aims to use elasticity to provide pressure instead. Paul Webb, a physician from Yellow Springs, Ohio originally proposed this idea in 1968, as a safer and more flexible alternative to the bulky Apollo mission suits. His idea didn't take flight until recently, however, when the US space programme began casting an eye towards the red planet.<br /><br />"For future field work on Mars, our number one problem is a space suit that works," says Chris McKay, an astrobiologist at NASA Ames Research Center in Moffett Field, California. Astronauts need something that is light and flexible enough to allow them to scramble about and dig holes, while still protective against the harsh conditions. <br /><br />Tight fit<br /><br />Webb's suit is made of a stretchy Lycra-like fabric that squeezes the body five times harder than medical support stockings. This makes it difficult to put on, admits Webb. But it is reasonably comfortable so long as the air the astronaut breathes is pressurized to match the suit's constrictiveness. "Otherwise," he says, "it hurts like hell."<br /><br />The inner suit would have to be covered with an insulating outer shell to regulate body temperature and protect the astronaut against radiation.<br /><br />Unlike an air-filled suit, an MCP suit would still function properly even with a small rip, says Webb; the astronaut's skin would simply bulge slightly to fill the hole. And it weighs only 39 kg, much less than the 180 kg of a

 

[tony873004]

Actually, the cold is the least of your worries. Here's why. You know how if you step outside in just a t-shirt in 50 degree Farenheit weather, it's not that uncomfortable, especially if the wind is still. But if you jump into 50 degree Farenheit water it's so agonizingly cold that it knocks the breath out of you? It'll kill you of hypothermia in under an hour. That's because water is much denser than air and is much better at sucking the warmth out of your body rapidly.<br /><br />But Mars' atmosphere is less than 1% as thick as Earth's. It has virtually no ability to draw heat from your body through conduction. You're only going to lose heat by radiating it away. And your body is not a good radiator.<br /><br />So even a light sweater under your spacesuit would likely make you break a sweat as soon as you started doing anything strenous.<br /><br />The exception is your feet. They are in direct contact with the ground which is -200 degrees Farenheit. The ground is a good conductor of heat and will rapidly draw heat from your body if you boots don't do a good job insulating you from the ground.<br /><br />So for cold protection, something light that is good at reflecting your body heat back at you, and good boots is all you need even in the middle of the night during a Martian winter.

 

[bushuser]

I think you will still need some of that long underwear with coolant tubes to help thermoregulation. That adds to the complexity/weight of the backpack. This compression stocking will be like wearing plastic shrink-wrap, since there will be no airflow between skin and fabric....<br /><br />actually, couldn't we just wrap the astronauts in shrink wrap below the neck, apply the heat gun, and get the same effect in a disposable wrap? <img src="/images/icons/smile.gif" />

 

[Leovinus]

But if you fall down or sit down, other parts of your body than your feet will touch something solid at -200. I don't know how you're going to avoid insulating the whole suit. <div class="Discussion_UserSignature"> </div>

 

[spayss]

And we might fall a lot. . I once listened to a talk on the muscles involved in walking and the speaker brought up the intricate interaction of each muscle to keep our balance. Lots of action and reaction at the sub conscious level of muscle activity. He said walking on the Moon isn't so difficult because the low gravity gives us time to compensate. We can sort of hop. Whereas on Mars, however, our reflexive actions could send us any which direction without the luxury of time to compensate....sort of like walking over a tightly pulled piece of rubber or a floor covered with marbles. We could learn to walk on Mars but only after a lot of practice and only by then remembering the limitation when out on the Martian surface.

 

[JonClarke]

-200??? Mars is not colder than Titan! remember that the skin won't come into contact with the ground, there will several layers, including insulating ones, between the sin and cold surfaces. Ifneccessary extra insulation can be built into knees, elbows etc. The gloves have to stay thin however, so they might need heating elements wired into them.<br /><br />This is a subject very dear to me, I have actually worn the prototype MCP glove that James Waldie developed for his PhD. It is really remarkably dextrous, it is more flexible than a thin wet suit glove and only slightly less flexible than a thermal glove. It is really remarkable to think that such a thin piece of material (actually three layers) is all you wodul need to protect yourself against hard vacuum.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[JonClarke]

