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At least 1,315 records · Page 73

MycoMaterials: Metal-Fungi Hybrids

There is an interest in creating aerospace structures that regenerate, communicate and that are capable of using carbondioxide as a fuel source. Before such a vision is achieved several fundamental questions must first be answered. For example, what are the optimal conditions and laboratory settings for mycelium growth and is it possible for mycelium to digest different metals to form metal-mycelium hybrid structures? Recent research has shown that fungi and photosynthetic organisms can absorb harmful metals. Eight different species of fungi were grown such as blue oyster (Pleurotus columbinus), reishi ling chi (Ganoderma lucidum), and shaggy mane (Coprinus comatus). Species of fungi were chosen based on their potential growth rate, potential strength and non-toxicity to humans. Metal-mycelium hybrids were developed by using both the cell and mycelium life stages. In experiments involving the mycelium stage, varying amounts of sterilized sawdust (0.5-1g), zinc sulfide (0.5-1g), and small pieces of aluminum foil (0.1-1g) were applied on top of the mycelium growing on petri dishes. For experiments using the cell stage, 8-9 drops of the fungal sample were applied to zinc sulfide (0.5-1g) and aluminum foil (0.5-1g). Mycelium (blue oyster) were grown on to differing quantities of aluminum foil. Cells (shaggy mane) have been grown onto aluminum foil with and without nutrients from the petri dish. Shaggy mane cells have also grown onto 0.5 g of zinc sulfide.

Kyles-Stewart, Maiya A.↗

Bionutrients-1, On-Demand Production of Nutrients in Space

Future long-duration missions face significant challenges maintaining crew health. A critical area is supplying adequate nutrition, as certain vitamins and nutrients in supplied foods and supplements demonstrate substantial degradation during extended storage. To address this issue, we are developing and flight-testing a platform technology that demonstrates in situ microbial production of targeted nutrients over extended mission durations. This 5-year experiment, known as BioNutrients-1, was started on the International Space Station in May 2019. It involves two components: an on-orbit hydration and production experiment; and the development of space-compatible, key bio-manufacturing microorganisms. On-orbit testing utilizes a small “production pack” system that encloses sterile edible growth substrate and desiccated Saccharomyces cerevisiae strains genetically engineered to produce the nutrients beta-carotene or zeaxanthin. On hydration and mixing of the production pack, the organisms revive and grow until limited by the depletion of growth media, hypothetically leading to consistent amounts of biomass and nutrients. In eventual mission applications, the packet contents would be heat treated to inactivate the microorganisms prior to consumption. For these flight experiments, the packet will not be heat treated, but will instead be frozen for return to Earth for analyses. In addition to the production pack trials, 14 different microorganisms/treatments were also delivered to ISS for long-duration storage. These samples will be intermittently returned to Earth and analyzed to determine survival rates and genomics. For this presentation, initial data from returned samples and ground controls will be discussed.

Hindupur, Aditya↗

NASA’s In-Space Manufacturing Project: Update on Manufacturing Technologies and Materials to Enable More Sustainable and Safer Exploration

