Postcards from Mars

Following a year of imagination, three weeks preparation, and a beautiful snowstorm the night before, Steve, Kevin, Tim, Terry, Amin, Colleen and Kai were successful in moving the airlock from the basement of Biosphere 2 to the new concrete pads, and then securing it to the side of the future crew quarters at SAM.

As noted in prior posts (Preparation, Concrete, and Pen & Pad), this was a significant engineering effort as we worked to find a way to merge a 30 year old, steel airlock chamber with the exterior aluminum wall of a new shipping container. While the weight of the airlock is held entirely by the new concrete pedestals, we had to bring the interior frame of the airlock box into an airtight interface to the exterior wall of the shipping container. As they are dissimilar materials (steel, aluminum) welding was not an option. Furthermore, we discovered that the silicon-rubber seal held between the airlock and the bulkhead wall in the basement of Biosphere 2 was yet pliable and fully functional. We left it in place, lightly cleaning the exposed face.

With careful placement by Tim at the wheel of the rented forklift, the 3000+ lbs airlock was moved a quarter mile from Biosphere 2 to SAM, and then to within 1/16″ of our desired location, pressed against the exterior wall of the container such that the silicone-rubber was touching at the bottom and lower sides. However, we discovered that the wall of the container was not fully vertical, slanting in 1/4″ over the total 9 foot rise. Furthermore, the airlock container was not square, one of the four corners was not touching the perfectly level concrete pedestals. We cut aluminum shims to make certain all four corners are equally load bearing, and to tilt the unit backward just a bit, enabling the silicone-rubber joint to be evenly pressing against the exterior wall of the container.

Kai drilled nineteen holes through the 3.5″ assembly of aluminum skin, insulation, stainless steel interior, and the newly fabricated 1/4″ steel plate which holds the frame for the interior pressure door. Using the original bolt holes and pattern of the airlock itself, nineteen 5″ bolts work to compress the silicone-rubber seal between the shipping container and airlock frame. Next, we will shave any exposed silicone-rubber to be level with the metal edge, and then cover with the Dow-Corning 795 silicone product that has proved itself over 30 years at the Biosphere 2.

As with any project in which old and new parts are assembled, there will be surprises. But in the end, we were able to make it work perfectly.

The University of Arizona Facilities Metal Shop completed the custom pressure plate based upon our design. Now we learn if our careful measurement, sketches, and computer layout were accurate. If designed correctly, this steel insert will distribute the load of the airlock attachment across the otherwise relatively fragile foam-filled sheet aluminum and corrugated steel walls of the insulated shipping container. With 19 five inch bolts across the top, left and right of the frame, we anticipate a rigid interface to hold the interior pressure door of the crew quarters airlock and primary entrance to SAM.

Colleen and John Z. cleaned the residual oil from the surface. Kai follows with a coat of a rust inhibiting primer. Amin and Kai conduct the final cuts and grinding to prepare for removal of the insulated wall unit and installation fo the airlock. Will it all come together? Will everything line up just right?

This particular story began with Pen & Pad, continued in Concrete, and concludes with Airlock Install.

With the 40 foot shipping container in place, and the airlock released from the Biosphere 2 basement bulkhead wall, we’re ready to attach the airlock to the exterior of the crew quarters as the primary entry and exit of the SAM habitat structure. As noted in a prior post, very careful planning has gone into the alignment of this pressure vessel extension such that it is structurally sound, hermetically sealed, and designed for a path of least obstruction from the Mars yard through the crew living space and workshop into the Test Module.

Kai and Colleen used plumb lines, triangulation geometry, and a level to assure the proper placement of the concrete forms. The end product is less than an eighth of an inch deviation in any direction over a 10 foot run. Thank you Terry for your guidance in the rebar placement, box ties, and assistance with the pour.

This particular story began with Pen & Pad, continues with Preparation, and concludes with Airlock Install.

In a conference call with a potential corporate partner we had completed introductions and moved into discussion of how we might work together, at SAM, when one of the team members asked, “What it’s like, a day at SAM?” and “Do you have plans and drawings, or do you just, well, go for it?”

I laughed, for the answer is both. Given that most of our effort in 2021 was refurbishing a thirty year old sealed structure (which did not include drawings or instructions) we reverse engineered as much as engineered, learning how the Test Module worked as we went.

Now that we have transitioned into new construction we are engaged in proper design and engineering, planning several steps ahead. As we fabricate the workshop-corridor and Crew Quarters from 20′ and 40′ shipping containers respectively, much of our time was this week spent in careful measurement of the containers in order to build both hand-drawn and computer models.

When I look back to my varied, formal education I can honestly say that my 8th grade drafting class was one of the most important ever taken. As with geometry, drafting is a language for precise communication. With a degree in Industrial Design I had once held advanced skills in rapid, 3D rendering by hand, though I admit to having not touched my pastels for two decades, and my markers were long ago dry and discarded. Yes, simple pen and paper ideation continues to beat a computer interface for immediate results, the ability to share an idea with someone standing right there, next to you, and provide foundation for computer models and fabrication of specific components.

