Postcards from Mars

As long as there is moisture in some form and iron atoms awaiting a bond, rust will form (Mars is a great example, on a very large scale). The Test Module lung was not designed to last for three decades, as the shell over top was not water tight and the pan beneath suffered from heavy rust. The SAM team has spent a great deal of time grinding, sanding, priming, painting, and sealing this structure over the past year in order that it might continue to provide an internal, positive pressure to SAM.

Volunteers Luna Powell and Elie Danziger removed the last bits of loose rust on the upper lung pan. This involved a pass with steel scrapers and sixty grit paper on an orbital sander. They then applied a coat of Rust-Oleum direct-to-rust primer before the final enamel will bring this historic structure back to life.

The Rust-Oleum primer has proved itself time and again at SAM as a go-to solution for otherwise challenging, heavily rusted steel. While it is an oil base, it has almost no odor after just 24 hours curing and can be top-coated with oil or water base paints (which is unusual). What’s more, the back of the can has an 800 phone number that is answered by a real, live human who actually knows what he or she is talking about! If only all products had this kind of support. (No, Rust-Oleum did not sponsor this post, but they should!)

Between the Crew Quarters (40′ shipping container) and Workshop (20′ shipping container) there will be a bridge. It will not offer a pressure door, although we may add a standard interior door for the sake of noise mitigation from the Workshop into the Crew Quarters. We have given this passage a good deal of consideration, with concern for the width and height being such that the average crew member does not have to mind his or her head or shoulders when moving tools or supplies, yet the passage is not so large that it cannot be closed. The step-up height is identical to that into the airlock, so the crew will be accustomed to the motion. The bridge must hold a hermetic seal, be insulated (as with the rest of the living space), and offer a stable, non-slip floor plate.

The first effort was to remove a 34″ wide by 72″ tall door way. Kai applied the cutting wheel while Colleen and our new volunteer Luna Powell took turns with the angle grinder to remove the rivets. We then peeled the exterior aluminum and interior stainless steel skins from the foam, used a reciprocating saber (“saws-all”) to complete the cut across the full depth, and pushed the foam panel out of the wall space.

While the Biosphere 2 was being built, a series of on-campus greenhouse structures, quarantine facilities, and insect farms were used to harbor the plants and animals collected from around the world. While in operation, some of these structures served as a botanical garden, a place for visitors to experience something similar to the Biosphere without being sealed inside. Last summer we removed five greenhouse structures to make way for the SAM outdoor Mars yard. Between this space and the Test Module remains a 6400 square foot greenhouse (that has seen better days). It is our intent to renovate this building, to become the SAM indoor Mars yard and terrain park. But first, we must replace the dilapidated plastic panels with a new, corrugated steel roof. This will serve the purpose of both protecting the Mars yard from the weather and minimizing the direct light and reducing the temperature in the warmer months.

This week saw Terry, Kai and Colleen engrossed from sunrise to sunset high above the concrete on a 45 foot cherry picker (a.k.a. “snorkel” or lift). While exciting to be 7-10 meters up, suspended on an incredibly powerful and precise articulated arm with six degrees of movement, it was an five exhausting days. The fumes of the diesel electric generator (which drives the hydraulic pump), the constant hum of the combustion engine and unceasing BEEP! with every motion of the vehicle up, down, left or right was tiring. The body’s adjustment to the constant motion of the bucket, as though standing on the deck of a sailing ship was enough to invoke a sense of unsteady legs and uneasy sleep when back on terra firma, as though returning from an ocean voyage and weeks at sea.

The panels were most often brittle and fractured, yet they remained resistant to this final effort to bring them down. With full body harnesses and tethers, helmets and gloves we pushed, punched, hammered, and sawed our way from one end of the greenhouse to the other a half dozen times to reach every corner. For Monday and half of Tuesday we moved along the outside north and south edges, reaching in to remove several rows of self-tapping screws from the plastic, aluminum, and steel interface. Wednesday through Friday we carefully navigated the lift through the interior of the building, ever so slowly rising, twisting, reaching through small corridors in the overhead frame, cables, and supports until the unnecessary debris and structure could be cut free.

Driving the lift became second-nature. Driving the wheels from nearly full extension was a testament to the design quality of the Genie. This journey was made complete with the installation of a new steel roof.

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.