NASA’s In-Space Manufacturing (ISM) project seeks to develop the materials, processes, and manufacturing technologies needed to provide an on-demand manufacturing capability for deep space exploration missions. The ability to manufacture and recycle some parts on demand rather than launch them from earth has the potential to reduce logistics requirements on long duration missions and enhance crew safety. With the launch of the first 3D printer (built and operated by Made in Space through a Small Business Innovative Research – SBIR -- contract) to the International Space Station (ISS) in 2014, the ISM project demonstrated the feasibility of operating an on-demand manufacturing system in a microgravity environment. This paper will provide an update on recent advancements in ISM under three key technology areas: manufacturing, recycling, and development of a design database. ISM continues to pursue development of manufacturing technologies for space applications and use the ISS as a critical test bed to prove out these technologies before deploying them on next generation exploration systems. Activities under this focus area include: characterization of materials manufactured using the Additive Manufacturing Facility (AMF), the second generation commercial 3D-printer on ISS, also owned and operated by Made in Space; development of prototype payloads for metal manufacturing through phase II SBIR contracts with Tethers Unlimited, Made in Space, and Ultra Tech Machinery; development of a multi-material fabrication laboratory capable of processing metals and providing inspection of manufactured parts through a Broad Agency Announcement (Techshot, Interlog, and Tethers Unlimited); an in-line sensing system for ISM platforms; and development of higher strength feedstocks for 3D polymer printers. In the area of recycling, the Tethers Unlimited Refabricator payload (an integrated 3D printer and recycler for ULTEM 9085) launched to ISS in November 2018 and began operating in early 2019. This payload represents the first demonstration of on-orbit recycling; down massed specimens will assess material degradation in the polymer over multiple recycling cycles to define limits on material re-use. Other work in the recycling area includes development of common use materials intended to be reused and recycled on space missions (Tethers Unlimited and Cornerstone Research Group) and a sterilization capability for multiple-use materials (ERASMUS from Tethers Unlimited). Concurrent with manufacturing technology and materials development work is creation of a design database, a curated list of parts that can be manufactured using the suite of In-Space Manufacturing capabilities.

Tracie Prater↗

Where Is the Upper Altitude Boundary of Earth's Biosphere? An Upcoming Stratosphere Exploration Mission

Earths atmosphere provides a relatively thin barrier to the severe conditions of space. Terrestrial microorganisms from our planets surface gets swept up into the atmosphere at rates which are influenced by meteorology, season, and variety of other regionally-dependent conditions. Residence time of microbes in the atmosphere, dispersal patterns, and metabolic activity in clouds are topics of special interest in tropospheric aerobiology. But what about even higher altitudes? A century of ocean exploration has allowed the scientific community to characterize marine life at every depth. Such knowledge was enabled by routine access, specifically, submersible vehicles with sample return systems. The outer reaches of Earth's atmosphere probably contain trace signatures of microbial life swept up from the surface, but high-altitude exploration (from 18-50 km above sea level) has been severely constrained by a shortage of reliable affordable sample acquisition systems. Thus, attempts to establish the upper altitude limits of Earths biosphere boundary remain unresolved. Previous conclusions based on observations of microbial growth and DNA signatures from samples collected in the upper atmosphere have resulted in extraordinary claims for the tenacity of life in the stratosphere. This altitude range can be regarded as a natural laboratory for examining the edge of habitability, a topic of central important to the field of astrobiology; in fact, stratosphere conditions (high UV light and low extremes of temperature, pressure, and relative humidity) closely resemble stressors associated with the surface of Mars. Moreover, low biomass detection instruments developed exploring Earths upper atmosphere can contribute to future strategies for life detection with spacecraft exploring other worlds. While pioneering, many past stratospheric microbiology studies have been qualitative in nature and lacking rigorous contamination control measurements to verify system sterility. We have designed, constructed, and recently flown a novel system for collecting upper atmosphere bioaerosols using the NASA C20A aircraft. We will report preliminary mission results from the lower stratosphere (characterizing abundance, diversity and survivability or airborne microorganisms), describe our methods for reducing false positives, and outline the open scientific engineering challenges in an ongoing effort to better establish Earths high-altitude biosphere boundary.

