Moon Miners' Manifesto

#105 May 1997

Aerogel: Windows, Sundows & Other Products for Space Frontier Vehicles & Habitats

Peter Kokh

A Call for Active Investigation and Research

Aerogel is the lightest known solid, literally foamed glass, though it can be made of other raw materials than Silica (Silicon Dioxide, common beach sand, the major component of both glass and quartz), such as Iron Oxide. First developed decades ago, we have begun to see new space age applications and refinements with exiting implications.

Aerogel is translucent, but until a recent manufacturing experiment in space, not quite trans-parent. Previous samples have had a somewhat blurring bluish cast caused by the uncontrollable inclusion of a certain percentage of larger "bubbles" in the froth. Bubble size has now been successfully controlled in micro-gravity, resulting in a product that not only transmits light, but views.

Its density is much less than a batt of fluffed fiberglass, giving it the added attraction of being a storybook insulator. On the other hand, it is quite porous, and could not be used, alone, to contain atmospheric pressure, against a vacuum, for example.

Given this information, what uses can we see for this remarkable material on the space frontier? We will try to give a glimpse of some of the possibilities. But bear in mind that the writer has not been able to find all of the information he considers relevant to such a forecast. Perhaps you can help, and we invite informed reader feedback. Specifically, we have no idea of what kind of mechanical strength the stuff has. Conservatively, we are assuming that it is very weak, that it can be broken, punched through, and snaps when bending pressure is applied.

Aerogel Windows?

For space use windows, it would apparently have to be sandwiched between two panes of normal glass. Could they be laminated? Would the glass-aerogel-glass sandwich be lighter in weight than an all glass pressure window? Would mylar be enough? If so, there would be a market for such windows if ever we start co-manu-facturing space stations and vehicles in space itself, for use as in-space ferries, or in amphibious craft that will work as well as lunar or Martian surface vehicles. We have a potential future market, but that's a lot of ifs.

Windows for lunar and Martian habitats? In both cases we have adequate supplies of suitable local raw materials. But the same reservations we brought up for aerogel windows on Earth will apply out there. Can we learn to make the stuff transparent in fractional gravity (1/6th, 3/8ths respectively)? Maybe, maybe not, more likely so on the Moon than on Mars.
If not, and transparent clarity is what we require, such aerogel panes (e.g. made from Lunar Silica in low lunar orbit) would be an expensive option, though perhaps less so than on Earth with its much deeper gravity well up which to bring the raw materials to be transformed. However, if what we want is light, more so than the view, or if we can tolerate a blue haze, we may well see some made-on-Luna aerogel sandwich windows. Might a selling point be superior protection against micrometeorite caused decompression accidents (insofar as, if laminated, the aerogel fill would tend to keep the window from shattering altogether)? A hole in aerogel should be minimal and neat.

Aerogel Thermal Insulation?

Aerogel as Acoustic Insulation?

Aerogel, given its minimum weight penalty, could be standard packing in interior space vehicle walls to control on board noise transmission. Any one who is spent time aboard a ship (or a submarine!) knows how important that could be.

Other Aerogel Building Products?

• UV-proof aerogel sandwich windows in on-surface unshielded "sun-rooms" in which Lunans could go to soak up the "sun" for periods tightly limited to control concomitant radiation exposure.

• Skylights in ramada canopies, minimally shielded structures under which routine out-vac surface activities could be performed in the "lee" vacuum they provide by workers wearing lighter weight pressure suits. [MMM # 37 JUL '90, p 3, "Ramadas"]

• Hydroshield domes, solaria, atria - in which translucent water is used as shielding (one of the striking suggestions of Marshall Savage in his "The Millennial Project") Question: how well does aerogel transmit red light, essential for plants?

• Water-filled "sun-dows" in habitat ceilings along the same principle. In both, aerogel would act as a transparent thermal insulator.

• Sun-exposed banks of clerestory window in otherwise normally shielded (cylindrical) pressurized settlement streets

• Lamp shade and lighttube sunport diffusers

• backlight diffusers

• translucent walls & dividers

• interior clerestories

Opaque formulations, (by the way, is aerogel "paintable"?) could include:

• Lamp shades
• drop ceiling panels
• exterior shade walls

If the stuff has, or can be given real structural mechanical strength, how about these uses:

• Floor underlayment
• light regolith shielding pans in a ramada canopy
• a sort of lightweight "dry wall" panel

Even if aerogel must be laminated to a much stronger structural material, it may find application as the inside surface layer of choice for built-on-the-Moon habitat structures made of local materials because it is much more water-resistant than glass (and by extension, than glass-glass composites, a top candidate material for making lunar habitat hulls). For the same reason, it could be used to line limited pressurized lavatube volumes, the walls previously laser or microwave fused to be air tight.

We must learn more, but the prospects for aerogel on the space frontier seem bright. MMM

References:

Aerogel Used to InsulateMars Pathfinder Rover (used to be at http://137.79.70.19/success/aerogelpio.html)

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