Colleen and I spent this week in careful, repeated measurement, design, and layout for the means by which we will attach an airlock (currently located in the basement of Biosphere 2) to the outside wall of the 40 foot shipping container. There are many challenges in doing this as the walls of shipping containers are not designed to carry a load, nor are they designed to sustain lateral compression. It is therefore imperative that the 5,000+ lbs airlock be supported on its own set of concrete pads, yet bound tight enough to the sheet aluminum exterior of the shipping container to extend the pressure vessel of the original Test Module.

In the same breath, we are conducting preliminary design of the interior, making certain the hatches and pressure doors are aligned for easy transition from the airlock into the 40′, the 20′, and the Test Module in a relatively straight line, with trip hazards limited and the space to either side of the hatches and pressure doors unrestricted by framing.

We have a long way to go, but it feels great to be making this kind of progress.–Kai

This particular story is continued in Concrete, Preparation, and Airlock Install.

Where in a home remodel you might make decisions based on aesthetics, energy efficiency, historic context, quality, an HOA, or price, in building a Mars habitat analog you are asking a different set of questions:

• What will maintain a hermetic seal?
• What will not invoke condensation given the temperature extremes in the high desert winters of southern Arizona?
• Does this immediately give off heavy VOCs? Will it subside over time? Stabilize completely?
• How will we maintain the pressure vessel when connecting these two structures?
• Given that our funds are limited, what off-the-shelf products will get us as close as possible to what might actually be used in a real, other-world habitat?
• What would NASA say to this selection of construction material, sealant, or paint?
• What will hold up to the variety of visiting teams?

While the 40 foot shipping container came to us fully insulated (refrigerated) and essentially sealed (save a few openings at the front which will be easy to fill), we searched for more than three months to locate an insulated 20 foot container, to no avail. The 40 foot unit will be the living space for the crew while the 20 foot will serve as a corridor from the airlock to the crew quarters and Test Module. To facilitate a reduced thermal load and associated electrical consumption (with our intent to eventually go off-grid), we are manually insulating the 20 foot container, from the floor to walls to ceiling.

Starting from the ground up, we are designing a system by which the floor is insulated using standard building materials (plywood, foam board, adhesives) that will remain outside (below) the hermetic seal such that the inhabitants will not be breathing the space that contains the resins and glues associated with these products.

Our first (bottom) layer is a tight steel mesh to keep the rodents from chewing their way in (we hope that pack rats do not yet inhabit Mars). Then a layer of plywood to provide support for the insulating foam board, the foam board, and then another layer of plywood to protect the foam from the top and to provide a solid surface for the fifth and final layer—sheets of carbon steel.

Continued with Installing the steel floor …

One year ago today Trent and Kai stood in front of the historic Test Module at Biosphere 2 and while smiling for the camera thought, “What the hell are we getting ourselves into?!”

It feels like a lifetime ago, far more than just nine months in one year (the summer spent in cooler climes). We have dug, cut, scraped, cleaned, welded, primed, wired, and assembled as only these photos essays can provide detail.

It’s been an incredible journey, a tremendous learning process, and we’re still going strong!

We have been waiting for this moment for more than a year—the placement of the shipping containers to serve as the workshop and crew living quarters. The concrete footings were poured in early December, the doors for the 20 foot unit removed and the hatch plate installed just last week.

Mark Scheicher (Crane Operator), Frank Campa (Oiler/Rigger), and Steven Carnahan (Rigger) from Marco Crane arrived 20 minutes early at 7:10 am. I ran from the Casita where Trent, Colleen, and I live on campus to the Service gate to meet the crane and support truck that carries the weights used to counter-balance the crane. On-foot I ran ahead of the convoy from gate to SAM, a quarter mile downhill.

John, Kevin, and Jason were already on-site. Given the tight move between the old botanical gardens and restaurant the truck driver chose to back his rig to enable an easier departure. About thirty minutes transpired as the crane assembled itself, stabilization arms extended and set on large pads, leveling the crane before its operation, weights moved to key locations, load straps connected.

Mark, the crane operator asked if the containers were full.

I responded “No, they are empty.”

He laughed, “Oh! This will be easy!”

Easy? Glad I am not operating the crane or running rigging on the ground. One false move, one nudge left or right of center and the Test Module could be bent beyond repair, windows cracked, fingers smashed, or worse! This is why we hired the experts.

The 20 foot unit was lifted into place first. In coordination with Frank’s hand signals, Mark hovered it just above the four concrete pads, perfectly level. He then lowered it bit by bit until it skimmed just above the surface, providing some friction with the concrete but not nearly its full weight. I was able to maneuver the entire unit with one hand, placing it within an eighth of an inch of my desire location. I checked the placement with the tape measure, making certain the container was parallel to the west wall of the Test Module, then called it good. The operator allowed the full weight to rest on the footings and the straps were disconnected.

The 40 foot unit was a bit tricky due to its size and our realization that one of the concrete footings had been incorrectly placed, off by an inch. Once this was noticed, it made sense why we could not nail our center points as accurately as the 20′. No worries, the unit is parallel to the 20′ and perfectly supported on the oversized 18″ circular pads. To see the crane operator and crew in action is a testament to the technology and skill employed. While I can explain the physics of hydraulics, it does not reduce my appreciation for the ability to move thousands of pounds within a fraction of an inch of a desired location, or to reduce the apparent weight from something that would turn a human into a pancake to something that can be maneuvered with ease.

With the containers in place, SAM became something more than a refurbished building. Nearly one year to the date of our first day in this project, the dream of our analog was given new form.