What’s Next after Industry Disruption by CubeSats? – Industry Disruption by Open Source

A decade ago, CubeSats featured almost exclusively in the academic domain only. The same can be said today for Open Source satellites. In the same way that CubeSats and the associated development mindset started in the academic community and are now embraced by commercial, civil and defence communities, the goal of the Open Source Satellite Programme is to initiate a similar outcome for open source satellite mission architectures by developing a design that is freely available for all to use. KISPE’s goal is to build a community of open-source contributors, collaborators and beneficiaries, including those from CubeSat and SmallSat teams who are at the forefront of adopting and championing non-traditional approaches to delivering space missions. A key characteristic of open-source projects is stakeholder engagement: to collaborate, iterate and improve elements of the architecture and design - and ultimately, to leverage and benefit from the design outputs. KISPE’s Open Source Satellite Programme is developing a robust, flexible satellite platform which addresses future market, mission and programmatic demands, leverages emerging technologies and is scalable for Nanosat to Microsatellite systems, enabling teams to utilise the platform as a low-cost “commodity” or infrastructure item on which to develop their specific mission

Electrochemistry of Molybdenum Aquo Ions

The electrochemical behavior of selected molybdenum aquo ions in acidic media is examined in relation to solution structure. The electrochemistry of Mo(VI) in non-complexing aqueous electrolytes is usually severely complicated by the oligomerization and subsequent adsorption of the reactant. This problem can be circumvented by employing dilute (≤ 10-4 M) solutions of Mo(VI) in 1 to 2 M trifluoromethanesulfonic acid. Under these conditions staircase voltammograms and pulse polarograms exhibit single, reversible waves that are consistent with the one-electron reduction of an unadsorbed, monomeric Mo(VI) species. The pH dependence of the reduction potentials suggests that two protons are consumed in the reduction of each Mo(VI). The monomeric Mo(V) reduction product undergoes spontaneous dimerization with a rate constant estimated as 103 M-1 s-1. It also reduces perchlorate and nitrate anions at a significant rate. The Mo2(V)/Mo2(III) redox couple in acidic solution involves an overall four electron-six proton transfer connecting the two participants. This redox process is characterized by extreme electrochemical irreversibility. Reduction of the Mo2(V) aquo ion to the Mo2(III) aquo ion proceeds with αna equal to 0.73 and a proton reaction order of 1.4. A chemical step with an inverse dependence on proton concentration precedes the reoxidation of aquo Mo2(III) to aquo Mo2(V). Plausible mechanisms are given for these observations. The trinuclear ions containing Mo(IV), Mo3O4(H2O)4+9(Mo3(IV)) and an oxalato derivative, Mo3O4(C2O4)3(H2O) 2-3, can be reversibly reduced in acidic media to trinuclear Mo(III) species. The reductions involve two sequential electron transfer steps with formal potentials that are pH dependent: [chemical equations; see abstract in scanned thesis for details]. Two waves are evident in voltammograms and polarograms of Mo3O4(C2O4)3(H2O)2-3 but with Mo3(IV) the two formal potentials are too close together to observe separate waves. However, logarithmic analysis of the shapes of normal pulse polarograms allowed the two formal potentials to be evaluated. The reductions of both complexes are believed to be accompanied by protonation of the bridging and capping oxo-ligands. The new, trinuclear Mo3(III) species resulting from the three-electron reduction of Mo3(IV) exhibits a characteristic EPR spectrum. The mixed-valent intermediate, Mo3(III, III, IV), is diamagnetic. Possible structural changes that accompany the addition of electrons and protons to Mo3IV) are discussed.</p

Advanced Modeling and Experimental Validation of Complex Nuclear Material Forms of Potential Transportation Concern

We present here computer modeling efforts to describe the time-dependent pressurization and gas-phase mole fractions inside sealed canisters containing actinide materials packaged with small (0.12 - 0.5 wt. %) amounts of water. The model is run using Chemkin software, and the chemical reaction mechanism includes gas generation due to radiolysis of adsorbed water, interfacial chemical reactions, and adsorption/desorption kinetics of water on PuO2 materials. The ultimate goal is to provide a verifiable computer model that can be used to predict problematic gas generation in storage forms and assure design criteria for short-term storage and transportation of less than well-characterized (with respect to gas generation) material classes. Our initial efforts are intended to assess pressurization and gas-phase mole fractions using well-defined 3013 container test cases. We have modeled gas generation on PuO2 with water loading up to 0.5 wt. %, at 300 and 525 K, for time frames of 3 years. Estimates of the initial H2 generation rates were determined using RadCalc and employed in the Chemkin model to assess time- and coverage-dependent system behavior. Results indicate that canister pressurization due to radiolysis is a relatively slow process, with pressure increases at 300 K of approximately 1.5 atm. for 5000 g of PuO2 packaged with 0.5 wt. % water. At higher temperatures (&gt; 400 K), desorption of water into the gas phase largely dictates pressurization and the gas-phase mole fractions. These modeling efforts provide a predictive capability for potential gas generation behavior that when augmented and validated by surveillance information will provide a technical basis for safe storage and transportation

Results from Testing Low-Cost, High-Performance Terrestrial Processors for Use in Low-Cost High-Performance Space Missions

