Launch Conditions Research Articles

The Deployment Mechanism of the E.T.PACK deorbit system: Functional and qualification tests

The Horizon 2020 (H2020) Future Emerging Technologies (FET) OPEN Project E.T.PACK is dedicated to advancing Electrodynamic Tether (EDT) technology by developing a specialized Deorbit Device prototype for end-of-life satellite deorbiting. In collaboration with the E.T.PACK consortium, the University of Padova conducted test campaigns aimed at evaluating the Deployment Mechanism design. This paper offers an overview of these tests, with a specific emphasis on the outcomes derived from tape spool examinations and deployment tests conducted on specific tape lengths. Furthermore, the paper delineates the setup for upcoming end-to-end deployment tests, highlighting the integration of a tape collecting machine to minimize manual intervention. The three-coil spool successfully passed qualification tests under thermal-vacuum conditions, exhibiting no instances of cold-welding. Additionally, shaker tests validated the spool ability to withstand launch conditions without requiring additional containment flanges. Furthermore, the Deployment Mechanism demonstrated its proficiency in smoothly deploying tapes with varying characteristics within the desired velocity range. Moreover, the deployment process, following a specific profile, proceeded seamlessly without any complications. Consistent continuity was maintained throughout the deployment processes, with no instances of jams or disruptions observed. These testing outcomes represent a fundamental step in the preparation and testing of the Engineering Qualification Model of the Deployment Mechanism, instilling confidence that subsequent end-to-end deployment tests will progress smoothly. To this end, a specific upside-down configuration will be implemented, and a recollecting machine was designed and manufactured to facilitate tape gathering, ensuring a streamlined and efficient testing process. A description of the end-to-end deployment test setup, including the recollecting machine, is also provided in this paper.

3D soft material printer as a mesoscale additive biomanufacturing platform for in-space manufacturing

With the burgeoning in-space manufacturing (ISM) industry, developing an on-demand additive manufacturing (AM) platform will be crucial for long-term space habitation. However, acute space boundary conditions, such as limited physical space, microgravity, vacuum, and others pose unique challenges for designing the printing process, the platform’s structure, and the materials’ printability. An AM platform operable in a space environment would enable production at the point of need (PoN), for example, on-demand food, nutrition, and pharmaceutical products. This research is focused on the design, fabrication, and testing of a 3D printer confined within CubeSat boundaries to study the feasibility of soft material printing aimed toward potential ISM applications. The printer unit was built using components off the shelf (COTS) while adhering to the severe spatial boundary conditions posed by the CubeSat dimensions and was tested using an edible material ink to demonstrate multi-layer prints of soft materials. Printing in ambient Earth conditions as well as under vacuum displayed consistent layer cohesion and comparison to 3D model data although vacuum prints showed visibly dehydrated prints owing to outgassing of air bubbles. The printer equipment’s structural integrity was validated under simulated launch and operation conditions using a vibration testing setup according to the NASA-recommended microsatellites standards. The results indicated that the printer assembly maintained its structural and operational integrity during and after testing. Using soft materials as the basis of testing allows scalability when expanding to more complex and structural materials to produce spare parts using a frugally engineered modular manufacturing platform.

Dynamic behavior of a wheeled rocket launcher using transfer matrix method of multibody system

Abstract One of the most sophisticated causes of unguided rocket dispersion is the uncertainties in launch conditions. This arises due to the fact that a launcher, in reality, shows dynamic behavior as it is a multibody system. This paper investigates the dynamic behavior of a wheeled rocket launcher that is loaded on a vehicle. The launcher and vehicle system are modeled as a multibody system using the transfer matrix method of multibody system (TMM). TMM is chosen due to its suitability for linear systems and its ability to obtain the overall transfer matrix for the entire system by performing successive matrix multiplications of the individual body’s matrix, thereby avoiding the complexity of solving the overall dynamic equations of the system. The developed dynamic model is then validated by comparing its results with those in the open literature using the Lagrange approach. The study considers dynamic loads that result from the rocket motion on the launcher. A parametric study is conducted to address the impact of launcher structural aspects. By investigating the dynamic behavior of the wheeled rocket launcher, this study aims to enhance the understanding of its performance.