Smith, David J.↗

BioNutrients-1: On-Demand Production of Nutrients in Space

Future long-duration missions face significant challenges maintaining crew health. A critical area is supplying adequate nutrition, as certain vitamins and nutrients in supplied foods and supplements demonstrate substantial degradation during extended storage. To address this issue, we are developing and flight-testing a platform technology that demonstrates in situ microbial production of targeted nutrients over extended mission durations. This 5-year experiment, known as BioNutrients-1, was started on the International Space Station in May 2019. It involves two components: an on-orbit hydration and production experiment; and the development of space-compatible, key bio-manufacturing microorganisms. On-orbit testing utilizes a small "production pack" system that encloses sterile edible growth substrate and desiccated Saccharomyces cerevisiae strains genetically engineered to produce the nutrients beta-carotene or zeaxanthin. On hydration and mixing of the production pack, the organisms revive and grow until limited by the depletion of growth media, hypothetically leading to consistent amounts of biomass and nutrients. In eventual mission applications, the packet contents would be heat treated to inactivate the microorganisms prior to consumption. For these flight experiments, the packet will not be heat treated, but will instead be frozen for return to Earth for analyses. In addition to the production pack trials, 14 different microorganisms/treatments were also delivered to ISS for long-duration storage. These samples will be intermittently returned to Earth and analyzed to determine survival rates and genomics. For this presentation, initial data from returned samples and ground controls will be discussed.

Hindupur, Aditya↗

Conceptual Model of Autonomous Seed Germination Habitat for Mars Mission

As human space exploration extends to Mars, the ability to germinate seeds in extraterrestrial environments is becoming a necessity. Recent technological feats such as the development of the European Modular Cultivation System (EMCS) have made botany experiments possible on the International Space Station (ISS). Despite preliminary designs, a biocompatible plant life support system capable of traveling to Mars has yet to be developed. This study focuses on two preparatory measures regarding seed germination in spaceflight: analysis of seed dormancy protocols and compact autonomous habitat development.The objective of this project is to conceptualize a habitat capable of preserving arabidopsis plant seeds on a long duration spaceflight for the purpose of germinating the first plants on Mars. The proposed container will require a compact, low wattage system to provide gas ventilation, artificial light, and water. A visualization system will also need to be developed in order to monitor seed germination remotely. In order to test the effects of dormancy durations on plant viability, we will conduct a ground study to monitor seed germination in seeds which have been dormant for three, six, nine, and twelve months. We will also compare the effects of different sterilization procedures. The results of this study will be instrumental in developing a viable procedure for transferring the first living plants to Mars.

Peter, Jonah↗

Preserving and Curating the Moon: Adventures in Lunar Core Processing

The lunar crust is the most easily accessible part of the Moon to both remote sensing and sample analyses and provides an archive of information about planetary formation, crustal evolution, and contains a wealth of information about the origin of the Earth-Moon system [e.g., 1-5]. The Apollo mission returned 382 kg of rocks, soil and core samples. Studies of these lunar samples are crucial for our understanding of the Moon’s formation and geological evolution, and for the past 50 years these returned samples have provided the foundation for lunar science [5]. The returned samples are stored and cared for in the lunar curation facility at NASA’s Johnson Space Center. This facility is comprised of a large suite of clean rooms, sample vaults for pristine and return samples, thin section labs, core and saw rooms, storage and working areas, and ancillary labs all designed to minimize contamination from the environment and other samples. Some of the returned samples were intentionally set aside and left unopened. Recently, the Apollo Next Generation Sample Analysis (ANGSA) initiative was designed to examine these pristine samples so the next generation of lunar scientists can further our insight into the Moon’s history. Here, we present the meticulous process that involves preparing for, and ultimately opening, one of the unopened core samples: Apollo 17 drive tube 73002,0,which was collected on the Moon from a landslide deposit near Lara Crater by astronauts Gene Cernan and Jack Schmitt. In order to open, examine, and curate 73002,0withminimalpotential contamination, great care had to be taken prior to opening its container. Beginning18 months before extrusion of the sample, all core processing equipment was pulled out of storage, identified, sorted, cleaned, and purged with nitrogen gas. However, limited institutional memory has made this step challenging as most of the former core processors from the Apollo area have retired or passed away. Twelvemonths prior to extrusion, table-top rehearsals were initiated to identify equipment and learn how it fits together and operates. Five months before extruding the real core, preparations further evolved to include the extrusion and dissection of a lunar core simulant. In addition, a mock-up glovebox was designed and built to allow for a more realistic practice environment. One month prior to extrusion, the actual core cabinet was prepared for use, which included fitting it with lights, a webcam, and power. The tool and equipment cleaning procedure was also modified to include increased cleanliness and sterility requirements. While still sealed, the core was CT scanned at the University of Texas at Austin to maximize its scientific return. Days before the extrusion, witness plates and foil were deployed inside the core cabinet to monitor potential particle and organic contamination within the cabinet. On Nov. 5th, 2019, core sample 73002,0 was successfully opened and extruded(Fig.1). Dissection of 73002,0 began immediately afterwards and is still under way. Processing this sample will help us prepare for future sampling missions and core extrusions and will enable new scientific discoveries about the Moon.

