Yearly Archives: 2023

In building SAM there are three primary objectives with each material chosen:

1. Will it last 15-30 years?
2. Does it provide the required strength and seal?
3. Does it off-gas once cured?

The SAM team has gained a deep understanding of working with metal, from cutting to cleaning, welding to grinding, primer, and paint, and with foam insulation panels and plastics too. The fiberglass reinforced panels (FRP) were installed in the 20 foot shipping container (SAM Workshop) over preformed Insofast panels. Given that the walls of the shipping containers cannot be penetrated for the potential of forming a leak, nor can the 40′ be welded due to the potential of melting the insulation between the stainless (interior) and aluminum (exterior) walls, adhesives must be employed. With a selection of dozens of brands and types, each of which carries its own marketing and promises, the SAM team has learned (sometimes the hard way) what works and what does not.

Silcone-base adhesives will adhere to most materials, but the final product is not a structure bond, the kind that can carry a load. While the Dow Corning 795 is foundational to the success of Biosphere 2, the Test Module, and SAM, it is not applied where load-bearing elements come to play (e.g. the shipping container wall, aluminum-based foam panels, and furring strips).

Loktite PL3 is the low-VOC adhesive recommended by Insofast and used in their instructional videos. While the final, cured product is stable and strong, it was learned that this product loses integrity when pressed too thin between the adhere layers. When pressed to a few thousandths of an inch, as is desired with wood glue, the product fails and the two layers can be separated by hand. But with the toothed ribs of the Insofast panels, the PL3 bead remains 1/8-1/4″ and provides substantial integrity, as marketed. However, this presents a challenge if the surface of bonded layer must remain parallel to the underlayment or even across multiple panels.

Sika Construction Adhesive is not found in the adhesives section of the local vendor, rather with concrete block and building materials. It is much thicker than PL3, gray in color, and does not appear to harden completely, rather it remains relatively flexible yet holds to a greater diversity of surfaces, including FRP. It is very difficult to work with, but holds to polystyrene where PL3 specifically states it cannot adhere to this medium.

Roberts 7200 Base Bond is a very different kind of product from the PL3 or Sika adhesives. It is much easier to work with, spreads with a toothed trowel and covers like oat paste. It is “zero” VOC (1g per liter according to the package) and has no odor when being applied. It provides quite a bit of working time in low temperatures, and can be cleaned up with water before it begins to harden. However, it must have at least one porous surface in order to form a bond, with the other surface designed for vinyl baseboard trim. The instructions make it clear that even a coat of paint on the wall must be removed in order for the paste to adhere to the wall board.

Tightbond III is the standard among woodworkers, the strongest of this family of wood glue products, and a staple in any wood shop. As the amount of wood in SAM is limited, it was used only to build the reinforced door frame and overhead beam that gives tremendous strength and stability to the nearly free-standing SAM bathroom.

Nashua Aluminum HVAC tape is what Mark Watney should have brought to Mars. It is one of the most versatile, capable products on the market, and the modern replacement for duct tape. While 795 and rivets have been used to seal more than 200 holes in the refurbished 40′ container (SAM Crew Quarters), it is aluminum tape that has properly secured the entire interface between the stainless steel walls and aluminum roof. We found it to be highly adhesive, malleable (to a limited degree), water resistant, and air tight.

This following test matrix was developed by SAM team member Luna Powell. All samples were tested at 24 hours, 3 days, and 5 days. The following summary is at the close of 5 days.

Adhesive	Wood	Backer Board	Aluminum
PL3	Cured to the point of not moving	Strong, almost impossible to peel up	Did not even adhere (at all)
Sika	Remains soft to the touch after ~5 days curing	Remains malleable, not impossible to peel up	Peeled up easily
Base Bond	Won’t shift side to side, but easy to peel up	Readily peels up; did not stick to backer board	Peeled up easily; wet in the middle

With bonded interfaces between dissimilar metals, metal to foam, foam to wood, wood to wood, and wood to polystyrene, the types of applied adhesives varies. This past month has seen a good bit of experimentation, some failure, and success with what is hoped to be a multi-decade solution. While there are certainly many more to explore, from off-the-shelf two-part epoxies to marine grade epoxies; from UV activated cements to fire resistant silicones, SAM has been built principally from what is immediately available from the consumer market.

From January 16-27 the SAM construction team continued to check off tasks, one by one. With the bathroom platform (originally built in April 2022) reinstalled, and the hole drilled for the toilet outlet, the waste water storage tank was adjusted to its final position and secured, the inlet and vent openings cut and rubber flanges installed.