The Effect of Moveable Fins on Trajectory and Aerodynamic Characteristics of Model Rockets

The application of the fins on the rocket are necessaryto achieveoptimal flight performance. However, the appearanceof gust wind can affectthe stability of the rocket during flight. To minimize instability, the fins are designed to be adjustable by changing the fin cant angles.This study aims to investigate the effect of different cant angles on rocket’s trajectory and aerodynamic characteristicsthrough computer simulation.The Open Rocket software is used to conduct the simulations. The range of cant angle in this study is from0°to 15°and the Clipped Delta fin design is chosen for this study. The launch condition is all the same for all the model rocketsand the launch site’slatitude and longitude wasbased on Parit Raja location. The trajectory characteristics were evaluated through simulations of altitude versus position east of launch, altitude versus position north of launch, and altitude versus lateral distance. Meanwhile, the aerodynamic characteristics were evaluated through simulations of stability margin and drag force over time. This study found thatthe maximum altitude for each model rocket is decreasing as the cant angle increases. Different fin’scant angles slightly alter the trajectory characteristic of model rockets,but they do not significantly impact the overall stability and drag characteristics during critical phases of flight. Higher cant angles resulted in shorter horizontal and lateral distances from the launch site to the apogee, suggesting a more vertical trajectory.

Simulation of the synergistic effect of multiple operation parameters on cavity soliton in nonlinear fiber resonator

All optical soliton communication is a new generation of ultra-long distance and ultra-high speed optical fiber communication technology. Optical cavity solitons (CSs), whose pulse property is unique, have shown great potentials in optical soliton communication systems. Here, a theoretical model of nonlinear fiber resonator for CS generation is proposed. The effect of pump laser and resonant cavity parameters on the CS pulse performance is detailedly investigated and deeply analysed. Furthermore, the synergistic effect of continuous wave (CW) pump laser power and pump pulse peak power, and the synergistic effect of dispersion condition, fiber nonlinear coefficient and fiber length on the generation and property of CS pulse are respectively discussed and summarized. Finally, the launch conditions and parameter variation tolerances of cavity soliton in nonlinear fiber resonant cavity have been successfully generalized. These results can provide important instruction to the experimental generation and optimization of CS pulse.

Numerical investigation of the influence of different barrel lengths on the interior ballistic process within an underwater submerged launch

Although underwater submerged launching has been rigorously investigated for decades, there remains a dearth of comprehensive understanding regarding the underwater interior ballistic characteristics for varying barrel lengths. To address this knowledge gap, the present study aims to explore, via numerical simulations, the initial velocity of interior ballistics, projectile drag, and the mechanism of initial flow field formation at the muzzle under various barrel lengths, thereby considering the influence of differing barrel lengths. The five distinct lengths of barrels are expressed as dimensionless ratios of the weight of water column in front of the projectile to the weight of the projectile in order to be more general. Five different ratios of water-to-projectile weight are investigated: 1.0, 1.2, 1.5, 1.8, and 2.0, all possessing identical diameters and evaluated under equivalent launch conditions. Different ratios significantly impact muzzle velocity, with shorter barrels yielding higher muzzle velocities, while ensuring complete propellant combustion. Further investigations indicate that variations in drag constitute the fundamental cause of initial velocity changes. Furthermore, it is observed that barrels of different lengths exhibit identical characteristics at the point of maximum drag. The initial flow field at the muzzle exhibits considerable variations in terms of length, profile dimensions, and intensity. The findings of this study offer valuable insights into exploring the mechanism of submerged launching and will be utilized to investigate the optimal barrel length.

Design and Analysis of Low-Gravity Simulation Scheme for Mars Ascent Vehicle

The sample carried back by the Mars Ascent Vehicle (MAV) is a potential flagship mission of deep space exploration in recent years. A low-gravity simulation experiment is an effective method and a necessary stage for verifying the performance of the MAV launch dynamic in Earth’s gravity. In this paper, the uniqueness of low-gravity simulation is illustrated by the classical pulley balance method for the high dynamic process of a test model of the MAV. Its movement direction is the same as the compensation force, which leads to the relaxation of the sling and the failure of the compensation force in traditional cable suspension. Here, three cable suspension schemes including an improved pulley balancing scheme based on a coordinate transformation scheme and based on a dynamic pulley group scheme are proposed. For the actual launch condition of the MAV, the motion state of the ascent under the schemes and the real Mars launch are compared, which proves the feasibility of the schemes. Among them, the improved pulley balancing scheme has the best gravity compensation effect, and the error between the average value and the required value is the smallest, only 1%.

