Journal of Spacecraft and Rockets, Ahead of Print.

The co-delivery of a direct-entry probe and an aerocapture orbiter from a single atmospheric entry state is a novel way to include ride-along probes or orbiters on interplanetary missions. This is made possible through combining two technologies: low-cost small satellites and aerocapture. This study investigates the feasibility of this co-delivery method from a flight-mechanics perspective. The availability

Self-actuated deployable space structures present a novel challenge for deployment dynamics modeling efforts, where the system-level influence of strain energy components must be captured. Here, the free deployment of an origami-folded structure through actuation of strain energy hinges is studied. Studies include experimental testing, multibody dynamics modeling, and finite element modeling. An approach

The electrostatic tractor has been proposed to touchlessly remove space debris from geosynchronous orbit by taking advantage of intercraft Coulomb forces. A controlled spacecraft (tug) emits an electron beam onto an uncooperative or retired satellite (debris). Thus, the tug raises its own electrostatic positive potential to tens of kilovolts, whereas the debris charges negatively. This results in an

The effect of thermochemical kinetics modeling on hypersonic flow over a double-cone geometry is investigated. The double-cone is simulated using three different approaches based on the Park model: nonequilibrium flow, equilibrium flow, and frozen flow for air at four different freestream conditions. The thermochemical model effects on the flowfield and surface properties are specific areas of interest

This paper investigates the thermal environment of launch pads during rocket takeoff. The rocket plume model is set up using the three-dimensional Navier–Stokes equations and realizable k−ε turbulence model. The aluminium oxide particles in the plume are considered by the Eulerian dispersed phase model. Comparing with the experimental data, the accuracy of the numerical model can be verified. On this

GPS satellites undergo surface contamination on the solar array coverglasses from repeated arcing events. Using NASA Air Force Spacecraft Charging Analyzer Program (Nascap-2 K) spacecraft charging simulation software, a GPS Block IIF satellite model was constructed and analyzed in realistic Medium Earth Orbit environments. GPS Block IIF satellites have Qioptiq CMG-type coverglasses (as do all other

A hybrid rockoon, which is a hybrid rocket launched from a high-altitude balloon, is proposed. The rocket system configuration was studied for single-stage or multiple-stage rockets, and the performance and range safety requirements were considered. The propellants of the hybrid-rocket motor are a low-melting-point thermoplastic fuel and nitrous oxide, which are beneficial, owing to their mechanical

This paper examines thermal response behind the high-Mach integrated control (HIMICO) experiment’s engine. In this experimental aircraft, instruments must be protected from heat load due to exhaust gas; therefore, a coupling calculation between the fluid and the wall is conducted to confirm the performance of HIMICO’s thermal protection system (TPS). First, the validity of the coupling calculation

A wide variety of missions could be enabled by extended orbital flight in extreme low Earth orbit, defined as an altitude range of 150–250 km. This study investigates the feasibility of a nanosatellite (mass <10 kg) using a propulsive, attitude control system in conjunction with a primary propulsion system to extend mission life. The primary propulsion system consists of a pair of electrospray thrusters

Early in operational testing for the InSight mission to Mars, it was discovered that the final maneuver to target the entry-interface point was unexpectedly sensitive to planned atmosphere updates that would be based on real-time measurements of the Martian atmosphere by Mars Reconnaissance Orbiter. Upon investigation, the team realized that the Phoenix mission also discovered this sensitivity during

The physical basis and application of the fundamental relationship governing the balance and utilization of available energy for a chemical rocket operating within the atmosphere are described. The relative contributions of the thermochemical availability and the kinetic energy of the stored propellant to the overall energy availability are shown. There are optimal flight velocities for which 1) overall

A novel approach for shape control of membrane structures is presented to realize their use in three-dimensional and variable configurations. The shape control is accomplished by exciting a spinning membrane. The membrane forms a shape consisting of several vibration modes, depending on the input frequency, and the wave surface stands still when its frequency is synchronized with the spin rate; that

Satellite formation establishment may consume considerable fuel if cross-track distance (CTD) is a mission requirement. This work proposes a strategy for significantly reducing the required fuel. Instead of direct out-of-plane maneuvers, it is suggested to use in-plane maneuvers, while using the nodal precession caused by the J2 perturbation. The CTD dynamics are analyzed, and representative formation

The importance of determining the sidereal rotation period of an astronomical object on future investigations pertaining to said object has been well documented in the literature. Researchers, however, have differed in their techniques used to estimate and model objects in the space catalog. In this paper, several period-estimation methods will be explored ranging across Fourier and phase-folding techniques

Aiming at the problem of silo design, the silo ejector model and ejector function were proposed. The properties of the static pressure matching function were studied. The critical conditions were analyzed when the engine total pressure, the diameter of the silo, and the outlet pressure of the mixing chamber changed. It is proved that the curve that shows the inlet pressure of the mixing chamber changes

Journal of Spacecraft and Rockets, Ahead of Print.