C H Krysher↗

Update on Feasibility of UV LEDs in a Spacecraft Wastewater Application

As the National Aeronautics and Space Administration (NASA) expands its scope and begins to venture into long-duration, manned space flights, the function and maintenance of spacecraft water systems becomes increasingly critical and difficult. New mission requirements limit opportunities for resupply and demand extended periods of uncrewed operations. Based on lessons learned from the International Space Station (ISS), one particular challenge of future spacecraft water systems will be maintaining adequate microbial control, especially in water subsystems and component-level elements, where effective long-duration biocontrol strategies do not currently exist. To ensure the reliability and redundancy in these systems, innovative technologies will be needed to ensure mission success. After proving feasibility of commercial-off-the-shelf (COTS) devices in flow-through applications in 2018, work focused on utilizing ultraviolet (UV) light emitting diodes (LEDs) in a wastewater tank application. This paper gives an update on the tank testing that has been performed to date. Using this technology may reduce the need for consumable resupply, such as filters or biocides, and minimize crew time to make the repairs on exhausted and/or compromised systems. The ultimate rationale behind developing a UV disinfection system is to increase the stability of water systems as requirements for sterility and microbial control become more stringent for deep space missions. The resulting data from this study will be used to narrow down possible technology demonstrations for selected ISS locations to assess the use of UV technology on future exploration-class spacecraft systems.

Susan N. Gilbert↗

Gas Effluent Analysis of the Heat Melt Compactor

The Heat Melt Compactor (HMC) reduces volume, heat sterilizes, stabilizes, and manages gas and water effluent of the International Space Station (ISS) trash. Processing the trash at high temperatures produces volatile gas compounds that need to be treated before venting to cabin and/or the Vacuum Exhaust System (VES) in the ISS. The release of gases may not meet the Spacecraft Maximum Allowable Concentrations (SMAC) requirement, if vented directly into cabin, and/or gases are incompatible for venting to the VES. In order to assess the HMC gas release and venting parameters, effluent gas analysis is conducted to determine contaminant load. This paper will analyze different collection and analytical methods of the effluent gas, and report corresponding data, such that these results can be used for process design and effluent management.

Heat Melt Compactor↗

Performances of the Heat Melt Compactor System in Various Operational Scenarios

The Heat Melt Compactor (HMC) system has been developed to manage the waste generated on board spacecraft during long-duration missions. The quantity and composition of spacecraft trash depends upon the mission and can have a very high daily variability. This requires a flexible system able to manage extreme waste scenarios. Most missions will generate on average about one kilograms of trash per astronaut per day, derived mainly from the spacecraft logistics supplies and consisting of clothing, food & beverage residues, packaging, paper, plastic, hygiene wipes, and many other personal or scientific items used and discarded by the crew. Uncontained and unprocessed waste is a health hazard and a habitat storage problem. However, trash also contains valuable resources such as water. HMC is designed to provide volume reduction, microbial safening and stabilization, water recovery, and radiation shielding material. The final byproduct generated by HMC is a sterilized tile with the consistency of hard plastic that can be safely handled, easily stored, and used for radiation protection. This paper provides the summary of an extensive campaign of testing performed using the HMC system to simulate different nominal and extreme operational scenarios and to generate the data necessary to finalize requirements for proto-flight hardware to be deployed to an International Space Station (ISS) EXPRESS Rack.

