But another simple way to give the sense of standing outdoors would be to have what we call the BubbleHab. It would be a clear tube extending from one of the habitat modules to a clear bubble. Inside that bubble could stand a couple of crew without having to put on a space suit. From their perspective, they might as well be standing outside, on the surface, in their socks!

The director for inflatable habitats at NASA graciously told us what the mass is for each of the layers in an inflatable habitat.

The thickest, at 10 kilograms per square meter, is for the outermost micrometeorite-orbital debris layer. But this layer is only needed in orbit where orbital debris and mircometeorites are a danger. On the Moon and Mars, local shielding can be used instead.

The other 5 layers are as follows:
- Abrasion-resistant layer (outermost and innermost layers),
- Kevlar straps to hold in the air pressure, and
- Two air-proof layers.

We have the masses of each layer listed here.

If you want a challenging math problem, calculate how large the footprint would be if you were to deliver a 100 metric ton inflatable that was a pancake-shaped cylinder at 3 meters in height.

Answer: 1.4 acres

But, wouldn't the weight of the dirt compress the habitat and crush the occupants? On the Moon, the dirt would weigh only 1/6th as it would on Earth. What's more, people don't commonly realize just how much force air pressure would push the dirt up.

A car's tire pushes up at 14.7 pounds per square inch. Put another way, at one atmosphere of pressure, air pushes up at nearly 10 tons per square meter. By contrast one ton of dirt on the Moon has a mass of about 1.6 tons meaning .27 tons of force pushing down. So the dirt would need to be 37 meters tall just to counterbalance the upward force of the air pressure. And clearly, we don't need that much dirt for shielding.

Rather, we will need to have very strong internal walls and tethers to make sure that the inflatables don't puff out to the spherical shape they want to be in.

We plan on using this so-called MattressHab to illustrate that air pressure can easily counter the necessary weight of dirt shielding.

One of the Network's original base concepts is called the UniHab. By this we mean a habitat with all of the areas needed by an Initial Permanent Crew of eight all unified into a single habitat.

The sections include four bedrooms, two bathrooms, a kitchen and living room areas, laboratory, dirty and clean garages, and also a greenhouse and centrifuge for artificial gravity.

We have now replaced this concept with the InstaBase design which roughly has the same sections of the same sizes but with a more aesthetically appealing appearance. In that case, shielding would be achieved by filling double walls with dirt on the Moon or on Mars with water.