CP violation in modified bipair neutrino mixing and leptogenesis

We study effects of CP violation in a modified bipair neutrino mixing scheme predicting $\sin^2\theta_{23}$ near both 0.4 and 0.6 currently consistent with experimentally allowed values. The source of CP violation is supplied by charged lepton mixing accompanied by a single phase, whose mixing size is assumed to be less than that of the Wolfenstein parameter for the quark mixing. Including results of leptogenesis, which is based on the minimal seesaw model, we obtain the allowed region of CP-violating Dirac and Majorana phases, which provides the observed baryon asymmetry of the universe in the case of the Dirac neutrino mass matrix subject to one zero texture.Comment: 5 pages, 30 figures, accepted for publication in Physics Letters

Multiple Water Propulsion Systems: All Propulsive Capabilities for CubeSats From LEO to Deep Space

The proposal is a multiple water propulsion system which combines a water resistojet and water ion thruster

Pre-Flight Testing Results of Multiple Water Propulsion Systems - Resistojet and Ion Thruster for SmallSats

This paper described re-flight flight testing results of the miniature water propulsion system combined an ion thruster and resistojet thrusters which is to be demonstrated on-orbit by JAXA’s program named Innovative Satellite Technology Demonstration-3. The unified propulsion system has a huge potential to expand micro/nano-spacecraft utilization and decrease the risk of debris

Modified cellular automaton simulation of metal additive manufacturing

Metal additive manufacturing (AM) technologies are attracting attentions not only as a fabrication process of complicated threedimensional parts but also as microstructure controlling processes. In powder bed fusion (PBF)-type AM, crystallographic texture can be controlled by scanning strategies of energy beam. To optimize microstructures, computer simulations for predicting microstructures play very important roles. In this work, we have developed simulation programs to explain the mechanism of the crystal orientation control. First, we simulated the shape of melt pool by analyzing the heat transfer using apparent heat conductivity when the penetration of laser beam through keyholes was taken into consideration because of the evaporation and accompanying convections. It was assumed that the primary crystal growth direction can be determined by the temperature gradient, and the crystals grow keeping the growth direction as generally recognized. The shapes of simulated melt pools agree well with experimental observations. The modified cellular automaton simulations successfully reproduced two typical textures with different preferential orientations along the building directions of (100) and (110) when the bidirectional scanning with and without a rotation of 90°, respectively, was accomplished between the layers.Kubo J., Koizumi Y., Ishimoto T., et al. Modified cellular automaton simulation of metal additive manufacturing. Materials Transactions 62, 864 (2021); https://doi.org/10.2320/matertrans.MT-M2021009

Development of the Water Resistojet Propulsion System for Deep Space Exploration by the CubeSat: EQUULEUS

In this study, Water micro-propulsion system AQUARIUS (AQUA ResIstojet propUlsion System) is proposed for 6U CubeSat: EQUULEUS to explore the deep space. AQUARIUS uses storable, safe and non-toxic propellant: water, which allows for downsizing of whole propulsion system to 2U and storing 1.2 kg water. Liquid propellant storage allows design of all propulsion systems below 100 kPa. The waste heat of communication components is reused to cover high latent heat of water. AQUARIUS has 4.0 mN and specific impulse of 70 s by less than 20 W power consumption. Breadboard model was designed and tested successfully. Engineering model is under developments and operations by using whole systems of EQUULEUS. AQUARIUS will be equipped with EQUULEUS scheduled to be launched in 2019 by SLS (Space Launch System)

Yamato 980459: Mineralogy and petrology of a new shergottite-related rock from Antarctica

Y980459, a new Martian meteorite from Antarctica, is composed of coarse porphyritic olivine grains (up to 2mm) set in the groundmass of olivine and pyroxene with abundant glassy mesostasis containing dendritic olivine and pyroxene. The overall petrography of Y980459 is similar to those of olivine-phyric shergottites, but the absence of plagioclase and Ca phosphates makes Y980459 unique. Because of the absence of maskelynite, Y980459 is not a shergottite if we employ the classic definition of shergottite. Both olivine and pyroxenes are extensively zoned. The most magnesian olivine composition is Fo86 and the olivine compositions are related to three different occurrence types of olivine (large phenocrysts, groundmass, and mesostasis). Pyroxenes have orthopyroxene cores (En81Fs17Wo2) mantled by pigeonite with the rims of augite. The mineralogy of Y980459 suggests that rapid crystallization of the parent magma caused significant undercooling and plagioclase did not nucleate. Probably, rapid transport of the Y980459 parent magma from the depth to the Martian surface crystallized olivine and pyroxene at first and eruption onto the surface quenched the magma producing the glassy mesostasis. Because olivine and pyroxene compositions of Y980459 are the most magnesian among Martian meteorites, Y980459 would represent one of the most primitive Martian magmas and derive from a highly reduced mantle. It seems that Y980459 contains no cumulus component, suggesting that Y980459 is a melt. In this sense, Y980459 is similar to QUE94201. The similarity in mineralogy and chemistry between Y980459 and olivine-phyric shergottites suggests derivation from a similar highly reduced mantle. However, Y980459 was the only sample that directly erupted onto the Martian surface without any accumulation processes

On-Orbit Demonstration of the Water Resistojet Propulsion System on Commercial 6U-Sat SPHERE-1 EYE

SPHERE-1 EYE, a 6U CubeSat developed by Sony Group Corporation, was launched at the beginning of 2023. The satellite included a water resistojet propulsion system, which is designed for orbit raising after the initial checkout. The water resistojet propulsion system consists of a tank, a vaporizer, nozzles, a control board, and a power processing unit. The form factor of the propulsion system is 1.25 U, the wet mass is 1.4 kg, and the achievable total impulse of the system is 170 Ns or higher. A unique design of the water propulsion system is a vaporization chamber generating steam at room temperature and low pressure, under 10 kPa. The performance measured on the ground shows a thrust of 2.7 mN, and a specific impulse of 60 s. A qualification test campaign including vibration, shock, thermal, throughput, and system performance tests was conducted, followed by acceptance tests. On-orbit demonstration was conducted on March 3rd and 16th for all four nozzles and the thrust generation was confirmed. The estimated thrust on orbit was 6.1 - 7.2 mN. Comparison between the on-orbit results and the ground tests demonstrated the functionality of the system as anticipated