There has been a significant and exciting increase in the use of microsatellites and cubesats in the past decade. However, it has proved difficult to scale up current cubesat avionics systems to enable larger, longer, more complex missions, and challenging to scale down traditional microsatellites to an affordable price point. The need exists for a system that provides the capability of a microsatellite at a cubesat cost; KISPE Space (“KISPE”) is developing the Next Generation Microsatellite Platform (“NGMP”) to address this need and is releasing the design as an open source resource via the Open Source Satellite Programme (“OSSAT”) A key enabler of developing a robust Next Generation Microsatellite Platform is the identification of a suitable low-cost microprocessor that can be used to form the foundation of an affordable, robust, flexible, performant and autonomous satellite platform avionics system. Space-qualified, long-lifetime, radiation-tolerant (or hardened) processors do exist, however, these technologies are very expensive and tend to deliver poor mission performance compared to the latest terrestrial Commercial-Off-The-Shelf (COTS) components and are not compatible with the limited resources available from cubesats and smallsats. We performed a test campaign to identify one or more commercially available microprocessors that leverage the latest innovations in microprocessor technology and which meet a set of system criteria that make them suitable for use as a microsatellite platform processor for a wide range of missions; from single modest spacecraft, through to proliferated architectures requiring autonomous operations. We are sharing these test results freely with the space community to advance small satellite capabilities and to stimulate the development of the next wave of cost-effective missions, applications and services. Three COTS processors (SAMV71, STM32H7 and SAMA5D3) were downselected for Total Ionising Dose (electron) radiation testing to characterize their performance in a representative space radiation environment, in partnership with the University of Surrey and with the input of OSSA T collaborators. All three processors were deemed to be candidates for further evaluation and derisking: The devices began to fail at 60kRads, 47kRads and in excess of 120kRads respectively

Fermi surfaces of single layer dielectrics on transition metals

Single sheets of hexagonal boron nitride on transition metals provide a model system for single layer dielectrics. The progress in the understanding of h-BN layers on transition metals of the last 10 years are shortly reviewed. Particular emphasis lies on the boron nitride nanomesh on Rh(111), which is a corrugated single sheet of h-BN, where the corrugation imposes strong lateral electric fields. Fermi surface maps of h-BN/Rh(111) and Rh(111) are compared. A h-BN layer on Rh(111) introduces no new bands at the Fermi energy, which is expected for an insulator. The lateral electric fields of h-BN nanomesh violate the conservation law for parallel momentum in photoemission and smear out the momentum distribution curves on the Fermi surface.Comment: 14 pages, 6 figures, 1 table, 1 equation, Accepted for publication in the Special Surface Science issue in honor of Gerhard Ertl's Nobel Priz

Enumeration of microbial populations in radioactive environments by epifluorescence microscopy

Epifluorescence microscopy was utilized to enumerate halophilic bacterial populations in two studies involving inoculated, actual waste/brine mixtures and pure brine solutions. The studies include an initial set of experiments designed to elucidate potential transformations of actinide-containing wastes under salt-repository conditions, including microbially mediated changes. The first study included periodic enumeration of bacterial populations of a mixed inoculum initially added to a collection of test containers. The contents of the test containers are the different types of actual radioactive waste that could potentially be stored in nuclear waste repositories in a salt environment. The transuranic waste was generated from materials used in actinide laboratory research. The results show that cell numbers decreased with time. Sorption of the bacteria to solid surfaces in the test system is discussed as a possible mechanism for the decrease in cell numbers. The second study was designed to determine radiological and/or chemical effects of {sup 239}Pu, {sup 243}Am, {sup 237}Np, {sup 232}Th and {sup 238}U on the growth of pure and mixed anaerobic, denitrifying bacterial cultures in brine media. Pu, Am, and Np isotopes at concentrations of {le}1x10{sup -6} M , {le}5x10{sup -6} M and {le}5x10{sup -4}M respectively, and Th and U isotopes {le}4x10{sup -3}M were tested in these media. The results indicate that high concentrations of certain actinides affected both the bacterial growth rate and morphology. However, relatively minor effects from Am were observed at all tested concentrations with the pure culture

Heart field origin of great vessel precursors relies on nkx2.5-mediated vasculogenesis

The pharyngeal arch arteries (PAAs) are transient embryonic blood vessels that make indispensable contributions to the carotid arteries and great vessels of the heart, including the aorta and pulmonary artery1, 2. During embryogenesis, the PAAs appear in a craniocaudal sequence to connect pre-existing segments of the primitive circulation after de novo vasculogenic assembly from angioblast precursors3, 4. Despite the unique spatiotemporal characteristics of PAA development, the embryonic origins of PAA angioblasts and the genetic factors regulating their emergence remain unknown. Here, we identify the embryonic source of PAA endothelium as nkx2.5+ progenitors in lateral plate mesoderm long considered to adopt cell fates within the heart exclusively5, 6. Further, we report that PAA endothelial differentiation relies on Nkx2.5, a canonical cardiac transcription factor not previously implicated in blood vessel formation. Together, these studies reveal the heart field origin of PAA endothelium and attribute a novel vasculogenic function to the cardiac transcription factor nkx2.5 during great vessel precursor development