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Patch, seal, and test

Pressure tests during SAM construction, Oct 20 - Nov 11 2022

This week we welcome volunteer Bindhu Oommen, a general surgeon from Dallas, Texas. Bindhu learned of SAM during the 2022 Analog Astronaut Conference and will be returning one week each month for the foreseeable future. We appreciate her attention to detail, surgical precision (sorry, it has to be said), and willingness to travel a great distance to assist our team. While she is gaining skills in fabrication, our team is entertaining conversations about the challenges of space medicine.

As noted in a prior post, we discovered that the silicone rubber patches applied to the lung in 2021 had failed. On Wednesday we carefully measured and cut the recently obtained EPDM rubber and on Thursday John Z., Bindhu, and Kai applied the rubber patches to the lung using the same procedure as that used to repair inflatable river rafts (rubber obtained from Discount Rubber Direct and glue from NRS).

On October 20 and 21, October 25 and (after applying the new patches) on November 11 (this essay) we conducted pressure tests of the expanded vessel at SAM. These tests are a means to locate leaks, fix those we can immediate address, and improve our methods for the continued sealing of the SAM habitat analog.

It is important to note that the various dips (graph a top) are the opening and closing of valves or temporarily patching holes during the test (Mark Watney—PVC tape is far more effective than duct tape). Ultimately, we are shooting for a smooth, steep rise from the start of the blower (~4.5 minutes on graph) to the maximum pressure when the lung is free from the ground (~10 minutes). The total duration of the test is not indicative of the leaks, rather when we terminated the blower, opened valves and/or doors, and allowed the lung pan to settle again to the floor.

Kai applies incense smoke as a means to visually detect leaks in SAM, Biosphere 2 Once again, we engaged simple auditory inspection to detect the leaks, and the application of incense smoke to visually see leaks we could not hear or to confirm the exact location of those we could hear. Ezio returned as our super sleuth outside of the SAM pressure vessel and to operate the blower. He located an additional three leaks, two by listening and one by smell, which was unexpected by highly fortunate.

By |2022-11-15T00:55:45+00:00November 11th, 2022|Categories: Construction|0 Comments

Fabrication in the dessert

Kai measuring the proportional sharing of a cinnamon roll at SAM, Biosphere 2 Kai cutting a cinnamon roll at SAM, Biosphere 2

Project management is a complex endeavor. Finding the right balance of give and take, guidance and learning is imperative for the long-term health and success of a team as diligently involved as that which is constructing SAM.

When Luna ventured to the cafe in Oracle before departing for an early weekend, John, Bindhu, and Kai found themselves in the challenging situation of having an extra pastry. This is one of those moments in which a team could be catapulted into the kind of grievance and mistrust from which it may never recover, or move through the situation with grace, stronger than ever.

We approached this with the same engineering precision applied to the fabrication of SAM, and the outcome was completely satisfactory.

By |2022-11-12T18:04:31+00:00November 10th, 2022|Categories: Construction|0 Comments

One hundred small steps

Cleaning the unthinkable! SAM at Biosphere 2

This past week has seen tearing things apart more than putting them together, which feels like progress lost even when we know it is the best way forward. In order to weld the perimeter of the end of the 20′ container we had to remove the west-end insulation panels installed this summer—two days of effort undone in a few hours. We learned how well the construction adhesive adhered and the properties of expansion foam in small and large spaces. What’s more, we cut channels in the side walls in order to visually see (and later test) the quality of the weld by exposing the seam on the inside for our auditory and visual inspection during consecutive pressure tests.

Between the Tuesday, November 1 and Friday when UA welders Charlie and Chad were onsite, we filled our days with myriad small projects, the kind otherwise left for when major efforts are complete. It was hard to focus, at first, but in looking back it feels good to have checked-off so many tasks.