HMC↗

SOTERIA: Searching for Organisms Through Equipment Recovery at Impact Areas

All spacecraft sent to the Moon have carried viable microorganisms with them. Because the Moon’s surface environment is sterilizing to life and the Moon itself is not considered to house indigenous life forms, NASA policy has not required the elimination or even the measurement of microbial contamination on lunar space equipment prior to launch. Yet multiple exposure studies have demonstrated that microorganisms can likely survive high-velocity impacts and exposure to space stresses for some time. Does any of the Earth biomass residing on lunar hardware remain viable? The Artemis program offers a chance to take advantage of this natural experiment, through a mission that is both feasible and promises to generate unprecedented data on microbial survival. We propose a two-phased mission in which imaging would be conducted to obtain data on previously crashed spacecraft near the Lunar South Pole, then astronauts would recover spacecraft debris to return to Earth for analysis of viable life and biosignatures. We propose the name SOTERIA for this planetary protection mission, for the Greek goddess of safety and delivery from harm.

astrobiology↗

Mission Concept for a Europa Lander

A NASA HQ-directed study team led by the Jet Propulsion Laboratory (JPL) with partners including Applied Physics Lab, Marshall Space Flight Center, Goddard Space Flight Center, Langley Research Center and Sandia National Laboratory has recently presented a mission concept for a Europa Lander that would search for bio-signatures and signs of life in the near-subsurface of the Jovian moon. The mission would follow the Europa Clipper multiple-flyby mission, planned for launch in June of 2022, which would provide reconnaissance imagery and other data to the Lander for use in selecting a scientifically compelling site and certifying it for engineering safety. The Europa Lander concept accommodates the Model Payload identified by the Europa Lander Science Definition Team (SDT) and documented in the Europa Lander Study 2016 Report released in February of 2017. The currently envisioned Europa Lander would launch on an SLS Block 1B as early as October of 2025 into a VEGA trajectory, arriving in the Jovian system as early as July of 2030. The baseline design of the integrated flight system includes a dedicated Carrier and Relay Stage, a Deorbit Vehicle composed of a Deorbit Stage consisting of a solid rocket motor (SRM), an MSL-like sky-crane Descent Stage, and a Lander which accommodates the instrument suite. The Lander would be powered by primary batteries over a 20-day surface mission. The science goals envisioned by the SDT require five samples taken from a depth of 10cm, a depth chosen to ensure minimal radiation processing of the potential biomarkers. Mission challenges include the large launch mass, unknown terrain topography, surface composition and materials properties, the high radiation environment, and complying with stringent planetary protection requirements. The mission concept uses a strategy of early risk reduction and overlapping requirements to provide robustness to harsh and uncertain environments. Early risk reduction efforts are aimed at maturing technologies associated with the sampling system, the intelligent landing system, high specific energy batteries, low mass and power motor controllers, and a thermal sterilization system.

Dooley, Jennifer↗

Analysis of CO2 Composite Spray Cleaning System Results

In a previous study, the cleaning efficiency of a CO2 composite cleaning system for particulate removal was tested. The study covered particles from spores to fluorescent particles of different sizes as well as a variety of substrate surfaces, including aluminum, titanium, stainless steel, and nitinol. Particles were deposited using aerosol (dry) and droplet (wet) deposition. Results from the previous study show that the CO2 composite spray system is capable of cleaning to sterility for aerosol deposited spores and is capable of cleaning a minimum of a 4-log reduction for droplet deposited spores. This minimum 4-log reduction matches current Planetary Protection dry heat microbial reduction requirements. In this paper we will present new data to further correlate the cleaning efficiency with how contamination was introduced to the surface, the surface roughness, and particle size. Possible causes for such correlations will be discussed.

