A lunar pressure tent from the movie Moontrap.

Pressure Tents
Tech Level: 10

When most people think of astronauts, they likely envision space-suited explorers floating freely in the void of space.

However, astronauts will not always work exclusively against large swaths of nothingness. On the Moon, asteroids, and other airless worlds, as well on the hulls of larger spaceships and space stations, they may sometimes run across situations and tasks that may prove beyond what they can handle in space suits alone. For this, they may require portable shelters that can withstand the harsh environments of space.

A similar technology, the Rescue Ball, has already been detailed in another article.

Tech LeveL: 10

In real life, pressure tents (also called Altitude Tents, with a variation called a Gamow Bag) are used today mostly in hospitals and occasionally for training for high-altitude mountaineers. The type intended for space would be much more advanced and robust, as they would be intended for one of the most hostile environments known to humanity—the vacuum of space.

Space-borne pressure tents were discussed tentatively for use on the Moon post-Apollo but never followed up on. They are mentioned briefly as available equipment in some science fiction tabletop RPGs, and one was featured in the scifi B-movie Moontrap.

Basically, a pressure tent is a small, transportable, inflatable shelter meant to temporarily house one or more astronauts and allow them to tend to tasks that their bulky spacesuits would make difficult or near-impossible. These might include fine manipulation of equipment or gathered samples, medical emergencies, quick suit maintenance or recharging, breaks for rest, eating, or sleeping, or use as an emergency shelter.

Pressure tents are intended to be used when access to a more proper facility may be too far away or too inconvenient to get to. For example, astronauts roaming away from their base on the surface of the Moon or other airless world. They may also be used on orbital construction and maintenance sites, to serve as emergency crew shelters or as low-cost break, eating, and sleeping facilities. Depending on size, they can accommodate from two to over a dozen astronauts or more at any one time.

Like with spacesuits, they would have their own dedicated life support system, complete with air supply, carbon dioxide scrubbers, filters, heaters, and more. Also like with spacesuits, they would use rebreathing systems to conserve on atmosphere as much as possible, meaning they would likely remain operational without resupply for up to several days, or until their power supply runs out, which ever comes first. Those used near bases, stations, ships, or other vehicles can be attached to those via umbilicals and draw power directly from them. Otherwise, they may need to run off batteries and/or portable power supplies such as a solar cell array.

The multi-layered fabrics of the tent would be very similar to those used by modern spacesuits. It would be very tough to prevent rips and tears, stretchable, and very well insulated against both radiation and against the harsh temperature extremes of space. However, if used on a particularly cold surface (such as the Moon regolith in shadow), an additional insulating tarp or blanket may need to be laid under it to prevent precipitous heat loss.

Simple pressure tents may look like little more than anchored, oversized balloons. However, spars and other flexible structures can be embedded in their fabric, allowing it to form any number of predetermined shapes, from hemispheres and rectangles to even triangular shapes that would be reminiscent of camping tents on Earth. Because they are meant at least partially for emergency use, they would likely be designed to be set up and pressurized within minutes.

Pressure tents may use what are referred to as zipper airlocks, and though the tents would likely use sealing systems more advanced than the everyday zipper, their use would be very similar. Basically, to enter a pressure tent, an astronaut would unzip the outer layer(s), step inside the small space, zip the outer layer back up, then zip and unzip the inner layer in turn. A middle layer may be added as an additional precaution, and the system would be set up so neither the inner nor outer layer would unzip unless the median one was securely closed. Very large or advanced pressure tents might have actual small doorway structures jutting out from their main body to act as airlocks. Others might not have an actual airlock ‘space’ and just be the zippered fabric layered directly on top of the other, meaning the astronaut cycling through would have the tent’s fabric draped over him like a sleeper under heavy bed sheets.

Because pressure tents may be regarded as emergency equipment, survival supplies such as a radio, rations, medical kit, basic tools, and other necessities might be included in their interiors and accessible once inflated.