Paragon Space Development Corporation (United States)

Gravi-morphoses affect the variability of plants and are the morphogenetic adaptation to different environmental conditions. Gravity-dependent phenotypic plasticity of gametophytes as well as gravi-sensitivity of moss protonemata in microgravity and simulated microgravity conditions are discussed. The moss protonema, a filamentous multicellular system, representing a juvenile stage of moss development, develops as a result of the elongation and division of the apical cell. This apical cell of the protonema is a unique object for research on moss gravi-sensitivity, as graviperception and gravitropic growth occur within the same single cell. Attention is focused on the influence of gravity on bryophyte ontogenesis, including the gravitropic reactivity of moss protonemata, gravi-sensitivity at the stage of leafy shoot development and sporogonium formation, gravity-influenced morphogenesis of apical cell budding, and gravity-dependent spiral growth patterns. The role of gravireceptors in the growth processes of mosses at the cellular level under microgravity conditions are being discussed, as well as the involvement of auxin transport, Ca2+-induced gravitropism and the cytoskeleton in gravitropic reactions.

NASA's projected return to the lunar surface with the Artemis program opens the possibility for technological developments that maximize human exploration in ways that were unimaginable during the Apollo program. Specifically, the implementation of heads-up displays (HUD) has the potential to greatly increase astronaut performance during extravehicular activities (EVA) by increasing their situational awareness, providing relevant scientific resources, and presenting live personal biometric data that can safeguard mission success and astronaut health. Though they are an excellent mechanism for conveying information without incurring unnecessary physical strain, the implementation of heads-up displays in the vacuum of space presents challenges including: illumination variance; brightness; contrast; interface control mechanisms; and the general volume of data that can be conveyed without inducing cognitive burnout through clutter. To satisfy the desire to improve astronaut performance with HUDs while also accounting for the above design challenges, ALEXEI, short for Augmented Lunar Exploration and Extravehicular Interface, was developed in the Embry-Riddle Aeronautical University (ERAU) Spacesuit Utilization of Innovative Technology Laboratory (S.U.I.T. Lab) to be an augmented reality interface that can enhance an astronauts ability to conduct successful, scientifically relevant EVAs on the lunar surface. The resulting deliverable was created for the 2020 NASA SUITS (Spacesuit User Interface Technologies for Students) Challenge and balances features that past and current astronauts have expressed a functional desire for while also being cautious of human limitations in terms of visualizing and synthesizing information. Those features include a simplistic visual appearance, which displays a breadth of information that monitors mission progress, provides detailed instructions of mission tasks, and displays biometric vital signs, while only requiring a minimalistic level of input control. Future development of this system will include implementing silent speech control (sponsored by the ERAU Office of Undergraduate Research), which reduces the amount of physical strain needed to control the interface, a robust navigational aid, and user testing in a high-fidelity environment to confirm the usability of the interface. Continued refinement of this device will meet 2021 NASA SUITS Challenge objectives and continue the S.U.I.T. Lab's mission of human-centric design to aid in exploration of the cosmos. The following paper will discuss the history of EVA mission architecture, current methodologies used to aid astronauts on EVA, demonstrate the need for AR display technology in an EVA environment, describe the human factors principles that guided the design of ALEXEI, and discuss the plans for future development and testing.

To date humans have travelled distances of up to roughly 350,000 km to the moon and stayed alive in the Mir Space Station for a record single mission length of 438 days. These numbers are compelling and encouraging because the technologies used to achieve those feats could be used to help achieve missions to further destinations. While missions to near Earth objects (NEO) and beyond may have durations shorter than or similar to some of our stays at ISS and Mir, they will span distances up to hundreds of millions of miles from Earth; this represents lengths tens to hundreds of times farther than current records with the important distinction of exponentially longer abort times and diminishing opportunities for resupply. Because of many technology attributes based on abort time, resupply opportunities and total distances, long missions to NEO or to Mars can draw on our experience at Station and in LEO, but we will need to dig deeper. Taking humans further into space will require new architectures and potentially disruptive changes to our mentality regarding system engineering and risk. This could mean new architectures, development cycles focused on a unified end goal, and spacecraft holding systemic margins of safety instead of relying on Earth for support. This paper is a top-down look at the requirements that have traditionally driven ECLSS architectures over the past two decades and the life support technologies that have been developed to meet those requirements. From a historical investigation, ideas for the next generation of ECLSS can be derived to bring us closer to humankind’s aspirations to travel beyond the Earth-Moon system.