Recent advancements in CubeSat technology unfold new mission ideas and the opportunity to lower the cost of space exploration. Ground operations costs for interplanetary CubeSats, however, still represent a challenge toward low-cost CubeSat missions: hence, certain levels of autonomy are desirable. The feasibility of autonomous asteroid flyby missions using CubeSats is assessed here, and an effective

The problem of minimum-time, low-thrust, Earth-to-Mars interplanetary orbital trajectory optimization is considered. The minimum-time orbital transfer problem is modeled as a four-phase optimal control problem where the four phases correspond to planetary alignment, Earth escape, heliocentric transfer, and Mars capture. The four-phase optimal control problem is then solved using a direct collocation

A linear aerospike nozzle is a kind of altitude adaptive nozzle that has optimum performance over the entire operational range. In this work, flow characteristics of a linear plug nozzle and a truncated plug with 40% plug length are studied numerically. Different flow types associated with an increase in nozzle pressure ratio, corresponding wall pressure variation and shock patterns are studied. The

Quantifying the thermal response of a heat shield is a key step in the design of a spacecraft to ensure its survivability during atmospheric entry. Recession and swelling of the thermal protection material have a drastic effect on both the heat transfer within the vehicle and aerothermodynamic transients. Postflight analysis of reentry can be achieved after recovery on Earth, but it is more difficult

The two leading perturbations acting on satellites in the orbital decay region of low Earth orbit are gravitational nonsphericity of the Earth and atmospheric drag. A detailed understanding of their properties is required to accurately predict satellite dynamics, such as the orbital lifetime. However, there is still room to improve current perturbation models in this region, especially for the atmosphere

The Rotary-Motion Extended Array Synthesis spacecraft is a dual-spin spacecraft with long tethers held in tension by the spin. This paper derives the free-space (not considering orbital effects) dynamics of this spacecraft, and it compares two controllers in performance and the effort expended. In contrast to prior work, one of the controllers used takes account of the tether motion rather than just

The Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) mission touched down in Elysium Planitia on 26 November 2018, becoming NASA’s eighth successful entry, descent, and landing (EDL) at Mars. InSight inherited the successful 2008 Phoenix (PHX) EDL system, flying a nonspinning, ballistic trajectory with a 70 deg sphere–cone aeroshell (2.65 m diameter), a disk–gap–band

Journal of Spacecraft and Rockets, Ahead of Print.

This paper investigates the use of deep learning techniques for real-time optimal spacecraft guidance during terminal rendezvous maneuvers, in presence of both operational constraints and stochastic effects, such as an inaccurate knowledge of the initial spacecraft state and the presence of random in-flight disturbances. The performance of two well-studied deep learning methods, behavioral cloning

CubeSats usually carry no propulsion system because of difficulties in scaling down existing propulsion technologies to meet the stringent size, volume, and power limits. The most challenging case in this context is the one-unit CubeSat: the use of which has been rapidly growing. To increase CubeSat functionality by allowing small orbit corrections, particularly due to orbit injection errors, this

This paper proposes an on-orbit servicing logistics optimization framework capable of performing the short-term operational scheduling and long-term strategic planning of sustainable servicing infrastructures that involve high-thrust, low-thrust, and/or multimodal servicers supported by orbital depots. The proposed framework generalizes the state-of-the-art on-orbit servicing logistics optimization

This paper presents a comparative study of six common pseudospectral (PS) methods for solving optimal spacecraft attitude control problems. The problems of minimum time, minimum control effort, and the linear combination thereof are considered here, for a rest-to-rest spacecraft slew maneuver. In this study, three traditional PS methods (Gauss, Legendre, and Chebyshev) and three variations of the novel

