Backward-facing step (BFS) configurations are relevant to many aerospace applications. An understanding of the underlying dynamics of such flows can aid in developing suitable control strategies. To this end, an unsteady analysis of a Mach 2 BFS flow is conducted. Large-eddy simulations (LESs), informed by linear perturbation analysis, are employed to characterize the range of frequencies encountered

Journal of Spacecraft and Rockets, Ahead of Print.

Rotating detonation rocket engine (RDRE) experiments have so far been limited to injectors with high pressure drop to limit injector–plenum coupling. However, this corresponds to a reduction in the potential performance benefits of RDREs. To investigate this phenomenon, two injection configurations with different total injection areas are compared with respect to overall engine operability, global

Numerous researches have been conducted on boron-based fuels and propellants due to the attractive theoretical energy potential of boron. However, sustained energy production during combustion of a boron-based fuel/propellant is still uncertain because efficient burning of boron is challenging. The present paper deals with various boron-loaded polymeric fuels, where activated charcoal (AC) is introduced

The U.S. Air Force Research Laboratory/U.S. Air Force Office of Scientific Research has sponsored the Boundary Layer Transition (BOLT) experiment to investigate hypersonic boundary-layer transition on a low-curvature, concave surface with swept leading edges. This paper provides a review of aerothermodynamic ground-test contributions by NASA Langley Research Center to the design of the BOLT flight

Journal of Spacecraft and Rockets, Ahead of Print.

Random vibration tests and acoustic tests are typical environmental testing approaches for verifying the dynamic environmental adaptability of a satellite, which should be selectively carried out on the ground before launch. Existing test criteria suggest that large spacecraft should be excited in a reverberation chamber, whereas a shaker should be used for a small spacecraft. With the development

The surfaces of the flight vehicles passing the low Earth orbit at high speeds of 7–8 km/s are placed in high temperature conditions, and the thermal protection system (TPS) is used to withstand that high temperature. Silicon carbide (SiC) is frequently used in TPSs because of its various material properties suitable for use in high temperature environments. It is important to predict the damage caused

Boundary-layer stability and laminar-to-turbulent transition are examined on the BOundary Layer Transition flight-test vehicle using predicted flow conditions at ascent and descent flight times. The parabolized stability equations technique is used predominantly for this analysis because it has proven to be efficient and accurate in modeling the transition process on other three-dimensional geometries

Responsive and resilient space-based systems are needed to satisfy changing mission requirements and react to unforeseen challenges. Nontraditional constellations, such as heterogeneous and rideshare constellations, have the potential to increase resiliency and responsiveness, as can using commercial off-the-shelf parts. However, these constellation types introduce design challenges that cannot be

Previous studies have demonstrated that the use of counterflowing supersonic jets operating in the long penetration mode (LPM), directed from the nose of blunt bodies against a supersonic/hypersonic freestream, can greatly reduce the drag and heat loads on the vehicle. However, the benefits of LPM for slender bodies of revolution operating at low supersonic speeds, applicable to supersonic transport

Flight vehicles that fly at high Mach speeds will be exposed to a severe aerodynamic heating problem, which leads to high surface temperatures and large temperature gradients. Thermal load will induce thermal stress, thermal deformation, and even thermal buckling. Therefore, the dynamic stiffness and the modal characteristics will be affected. In this paper, several tests are carried out for a plain

Burning tests of a laboratory-scale hybrid rocket engine were carried out with gaseous oxygen and a microcrystalline-wax-based fuel to look into the feasibility of using an intrusive resistor-based sensor for measuring the fuel regression rate. This initial screening was driven by the need for real-time control of the oxidizer-to-fuel ratio in altering-intensity swirling-flow-type hybrid rocket engines

With the global push to commercialize space, humans are launching objects into orbit faster than natural effects are removing them. Orbital debris is especially dangerous because it is capable of exponential growth due to cascading collisions between orbiting objects. To ensure the long-term accessibility to space, high-risk objects must be actively removed to limit growth of the orbital debris population

Using the NASA Design Reference Architecture, an Aerojet Rocketdyne vehicle architecture, and a University of Alabama in Huntsville nuclear thermal propulsion engine model, the performance of a Mars transfer vehicle using hydrogen propellant seeded with argon was analyzed. Seeded hydrogen, up to a maximum seed mass concentration of 55.85%, increased engine and vehicle performance by reducing pressure

To improve scientific knowledge of boundary-layer transition physics on increasingly complex geometries, the Air Force Research Laboratory/Air Force Office of Scientific Research has sponsored the Boundary Layer Transition (BOLT) Experiment to obtain measurements of hypersonic boundary-layer transition in flight on a low-curvature concave surface with highly swept leading edges. This paper will summarize

Journal of Spacecraft and Rockets, Ahead of Print.

