Research & Development

This phase of assembly requires in-house fabrication of key, custom components, fittings, and seals. University of Arizona undergraduate students Alyssa Ackerman, Brendan Phoebe, and Jeff Buskirk joined the SAM team mid October to work along side lead engineer Griffin Hentzen, and in 2026 will assume his role, as a team, when he ends his one year engagement at SAM.

The filters, gaskets, and seals internal to the chamber stack and between the chambers, and introduction of a commodity water chiller in combination with a heat exchanger provides a closed coolant loop to maintain adequate low temperatures for maximum efficiency of the total system.

Alyssa, Brendan, and Jeff each bring a unique experience, valued skills, and confident energy to this project, and are already contributing to the overall project at an incredible rate.

Experiment | Design | Components | Assemble | Fabrication | Operation (coming soon)

by Griffin Hentzen, ME

We are thrilled to enter the assembly phase of the project! We have all primary components needed to build the assembly, with many system components already mounted on the grid wall. Unlike most spaceflight hardware which is tightly packaged to maximize efficiency, our system has plenty of room. We are opting to make the assembly modular and spread components out as much as needed to make assembly, integration, and testing as easy as possible. This unit will be an experimental unit that we will want to be able to upgrade or alter at any given time.

The large chamber stacks have many different sections. At both ends, they contain diffuser chambers which simply allow the air to transition from a relatively thin tube into the full volume of the chambers. The largest chambers within each chamber stack are the sorbent and desiccant chambers. The sorbent chamber adsorbs CO2, but is sensitive to water vapor; the desiccant chamber adsorb water vapor to allow the sorbent chambers to function properly. The medium-sized middle chamber is a plenum chamber that contains a large check valve, and a side-exit port. The three small chambers are spacer & instrumentation chambers that allow for us to easily plug in power and data lines to components inside the chambers without compromising the seal quality. They are separate chambers to ensure modularity, and give us the flexibility to change around positions in the future.

Also mounted are the blower (blue), the blower controller (black box), and the vacuum pump (silver, white and black), which allows for us to pull a vacuum on the zeolites/sorbent to desorb them of CO2.

There are many more components in the system, including a number of valves, a heat exchanger, high-temperature tubing, and a healthy amount of instrumentation and wiring. So far we have primarily been fit testing and ensuring all components will mount correctly to the 80/20 wall. The mounting structure is designed to allow for maximum modularity and ease of assembly and maintenance compared to a system that is welded together, permanently in place. It allows us to move any given component up/down, left/right, or in/out.

Experiment | Design | Components | Assemble | Fabrication | Operation (coming soon)

The first batch of custom-built components has arrived in the mail and from the University of Arizona Machine Shop, a full-featured, solutions provider for all things custom built. The shop manager Larry Acedo has worked on dozens of space craft, world-class telescopes, and inventions of all specs and abilities. He maintains a small showcase of the myriad array he and his associates have built, over the decades. It’s worth a visit, even if you don’t have something for Larry to immediately entertain.

At the same time, Kai and Griffin hung the four rows of 3″ x 1.5″ 80-20 aluminum rails that will be the wall-mounted backbone of the 4-bed CO2 scrubber in the Experimental Air Revitalization Laboratory (EARL) at SAM. This system enables infinite adjustment in both the x and y directions, and can safely support hundreds of kilograms.

Experiment | Design | Components | Assemble | Fabrication | Operation (coming soon)

EXPERIMENT #4
Seeds prepping – September 2th
Seeds sowing – September 3th
Seedlings Transplant – September 22nd
CO2 injection and Experiment Start – September 23rd
Matthias Ingress – October 13th
Plants harvest and kill – October 20th
WBA Ends – October 26th
TM cleaning and prep – October 27th to October 30th

This experiment coincides with the World’s Biggest Analog (WBA) and introduced a human in-the-loop.

This spring brought us to the close of four years of design, development, and construction of a unique, world-class, hermetically sealed research facility for bioregeneration (air revitalization with plants) for long-duration human space exploration.

SAM is now actively hosting what will be the first of many years of experiments in which we grow a specific species of food cultivar to determine it’s growth rate and carbon sequestration against three Vapor Pressure Deficit values.