This paper presents the experimental and analytical results of a heat rejection system consisting of a single-phase mechanically pumped loop and a space radiator. It has been developed for future crewed exploration missions to provide a large amount of heat dissipation capability. The radiator consists of a honeycomb radiator, eight aluminum pipes inserted through the honeycomb core, and two aluminum

Future exploration and human missions on large planetary bodies (e.g., moon, Mars) will require advanced guidance navigation and control algorithms for the powered descent phase, which must be capable of unprecedented levels of autonomy. The advent of machine learning, and specifically reinforcement learning, has enabled new possibilities for closed-loop autonomous guidance and navigation. In this

On 26 November 2018, the Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) lander successfully touched down on the surface of Mars. Program to Optimize Simulated Trajectories II (POST2) of NASA Langley Research Center was used during both project development and flight operations to assess the entry, descent, and landing (EDL) vehicle performance against related

The management of fluids in space is complicated by the absence of relevant buoyancy forces. This raises significant technical issues for two-phase flow applications. Different approaches have been proposed and tested to induce phase separation in low gravity; however, further efforts are still required to develop efficient, reliable, and safe devices. The employment of diamagnetic buoyancy is proposed

This paper presents an improved backstepping control scheme with the adaptive estimation for nonlinear missile systems. First, the inherent nonlinearities and large uncertainties caused by high angle of attack are approximated by a higher-order polynomial with unknown time-varying coefficients, which is easily estimated by using adaptive parameter estimation technique. Then the prescribed performance

Systems enabling long-duration crewed missions are expected to have high probabilities of success through sparing of components. To enable such systems, the tradeoff between reliability and mass needs to be incorporated early in the design phase to ensure that the requirements are optimally captured. Additionally, effective operational sparing policies need to be devised in the early design phase as

Journal of Spacecraft and Rockets, Ahead of Print.

The optimization of low-thrust, multirevolution orbit-transfer trajectories is often regarded as a difficult problem in modern astrodynamics. In this paper, a flexible and computationally efficient approach is presented for the optimization of low-thrust orbit transfers under eclipse constraints. The proposed approach leverages a new dynamic model of the orbital motion and a Lyapunov-based initial-guess

Orbital debris in Earth orbit poses a threat to the future of spaceflight. To combat this issue, this paper proposes a novel robotic mechanism for non-cooperative capture and active servicing missions on non-cooperative targets; specifically, a tendon-driven manipulator is assumed for this work. The capture mechanism is a prototype symmetric two-link gripper driven by an open-ended cable-sheath transmission

The determination of aerodynamic coefficients for complex high-speed vehicles still requires experimental measurement. This paper details the development of the free-flight measurement technique within the University of Oxford High Density Tunnel. In particular, a novel image processing technique is developed for calculating the position of the model from high-speed video. This study focuses on the

In this work, near-infrared and ultraviolet spectroscopic data collected during the Hayabusa spacecraft reentry is used as the basis for validating numerical and experimental studies using the compressible flow computational fluid dynamics code Eilmer3 and the University of Queensland’s X2 expansion tube. Spectra generated numerically from simulations of the full-scale vehicle at the selected trajectory

The methods and processes available for planning have historically been unable to provide decision-makers with objective, quantitative information from both the upper strategic levels and lower technical levels of the space program. Instead, decision-makers must turn to qualitative assessments, disconnected from any of the fundamental, technical details, where inconsistent comparisons and secondary

With an ever increasing geopolitical relevance of human lunar exploration, the world’s space agencies show an increasing interest in its implementation in the very near term. In August 2020 the International Space Exploration Coordination Group has published a supplement to its Global Exploration Roadmap that focuses on the envisioned future lunar architecture based on objectives of sustainability

In this paper, design and optimization approaches are applied to a hybrid-powered small-satellite launcher, namely a deterministic and a robust-based method. A unique hybrid rocket engine is considered, employed in different numbers in each stage of the three-stage launcher: six, three, and one, respectively, in the first, second, and third stage. Liquid oxygen and paraffin-based fuel are considered

Reentry radiation is one of the key phenomena to take into account while designing an Entry Descent and Landing (EDL) phase for sample return and some gas/ice giants’ missions. In the case of an ablative thermal protective system (TPS), the physicochemical processes involved produce a large amount of dust and phenolic gases that can obstruct the optical path. The QubeSat for Atmospheric Research and

The large number and significant variety of systems available for space exploration missions produce countless potential architecture combinations. Compounding this are the scheduling intricacies of system life cycle phases and time-dependent operational dependencies, as well as the uncertainty associated with each system and technology in terms of cost, schedule, and performance. Traditional architecting

Journal of Spacecraft and Rockets, Ahead of Print.