Numerical study on the pulsation characteristics of tail cavities under vertical launching conditions

This study aimed to analyze the pulsation characteristics of tail cavities at different Froude numbers under vertical launching conditions. The improved delayed detached eddy simulation (IDDES), volume of fluid (VOF) model, adaptive mesh refinement (AMR), and overlapping grid technique were adopted to model the pulsation characteristics of the tail cavity. The feasibility of the model for predicting dynamic behaviors was verified by comparing the numerical and experimental results. The results demonstrated that the volume of the tail cavity pulsated periodically. However, the concurrent expansion and contraction in the integral tail cavity resulted in a relative state of cavity volume pulsation. When the expansion rate exceeded the contraction rate, the cavity volume increased, otherwise, decreased. In addition, four flow patterns were observed in the tail cavity: smooth, irregular, hybrid, and cavity-shedding regions. An increase in the Froude number augmented the tail cavity volume and proportion of irregular regions, and reduced the proportion of hybrid regions.

Mode-dependent analysis of a fiber optic curvature sensor with sensitive zone

In this paper, mode-dependent analysis of fiber optic curvature sensor with precision machined structural imperfections (teeth) as sensitive zone is conducted. Using controlled input or light source launching conditions sensor response is measured for different modes excited in the multimode optical fiber. Study shows that as curvature changes there is significant difference in how sensitive zone affects low and high order modes propagating through the fiber. Obtained measurement results provide further insight into FOCS response and open possibilities for development of new measurement approaches which represent a significant step forward for FOCS based measurement systems. Guidelines for maximizing sensor sensitivity, increasing measurement reliability and even avoiding intensity based measurement by measuring changes in the width of the sensor’s output light intensity distribution are discussed in this work.

The Effects of Target Thicknesses and Backing Materials on a Ti-Cu Collision Weld Interface Using Laser Impact Welding

This study demonstrates that the thickness of the target and its backing condition have a powerful effect on the development of a wave structure in impact welds. Conventional theories and experiments related to impact welds show that the impact angle and speed of the flyer have a controlling influence on the development of wave structure and jetting. These results imply that control of reflected stress waves can be effectively used to optimize welding conditions and expand the range of acceptable collision angle and speed for good welding. Impact welding and laser impact welding are a class of processes that can create solid-state welds, permitting the formation of strong and tough welds without the creation of significant heat affected zones, and can avoid the gross formation of intermetallic in dissimilar metal pairs. This study examined small-scale impact using a consistent launch condition for a 127 µm commercially pure titanium flyer impacted against commercially pure copper target with thicknesses between 127 µm and 1000 µm. Steel and acrylic backing layers were placed behind the target to change wave reflection characteristics. The launch conditions produced normal collision at about 900 m/s at the weld center, with decreasing impact speed and increasing angle moving toward the outer perimeter. The target thickness had a large effect on wave morphology, with the wave amplitude increasing with target thickness in both cases, peaking when target thickness is about twice flyer thickness, and then falling. The acrylic backing showed a consistently smaller unwelded central zone, indicating that impact welding is possible at a smaller angle in that case. Strength was measured in destructive tensile testing. Failure was controlled by the breakdown of the weaker of the two base metals over all thicknesses and backings. This demonstrates that laser impact welding is a robust method for joining dissimilar metals over a range of thicknesses.

Backspin in Ruellia ciliatiflora does not maximize seed dispersal range, but provides moderate dispersal range thatisrobust to launch conditions.

Ruellia ciliatiflora is a perennial herb whose fruits explosively dehisce, launching their thin disc-like seeds over 6 m with a backspin up to 1660 Hz. Whileithas been previously shown that the backspin launch orientation minimizes the aerodynamic drag experienced by the seeds, it is not immediately obvious whether backspin is also the range-maximizing launch orientation. Here the three-dimensional equation of motion of a thin, spinning disc flying through a fluid medium was derived and solved numerically to simulate the flight of seeds of R. ciliatiflora under different launch conditions. Simulations of seed flights reveal that the range-maximizing launch orientation lies between sidespin and topspin, far from the backspin that is observed in nature. While this range-maximizing orientation results in dispersal ranges of nearly 10 m, the precise orientation is highly sensitive to other launch parameters, chiefly spin rate and launch angle. By contrast, backspin, which yields moderate dispersal ranges about 60% of the range-maximizing orientation, is robust to perturbations in launch parameters that the plant cannot precisely control.

Variation of Falcon 9 noise at far-field recording sites

The rapid launch cadence of SpaceX’s Falcon 9 rocket provides the opportunity to study the relative consistency of far-field noise propagation. Acoustical measurements of several Falcon 9 launches have been made on and near Vandenberg Space Force Base at a far-field location 8.4–14 km from the pad. This paper compares collocated measurements from different Falcon 9 missions to begin to understand data variability as a function of launch and environmental conditions at far-field locations. The 8.4 km location has been measured over 10 times, whereas other locations span subsets of launches. This comparative analysis includes time-varying levels, spectra, and waveform statistics, such as the pressure derivative skewness. Time periods of particular interest are liftoff, peak noise, and late into the launch when the vehicle is significantly downrange. [Work supported by USACE.]

