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Optimization of the Root Zone in Controlled Environment Agriculture
Get PDFControlled environment agriculture (CEA) helps grow plants in spaces where resources like water and nutrients are limited, such as deserts or spacecraft. Effective management of water in the root zone, the area where plant roots grow, is vital to keeping plants healthy, especially in closed-loop systems where water cannot be wasted, as will be necessary for long-duration space missions.
An improved automated watering system designed for use in space-like environments was developed over several trials. Early designs using suction to draw water through tubes faced problems with uneven watering and roots blocking the tubes. Switching to a system that pushed water through the tubes improved the consistency of water delivery. Additional improvements included using stronger, thicker tubes and special materials to prevent clogging from microorganisms. These upgrades made the system more reliable and long-lasting.
In this research, we also looked at ways to improve the growth in peat-based growing media by carefully controlling how much water was available to the roots. Peas, mizuna, and lettuce were grown using a special irrigation system with ceramic tubes placed below the surface. The tubes provided water and nutrients directly to plant roots at different moisture levels. Plants grew well across a wide range of moisture conditions with better performance observed at 50% of the maximum water content, but very wet conditions reduced root growth. This shows that carefully balancing water and air in the root zone is crucial for plant health.
Finally, we tested whether it was possible to grow multiple crops in the same peat-based media without changing it, mimicking a no-till farming approach. The results showed that when carefully managed, the same peat media could support repeated crop growth with little decrease in productivity. This method significantly reduces waste and the need for fresh supplies.
Overall, this research demonstrates practical root zone management approaches for more sustainable plant cultivation in controlled environments, highlighting strategies useful for both agriculture on earth and future agricultural practices for space
Night Sky Brightness Caused by Orbital Reflectors
Get PDFWe are in the process of developing a system which redirects the incoming sunlight to a stationary ground target after sunset and before sunrise. One of the purposes is to extend operating hours of solar-farms to after sunset and before sunrise. Our system contributes to light pollution as a by-product. We have developed an optical model to predict the night sky glow caused by the light coming from an orbital reflector. In this paper we will review some work done by others on the night sky brightness caused by artificial city lights first, then present our results of model predictions on light pollution caused by orbital reflectors, and show how they compare with natural night sky background, measured full-moon night sky brightness, and some data measured for locations near a city or a campus
Small Satellite Enabled Human Capital Development Approaches for a Space Professional Cadre
Get PDFThe rapid growth of the commercial and government space sectors has highlighted a critical shortfall in qualified talent. Addressing these gaps requires innovative educational programs that can efficiently develop human capital without extensive resources or extended classroom requirements. This paper will explore these challenges and present solutions through a focus on Small Satellite (SmallSat) resources and lessons learned from previous attempts, as well as highlighting a number of emerging programs that are quickly helping to address this growing concern.
One promising approach is the Space Force Cadet Corps Cadet Training in Space, Cyber, and Artificial Intelligence/Machine Learning. This program exposes cadets to potential careers in government, military, and civilian sectors, emphasizing leadership and aerospace education. The initial “Space” focus is on training cadets in Space Missions and Operations, Small Satellite Design and Development, Astrodynamics/Space Environment, Space Law/Policy, and Space Cybersecurity/Network defense. By providing hands-on experience and expert guest speakers, cadets gain valuable insights preparing the next generation of space enthusiasts. Utilizing small satellites as the technology baseline allows SFCC cadets to gain experience quickly and at low cost, parallel to the arguments made for small satellite development in Fleeter’s seminal text, “Logic of Microspace”.
Another innovative program is the Space Operations Certification Program offered by Lake Superior State University. This certification program equips students with a well-rounded suite of skills, including a fundamental understanding of the space environment, orbital dynamics, and pragmatic skills involved in space system operations. The program emphasizes real-world experience through experiential learning at the Homestead Mission Operations Center (HMOC), leading to opportunities for co-op and internship positions with leading employers in the space industry. Here, small satellites were utilized as test articles for the students to demonstrate satellite operations proficiency, from digital twins of well known small satellite demonstration missions, to conducting live satellite tracking and communications sessions with on-orbit small satellites designed for open source interactions.
These programs demonstrate that effective human capital development for space professionals can be achieved through targeted educational initiatives that cost-effectively leverage SmallSat resources and provide targeted, practical, hands-on learning experiences necessary for growing the Space cadre. By highlighting these programs and sharing lessons learned, the authors aim to inspire and guide future efforts in addressing the talent shortfall in the space sector
Dream Big: A Novel, Flexible and Robust ½U ThinSat Constellation Solution
No full textThe Dream Big project is a joint initiative between NearSpace Launch (NSL) and NearSpace Education (NSE), combining commercial satellite development with hands-on educational outreach. Focused on advanced manufacturing and space entrepreneurship, the program engages university teams in designing, building, and integrating custom payloads into a novel ½U ThinSat bus. Over the past year, six Midwestern universities completed Phase 1, culminating in the development of six student-built payloads integrated into the NSL bus scheduled for launch in late 2025 or early 2026.
