This Paper uses Reinforcement Meta-Learning to optimize an adaptive integrated guidance, navigation, and control system suitable for exoatmospheric interception of a maneuvering target. The system maps observations consisting of strapdown seeker angles and rate gyroscope measurements directly to thruster on/off commands. Using a high fidelity six-degree-of-freedom simulator, this Paper demonstrates

Landing on celestial bodies typically includes a free fall to the body surface and requires energy dissipation. Landing sites can exhibit many uncertainties, especially in surface parameters. Therefore, robustness is required irrespective of variations in landing conditions. Conventional mechanisms, such as shock absorbers or airbags, have repeatedly achieved safe landings; however, they are not reusable

Gauging propellant fuel of spacecraft in outer space has been an issue, because their liquid fuels tend to float, slosh, adhere to the tank walls, and form bubbles under low-gravity conditions. For this reason, conventional fuel gauging techniques may not be an accurate way of gauging the fuel in space. In this paper, we report a flexible monolithic printed assembly of electrocapacitive volume tomography

This paper proposes a metallic spring root hinge to effectively stow and deploy a collapsible and rollable tubular carbon fiber reinforced polymer (CFRP) boom. The proposed hinge consists of two half-cylindrical parts with narrowed regions and a hole. One of the ends of the hinge is fixed to a hub with the circular cross section, and the other end that is connected to the boom is flattened with the

Journal of Spacecraft and Rockets, Ahead of Print.

Image-based terrain relative navigation is expected to play an important role in the safe operation of upcoming lunar exploration missions. This work provides a detailed treatment of how visual odometry direction-of-motion measurements may be constructed using images from a monocular camera and without the need of an onboard map of the lunar surface. Substantial care is required to achieve best-possible

Chip scale atomic clocks (CSACs) have the potential to provide CubeSat missions with precision timekeeping capabilities to support onboard radiometric tracking, reducing dependence on ground support. This work considers a baseline orbit determination (OD) scenario for a low-Earth-orbit CubeSat, with one-way radiometric measurements made onboard using a CSAC as the timing reference. Methods for simulating

With upcoming heavy and superheavy lift rockets targeted for launch in 2021, a new class of payloads can be launched into low Earth orbit. This paper presents a design for a space station capable of being lifted by a single Blue Origin New Glenn vehicle. Once assembled on orbit, it contains more than twice the pressurized volume of the International Space Station (ISS). The pressurized volume of traditional

Future space missions, such as return from Mars, will require entry speeds of the order of 15 km/s. These harsh conditions are dominated by radiative heat flux and have large modeling uncertainties related to radiative coupling, such as precursor radiation and ablation radiation coupling. These conditions have also never been tested in a flight scenario and have limited ground testing data available

Materials used in the fabrication of landers for Venus exploration need to be carefully selected to assure functional durability throughout anticipated prolonged future mission durations in the harsh conditions that include 460°C and 9.2 MPa pressure with supercritical CO2 and trace corrosive gases. Previous work has shown the adverse effects that trace quantities of the atmospheric sulfide and halogen

This study investigates the effects of single, double, and multi-protrusion on the performance of a hybrid rocket with two different L/D ratio motors, mainly 12.5 and 18. Wax and gaseous oxygen were used as fuel and oxidizer, respectively. It has been observed from studies that the performance of a hybrid rocket is sensitive to the number of protrusions and their locations within the motor. Between

In the discharge ground tests of satellites, an electron beam is mainly used to simulate the electron environment on geostationary orbit; however, the insulator is charged on the orbit by photoelectrons by vacuum ultraviolet rays during sunshine. Discharge occurs when the insulator surface exceeds the discharge threshold voltage. Whether the discharge threshold differs between the electron beam and

It is well known that the Orion capsule was born as a rescue shuttle for the International Space Station. NASA developed the Orion project for the transportation of instruments and astronauts to moon, Mars, and beyond. Orion is similar in shape but larger than the Apollo command module; Orion will be able to host up to six astronauts, but Apollo command module could host only three astronauts. The

During draining of liquid propellants from propellant tanks of spacecraft rocket engines, air core vortex can be formed and this can result in blockage of drain port. Supply of required amount of fuel (propellant) to the engine may get adversely affected due to this, which can lead to poor engine performance. Hence, vortex suppression is a practical necessity in this space application and this forms

