The MDRS Hab is far from airtight. This condition does serve to keep the air fresh, but at a price in heating (and cooling) costs (Thermal Management) as well as acceleration of the rate at which the interior becomes noticeably dusty. These deficiencies in the design and construction, as well as occasional modification (e.g. relocation of utility ingress) do not affect the various categories of activities we have been trying to simulate here over the first five years. The point is that it does make Hab Life Support Systems quite impossible to simulate here. While we do have to pick our battles with cost-benefit ratios in mind, for relatively little remedial expenditures, we could attempt more challenges now orphaned.

Some would dismantle the Hab and put it back together with greater care. Some would just replace the current structure with one designed more tightly from the outset. But the least expensive option is to take a census of all the existing loose fittings, gaps and holes and find the right cover, mask or plug for each type.

I. Gap and Hole Census

(1) Segment Joints: The Hab has 12 segments with the joints running from the bottom of the hull to the top of the dome. On the outer hull wall, all segment joints need to be taped. The trick is to find a white tape that will remain white through continued exposure to UV, summer heat and winter cold, and remain pliable.

(2) The roof covering integument has been compromised. In some places it has come loose from the steel surface to which it was bonded, and flaps in the wind. In others, it leaks onto the upper deck and/or the attic deck above the crew staterooms.

(3) Windows:

3a) The East-facing upper deck porthole, now the EES Emergency Escape Scuttle, loosely fits in its frame with an obvious gap in the upper right quadrant as viewed from inside. From the outside, to the lower right, is a slash in the hull apparently made by an errant reciprocating saw used to cut the hole in the hull. That slash needs taping.

3b) The window in the Commander’s Stateroom (#6) is very drafty, indicating a breached seal at some point. No attempt was made to find the leak source.

3c) An unframed square window hole was cut in segment 10 (numbering from left to right with the EVA Hatch being in segment 1) at the top of the upper deck (03) that appears to overlap the interior divider wall between staterooms #3 and 4. The hole runs clear through the outer hull and insulation but is blocked by the interior drywall of both staterooms. The 2x4 studs with which the interior divider wall is framed are clearly visible. Evidently, a window hole was cut without referring to the blueprints for the stateroom stud wall locations. This hole is a source of draft, dust, and plainly looks unforgivably sloppy and shoddy from the outside. From the outside This hole should be insulated then covered. As an option, there is a framed and glazed spare window that would fit this hole in the Antarctic storage area.

(4) There are three large square holes in the upper part of the lower deck wall, one at the right edge of segment 7 and 2 side by side at the left edge of segment 8. From the inside these are visible in the crawl space above the shower room where the air conditioner and heater are installed. These three holes do not seem to be in use, and present a klutzy impression from the outside as well as likely points of draft and dust ingress.

(5) There are half a dozen other holes from 1" to 4" in the outer hull. some of which are for utilities, and all of which are loose fitting. These gaps need to be plugged with insulating foam and cover sheet or tape.

(6) Both the front EVA airlock door and the rear Engineering airlock door fit very loosely within their jambs, with gaps on the order of 1 inch wide on both sides and top, and an enormous gap 2-3" below. These are the most outrageous gaps of all and will admit sizable creatures we’d rather not have as visitors, much less permanent guests. True, for both airlocks there are inner doors which fit much better. But if we can keep dirt, dust, mud and creatures out of the airlocks, it would be better. The solution is simple: custom fitted stops on sides and top, and a custom fitted step-over threshold-stop at the bottom.

7) Both the front and rear porches and steps are made of wood framing and plywood. These are unlikely materials to be found on Mars or the Moon, at least near term. While they give a hobby-carpenter look to the hab, this less than desirable first impression is not the problem. The problem is that these surfaces do little to help avoid the tracking in or dirt and mud. It would be ideal to replace both porches and their steps with steel framing and open grating surfaces. A less expensive option would be to replace with open steel grating just the horizontal surfaces, the ones with which boots and shoes come into contact. We might be able to find a donor for this grating.

8) The lower deck flooring is made of diamond tread steel plating. It is very durable and easily cleaned. But not all the joints where these plates come together are tight. There are places where one can look through and see the soil below the Hab. We need to find a suitable and durable way to close these gaps.

II. Advantages of Sealing the Hab's many Gaps and Holes:

(a) Thermal Management: we would be able to keep the lower deck warm simply by fan-ducting warm air from near the Hab upper deck ceiling to vents along the lower deck floor. If we did this now, most of that warm air would escape to the outside. This method of achieving thermal equilibrium in the Hab without much additional energy expenditure could be made more efficient by installing an insulated skirting to cover the 2-4 foot gap above ground level, as crew 44 has suggested. This skirt would have removable panels for access to systems housed below the Hab: ingress/egress for water and electricity, and the reserve power battery cluster. A not inconsiderable benefit would be the end to freezing pipes, at least during the season when the Hab is occupied.

(b) An air/heat exchanger would bring in fresh air and duct out stale air, without significant loss of heat.

(c) Now we have a Hab in which we can control humidity. Currently, Hab air is very dry. We are in the desert, after all. This dry air is the source of much discomfort especially in the nostrils, but also in the throat, the eyes, and the skin.

(d) "Closing" the Hab as advised above, will not make it spaceship tight. But it may make it tight enough, were we ever to embark on a much more ambitious greenhouse project, to recycle not only gray and black water, but also stale air.

These are goals worth striving for on the path to Mars as well as to the Moon and elsewhere where we will have to reencradle ourselves in mini-biospheres of our own making and maintenance, learning "to live downwind and downstream of ourselves." Someday, we will export such technology back to Earth.