What humanity has worn when beyond the Earth’s atmosphere so far can still be seen as experimental garments. Only the most recent spacesuits do not need to be custom made for the person who will ware it. This will change only when the number of people traveling to space grows. By the time the first person to leaves the cradle what is worn in space will have evolved. The largest reason for this is what is worn now provides only the absolute minimal functionality.
What Wrong with What I’m Wearing
All spacesuits so far have been variation on what is called a balloon suit. It is easy to see where the name comes from as everyone looks like it was inspired by the Michelin Man. There is a long list of problems with this design. Mobility is very restricted and even light physical activity is exhausting. Related to this is that the suit pressure must be kept very low or mobility is near impossible which creates 2 other problems. First is that very low pressures require the air in the suit being pure oxygen to prevent hypoxia. The problem with this is even at very low pressures pure oxygen is quite flammable. This has yet to have created an issue in use in space but it is possible a spark or a micrometer could ignite the air in the spacesuit severely burning or killing the person waring it. Second because of the danger of fire normal cabin pressure is closer to sea level pressure; this means that using the suit requires hours of pre-breathing before each use to avoid the bends. Another problem is that as the suit is a single large balloon any puncture of the spacesuit is potentially lethal. Finally the current designs usually takes over 2 hours to put on, including safety checks, and requires help from another person to put on all parts of the suit. Also it takes at least 5 minutes to remove even the top layer of the suit. This means it will not be very useful in an emergency. Even what is worn in the main cabin could be more functional than the coveralls that are currently worn.
An alternative to the balloon suit is the hard shell suit. The main benefits is of this type is that it can be a full pressure suit so no lengthy pre-breathing and it can be put on and taken off relatively easy. The problems with the hard suits are they are heavy, expensive, bulky, much more complex and requires padding to prevent abrasions. By definition the materials that make up a hard suit are not flexible so any point where flex is needed there must be one or more joints or bearings. This adds to the mass of an already heavy suit and the complexity increases the cost. Also in a surface environment dust can get into the joints and bearings reducing their effectiveness. As every point of flex is another seal the possible points of failure on the suit are multiplied. The suit also tends to have a larger volume than a soft suit because the must be padding between the occupant of the suit and any part of the shell. With so many joints any point where the occupants skin could press against the outer shell would be a possible cut, scrape or bruise. So far several designs for hard shell suits have been developed but none have been put into active service.
The current EVA suits used and a majority of the development money is going into spacesuits that are hybrids of hard shell and balloon suits. The largest advantage is reducing the suit up time. Future development hopes to eliminate the pre-breathing by accommodating full pressure in the suit. Flexibility remains an issue and for longer stays on the Moon or Mars this will be a critical factor.
If you missed it this was what Elon Musk believes should be the defining characteristic of a spacesuit. Now this may seem weird but it may be that the design that fits his description may end up the best one. The concept is rather than retaining actual atmospheric pressure over the entire body use mechanical compression to provide the equivalent of atmospheric pressure over most of the body. The mechanical counterpressure (MCP) suit or skin suit is not a new idea as the first development started in 1959. The most important benefit of the MCP spacesuit is that it promises greater and easier mobility than any other suit design. Most of the suit would not be air tight allowing the wearers sweat to evaporate normally eliminating the need for the liquid cooling garment required in all other types of spacesuits. Weight of a MCP suit is likely to be around 5 kg making a huge savings in launch costs and most of the suit could fit inside the helmet. With a standard suit any damage to the suit could lead to fatal decompression but damage to a MPC suit would only cause loss of counterpressure at the point of damage and might only result in bruising. It is estimated that a MCP suit would cost $500 thousand as opposed to $4 to $10 million for most other spacesuits.
The biggest drawback originally was that that it took much longer than other spacesuits to get into. This was mainly due to the fact that the counterpressure was supplied by a large number of zippers and straps. It is difficult to maintain even counterpressure over the entire skin without sacrificing mobility. Also current designs only can maintain the minimum pressure resulting in the same issue with the lengthy pre-breathing requirement. All of these drawbacks are largely a matter of development required. Current suit designs using advanced materials are making progress toward making suit up time faster and make the suit pressure higher. More research will be needed before the MCP suit replaces current designs but the advantages will be worth the effort.
What to wear inside capsules is likely to change. The surprising thing here is that what is worn inside may look a lot like what is worn outside. Currently the usual garb is either jump suits or polo shirts and slacks or shorts. Other than protecting modesty current clothing serves no function. There a variety of health issue related to microgravity that could be mitigated by a new suit design. The Gravity Loading Countermeasure Skinsuit is designed to mimic the effects of gravity on the human body. This could help prevent loss of bone and muscle loss and elongation of the spine. It is possible that some merging of the MCP and the Gravity Loading suit will happen and in the future EVA might require little more than putting on breathing apparatus.
- Donning the Spacesuit – Canadian Space Agency
- Wikipedia – Space activity Suit
- Wikipedia – Liquid Cooling and Ventilation Garment
- Gizmag – King’s College London develops skinsuit