  • Cleaned the conduit from the TM to the site of the original, external data terminal.
  • Removed the 2021 lung patches with heat gun and careful application of pressure.
  • Installed the insulating ceiling panels to the SAM Air Intake Room (AIR).
  • Chipped the entrance to the TM-to-lung tunnel in prep for primer.
  • Removed the TM outer (non-sealed) door and hinges; sanded, primed.
  • Scraped, sanded, and primed the final, inner segments of the lung pan.

In a project such as this, there are moments no one will forget. One such moment was when we decided to reverse the flow of air in the shop-vac and blow any debris out of the two PVC conduits we retained that once carried power and data from the TM to the computer terminal and data analysis terminal. We were horrified and at the same time overtaken by laughter when not only did a cloud of dirt, seeds, droppings, sticks and twigs fly into the air, but a mummified rat too!

We realized then we had to clean these pipes well beyond simply blowing air. We repeatedly filled them with water and bleach and using the vacuum in reverse, created a water fountain until it ran clean (banner at top). The words “Disgusting!” and “Oh no! That is really gross” were heard over and over followed by “Let’s do it again!”

By |2022-11-12T17:46:20+00:00November 4th, 2022|Categories: Construction|0 Comments

Seal, test, and praying mantis

John Zelenky conducting leak detection at SAM, Biosphere 2

With our second full week back at SAM we remain focused on sealing and pressure testing, with some landscaping of the desert immediately surrounding SAM after a summer of intense rain and immense growth. We welcome Ezio Melotti, lead developer of the SIMOC project, and the return of Anastasia Stepanova, former engineer for the SIRIUS analog in Moscow, now PhD student at the Colorado School of Mines and SAM team member.

In preparation for this third pressure test of the expanded SAM vessel, we applied a proper fill of Dow-Corning 795 silicone in the window channels, providing the needed wider, deeper seal. We activated the lung blower in the SAM Air Intake Room (AIR) and as with the prior test the lung rose and the pressure increased.

Using the technique described by William Dempster and Linda Leigh, we lit incense and moved slowly through SAM, module to module, interface to interface and sure enough! —we were able to visually confirm the leaks we could hear, and discover a few more too.

Through this test run it became clear that the plates that cover the end of the 20′ shipping container will need to be welded for the complex assembly of steel stud framing was not something we could satisfy with 795 alone, especially if we desired to apply something more than a finger bead to those critical areas.

Before deflating the lung, Ezio notified Kai (via radio) of a previously unnoticed hissing sound. Kai entered the lung from the TM (through the tunnel) and discovered that roughly half of the patches applied to the holes in the original membrane were compromised—dried and cracked in just a little more than a year. This was completely unexpected, but perhaps a known function of siliconized rubber that was overlooked. Kai, John, and Luna have subsequently, carefully removed the old patches with new EPDM material (similar to the original membrane) on its way to Biosphere 2.

What’s truly incredible is that the lung rose at all given the number of holes in the membrane in addition to the known leaks in the TM, 20′ and 40′ shipping container. This gives us great confidence in our ability to maintain pressure for long periods of time, days, possibly weeks once all leaks are properly managed.

The UA welders will arrive on Tuesday to complete seals of two more interfaces, and then we’ll be back in the running for another pressure test and continued construction. Stay tuned!

By |2022-11-12T04:24:03+00:00October 25th, 2022|Categories: Construction|0 Comments

The first pressure test of the expanded SAM

Lung inflation of SAM at Biosphere 2

In preparation for our first pressure test of the expanded SAM vessel, we applied a thin fill of Dow-Corning 795 silicone to the channels where two original Test Module windows were replaced by a single steel hatch plate in late 2021, just enough to hold a temporary seal. 795 is an incredible product, remaining flexible after 35 years (even in external Arizona applications).

It is our intent to apply the method used by the Biospherians. While 795 provides a flexible, long-lasting seal, it is gas permeable. While a shallow seal will hold pressure immediately, it will leak more gas than a deeper seal, over time. Therefore we will ultimately apply a silicone bead approximately 3/4″ wide and 3/4″ deep for the given pressure differential.