The present study investigates the feasibility of deploying multiple CubeSats from low Earth orbit to near-Earth asteroids for an increased scientific return and reduced mission costs. It is found that for an escape time of 300 days, solar cell and battery degradation are 11 and 28%, respectively. The escape orbital plane inclination of 51.6 deg reduces the overall radiation dosage and requires 2.51 kg

This paper compares the cooling effect on the launch pad with two different levels of water cooling system used in the Long March 7. The rocket plume model is set up based on the three-dimensional Navier–Stokes equations solved by the realizable k-ε turbulence model. The Eulerian dispersed phase (EDP) model is employed to describe the injected cooling water. Comparing with test data, the validity of

Wind-tunnel experiments were performed to quantify boundary-layer instabilities both on and off the surface of a 33% scale model of the U.S. Air Force Research Laboratory/U.S. Air Force Office of Scientific Research Boundary Layer Transition (BOLT) flight geometry. Measurements were obtained in the Mach 6 Quiet Tunnel and Actively Controlled Expansion (ACE) tunnel located at the Texas A&M University

A three-axis attitude estimation scheme is presented using a set of albedo interfered coarse sun sensors (CSSs) of Earth, which are inexpensive, small in size, and light in power consumption. For modeling the interference, a two-stage albedo estimation algorithm based on autoregressive model is proposed. The algorithm does not require any data, such as albedo coefficients, spacecraft position, sky

The growing interest in small satellites (smallsats) is primarily a function of their affordability and versatility across a wide range of space mission applications. For these reasons, smallsats have found valuable applications in government, industry, and academic settings. The continued advancement of smallsats depends on the ability of the aerospace industry to supply affordable, reliable, and

Planetary orbit insertion maneuver is one of the most critical events in deep space exploration missions. Once the spacecraft fails to decelerate enough to stay in the planetary orbit, it escapes from the vicinity of the planet. In some cases, such as the Akatsuki mission of Japan Aerospace Exploration Agency (JAXA), a feasible recovery trajectory was found after an engine malfunction; however, in

The Advanced Supersonic Parachute Inflation Research Experiment (ASPIRE) was a series of sounding rocket flights aimed at understanding the dynamics of supersonic parachutes that are used for Mars robotic applications. Although the 2012 Mars Science Laboratory (MSL) had a successful deployment of a supersonic parachute, postflight analysis and the results of the Low-Density Supersonic Decelerator project

This paper presents a geometric approach for a sun (or any bright object) avoidance slew maneuver with pointing and actuator constraints. It is assumed that a gyrostat has a single light-sensitive payload with control-torque and reaction wheels’ angular momentum constraints. Furthermore, it is assumed that the initial and final attitudes, an instrument’s line-of-sight vector, and sun vector are known

NASA’s Mars Design Reference Architecture 5.0 presents architecture options for a crewed Mars mission. This paper compares the cryogenic chemical-propulsion option in that study with an alternative: water-electrolysis propulsion. Propellant is stored as liquid water instead of cryogenic hydrogen and oxygen, and then electrolyzed on demand into gaseous hydrogen and oxygen for combustion. This addresses

Recent development of deep learning has shown that a deep neural network (DNN) is capable of learning the underlying nonlinear relationship between the state and the optimal actions for nonlinear optimal control problems. In terms of hypersonic flight, this suggests that the DNN-based trajectory controller may be considered to take over all or part of the onboard trajectory generation and guidance

In a swing-by maneuver, the variation of energy of the spacecraft is controlled by the angle, velocity, and distance of approach. These parameters are defined by the incoming trajectory, when the spacecraft is far from the planetary atmosphere. The passage of the spacecraft by the atmosphere generates aerodynamic forces, affecting its trajectory and giving new forms of control, which are functions

The objective of this work was to investigate a multifidelity modeling approach to accurately and efficiently predict the aerothermal response of a large-diameter deployable hypersonic entry vehicle in Mars entry. A cokriging-based multifidelity modeling approach was developed that used several refinements including lower–upper decomposition for parallelization, distance weighted root-mean-square error

The use of regional-coverage satellite constellations is on the rise, urging the need for an optimal constellation design method for complex regional coverage. Traditional constellations are often designed for continuous global coverage, and the few existing regional constellation design methods lead to suboptimal solutions for periodically time-varying or spatially varying regional-coverage requirements

Entry trajectory optimization for hypersonic vehicles has been formulated as constrained optimal control problems, which are difficult to solve because of the existing high nonlinearity and nonconvexity. In recent years, convex optimization has shown promise for real-time onboard applications with the state-of-the-art interior-point methods. In this paper, line-search and trust-region techniques are

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