Journal of Spacecraft and Rockets, Ahead of Print.

Single-event, drag-modulated aerocapture has become a promising control scheme in the past decade. However, these architectures suffer from exhausted control authority post-jettison. Multiple drag-skirt jettison events have been shown to enhance aerocapture performance, yet still suffer from unidirectional control capabilities. An apoapsis target biasing method is introduced to improve multi-event

Performing orbital insertion around Mars using aerocapture instead of a propulsive orbit insertion maneuver allows the saving of resources and/or the increase of the payload mass fraction. Aerocapture has never been employed to date because of the high uncertainties in the parameters from which it depends, mainly related to atmospheric density modeling and navigation errors. The purpose of this work

Journal of Spacecraft and Rockets, Ahead of Print.

In this paper, the authors investigate whether airbreathing engines have useful application to vertical takeoff and vertical landing systems, which currently represent the mainstream for reusable launch vehicles. A theoretical analysis has been performed to determine the net impact of the specific impulse benefits and weight penalties of a vertical takeoff reusable launch vehicle fitted with an airbreathing

The out-of-plane and in-plane deployment dynamics of a flexible space structure, namely, a solar sail quadrant consisting of a membrane attached to two support booms, are considered. The equations of motion of the system are obtained using a time-varying generalization of the extended Hamilton’s principle. They are then discretized via quasi-modal expansion of the deflections as truncated series involving

Numerical techniques for designing frozen repeat orbits as reference trajectories have been extensively studied for polar orbit missions. For near-equatorial orbits, larger perturbing forces are experienced at lower inclinations. The greater perturbations make such near-equatorial orbits’ long-periodic behavior much more sensitive to changes in initial conditions. Thus, a more careful selection of

Supersonic accelerators use sabots to suppress bore balloting. However, sabot separation induces flight deviation in projectiles owing to their interactions with fluids and shock waves. A seamless calculation of the acceleration phase in the tube and the full separation process using 3-D computational fluid dynamics coupled with rigid body dynamics is presented in this study to investigate the shock-wave

This paper develops a framework that models and optimizes the operations of complex on-orbit servicing infrastructures involving one or more servicers and orbital depots to provide multiple types of services to a fleet of geostationary satellites. The proposed method extends the state-of-the-art space logistics technique by addressing the unique challenges in on-orbit servicing applications and integrates

Operating Earth-observing satellites requires efficient planning methods that coordinate activities of multiple spacecraft. The satellite task-planning problem entails selecting actions that best satisfy mission objectives for autonomous execution. Task scheduling is often performed by human operators assisted by heuristic or rule-based planning tools. This approach does not efficiently scale to multiple

Blunt-nosed launch vehicles featuring large nose-cone angles experience high levels of pressure fluctuations over the payload region at transonic Mach numbers due to shock-wave/boundary-layer interactions. The main cause for this phenomenon appears to be flow instability associated with separated flow and formation of a vortex pair. Interactions between the induced velocity of the vortex pair and oncoming

The energetic electrostatic analyzer has been developed to act as a miniaturized, rugged, and low-cost instrument capable of providing in situ measurements of ion or electron energy and subsequent derived density, temperature, and spacecraft potential. We present laboratory calibration results using a magnetically filtered low-Earth-orbit plasma simulator to quantify the effects of spacecraft charge

This paper presents simulation models and an analysis of the hovering capability of an electrostatic spacecraft around a small celestial body. The hovering capabilities of an electrically actuated spacecraft are evaluated by combining orbital dynamics analysis with 3-D fully kinetic particle-in-cell simulations of asteroid/spacecraft interactions with the solar-wind plasma. The zero-velocity curves

Numerous missions are being proposed which involve multiple spacecraft operating in close proximity in harsh charging environments. In such missions, the ability to sense the electrostatic potential on a nearby object is critical to prevent harmful electrostatic discharges or to leverage Coulomb interactions for relative motion control. The electron method is one such technique for touchless potential