Chung, Shirley↗

An Orbiting Sample Capture and Orientation System Architecture for Potential Mars Sample Return

An orbiting sample capture and orientation system architecture for a Rendezvous and Orbiting Sample Capture System (ROCS) concept was developed to enable spacecraft based, in-orbit capture, orientation, and transfer of a Mars sample container into a containment vessel as part of a potential Mars Sample Return (MSR) campaign. An analysis of the system functions, requirements, interactions, and constraints was performed. A trade study was carried out on relevant technologies, and a set of evaluation criteria was developed to help determine the most feasible concepts for implementation. The Mars Capture and Re-orientation for the potential Next Mars Orbiter (MACARONE) concept is proposed as a promising system architecture for the ROCS Capture and Orient Module (COM). The concept uses a sliding trap door for Orbiting Sample (OS) capture, a Motorized Cups Mechanism for OS orientation, and a 2 DOF Turret Arm with a paddle for transferring the OS into a containment vessel. This approach facilitates modularity, development flexibility, test-ability in a 1G environment, analyze-ability without the need to simulate or test for 0G contact dynamics, ability to encapsulate potential dust surrounding the OS, and ability to be ejected to reduce the probability of Earth exposure to non-sterilized Mars material.

Lalla, Karan↗

An X-Ray Spectroscopic Search For Dark Matter And Unidentified Line Signatures In The Perseus Cluster With Hitomi

The reported detection of a 3.5 keV emission signal in the Perseus cluster core by Bulbulet al. (2014, ApJ, 789, 13) was ruled out at high confidence in analysis conducted by Aharonian et al. (2017, ApJ, 837, L15) of X-ray spectra at 5 eV energy resolution obtained with the Hitomi observatory Soft X-ray Spectrometer (SXS). Using the same data, we search the full 2–12 keV SXS energy band for previously unidentified emission and absorption features. No significant unidentified line emission or absorption is found. Line flux upper limits (1σper resolution element) vary with photon energy and assumed intrinsic width, decreasing from∼100 at 2 keV to<10 photons cm−2s−1sr−1over most of the 5–10 keV energy range for a Gaussian line with Doppler broadening of 640 kms−1. Limits for narrower and broader lines have a similar energy dependence and are systematically smaller and larger, respectively. These line flux limits are used to constrain the decay rate of hypothetical dark matter candidates. For the sterile neutrino decay rate, we place new constraints over the mass range of 4–24 keV with mass resolution better than any previous X-ray analysis. Additionally, the accuracy of relevant thermal spectral models and atomic data are evaluated. The Perseus cluster spectra may be described by a composite of multi-temperature thermal and active galactic nuclei (AGN) power-law continua. Superposed on these, a few line emission signals possibly originating from unmodeled atomic processes (including SiXIV and FeXXV)are marginally detected and tabulated. Comparisons with previous X-ray upper limits and future prospects for dark matter searches using high-energy resolution spectroscopy are discussed.

Takayuki Tamura↗

Radiocatalyst for Radiation Protection and Microbial Control

Radiocatalysts are materials that reduce the activation energy required to split water into hydrogen and reactive oxygen species (ROS). They are activated by radiation and can be used to improve the ability of water to act as a radiation barrier. This paper reports the results of an experimental evaluation of a gold radiocatalyst. This work provides a preliminary evaluation of the ability of these types of catalysts to increase the efficiency of water hydrolysis when exposed to different types of radiation (GCR). Although the radiation exposure devices used in this testing were not capable of generating radiation as diverse as is commonly found in space, the testing is useful in evaluating the function of these radiocatalytic nanoparticles when exposed to a a subset of the types of radiation that are found in GCR. The results are relevant to evaluating the use of this material for both space radiation protection and the production of useful byproducts, such as ROS, which can be used to maintain the sterility of stored water supplies. Radiocatalysts are materials typically used in radiation cancer therapy to improve the kill rate of tumors. These nanoparticles can be directly injected into tumors or functionalized to enter tumor cells via the blood stream. When they are exposed to radiation, they produce ROS. ROS are water hydrolysis products such as OH¯, O¯, O3, H2O2. This study used radiocatalytic 1.8 nm gold nanoparticles functionalized with citrate. These nanoparticles were tested through exposure to Xrays, 56Fe particles and gamma rays to demonstrate activity to a variety of radiation sources. The results demonstrate that radiocatalysts can improve the radiation absorption of water by a factor of 3 to 8 and can effectively kill bacteria at radiation levels above 1 Gy.