MCP pressure and inner garments are nothing like shrink wrap. They are permeable fabrics, knitted and woven, respectively. So sweat can boil or sublime off. Such suits have only been tested in vacuum chambers so there has not been exposure to hard sunlight or deeply cold surfaces, but in the chamber at least active thermoregulation was not needed for the range of activities, which included walking, running, climbing and using a range of tools that was performed. AS gas pressure suit would have needed active thermoregulation even in a chamber for these. This was done by Webb back in the late 60's and 70's<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[gsuschrist]

Spayss,<br /><br />That also leads to a potential seasickness effect. The balance in the inner ear and visual signals are at odds and the result could be upchuck of Martian breakfast. <br /><br />Is there any need for radiation protection? Would a three year trip to and stay on Mars have any allowance for the luxury of extra radiation exposure? Would humans be able to walk around without the shieding provided by a vehicle of some sort?

 

[JonClarke]

The risks of both radiation sickness and disorientation have been greatly exaggerated. A 2.5 year mission with standard radiation protection falls inside currently exposure limits. Apollo astronauts did not feel motion sickness walking on the moon with less than half the gravity that Mars, so why should they feel queasy on Mars?<br /><br />There is a growth industry in trying to predict unlikely risks facing people on Mars and blowing them out into potential show stoppers. Some are truly bizzare - hexvalent chromium is one, now motion sickness is another.<br /><br />Anyway, back to MCP suits. <br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[gsuschrist]

"Apollo astronauts did not feel motion sickness walking on the moon with less than half the gravity that Mars, so why should they feel queasy on Mars?"<br /><br /> The issue is not the amount of gravity. Folks can walk in water and not get sick. The issue is the visual signals and impact of balance compensation. This is why closing one's eyes helps to diminish queasiness.

 

[JonClarke]

Since healthy people do not experience such queasiness on earth or the moon why posulate it will happen on Mars? <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[JonClarke]

Just to summarise the advantages of MCP vs GP suits. MCP suits offer:<br /><br />Lower consumption of O2, power, water, possibly as much as half. This has major implications for the endurance and mass of the PLSS, as well as the effects on the wearer.<br /><br />Lower suit mass without the PLSS and can much more be compactly stowed. More suits can be stowed allowing redundancy on long missions.<br /><br />Higher safety - a cut or tear in an MCP suit will not be fatal or even life threatening. <br /><br />Does not need a O2 prebreathing period, unlike the shuttle suit. <br /><br />Greater reliability - fewer moving parts and no pressure tight bearings. Thus they require less maintainence and are more easily repaired with fewer parts needed.<br /><br />Much greater dexterity in the arms and gloves. This makes detailed field science and engineering much easier and less tiring. This feeds back to lower consumable consumption because they are less tiring to wear.<br /><br />Greater overal flexibility, making climbing, walking, even running much easier. This results in a greater range of field operations that can be carried out and less strain on the wearer. Current MCP suit require 1.5 times the extertion to do a task as doing it naked. An Apollo era EVA suit required 3 times as much effort.<br /><br />The main issues for MCP suit development (other than resistance of entrenched vested interests) are:<br /><br />Doning and doffing. This is very long and laborious, longer than an Apollo suit (which required 2 hours). However it is less time than is required with a shuttle suit including the prebreath period. However a range of technologies are promising to ease this.<br /><br />Negative and complex body surfaces present challenges to supplying equal pressure. These include the spinal trough, the armpits, the male groin and the female chest. <br /><br />dealing with wase elimination has yet to be addressed. The earlier MCP suits did not have any waste management system. The expe <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[bushuser]

The shrink wrap comment was facetious, but the comment about cooling was serious. I did not understand that the MCP materials allowed for evaporation and air circulation over the skin. I hope they breath better than the "breathable" Gortex garment I wear everyday in surgery. That truly is a plastic bag, provoking sweat with no exertion at all.<br /><br />How much would simple zippers help to speed up slipping into one of these stocking-like MCP garments?

 

[JonClarke]

The suit itself would be a very open weave material. on James Waldie's glove It looks like pantyhose on steroids. The loose outer layers would be like a ski suit. The materials would also be wickable as well as breathable, drawing mositure away from the skin.<br /><br />The Webb activity suit used a lot of zips. This was OK but heavy duty zips next to the skin are quite uncomfortable. Remember when put on current MCP suits at one atmosphere the they is about nearly astight as a blood pressure cuff. As the atmosphereic pressure drops this reduces to a compfortable snuggness. hence the interest in electroactive fibres that loosen when activated and then tighten to a preset tension.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>