Sublimators have been used as heat rejection devices for a variety of space applications including the Apollo Lunar Module and the Extravehicular Mobility Unit (EMU). Sublimators typically operate with steady-state feedwater utilization at or near 100%. However, sublimators are currently being considered to operate in a cyclical topping mode, which represents a new mode of operation for sublimators. Sublimators can be used as a topper during mission phases such as low lunar or low earth orbit. In these mission phases, the sublimator will be repeatedly started and stopped during each orbit to provide supplemental heat rejection for the portion of the orbit where the radiative sink temperature exceeds the system setpoint temperature. This paper will summarize the effort put into understanding sublimator response under a transient heat load. The performance will be assessed by detailing the changes in feedwater utilization due to transient starts and stops during various feedwater timing scenarios. Sublimator start up utilization will be assessed as a possible relationship to transient performance of a sublimator. This paper will also provide recommendations for future sublimator designs and/or feedwater control.

<div class="htmlview paragraph">The Sublimator Driven Coldplate is a unique piece of thermal control hardware that has several advantages over a traditional thermal control scheme. The principal advantage is the possible elimination of a pumped fluid loop, potentially saving mass, power, and complexity. Because this concept relies on evaporative heat rejection techniques, it is primarily useful for short mission durations. Additionally, the concept requires a conductive path between the heat-generating component and the heat rejection device. Therefore, it is mostly a relevant solution for a vehicle with a relatively low heat rejection requirement. This paper describes the design of an engineering development unit intended to demonstrate the feasibility of the Sublimator Driven Coldplate concept.</div>

<div class="htmlview paragraph">Theoretical analysis<span class="xref"><sup>1</sup></span> has predicted that the driving factors in flow stagnation of a radiator panel in a pumped fluid loop system are:</div> <div class="htmlview paragraph"> <ul class="list disc"> <li class="list-item"><div class="htmlview paragraph">the viscosity of the working fluid,</div></li> <li class="list-item"><div class="htmlview paragraph">the temperature drop between the fluid inlet and outlet on the panel (limiting the amount of heat rejection achievable with a single radiator panel), and</div></li> <li class="list-item"><div class="htmlview paragraph">the magnitude of the cooling differential between the tubes on the panel.</div></li> </ul> </div> <div class="htmlview paragraph">Historically, manned spaceflight has used high viscosity, non-toxic glycol/water mix working fluids for pumped fluid loop radiators where panel fluid outlet temperatures are in a range where flow stagnation due to viscosity increases becomes a serious issue. Radiator panel flow stagnation occurs when fluid stops flowing through some of the panel fluid tubes, effectively reducing radiator size and heat rejection capability. If this phenomenon can be adequately understood, stagnation can be used advantageously as system heat rejection needs vary.</div> <div class="htmlview paragraph">The focus of this paper is to evaluate the effect of radiator design parameters on the panel fluid tube flow stagnation point in a man-rated pumped fluid loop system with a goal of maximizing radiator panel heat rejection while increasing fluid system stability and stagnation predictability.</div> <div class="htmlview paragraph">Using a Thermal Desktop® (<a href="http://www.crtech.com" target="_blank">www.crtech.com</a>) model of a radiator panel with fluid tubes, the sensitivity of the radiator fluid stagnation point to uniform changes in sink temperature, fluid inlet temperature to the radiator panel, radiator panel thickness, fluid tube internal diameter, fluid tube length, and working fluid viscosity is evaluated.</div>

The buckling performance of patent-pending spacecraft structural radiator geometry has been studied using finite element analysis (FEA) and subscale physical testing to support preliminary indications of significant mass savings by combing thermal and structural systems. The primary goal was to prove that incorporating a crescent shape into the spacecraft skin also acting as radiator panels could significantly increase the load capability of the design with minimal mass penalty. Physical testing was used to support analysis, as manufacturing imperfections and restraining variations cannot be avoided and are not accounted for in the analysis. Overall results successfully supported the increased capability of the crescent and validated the use of FEA models to predict buckling of the geometry using a knockdown factor.