Construction of the bathroom walls was conducted from the shower stall to the door and then far wall, each section building upon the prior for both placement and stability. With very limited space (even if luxurious by NASA standards), every fraction of an inch had to be just right, literally built around the shower basin on three sides while leaving room for the plumbing that will be the 100% recycled water system with small water storage, pump, and filters.

Two significant challenges emerged: building a sturdy, essentially self-stabilized bathroom box within the 40′ shipping container without penetrating the walls, as a screw or rivet could introduce a leak point behind a structural member we’d never be able to reach again; and minimizing condensation formed at the interface of warm, moist air (from the shower) and the cool, interior metal lining of the 40′ shipping container in the winter months. We decided to enclose the top of the shower to reduce condensation and to give us an overhead surface on which we can mount a water storage tank, pump, and/or filter.

The steel bathroom door was reduced in height to match the vertical dimension of the crew quarters-to-workshop bridge. This required a rebuild of both the top and bottom, and total refabrication of the door jam itself. The end result is beautiful and strong, with interlaced, laminated joints. The bathroom has been a work in progress since the start of 2023, and will surely require a few more, but it will be well worth the effort when complete.

We chose colors from the SIMOC-SAM logo to hi-light a few exterior elements of the physical SAM structure, including the lower, outer lung wall and the outer entrance to the Test Module. Sean continued his critical work in revitalizing the three pressure doors, all original to the Biosphere 2 experiments of the 90s. This included multiple applications of PB Blaster, a steel brush, and bucket of soapy water.

In addition to the physical work at SAM, critical components and key appliances were ordered, including the electric actuated valve control the SAM AIR blower, convection microwave oven, bread maker, rice cooker, and water filters. A WiFi hotspot will provide internet for the first mission until a narrow-beam transceiver is in place, providing dedicated, point-to-point communication from Mission Control to SAM itself. The SAM internet and email server is ordered and on its way, with a very unique means to simulate the light travel-time delay developed just for SAM.

Yes, the title of this essay is an often used phrase, but one for which we seldom tire—especially when we have a tunnel, and with the final coat of paint the light really is brighter!. We are entering 2023 with a tremendous sense of accomplishment and forward momentum. For the hundreds of tasks we completed in 2022, many of which were monumental, multi-week undertakings, what remains is an exercise in a half dozen well defined projects (with many components) until all systems are functional.

Every Sunday evening SAM project lead Kai Staats delivers an email to the team with a list of items accomplished, those that remain, and where to focus our effort. The top five foci for December into the New Year are:

1. Sealing SAM, with validation through consecutive pressure tests.
2. Electricity in the 20 and 40 containers, then finish in the TM.
3. Complete the bathroom construction, then add power and running water.
4. Build-out the kitchen, shared space, and sleeping quarters.
5. Build-out the sensor array and start collecting data.

And a summary of most (not all) of the tasks completed in the past 45 days:

Test Module
– Install and seal 2 replacement windows – DONE
– Sand TM-to-lung tunnel – DONE
– Prime TM-to-lung tunnel – DONE
– 2x coats white enamel paint TM-to-lung tunnel – DONE

Workshop (20′ container)
– Complete roof panels – DONE
– Install all wall panels – DONE
– Poor concrete and mount workshop mini-split A/C condenser – DONE
– Install furring strips at bridge-end – DONE
– Fill voids with 1/2″ insulation panels, spray foam edges – DONE
– Install FRP at bridge-end – DONE
– Mount workshop electric power panel – DONE
– Mount electric power mounting rails – DONE

Crew Quarters (40′ container)
– Complete fabrication of the 40′ pressure door – DONE
– Clean, prime in/outside of 40′ pressure door interface – DONE
– Remove former name and logo from both sides of 40′ – DONE
– Prime bare metal areas of exterior – DONE
– 2x coats white enamel on exterior top/bottom trim, faces – DONE
– Seal floor edge at south end of 40′ – DONE
– Install insulation at door-end – DONE
– Install furring strips at door-end – DONE
– Fill voids with 3/4″ insulation panels, spray foam edges – DONE
– Install RFP at door-end – DONE
– Install FRP in the bathroom – DONE
– Mount RV wastewater holding tank – DONE
– Install toilet and drain – DONE
– Continue to pressure test, patch and seal …

We now move into the second half of January focused on electricity, plumbing, food prep, shower and toilet, and sleeping pods. Almost there!