The Laser Ranging Interferometer onboard the Gravity Recovery and Climate Experiment Follow-On satellites is the first laser interferometer in space measuring satellite-to-satellite distance variations. One of its main noise sources at low frequencies is the so-called tilt-to-length coupling, caused by satellite pointing variations. This error is estimated by fitting a linear coupling model, making

The Boundary Layer Transition (BOLT) Flight Experiment is to launch soon on a sounding rocket to obtain hypersonic data on a complex geometry with swept leading edges and concave surfaces. BOLT was designed to provide two distinct experimental surfaces on opposite sides of the vehicle. One side of BOLT, referred to as the primary side experiment, was specifically dedicated to boundary-layer transition

Large navigation and atmospheric uncertainties have historically driven the need for a mid-lift-to-drag-ratio (mid-L/D) vehicle with (L/D)max of 0.6–0.8 for aerocapture at Neptune. Most planetary entry vehicles flown to date are low-L/D blunt-body aeroshells with L/D less than 0.4. The lack of a heritage mid-L/D aeroshell presents a major hurdle for Neptune aerocapture, as the development of a new

Application of indirect optimization methods to solve constrained optimal control problems is not a straightforward task. This study presents a new construct, the Uniform Trigonometrization Method (UTM), that enables handling problems with control bounds and state path constraints within the indirect formalism. First, three different classes of problems are discussed with 1) bang–bang and singular

Experiments on a subscale model of the U.S. Air Force Office of Scientific Research Boundary Layer Transition flight experiment were made in the Boeing/Air Force Office of Scientific Research Mach-6 Quiet Tunnel. Infrared thermography and temperature-sensitive paint were used to measure the surface temperature and heat transfer and provide images of streamwise streaks with the model at 0, 2, and 4 deg

The ionic liquid, 1-butyl-3-methylimidazolium acetate ([bmim][Ac]), was used to remove carbon dioxide (CO2) from a simulated spacecraft cabin atmosphere (2 mm Hg (267 Pa)) partial pressure of CO2 with balance of nitrogen (630 mm Hg total pressure). Three gas–liquid contactor configurations were experimentally characterized to measure the rates of CO2 removal from the simulated atmosphere with [bmim][Ac]

Heat-shield design for spacecraft entering the atmosphere of Mars may be affected by the presence of atmospheric dust. Particle impacts with sufficient kinetic energy can cause spallation damage to the heat shield that must be estimated. The dust environment in terms of particle size distribution and number density can be inferred from ground-based or atmospheric observations at Mars. Using a Lagrangian

The ability to model atmospheric drag is critical for precise satellite orbit prediction below 1000 km altitudes. Uncertainty in atmospheric drag comes primarily from estimates of the atmospheric mass density and the spacecraft drag coefficient. Mismodeling the drag coefficient introduces errors in densities derived from atmospheric drag that are then used to predict drag forces and satellite orbits

Peak heating points for the entry into Uranus, Neptune, and Saturn exhibit highly nonequilibrium shock layers, and are not well understood. This paper describes an experimental study in the X2 expansion tube at the University of Queensland, using a condition with a higher concentration of helium than exists on Saturn, with a shock speed of 18 km/s, to simulate radiation during blunt body Saturn entry

Drag modulation provides a straightforward approach to aerocapture trajectory control. In this paper, two guidance algorithms are assessed for Venus aerocapture: a predictive-trigger and a numerical predictor–corrector. A hybrid root finder is developed for both single- and multistage jettison. Architecture performance is assessed using Monte Carlo methods. Two apoapsis altitude targets, 2000 and 10

Although several investigations have been performed regarding the fundamental physics of axial-injection, end-burning hybrid rocket motors, investigations into the mission performance of a propulsion system based on this hybrid rocket motor configuration are limited. This Paper provides analysis of the performance characteristics of axial-injection, end-burning hybrid rocket motors based on the results

The purpose of this paper is to present results of an uncertainty and sensitivity analysis study of commonly used turbulence models in Reynolds-averaged Navier–Stokes codes due to the epistemic uncertainty in closure coefficients for shock-wave/turbulent boundary-layer interaction simulations. The study focuses on the analysis of an axisymmetric shock-wave/boundary-layer interaction (ASWBLI) turbulence