My graduate student Atila Meszaros and SAM Site Manager Luna Powell managed a perfectly executed test run of dwarf wheat, peas, and quinoa. The peas are a unique variety developed by Dr. Bruce Bugbee and his team at Utah State University. Smaller than standard, they produce a remarkably high seed yield–perfect for the Moon or Mars.

Furthermore, we are working with Dr. Lucie Poulet and her graduate student to determine key characteristics of the peas, including the density and dimensions of the leaves. All of this work is inspired by the legacy of NASA veteran Raymond Wheeler who was instrumental in motivating my dive into the world of bioregeneration in 2017 with my very first concept for SIMOC.

June through mid August saw completion of two full, six week runs of peas (2 weeks incubation at B2; 4 weeks in SAM) only to be met with the reality of one too many system failures and mistakes, forcing a total restart this past Thursday. That is the rigor of science–if the experiment is not done right, you do it again … and again. I am proud of Atila and Luna for not hesitating to set aside more than three months of hard, daily work in the name of solid science.

Our current experimental configuration is built around a nearly fully automated, computer controlled system that Atila, Luna, and Tanner Conrad, Research Technologist (under Dr. Murat Kacira) at UA CEAC assembled and programmed. It maintains a constant 800 ppm of CO2 such that by monitoring the amount of CO2 injected (from a cryogenic tank via gas manifold) we know the maturity of the peas and can plot, with a high degree of accuracy, the growth function and as such, ability for any food cultivar to revitalize cabin air.

The culmination of this series of experiments comes in October in conjunction with the World’s Biggest Analog where veteran SAM team member Matthias Beach will be sealed inside for two weeks. During the first week his CO2 will be sequestered by the peas (at least, that’s the hypothesis). On the morning of the 8th day he will harvest the peas, remove them from the habitat through the airlock for external processing and analysis, and then complete the mission with no CO2 removal to demonstrate the amount of CO2 that was being sequestered by the plants.

Learn more about this series of experiments …

EXPERIMENT #3
Seeds prepping – August 3rd
Seeds sowing – August 4th
Seedlings Transplant – August 18th
CO2 injection and Experiment Start – August 19th
Plants harvest and kill – September 16th
TM cleaning and prep – September 16th to September 22nd

This summer was one of adventure for the entire SAM crew.

Kai and Trent enjoyed a trip down the Grand Canyon mid-May with directors and volunteers for the National Space Society, the final voyage of this seasonal journey in memory of the incredible (and greatly missed) Anita Gale who departed planet Earth in May 2024.

Kai and Colleen attended the National Geographic Society’s Explorers Fest and then ventured on to Mongolia for six weeks, teaching English, exploring the foot of the country’s largest glacier, and kayaking wild rivers.

Kai Nevers and his partner Kate spent a month traveling around Greece and Italy … ending the trip with a 1 week hut-to-hut hike in the Dolomites.

Trent was wreck diving with the Explorers Club in the Great Salt Lakes.

Luna enjoyed time with family in rural Maine and sought refuge from the summer heat in Northern Arizona.

Griffin took his first trip overseas and presented two papers for SAM at ICES 2025, Prague.

Atila explored the beaches and jungle of his home country Peru.

Bindhu attended the Humans to the Moon and Mars summit in Washington D.C. followed by the Aerospace Medical Association conference in Atlanta, Georgia, related to the SAM MedBay project. She visited a colleague from the Analog Astronaut Conference in England, where she rode her first wave on a surf board, visited the Eden Project, and prehistoric Stonehenge.

Nathan explored lava tubes in Hawaii.

Shantano got his first, single author paper accepted to the CAIP conference, presented at the Sagan Summer Workshop for a hands-on project on occurence rate of exoplanets, and captured a thunderstorm and Saturn’s moon Titan on his phone.

And Matthias ventured to Devon Island with the Mars Society as XO for the Advance Team to prepare the Flashline station for Missions 17 and 18.

And somehow, despite the incredible travel, we got a lot done at SAM!

EXPERIMENT #2
Seeds prepping – July 2nd
Seeds sowing – July 3rd
Seedlings Transplant – July 17th
CO2 injection and Experiment Start – July 18th
Plants harvest and kill – August 15th
TM cleaning and prep – August 15th to August 17th

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