In addition to satellite development, teams conducted high-altitude balloon flights to validate hardware and promote STEM engagement in their communities. This presentation will showcase the system’s innovative flight and ground support technologies, highlight contributions to workforce development, and share key progress updates, challenges faced, and lessons learned from across the program
DebrisFind: A CubeSat Mission for Evaluating Space Debris Flux in Low Earth Orbit
No full textProliferation in low earth orbits, both operational satellites and defunct or debris items, poses a significant challenge to the long-term sustainability of space operations, and the difficulties in tracking and measuring mm-scale has increased the uncertainty of contemporary statistical models like the NASA Orbital Debris Engineering Model (ORDEM) and ESA MASTER and their statistical debris flux predictions. This uncertainty both complicates orbital mission risk assessment and impedes remediation efforts. This paper develops a CubeSat mission that informs these statistical models through in situ flux determination, providing a comparison of debris flux levels in Low Earth Orbit (LEO). The optimum orbit for this mission is chosen by considering different objectives based on flux levels and active satellite density, with the constraint of CubeSat operational limits. The results suggest that the highest debris flux is concentrated at a 98.7° inclination, likely due to the prevalence of sun-synchronous satellites. To maximize data collection, DebrisFind is planned for a 650 km orbit—an altitude that balances a high debris flux density with the operational constraints of CubeSat missions. The mission’s core payload evaluates two conceptual designs for a deployable mechanism capable of unfolding a thin debris detector sheet, along with an onboard optical system designed to detect and characterize debris interactions on the deployed surface. Over the mission lifetime, the debris detector sheet is expected to detect ∼100 sub-millimeter particles per square meter of area. Complementary to the main mission, an additional camera system passively monitors debris, providing validation of optic flow-based detection methods. It also explores the feasibility of using trajectory deviations as a signal for debris collision detection. The mission’s findings will contribute to refining space debris models and improving collision risk assessments for future spacecraft. By providing real-world flux data at small size scales, DebrisFind will help bridge the gap between theoretical predictions and observed debris populations, supporting the development of more effective mitigation strategies for sustainable space operations
Successful Demonstrations of the ELROI Satellite License Plate
Get PDFELROI (Extremely Low Resource Optical Identifier) is a system that attaches a small, cheap, low power, autonomous blinking light to a satellite or other space object to allow it to be unambiguously identified by ground observations using a small telescope. This can provide a resolution to the space object identification problem for future launches at minimal technical and financial costs to the satellite operator. In 2024, two satellites carrying ELROI Space Object Tracking Units were successfully launched on separate rocket launches. As reported here, in both cases ELROI provided the first definitive identification of each satellite, sooner than achieved by conventional techniques
Game-Changing Technologies for Green Propulsion Operating With 98% Hydrogen Peroxide
Get PDFThe propellant grade hydrogen peroxide is coming back to space industry. While launcher applications would accept lower grades of High Test Peroxide (HTP) for cost reduction, the highest possible concentration matters much more for in-space propulsion. Every 1% in peroxide concentration translates to the propulsive performance (specific impulse) roughly in 1% for monopropellant and 0.5% for bipropellant.
The highest HTP grade provides certain advantages. While being more reactive, it requires less catalyst for its full decomposition, resulting in hardware mass and cost reduction. When used with any kind of bipropellant (either catalyst-augmented or hypergolic, and including hybrid), the highest grade HTP provides also the shortest possible ignition delay. However, decomposition temperature of 98% HTP has its price in a challenging catalyst technology. Pure silver, usually coated with samarium oxide, is no more applicable, even supported on e.g. nickel wire mesh. Ceramic supported platinum has been identified as very active and compliant with thermal requirements for 98% HTP. However, the brittle nature of microporous ceramics appeared to be a limiting factor for certain purposes.
While working with the European Space Agency (ESA) for over 10 years, the authors explored critical issues and requirements linked to space propulsion and understood how to work together to develop game-changing technologies for 98% HTP. Requirements, related to hydrazine catalysts, have been found challenging but motivating. Multiple iterative loops with conventional solutions for HTP and a failure in the identification of the right one indicated a different approach to this issue. A monolithic, fully-metal, macro-porous structure, coated with specially selected composition of active materials, appeared to be a perfect answer for 98% HTP. A three-dimensional, sponge-like metal foam ensures better mixing and reaction rate than any straight-channel cordierite catalytic insert and remains resistant to multiple cold starts. No movable parts means no abrasion and void creation. This affects the chamber pressure stability. Several ground demonstrations of this technology have proved its great potential. One of these includes over 20 kg of the propellant throughput with an in-house developed 1 N thruster. This demonstration combined up to 2 hour steady-state burns and over 10000 pulses of variable duration and frequency. The pressure roughness (3σ) has been maintained at the level of 1,5% from test to test. Good repeatability of transients and impulse bits has been achieved. Successful tests in a higher scale (200 times by mass flow rate) and with a higher bed loading proved the scalability of this technology.
