Research & Development

The following was written by University of Arizona graduate student Atila Meszaros, and lead researcher on Bioregeneration experiments at SAM. Any changes from the original body of text are in [brackets].

We are reaching the end of the second week of our first peas-experiment, still tweaking here and there, but learning pretty much every day. We are developing protocols and knowledge that will help us perfect growing cultivars at SAM for the next few years.

Since the last TODO list, before the experiment, we had 43 different activities to complete, each one with its own ramifications and tasks. But with everyone’s help we managed to pull through and we were able to finish the set up for the experiment. The next runs should be relatively painless from now on [in theory].

• All monitoring and control for our main systems are wired, programmed, automated, and up and running. Something I will tackle soon, for both my thesis and SAM, is [a compilation of] the physical and computing processes—how I wired everything to each line of code, [including] video tutorials on how to operate Campbell and Logger net.
• All data is saved in several places, the local computer at the IT room, [our shared SAM] Google Drive, and my personal PC. We are taking measurements every second, I will probably change it to every 10 seconds if the data gets too heavy to process. Just in 10 days we had 8 million data points. A little bit too much but it doesn’t hurt for now.
• All racks are fully functional and with newly installed devices: extra lights, extra fans, new pumps, water pressure probes. We are reaching around 500 PPFD on our racks. Comparing it with Dr. Wheeler’s and Chinese Lunar Palace, their numbers vary between 400-600 for their highest output crops, and 700 PPFD for wheat. We are in a good range for our PPFD, although I would like to implement the dimmers in the future to have more flexibility. However, this also means that more lights cannot be added unless they are intercanopy lights that go in between the plants.
• Temperature as we know is our biggest issue now. Hopefully with the recharge of the [failed mini-split unit], this gets solved for the foreseeable future. Our brand-new humidifier system is working perfectly, providing consistent values between the 40-45% relative humidity. We don’t see any reason why it would not provide the same consistency on higher humidities as we move the VPD. All the Whirlpool dehumidifiers have a range between 35%-80% currently setting is 45%. We haven’t seen any algae accumulation in the translucent tubes.
• The crops seem to be growing strong and healthy. Revisiting the reflective wall experiment, where it took 20 days for us to see the first pea pods, 12 days since the transplanting, we are already seeing some of them in all the racks. One disadvantage of not being able to go inside, is not being able to record events like these every day. The addition of inner-rack cameras could be a possibility that we add in the future.
• The CO2 injection gave us some problems the first days, as we were figuring out how to properly manage the regulator + CO2 tank. The CO2 tank gauge needs to be completely open, while every pressure change is in the regulator. I know it makes sense as I said it, but we didn’t want to have too much pressure at the beginning, so we half-opened the CO2 tank gauge. [Then] we find out that that CO2 gas output would shut off. Now, the system is working as intended, and we have consistent CO2 injections.
• Now, on CO2. After some comparison between the SIMOC arrays, Campbell, and the handheld CO2 device. We have concluded that the SIMOC values at the TM are off by approximately 100 ppm. Talking with Ezio he mentioned that the calibration might be off. The numbers are ultimately constant, with the same offset value at different points. I am confident we can just process this post data recollection. I didn’t want to change the offset just yet, in case I was wrong, and it was an error from my devices.
• The CO2 addition during the time that we go inside the TM is considerable. 20 minutes between Luna and I can increase more than 100 ppm. Every time we go inside, we have a specified agenda that we tackle as fast as possible. Tomorrow, we have a scheduled ingress, and I am thinking about running the blower with extra ports open so when we worked inside the CO2 ppm remains closer to 800, instead of taking longer to stabilize.

EXPERIMENT #1
Seeds prepping – May 28th
Seeds sowing – May 29th
Seedlings Transplant – June 12th    
CO2 injection and Experiment Start – June 13th
Plants harvest and kill – July 11th
TM cleaning and prep – July 11th to July 16th

Since January 2021 the SAM team has grown from Kai Staats and Trent Tresch and a host of volunteers to an international cadre of staff members who contribute a wealth of knowledge, experience, skills, and motivation to bring to life an advanced research center for human space exploration.

Visit the all-new SAM Team page …

by Griffin Hentzen, ME

As we move into the test phase, we are running a series of tests to ensure that certain custom components will perform as expected. One component of significance is the metal chambers that will hold the desiccant and sorbents. In order to remove a given amount of CO2, the system needs to move a specific volume of air in a given period of time.

The silica and zeolite beads in the beds cause a significant amount of resistance to that airflow, so it is essential we can calculate the blower capacity for the given, required flowrate. For this immediate test I am repurposing metal chambers and valves used in a previous senior design project (2022), with a new, small blower.

We will measure the pressure drop (the amount of pressure needed to push air through at a given rate) across the metal chamber as well as the flowrate of air. We will control the flowrate by incrementally opening and closing a bleed valve that enables a limited portion of the air to bypass the chamber entirely.

Once we have the correlation between the flowrate and the pressure drop, we will be able to predict the pressure drop in chambers of different sizes and different flowrates. This will allow us to determine the requirements for the final blower we select.

Design | Experiment | Components | Assemble | Fabrication | First Run

by Griffin Hentzen, ME

In any closed environment such as a house, school, or pressure vessel, carbon dioxide (CO2) builds up at a rate dependent on the volume of the space, the number of humans inside, and the degree of closure. With a spacecraft, we will assume complete closure, for our baseline design. After a certain amount of time, the increased CO2 levels can have adverse effects on the crew members. For this reason, all crewed spacecraft have some method of removing CO2 from the cabin air.