radiocatalyst radiation protection biocide↗

The Effects of Plasma Application on Radish Seeds with Implications for Space Crop Production

In extended space missions, the astronaut diet will consist mostly of prepackaged foods. This could result in nutritional deficiencies due to the gradual breakdown of certain vitamins. To address this deficiency, fresh produce must be grown from seed during spaceflight. Stored seeds, however, can be vulnerable to microbial contamination which could jeopardize plant health and crop food safety. To alleviate this concern, the current practice is to sanitize seeds on the ground before spaceflight to the International Space Station (ISS). Methods of seed sanitization include alcohol soaking and chlorine gas fumigation, which have harmful effects on the environment and human health. Plasma application is a new sanitization approach that avoids these negative side effects while potentially elevating germination rate and improving growth rate; yet plasma application requires specific exposure time, power, and pressure to achieve these benefits. In the present study, Raphanus sativus ‘Cherry Belle’ radish seeds were exposed to either low pressure (Diener) plasma or atmospheric pressure plasma for varying increments of time (30s-1200s). Data collected includes immediate germination rate (viability) and microbial log reduction. Additionally, seeds were stored for later germination rate testing. Microbial assay controls have highlighted variability in initial microbial load between individual seeds, and further work is being performed to determine the standard microbial load of an untreated seed. In some samples, a negative log reduction was observed after plasma treatment encouraging further study to determine if the plasma is perforating the seed coat and releasing endophytic microbes. Treatment with Diener plasma shows promising microbial log reduction, but lower viability. In contrast, treatment with atmospheric pressure plasma offers high viability, but poor microbial log reduction. Further study will aim at determining whether plasma treatment is effective at not only sanitization, but sterilization. This research was funded by a NASA grant at the Kennedy Space Center.

Plasma↗

Remodeling BioSentinel’s Microbial Metabolism Measurement System

BioSentinel, the first biological CubeSat beyond low Earth orbit, will investigate how Saccharomyces cerevisiae responds to ionizing radiation using optical measurements of a colorimetric metabolic indicator dye (alamarBlue). To map optical data to more detailed metabolic measurements, a microbial culture system for ground testing was designed consisting of a 400 mL beaker and a rubber stopper with pass-through holes for its five sensor probes (electrical conductivity, pH, oxidation-reduction potential, dissolved oxygen, optical density). The initial design had several drawbacks. It was only partially reusable due to its one-time sealants: Teflon tape and parafilm. A steady increase in oxygen levels within the sensor’s testingdata indicated the design was not sufficiently airtight. Degradation of the rubber stopper’s elasticity due to sterilization and reinsertion of the probes led to poor robustness and eventual replacement. The vessel’s large headspace didn’t reproduce flight conditions and a large culture volume required more reagents. The system has been redesigned to contain a rigid, biocompatible polycarbonate disc lid that allows for threaded inserts. The culture vessel’s height will be reduced from 110 mm to 65 mm to decrease overhead space and material costs. A more reliable seal will be achieved with a gasket and clamps. The optical probe records absorbance at four wavelengths to characterize cell density and alamarBlue dye ratios. A pneumatically operated plunger draws media through the hollow interior of the probe. Currently, deformation of the silicone on the plunger causes asymmetrical movement and a drift from its initial state. Designs are being developed to limit the plunger’s travel for a more accurate measurement cycle. The remodeled system is under construction and will be tested for leaks and accuracy. The measurements collected will be used to provide additional insight into the optical data returned from the BioSentinel mission.

Astrobiology↗