In this study, a numerical analysis of pogo instability in liquid propulsion rockets was conducted and an optimization of the pogo suppressor was attempted. Pogo analysis was carried out using numerical results obtained via the major models for fuselage structure, feedline, and propulsion systems. In the structural system, the fuselage vibration modes were obtained and the relevant meta-model was constructed

A neutral beam propulsion technology demonstrator has been fabricated and tested. It uses gas diffusion neutralization to create a globally neutral plasma from an ion source. Thrust measurements for the neutral beam demonstrate that thrust at the very low 100 μN levels produced by this system can be measured during thermal drift of the variable amplitude hanging pendulum with extended range thrust

This research focuses on the design and reconstruction of the first touchdown of Hayabusa2 on the asteroid Ryugu. Because of the plethora of boulders, the landing operation required high accuracy to ensure spacecraft safety. This paper therefore investigates a pinpoint touchdown sequence using a retroreflective marker as an artificial landmark. First, the dynamical environment in the vicinity of Ryugu

Robotic on-orbit servicing (OOS) is expected to be a key technology and concept for future sustainable space exploration. This paper develops a novel semi-analytical model for OOS system analysis, responding to the growing needs and ongoing trend of robotic OOS. An OOS infrastructure system is considered whose goal is to provide responsive services to the random failures of a set of customer modular

Small, expendable drop probes are an attractive method for making measurements in the lower atmosphere of Venus, augmenting the capabilities of orbiters or aerial platforms that must remain in the benign temperature region above 50 km altitude. However, probe miniaturization is impeded by the need to provide thermal and pressure protection for conventional payloads. This paper determines the minimum

In 2010, the U.S. National Research Council proposed planetary entry probe missions to Uranus and Saturn. This paper details an investigation exploring the operating limits of the X2 superorbital expansion tube at the University of Queensland for the simulation of atmospheric entry test conditions related to these missions. Theoretical calculations indicate that X2 can recreate the stagnation enthalpy

The heliogyro solar sail maneuvers by actuating high-aspect-ratio blades at their root with sinusoidal pitch profiles, producing spin-averaged forces and moments. The lightweight blade material has little inherent damping, requiring active control to attenuate blade vibration caused by maneuvering. Paradoxically, some amount of inherent damping at the blade’s higher-frequency modes is needed to add

A four-engine liquid launch vehicle is studied to analyze the influence of afterburning reactions on the plume flowfield of a rocket exhausted jet. To accurately simulate the afterburning flow of the rocket exhaust plume with multispecies and chemical reaction, the three-dimensional compressible Navier–Stokes equations and realizable k-ε turbulence model are used to establish the rocket supersonic

Understanding, predicting, and controlling fluid slosh dynamics is critical to safety and improving the performance of liquid propulsion systems for space missions. Computational fluid dynamics simulations can be used to predict the dynamics of slosh. Experimental and numerical studies of water slosh have been conducted; however, cryogenic slosh data relevant for validating computational fluid dynamics

This paper presents a trajectory-based heating and ablation study of the Galileo probe forebody flow and thermal protection system performance. The validity of modeling assumptions regarding diffusion, radiative heating, and ablation made in previous work, including preflight predictions, are addressed. The Navier–Stokes equations are solved assuming a one-temperature chemical nonequilibrium flowfield

According to the new characteristics of the solid–liquid strap-on launch vehicle and the liquid oxygen/kerosene staged combustion cycle engines, a finite element model of the launch vehicle propulsion–structure coupled system subjected to pogo was presented in this paper. In the model, the structure was represented by a longitudinal–lateral–torsional integrated finite element model with a three-dimensional

In this paper, a structural health condition monitoring method for the cryotanks based on impedance and Lamb waves is presented. The method consists of four stages: environmental awareness, damage prewarning, sensor network self-diagnosis, and structural damage detection. In the environmental awareness stage, the change of environmental temperature is monitored by the changing trend of the sensor impedance

Journal of Spacecraft and Rockets, Volume 57, Issue 4, Page 851-856, July 2020.

This paper describes three-dimensional (3D) stereo reconstruction efforts for the full-scale supersonic parachute deployment tests performed under the NASA Advanced Supersonic Parachute Inflation Research Experiment (ASPIRE) program. Specific time-resolved data products that have been generated for the ASPIRE tests and are presented in this work include parachute projected area, parachute vent-hole

A deep-space galactic cosmic ray (GCR) shield in the form of a field-reversed array of superconducting coils is investigated. Exploiting the physics of plasma confinement, the shield forms a shell of magnetic energy which protects the interior from GCR flux. It is constructed from two concentric spherical assemblies of superconducting coils, each arranged in the same manner as lines of latitude on