After synchronizing the Vernier barometric pressure sensor and two cell phones with barometric sensors, all three of which register to one one-hundredth of a PSI (0.0n), and set the timer, Ezio and Kai remained outside while John and Luna were sealed within. We activated the lung blower in the SAM Air Intake Room (AIR), the lung rose, and … we could hear all kinds of leaks across the TM, 20′ and 40′ shipping containers! Most of these leaks were anticipated, some new and unexpected. It was an exciting event from start to finish. John and Luna marked leak points with blue painters tape while Kai recorded leak points with a camera on the outside. The test ran roughly one hour and twenty minutes, start to finish, and was a complete success given the function of the lung and what was learned.

We recorded a barometric pressure baseline, the start of the blower, rise in pressure, maximum pressure achieve when the lung plate lifted from the floor, and the gradual drop of the lung plate and pressure when it again sets down. We achieved roughly 50% of the desired 0.1 PSI increase in pressure, as calculated in our June 2021 pressure test.

John and Luna patched a number of holes and ran a second test the following day. The third test was run following the Mars Society conference.

By |2022-10-30T03:48:41+00:00October 20th, 2022|Categories: Construction|0 Comments

Back to the grind(ing wheel)

Kai grinding heads of sheet metal screws on SAM at Biosphere 2 Luna applies 795 silicon to screw heads in SAM at Biosphere 2

With the daytime temperatures quite comfortable and the SAM team fully recovered from the last construction sprint, we are back to SAM with a singular focus — achieve a hermetic seal and hold an internal, positive pressure for as long as possible.

To this end, every sheet metal screw that extends from inside to out is backed out of its threads, coated with 795 silicon, and seated again. All temporary silicon finger beads will be replaced with silicon channels or welding to minimize the gas transmission over time. The final rows of insulation in the 20′ shipping container (SAM workshop) are being completed, a job unfinished from the final days of our effort in July.

This is the best part of a multi-year endeavor, when the team has worked together through thick and thin, through snowfall and in the blazing sun, success, failures, and everything in between—all project segments that lie ahead are well defined and each week we feel we are making progress toward the goal of providing a hi-fidelity research vessel for visiting, research teams.

We are eager to conduct our first pressure test since June 29, 2021!

By |2022-10-30T03:51:44+00:00October 18th, 2022|Categories: Construction|0 Comments

Let’s get this thing done!

A row of insulation cures in SAM at Biosphere 2 John Z., Luna Powell, and Kai Staats have arrived to Biosphere 2 for a final three months construction sprint, working sunrise to sunset (and then some) to complete this high fidelity Mars habitat research station at Biosphere 2. We have until the close of 2022 to complete fabrication and testing of the expanded pressurized vessel, electrical wiring, plumbing, and interior layout with January for extended testing and fine-tuning of systems and procedures before receiving first teams in 2023.

We look forward to returning team members Atila Meszaros, Sean Gellenbeck, Anastasia Stepanova, and Grant Hawkins, and new additions Ezio Melotti, Bindhu Oommen and Nathan Schmit.

Stay tuned for photos, stories, and data!

By |2022-10-30T03:53:04+00:00October 13th, 2022|Categories: Construction|0 Comments

A Midsummer Day’s Weld

A bobcat next to the Test Module at SAM, Biosphere 2 Welding the 20' to TM interface at SAM, Biosphere 2

Welding the 20' to TM interface at SAM, Biosphere 2 Chharlie welding the 20' to TM interface at SAM, Biosphere 2

As we are constructing SAM from three exiting structures (the original Biosphere 2 Test Module (TM), a 20′ and a 40′ shipping container) no two interfaces between these units is identical. Rather, each is an experiment in design where the corridor must be ridged to support the weight of a human passing inside, protected from the elements so as not to rust or degrade over time, and attached on both ends so as to maintain a pressurized seal between dissimilar materials.