Sometimes a single-use system, called a non-regenerable CO2 removal system, is employed. You can find these on short duration spacecraft like SpaceX Crew Dragon or the Boeing Starliner. These systems are simple, but since you can’t regenerate them (remove the CO2 and re-use) on orbit, they are not well suited for long-duration missions.

This is why we are designing a regenerable CO2 removal system for SAM, one that has the capability of capturing (adsorbing) and then releasing (desorbing) CO2 when desired. These systems are in use on the International Space Station (ISS) and are planned for future space stations and long-term crewed missions. SAM will leverage the existing design of the 4-bed-CO2 removal system (4BCO2) currently in use on ISS as the primary CO2 system, under a technology license from NASA Marshall. This will enable SAM crews to remain sealed inside for long duration (multiple week) missions.

I have the honor and priveledge of working with Dr. James Knox, a world leading expert on carbon dioxide removal systems and NASA veteran of nearly three decades. He is working as a consultant with SAM through the University of Arizona.

The 4BCO2 system employs a 4-bed, molecular sieve, thermal-vacuum, swing adsorption cycle. Let’s break that down. 4-bed simply means there are four main metal chambers that hold minerals called desiccants and zeolites. These minerals are very good at capturing water vapor and CO2 at the molecular level (thus, “molecular sieve”). The machine cycles between modes of adsorbing or desorbing (capturing/releasing) water vapor and CO2 based on the temperature and vacuum pressure we apply to them. When the bed is desorbing its CO2, we direct that CO2 down a specific line to permanently separate it from cabin air. Each bed will be adsorbing CO2 or water vapor, and then the cycle will switch, and the bed will “swing” into the other mode. Thus, 4-bed molecular sieve thermal-vacuum swing adsorption cycle.

We have designed or selected most of the essential components at a preliminary level, and are looking forward to seeing how the project progresses. The metal chambers and all flanges are designed by our team and will be manufactured by the University of Arizona’s Welding and Fabrication Facility. Major components such as the valves, blower, heat exchanger and vacuum pump will be Commercial-Off-The-Shelf (COTS) components that meet the required specifications.

Design | Experiment | Components | Assemble | Fabrication | First Run

January 17-19, 2026
University of Arizona Biosphere 2
Space Analog for the Moon & Mars (SAM)

Lead by Bindhu Oommen, MD and Kai Staats, MSC, this unique workshop brought together four practicing surgeons, two NASA consultants and former NASA flight surgeons, a SpaceX and VAST consultant, two graduate engineering students, and engineers and inventors with the SAM team.

In attendance were David Wexler, Michael Hodapp, Thomas Hoffman, Madelyn Hoying, Connor MacRobbie, Trent Tresch, Griffin Hentzen, Bindhu Oommen, and Kai Staats. The attendees gathered at the University of Arizona Biosphere 2 and Space Analog for the Moon & Mars to discuss, debate, and design an other world medical bay with surgical capabilities.

This was not a typical gathering with laptops, PowerPoint, and laser pointers. In fact, no one gave a presentation at all. Rather, the goal as to engage hands-on, to be designing as a team, working with our hands. Kai Staats led a small engineering challenge midway through the first day, to stimulate the way we solved problems.

The goal was to successfully hold a stone (various masses to choose from) on as few shish kebab sticks as possible, using string and glue as binding agents. It was a lot of fun, and lead into a lively discussion of what, exactly, will be needed to facilitate a fully functional surgical bay far, far from home.

AGENDA

Friday, January 17
Arrive to Biosphere 2, gather, get to know each other, and enjoy home made pizza in Casita 1300

Saturday, January 18
An all-day, “hands-on workshop where we start putting our ideas
down, so we can build something tangible. [We are] not expecting formal, stand-up
presentations, rather round-table discussion, ideas, concepts, and designs. Our imaginations are the limit.”

As a guide to the discussion, we propose the following:
1) Historic, industry review
2) Conditions List
3) Capabilities

Sunday, January 19
A behind-the-scene tour of Biosphere 2 and departure.

This year will see a shift in the SAM team. While in a corporate environment it is expected that the team and total productivity always grow, in an academic environment teams fluctuate—semester to semester, research project to research project, year to year.

At the start of the SAM project in January 2021 all team members were volunteers, including Kai and Trent. With a dozen volunteers that spring, the team then shrunk to just a few in the fall, growing steadily again through 2023. Volunteers provided what time they had. Some became paid staff. Students graduated and moved to jobs in their field.

The fall of 2024 was a transition with the realization that the SAM project had matured, now requiring more than pairs of willing hands and a willingness to learn new skills—SAM needs focused skill-sets and experience to bring specific ideas to form. This resulted in our first ever job posting and a new hire.

Griffin Hentzen comes to us from Purdue where he recently graduate with a BSc in Aerospace Engineering from Purdue University. He has interned at Sierra Space for two semesters, with a focus in carbon dioxide scrubber systems. He will be focusing this year on the design and fabrication our new CO2 scrubber at SAM, working closely with Dr. James Knox (also a part of the SAM team) and Director of Research lead Kai Staats, while lending a hand in myriad tasks as presented.

Welcome Griffin!

Masters student Amy Sawyer, working under Arizona State University professor Changbin Chen, has completed a one month study of four species of tomatoes, grown in the next-gen hydroponics system at SAM, a Space Analog for the Moon & Mars located at the University of Arizona Biosphere 2.