
 LiteBIRD the Lite (Light) satellite for the study of B-mode polarization and Inflation from cosmic background Radiation Detection, is a space mission for primordial cosmology and fundamental physics. The Japan Aerospace Exploration Agency (JAXA) selected LiteBIRD in May 2019 as a strategic large-class (L-class) mission, with an expected launch in the late 2020s using JAXA’s H3 rocket. LiteBIRD is planned to orbit the Sun-Earth Lagrangian point L2, where it will map the cosmic microwave background (CMB) polarization over the entire sky for three years, with three telescopes in 15 frequency bands between 34 and 448 GHz, to achieve an unprecedented total sensitivity of 2.2 μK-arcmin, with a typical angular resolution of 0.5○ at 100 GHz. The primary scientific objective of LiteBIRD is to search for the signal from cosmic inflation, either making a discovery or ruling out well-motivated inflationary models. The measurements of LiteBIRD will also provide us with insight into the quantum nature of gravity and other new physics beyond the standard models of particle physics and cosmology. We provide an overview of the LiteBIRD project, including scientific objectives, mission and system requirements, operation concept, spacecraft and payload module design, expected scientific outcomes, potential design extensions and synergies with other projects. Subject Index LiteBIRD cosmic inflation, cosmic microwave background, B-mode polarization, primordial gravitational waves, quantum gravity, space telescope

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Probing Cosmic Inflation with the LiteBIRD Cosmic Microwave Background Polarization Survey

In this study, analysis of flow properties around a sphere and its aerodynamic coefficients in the high-Mach-and-low-Reynolds-numbers conditions is carried out by direct numerical simulations solving the three-dimensional compressible Navier–Stokes equations. The calculation is performed on a boundary-fitted coordinate system with a high-order scheme of sufficient accuracy. The analysis is conducted by assuming a rigid sphere with a Reynolds number of between 50 and 300, based on the diameter of the sphere and the freestream velocity and a freestream Mach number of between 0.3 and 2.0, together with the adiabatic wall boundary condition. The calculation shows the following yields: (1) unsteady fluctuation of hydrodynamic forces become smaller as the Mach number increases under the same Reynolds number condition, (2) the drag coefficient increases with the Mach number due to an increase in the pressure drag by the shock wave, and (3) an accurate prediction of the drag coefficient in the supersonic regime using traditional models might be difficult.

Investigation on subsonic to supersonic flow around a sphere at low Reynolds number of between 50 and 300 by direct numerical simulation

Kerosene and methane are two promising candidate propellants for a future reusable booster stage. This study assesses the merits of both propellants and compares their respective performance when used in a booster stage. First of all, the principal properties of both propellants are identified. An analysis of a comparable full-flow staged combustion cycle engine for each propellant follows. The final assessment is made based on the results of a performance analysis of a launch vehicle making use of these motors in reusable fly-back boosters. The use of kerosene as propellant leads to a lower booster dry mass, making it the preferred choice if no operational benefits of methane can be identified.

Kerosene vs. Methane: A Propellant Tradeoff for Reusable Liquid Booster Stages

This paper presents a computational study of the flow and flow-induced acoustic fields of a supersonic jet impinging on an inclined flat plate. For the numerical simulations, we solved three-dimensional compressible Navier-Stokes equations with a modified weighted compact nonlinear scheme. We analyzed the simulation results mainly from the viewpoint of the acoustic emission and propagation mechanism, and we investigated the acoustic field characteristics such as directivity, their spectra, and acoustic wave source positions. The acoustic fields indicate that there are at least three types of acoustic waves in all the cases considered in the study: (i) Mach waves generated from the shear layer of the main jet, (ii) acoustic waves generated from the impingement region, and (iii) Mach waves generated from the shear layer of the supersonic flow downstream of the jet impingement. The indication of the second type of wave (ii) is important because the commonly used empirical method for the estimation of the aco...

Aeroacoustic waves generated from a supersonic jet impinging on an inclined flat plate

Subscale model tests and a numerical investigation are performed to predict and attenuate the acoustic level of the Epsilon launch vehicle at liftoff. Requirements for the subscale model test to predict a full-scale acoustic environment are investigated, and then the scale size of the model test is set at 1/42. The launch pads employed herein are designed to attenuate reflection of the Mach wave radiated from the free jet and the acoustic wave due to the jet’s impinging on the flame deflector. When comparing the acoustic result taken at the fairing location with that at three different altitudes, 9De, 14De, and 22De, where De represents the nozzle exit diameter, the acoustic level observed at 14De is the highest and exceeds the design requirement at all frequencies. It is revealed from the numerical analysis that the reflection of Mach waves radiating from the free jet within the flame path is the dominant acoustic source. A front cover is attached to the vertical flame path to shield the Mach wave radiat...

Study on Acoustic Prediction and Reduction of Epsilon Launch Vehicle at Liftoff

Numerical simulation was carried out to investigate the generation mechanism of pressure waves radiated from the H-IIA launch vehicle at lift-off. It was revealed that the Mach wave due to the large-scale structure of the unsteady supersonic exhaust plumes is the dominant noise source. The Mach wave propagating obliquely downstream is reflected from the constructions of the launch-pad, and then, turns to reach the vehicles, resulting in the acoustic loading. It was also found that the fluctuating supersonic plume entering into the flame duct is the dominant noise source that appears in the flame duct. Then, the pressure wave propagates through the flame duct and is ejected outside to the vehicle.

Generation and propagation of pressure waves from H-IIA launch vehicle at lift-off

During the powered ascent of a multi-nozzle launcher, its afterbody is subjected to severe heat flux. In this paper, numerical analysis is performed to directly simulate the plume/plume interaction and its reversed flow that cause the severe heating rate on the afterbody. The external airflow conditions are parametrically changed in supersonic flight regime to investigate the influence of chamber to ambient pressure ratio on the plume/plume interaction and the heating rate on the vehicle afterbody. Al2O3 particles in the solid rocket exhaust plumes and radiation heating from the plumes are modeled in the computation. The comparison of the total heating rate on the afterbody with the measured data is also discussed.

Numerical Analysis of Plume Heating Environment for H-IIA Launch Vehicle during Powered Ascent

Current study status of the advanced technologies for the J-I upgrade launch vehicle - LOX/LNG engine

H-IIB launch vehicle is the latest most powerful Japanese rocket which is developed by JAXA and MHI. Development of H-IIB is based on the heritage of H-IIA in order to minimize risks and save resources. There are only two major items to be newly developed, which are the 5.2m-diameter propellant tanks and the main engine cluster technology. The overview of the clustered propulsion system of H-IIB and its development plan are described in this paper.

Development Status of H-IIB Launch Vehicle Propulsion system

Attenuation of sound by water droplets in air is analytically investigated. This is one of the mechanisms of the noise reduction in actual rocket launch where water is injected to jet plume. The scattering and absorption by the droplets are considered as the attenuation mechanisms. It is found that the absorption is superior to the scattering for fine droplets, such as fog or mist. Then we estimate the attenuation of sound for the experiment using subscale solid rocket motors. The result agrees well with the experimental data within the frequency range where the assumptions of this study are valid.

Makoto Arita

Papers

Generation and propagation of pressure waves from H-IIA launch vehicle at lift-off

Numerical Analysis of Plume Heating Environment for H-IIA Launch Vehicle during Powered Ascent

Current study status of the advanced technologies for the J-I upgrade launch vehicle - LOX/LNG engine

Development Status of H-IIB Launch Vehicle Propulsion system

Study on Attenuation of Sound by Droplets