We learned a great deal in the study of the TM. The 5’x5′ windows are held in a steel frame which itself it bolted to the TM. A 3/4 inch channel between the inside of the window frames and the steel frame of the TM is filled with 795 silicon to provide a pressure seal and low-permeability gas release over time. This system has remained untouched for more than 30 years and remains 100% sealed, even flexible to the touch. It was our intent to duplicate this method for all interfaces, however, we determined that the effort would result in more welding overall than simply welding the interfaces themselves.

As such, we asked James Parker, Supervisor of the University of Arizona Metal Shop to let us know when his team could give us a full day at SAM. On August 18 Charlie and Steven applied their expertise, successfully welding the side walls, tops and bottoms of the corridor between the Test Module and 20′ container, and between the 20′ and 40′ containers. Kai removed the insulation from the exterior prior to the welding team arrival, and when complete (and cool to the touch) applied a coat of primer to the exposed areas, then replaced the insulation sheets.

By |2022-10-28T05:11:27+00:00August 18th, 2022|Categories: Construction|0 Comments

Photos of SAM, July, 2022

SAM at Biosphere 2

And with the close of June, first week of July already come and gone, we are departing Biosphere 2 for our second summer, returning in early October to initiate the final three months of SAM construction, conduct pressure tests, and prepare for our first team arrivals in early 2023.

See you then!

By |2022-10-21T05:23:15+00:00July 12th, 2022|Categories: Construction|0 Comments

Wrapping up for the summer

John Z installing insulation panels in the SAM Workshop at Biosphere 2

With the final three weeks of work at SAM, John Z., Luna, and Kai completed many small projects, wrapping up loose ends to the second, entering third phase of construction. Luna replaced more than 300 original nuts and washers that hold the sealed windows in place with stainless. The skylight mounted as the bathroom window was temporarily removed to apply a generous layer of Dow-Corning 795 silicone (the same used on the Test Module and Biosphere 2) and reset. The variety of tomatoes grown inside the Test Module for the Analog Astronaut Conference produced delicious fruit, were consumed, the plants composted. Several afternoons were spent loading aluminum stays and struts, scrap metal from the roof panel installation for delivery to the roll-off metal recycling bin behind the B2 Energy Center.

For a sum of three weeks John Z., Luna, Kai, and Sean insulated the 20 foot shipping container which will serve as the workshop for SAM. The panels were provided by InsoFast, a low VOC product specifically manufactured for a given shape of container (thank you Angus for the recommendation). While the installation video showed professionals completing a 20′ container in 12.5 minutes, we required something closer to 12.5 days (maybe a bit more). It’s tedious, exacting work but in the end, a good solution. The built-in “studs” provide support for 500 lbs and provide a high “R” value and moisture barrier of close-cell foam.

MrCool manufactures an innovative, do-it-yourself mini-split heat pump—an air conditioning unit with both the condenser and lines pre-pressurized with coolant. It really is quite clever and relatively simple to install, requiring only two crescent wrenches, two screw drivers, hole saw, PVC tape, and some careful planning. We probably spent as much time in measurements as in the actual hands-on effort, which paid off. Given that SAM is not your normal house, we were very careful to consider how we would maintain the hermetic seal given the need to cut a hole through the wall of the insulated 40 foot shipping container. Our solution was simple: we placed a patch of PVC tape over the hole which houses the pressurized lines and electrical line for the air handler, and cut an “X” incision to push each line through with minimal exposure. From the outside we re-filled the space between the interior stainless steel, and exterior aluminum skin with spray foam that pressed against the PVC tape, expanding to the outside again. Now, spray foam is bonded to spray foam in that insulated cavity and we hope, sealed. The outside of the hole is covered by a water tight electrical box leading to the insulated, pressurized coolant lines for maximum thermal retention.

For now, the unit runs off an extension cord (measured 7A, max 11A at 110V) and will be properly hard-wired once we run additional lines from the main feed. Within thirty minutes the Crew Quarters was a cool 78F compared to the 100F+ outside. It works! And we are set for the summer.

By |2022-07-12T20:33:49+00:00July 8th, 2022|Categories: Construction|0 Comments