Postcards from Mars

We are becoming regulars are Superior Steel, Tucson, where every shape and size of factory steel can be found. It is a commodity that we take for granted, as we use steel products each and every day. Yet the tremendous volume of steel manufactured, distributed, purchased, and fabricated is astounding. Learning to work with steel is both a science and an art. At SAM we are working to build a research facility that will serve for a generation, and at the same time explore fabrication techniques that inform our understanding of how to live in a pressurized vessel.

Four hydroponics racks have arrived to Biosphere 2! These systems distributed by Hort Americas are designed for research in that they are durable, agile, and smaller than commercial racks. While we await the water pumps, plumbing assembly, and lights we got to work. New to the team William Nichols is working with us to install, test, and maintain this grow system under the expert guidance of Dr. Gene Giacomelli of the University of Arizona CEAC facility. With 200 heads of lettuce already sprouting in an incubator, we are eager to transfer the partially mature plants to SAM for the first official crop in our new, permanent system.

As the systems came with casters appropriate for a research lab or industrial floor, not the one-in-twelve slope of our stainless steel tub, we took the four bases to the University of Arizona Facilities Metal Shop and secured a 3/8″ nut to the bottom. High quality swivel feet enable us to maintain a strong, stable base over the unusual floor.

With the removal of the massive refrigeration unit from the forward end of the 40 foot shipping container, the process began to determine how, exactly, to seal it up again. As with the steel plate fabricated to replace two windows on the Test Module, a larger, much heavier plate now provides a bolt-on pressure seal for the end of the 40 foot shipping container.

At 81″ x 89″ the size of the plate dictated two 1/4″ thick sheets welded along a seam or a single sheet of 3/16″ which is considerably heavier. We opted for the later, and discovered just how hard it is to manipulate that much steel. With the Test Module plate no two holes were equally spaced and yet, with careful measurements we were able to get the bottom and top rows of holes perfectly set without any adjustments. With this new plate the threaded inserts were factory set and we applied the same careful measurements, double checking with even the diagonals less than an eight of an inch over 100.

We drilled an 1/8th inch pilot, then 1/4″, 3/8″, 1/2″, and a few 5/8″ before the bit grew dull and jammed the drill one too many times. Our attempt at sharpening the bit produced a sharp edge, but it dulled too quickly, a typical artifact of sharpened bits used against metal. The attempt to go straight to the final 3/4″ bit was fatal, destroying the transmission in the battery powered drill and then nearly breaking Kai’s wrist with a more powerful corded unit. Clearly, we were not applying the correct tool for the job.

We took the ~500lbs plate to the B2 machine shop and used the stable drill press on the slowest speed. With a new titanium bit and ample cutting oil Kai and Colleen were able to complete all 30 3/4″ holes in less than four hours. However, despite precise measurements the holes were not all aligned. Using a car jack and 2×4 we shifted the plate to align the greatest number of holes possible, and then hand ground the remaining holes into an oblong shape such that the bolts would all enter by hand, without the use of a wrench. This assured no cross-threading and in the end, a solid fit.

This is a clear example of the old adage, “Perfect is the enemy of good enough” for had we simply used the 3/4″ sloppy hole saw (which we tested on the first hole), nearly all of the bolts would have fit on the first go, saving two days extra labor. It remain unclear how the measurements were ill fit, but may be a combination of too many stages of bits compounded by the threaded inserts in the container frame not being perpendicular to the face and set back 1/2″ each, causing the bolts to enter at an obscure angle.

Welcome to Renovation 101!

With the original use of the Test Module (1987-1990) the heat exchanger suspended from the space frame was fed temperature controlled water from an adjacent building via underground copper tubes. The air brought into the lung by means of the blower was also, originally introduced in the same adjacent facility.

Over the course of thirty years of disuse the desert took over, rendering that building as unfit for air intake (to be kind). As such, in June of 2021 Trent and Kai removed the blower, cleaned it thoroughly, and remounted it on an exterior, concrete wall of the lung structure. And after thirty years it still worked flawlessly!

The concrete structure supporting the south, steel wall of the lung appears to have had a design intent greater than what was completed, for several pieces of half inch rebar remained exposed, and a hip-high concrete block wall remained unfinished. It also appears a door was intended, but never installed.

As it is very important to the health of the crew and science conducted that the quality of air be maintained to the highest standards. As such, the SAM team set out to build the SAM Air Intake Room (with the very clever acronym “AIR”). For any of you who have built a wood frame to fit an existing, not-a-single-corner-is-square construction, the effort is as much creativity as it is proper framing.

What we had hoped to be a solid week and a day or so became two full weeks with the steel door yet to be hung. But in the end, John Z., Luna, Elie, Colleen and Kai have transformed what was an unpleasant space into something quite professional. Once complete, the air entering the SAM lung will pass through a HEPA particle filter and then one or two activated carbon filters before entering the blower and lung. The flow rate and quality of air will be monitored and recorded using a sensor array tied to SIMOC, now in its final development by an Arizona State University Computer Science Capstone team.

While shipping containers ‘air tight’ (or close to), creating a pressurized seal between two shipping containers is a unique challenge. Our 40 foot refrigerated unit has a corrugated stainless steel interior wall, two inches of expansion foam, and a flat aluminum exterior wall. The 20 foot container is composed of heavy, corrugated steel without insulation. No simple manner connects these dissimilar shapes and materials; no computer model can automatically deliver the obvious solution. Rather, hands-on experimentation is required to design the most effective interface.

In 1986 the Biospherians developed systems to maintain a pressure seal, meaning they didn’t just glob a massive amount of silicon across every interface but considered how to best retain the internal air with the least chance of failure. The 3/4″ “U” channel, backer bead, and Dow-Corning 795 silicone proved to be an effective, long-term solution that thirty three years later yet holds a pressure seal. We are working toward something similar, looking at the interface between sheets of steel as an interface, not just a joint between two planes. It’s not easy.

The doors of the 20 foot shipping container were removed. We are now constructing a steel stud and plate wall that will offer a solid, stable, pressure tight exterior interface and support the 40 foot container to 20 foot container air-tight bridge for the mission participants, enabling them to move readily between the Crew Quarters and Workshop, accordingly.

In the third week of January we installed the first four of five layers of the 20 foot shipping container floor. As described in a prior post, this multi-layer effort serves four purposes: a) to keep pack rats from chewing through the bottom, b) provide strength, c) to provide insulation, and d) to seal the plywood and glue outside of the breathable air space. In this respect, the floor is in and of itself part of the experiment as it differs from both the Test Module (stainless steel) and 40 foot shipping container (insulated undercarriage, aluminum rails, and cork-backed Marmoleum). Each floor will serve a different purpose. Each floor will behave and age in a different manner.

We desire to learn how various floor surfaces are to clean and maintain. How do the research teams feel when walking on them with hab shoes, in socks, and barefoot? Which will hold up to the shuffle of equipment and furniture, the unintentional spilling of water, and the repelling of dust from the Mars yard?

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.