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
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.
Experiment | Design | Components | Assemble | Fabrication | Operation (coming soon)
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.
Experiment | Design | Components | Assemble | Fabrication | Operation (coming soon)
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!
The SAM Team has this fall sustained a rigorous forward progress. Unlike the prior three years of design, development, and fabrication, this semester has seen us developing programs and collaborations as much as physical structures. This growth is welcomed, but it has also broken the tradition of weekly updates in the form of photo essays to this blog site.
As such, until those stories can be built, backdated, and posted, here is a quick summary.
And that is just the beginning of what will prove to be the most exciting phase of developments at SAM in 2025!
Last week SAM team members Kai Staats, Bindhu Oommen, Matthias Beach, Ezio Melotti, and Trent Tresch attended the International Astronautical Congress (IAC 2024) in Milan, Italy. Kai presented a paper titled “A Reduced Gravity Simulator at the Space Analog for the Moon & Mars (SAM) Terrestrial Habitat Analog at Biosphere 2” and Bindhu presented a paper titled “The Space Analog for the Moon and Mars (SAM): a hermetically-sealed and pressurized terrestrial analog station and research facility, from inception to crewed analog missions and beyond.”
This week the team ventured overland from Milan to Innsbruck, Austria to meet with Dr. Gernot Grömer, president of the Austrian Space Forum (OeWF) wherein they enjoyed a hands-on introduction to their reduced gravity simulator and renowned analog space suit program. The teams explored potential, near-future collaborations and alignment of resources as they each work to support the AAC World’s Biggest Analog.
Once team members are returned to the US and settled in, several overdue updates to this website will be conducted.
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.
This short video has Trent Tresch in the SAM RGS simulator, demonstrating four gaits used by the Apollo astronauts both in analog training and on the Moon: walk, loping stride, unilateral skip (a.k.a. “Schmitt Skip”, and “kangaroo” hop. Matthias Beach is walking behind the rig in order to provide a more smooth motion profile, to compensate for the tendency of the counterweight mass to invoke oscillations along the x axis until full momentum is built. He is not pushing the rig, rather enabling Trent to enter the research grid more effectively. A future addition to the SAM RGS will be a computer controlled motor that compensates for the kinetic lag caused by the increased mass.
These video segments are central to an analysis of motion over x (forward/back) and z (up/down) coordinates for a paper to be presented at the International Astronautical Congress 2024, Milan, Italy.
The paper will be made available at the Resources section of the SAM website once published in the conference proceedings.
There are times when a narrative is a necessary companion to a photo. There are times when a photo is worth a thousand words. And then there are times when you scratch your head and wonder …
As part of the overall design strategy for SAM’s life support system architecture, the SAM team is looking at developing a hybrid solution that incorporates both physicochemical (mechanical + chemical) elements along side bioregenerative (plant-based) elements. The team is working on developing all these elements simultaneously to ensure they are designed to interface effectively. Luna and Sean have been hard at work focused on the bioregenerative side of this critical part of the SAM architecture.
On April 22-25 of this year, the team met with a research group from the Technical University of Munich (TUM) with a research focus on the use of algae cultivation for the support human space travel. The team consisted of Gisela Detrell, Lina Salman, and Sergio Santaeufemia Sánchez. Through the TUM team’s hard work, they secured the support of their university to meet with the SAM team in person and explore how our research could overlap to be mutually beneficial. As part of this discussion, the TUM team flew out to Tucson to see SAM and Biosphere 2 in person.
The workshop occurred over 4 days, providing ample time to share what we were working on and to see how we overlap each other.
During day 1 of our workshop, Sean took the TUM team on a briefn tour of the U of A main campus and had the opportunity to meet with Dr. Joel Cuello who also researches in the field of the application of algae to supporting human space travel. The discussion lead to some exciting insights and possibilities for future collaboration. The second day the team was hosted at the B2 campus and the TUM team shared about the wide variety of research projects they are working on including photobioreactor (PBR) design and modeling, student and public workshops focused on human space travel, and how SAM could incorporate at PBR into its design. A photobioreactor is a system that provides the light an nutrients needed to cultivate an algal culture.
Day 3 of the workshop was tour day where the team was taken on a private tour of the Biosphere 2 facility and SAM. This was extra special for the TUM team as they teach about the history of Biosphere 2 in some of their classes. With this being the first opportunity any of them had to visit in person, they got the full experience and will now be able to speak from personal experience in their lectures! The SAM tour focused primarily on the habitat facility as the Mars Yard wall build was occurring simultaneously. Dr. Cuello also joined for the tour of SAM and was excited to see the facility in person for the first time as well. The fourth and final day of the algae workshop was an opportunity to discuss how we move forward as a team and the actions we can take to explore how we can continue to work together moving into the future. We are excited to continue to explore with and learn from the TUM team especially to eventually see the integration of a photobioreactor within the SAM habitat!
Overall, the visit to Tucson was a very productive discussion and we are all excited about the possibilities the future holds for our teams to continue to work together. Luna and Sean will be headed to Germany to see the the TUM facilities in December and are excited to continue exploring synergistic working possibilities for our teams!