The paper presents challenges encountered by the authors, approach, and methods applied to solve certain issues concerning propulsion technologies for 98% HTP. Test results with 1N monopropellant thruster and 420 N catalyst-augmented bipropellant engine have been discussed. The authors introduce their further development plan for an innovative, long-lasting and fast-response catalyst bed, considered as a game-changing technology. This scalable catalyst bed is applicable not only for monopropellant, but also for various types of bipropellant thrusters, including liquid and hybrid
Designing Coordinated Multi-Vehicle Networks for LEO-to-GEO Transport Using Low-Thrust Propulsion
Get PDFElements of on-orbit servicing (OOS), such as propellant depots and refuellable servicing spacecraft (servicers), offer promising means to extend the operational lifespan of Earth-orbiting assets. While current concepts for reusable in-space transportation often rely on a single, versatile servicer to transfer payload satellites to high-energy orbits, an alternative approach to this monolithic architecture may employ a network of space-resident transport vehicles to move payloads from low-Earth orbit (LEO) to geostationary orbit (GEO). This paper investigates how servicers equipped with low-thrust propulsion can be used to design fuel-optimal, multi-vehicle transport architectures under temporal constraints. A set of analytical solutions is derived to estimate the time-of-flight and propellant consumption for low-thrust transfers between circular inclined orbits with differing right ascension of the ascending node, accounting for constant thrust and J2 perturbation. Leveraging these analytical methods, a genetic algorithm is employed to optimize the placement of depots and staging orbits, as well as the sequence of maneuvers for each servicer. This methodology enables rapid trade space exploration of servicer constellation designs, which is further used to assess the impact of varying network size and servicer mass on transport performance through numerical Monte Carlo simulations
Contrasting Effects of Climate Warming on Hosts and Parasitoids: Insights From Rocky Mountain Aspen Leaf Miners and Their Parasitoids
Get PDFBecause temperature has pervasive effects on biological rates, climate warming may alter the outcomes of interactions between insect hosts and their parasitoids, which, for many host species, constitute the single largest source of mortality. Despite growing interest in parasitoid-host responses due to climate change, there are few empirical tests of thermal tolerance differences between non-model lepidopteran hosts and their parasitoids and almost none from mountain ecosystems where warming is occurring more rapidly. We examined the thermal ecology of a host–parasitoid interaction in the Rocky Mountains using the wild populations of the aspen leaf miner (Phyllocnistis populiella) and a set of previously unknown eulophid parasitoids that attack them. Host and parasitoid development rates were differentially sensitive to temperature. In addition, upper thermal limits of adult parasitoids were lower than those of host caterpillars, and in choice experiments, parasitoids reared at different temperatures showed no plasticity in preferred temperatures. However, when coupled to simulations of leaf microclimates in aspen canopies, these observations suggest, contrary to expectations, that climate warming may potentially benefit parasitoids
Setting Salinity Water-Quality Standards Protective of Aquatic Life: Insights From Analyses of the Effects of Salinity on Stream Insects
Get PDFFreshwater ecosystems are becoming saltier due to human activities like agriculture, urbanization, and resource extraction. This change in salinity is important because we know very little of how stream salinity affects aquatic insects at natural concentrations, much less at elevated concentrations. Increases in salinity may harm aquatic macroinvertebrates, which play important roles in stream food webs and are widely used as indicators of ecosystem health. Understanding how salinity affects aquatic insect growth, survival, and distribution is critical for developing effective criteria protective of aquatic life, but existing methods often rely on field surveys where multiple environmental factors covary, making it hard to isolate the effects of salinity from other pollutants. My research aimed to improve how we assess the effects of stream salinity on aquatic macroinvertebrate distributions and viability. In my second chapter, I conducted lab experiments to test how salinity and temperature affect the survival and growth of three stonefly species and compared these results to field-based estimates of thermal and salinity sensitivity. I found that temperature had a stronger overall effect on survival and growth than salinity, and that the only temperature results aligned in rank order with field-derived sensitivity estimates. In my third chapter, I developed models to assess whether variation in larval aquatic insect body size across different stream sites could be linked to salinity and other environmental conditions. I found that salinity and temperature were associated with large differences in body size for some, but not all, species. In my fourth chapter, I evaluated a common method used by water quality agencies to set salinity thresholds protective of aquatic life and identified several sources of bias: the varying number of individuals in subsamples used to inform the model, analytical methods chosen to estimate species\u27 salinity sensitivities, and the presence of other stressors. Together, the findings from my research help clarify how salinity affects aquatic insects and how salinity standards can be developed to better protect freshwater ecosystems