One of the primary mission objectives for the Mars 2020 rover is to drill rock core samples and store them in tubes that could be retrieved and returned to Earth on subsequent missions. A major challenge to the success of this mission is achieving hermetic-level seals on the tubes that contain the rock samples in order to preserve relevant science data. Traditionally, hermetic seals are created using

The thermal protection performances of polymethylmethacrylate-impregnated porous carbon ablators with three different densities were examined in an arc wind-tunnel test. The more impregnated ablator exhibited significantly higher exhaust gas pyrolysis and heat absorption, which improved the recession resistance, the gas-blocking effect for convection heating, and the thermal insulation of the ablator

High-fidelity numerical results have been obtained for low-disturbance wind-tunnel tests of transitional flow including isolated, discrete roughness elements on a 7 deg half-angle cone. Solutions for a range of roughness heights, two angles of attack, and several levels of introduced disturbances were calculated using a wall-resolved high-order, high-fidelity simulation methodology. It was found that

Low-thrust spacecraft trajectory optimization for the many-revolution orbital transfer problem is especially challenging due to the high problem dimension and perturbing accelerations that prevent or complicate accurate analytical solutions. This analysis seeks to simplify the calculation of the nonaveraged spiral trajectory through the use of the well-known Q-Law guidance algorithm. Here, Q-Law is

A mission design study was conducted demonstrating for the first time the feasibility of a combined Pluto orbiter–Kuiper Belt explorer mission using present-day electric propulsion (EP) performance and launch vehicles, assuming that radioisotope thermoelectric generator (RTG)–sourced electricity would power the EP system, a not-yet-demonstrated but low-risk capability. This mission breaks the scientific

Although the historical and technical details of Project Apollo have been extensively documented in literature, current records indicate that there is still a lack of an early-design-phase, physics-based, parametric sizing quantification of the engineering decisions that made Apollo a success. Historical texts that explain the design decisions of Apollo do so in a predominantly qualitative manner,

In preparation for the Center for Space Research Release 6 of Gravity Recovery and Climate Experiment (GRACE) data, 32 accelerometer parameterization schemes are analyzed, which combine skew-symmetric, symmetric, and full-scale matrices with four different bias parameterizations inspired on those used on Release 5. After three selection stages, it has been determined that the daily full-scale matrix

Journal of Spacecraft and Rockets, Ahead of Print.

Journal of Spacecraft and Rockets, Ahead of Print.

Using a NASA Design Reference Architecture, a nuclear thermal propulsion engine model was developed to numerically examine the effects on engine performance by adding heavy noble gases into the hydrogen propellant stream (seeding) before the reactor inlet. Seeded hydrogen, up to a maximum seed mass concentration of 55.85%, increased engine performance by reducing pressure losses, decreasing reactor

This paper proposes an efficient shape correction method for high-precision deformable reflectors. To this end, the specific error modes that affect the antenna performance are selectively corrected by simultaneous optimization of the structure and the actuator locations. First, a method to correct the specific error modes by design optimization is formulated, where a residual surface error vector

In a sun-heading determination scenario, coarse sun sensors (CSSs) can be paired with rate gyroscopes in order to estimate sun-line direction and rotation rate. Relying solely on CSS measurements for sun-heading and spacecraft rotation rate estimations is advantageous in scenarios where reliance on the fewest number of devices is desired. Here, the challenge is to find a robust method for heading determination

Blunt nose cones used in launch vehicles can excite buffet due to shock oscillations over the payload fairing on the leeward side at transonic Mach numbers and small angles of attack. Wind-tunnel tests show that the overall aerodynamic characteristics, such as the pitching moment and location of the center of pressure, experience sudden jumps at these conditions. Thus, the longitudinal stability and

Subcentimeter orbital debris is currently undetectable using ground-based radar and optical methods. However, pits in space shuttle windows produced by paint chips demonstrate that small debris can cause serious damage to spacecraft. Recent analytical, computational, and experimental work has shown that charged objects moving quickly through a plasma will cause the formation of plasma density solitary

Conformal ablators are low-density composite materials comprising a flexible fibrous substrate and polymer matrix. Recent advancements have improved the efficiency of conformal ablator fabrication through vacuum infusion processing, which injects resin into a fiber substrate enclosed in a matched mold under vacuum. A conceptual design methodology was developed combining a Darcy’s law simulation of

The use of multimodal space propulsion has the benefit of increasing satellite mission flexibility with the ultimate goal of decreasing mission development costs. The present paper explores the development of a dual-mode thruster for small spacecraft. By combining an electrospray within the confines of a cold gas nozzle, the fabricated and tested propulsive device can operate either in a high thrust