Variation of Falcon 9 noise in the mid-field

The rapid launch cadence of SpaceX’s Falcon 9 rocket provides the opportunity to study the relative consistency of noise radiation. Acoustical measurements of several Falcon 9 launches have been made on and near Vandenberg Space Force Base within 1 km of the launch pad. This paper compares collocated mid-field measurements from different Falcon 9 missions to begin to understand data variability as a function of launch and environmental conditions. One location 395 m from the pad has been measured over 5 times. This comparative analysis includes time-varying levels, spectra, and waveform statistics such as the pressure derivative skewness. Time periods of particular interest are liftoff, peak noise, and late into the launch when the vehicle is significantly downrange. [Work supported by USACE.]

Polynomial shaping based three-dimensional impact angle and field-of-view constrained guidance

This paper proposes a polynomial-based three-dimensional (3D) impact angle-constrained guidance law considering the seeker's field-of-view (FOV) bound. The guidance laws are derived using nonlinear coupled dynamics of the interceptor-target engagement against stationary as well as constant velocity targets. Line-of-sight (LOS) orientations between the interceptor and the target in both pitch and yaw planes are shaped as two cubic polynomial functions of relative range. An explicit expression for the look angle of the interceptor is acquired in terms of the LOS polynomials. This expression facilitates the embodiment of the FOV constraint in the boundary conditions inflicted on the polynomials. A system of equations with the eight unknown coefficients is obtained by employing the appropriate launch and terminal conditions of the interceptor-target engagement. Reference LOS angle and lead angle profiles are generated using the calculated coefficients, complying to which the interceptor achieves a zero miss distance with desired impact angle and FOV constraints. A tracking controller is then designed using a nonlinear control technique that enables the interceptor to follow reference lead angle profiles in mutually orthogonal planes. Unlike the already existing guidance strategies for 3D impact angle and FOV-constrained target interception, the proposed nonlinear guidance strategy is designed without the use of linearization or decoupling. Moreover, no switching logic or multi-phase guidance structures are employed in the proposed guidance strategy, which eliminates possible jumps in the guidance command. The effectiveness of the proposed guidance law is validated using numerical simulations, along with a comparison study with the existing strategy.

Design of all-fiber 2D MMI based optical devices using 1D mode propagation method

We show that the mode propagation analysis in a 2D confined optical device can be bifurcated into two 1D problems. In our method, a given 2D launch field profile is divided into two 1D profiles and suitably aligned with the 1D waveguide, acting as independent launching conditions. This method shows that the complete propagation problem of a 2D waveguide, which involves the computation of 2D mode field profiles and their propagation constants, can indeed be solved as two 1D problems. Our method is verified with the beam propagation method through a commercial simulator. Based on our analysis, we design MMI-based optical devices using square core multimode optical fiber such as wideband power divider and combiner at 1550 nm. Furthermore, the practical considerations, such as fabrication tolerance and operation bandwidth for these devices, are investigated to ascertain operational advantages.

Sound power of NASA's lunar rockets: Space Launch System versus Saturn V.

To improve acoustical models of super heavy-lift launch vehicles, this Letter reports Space Launch System's (SLS's) overall sound power level (OAPWL) and compares it to NASA's past lunar rocket, the Saturn V. Measurements made 1.4-1.8 km from the launchpad indicate that SLS produced an OAPWL of 202.4 (±0.5) dB re 1 pW and acoustic efficiency of about 0.33%. Adjustment of a static-fire sound power spectrum for launch conditions implies Saturn V was at least 2 dB louder than SLS with approximately twice the acoustic efficiency.

A Study on the Characteristics about Shaft Deflection According to the Change in Manufacturing Sequences

Recently, the amount of orders for large container ships based on eco-friendly fuel is increasing. Container ships have very different characteristics of cargo as comparing other type cargo carriers, having a unique arrangement of structural members. In this reason, the classification societies propose major governing conditions that affect independent shaft alignment calculations based on detailed analysis. In this study, the change in displacement around the shaft system, which occurs in the manufacturing process, was investigated using structural analysis modeling. The manufacturing process is divided into PE (Pre-erection), welding according to the erection sequences, lifting the block, setting on the dock, and finally reviewing the launching conditions. The results of this study, the displacement of the shaft system during the manufacturing stages were confirmed. The change in the number of block supports had the greatest effect on the change in deflection rather than the effect of welding heat, and the final results were similar to those of the PE condition. The shaft centering analysis can be predicted correct value in advance if the characteristics of deflection change according to the process are known, and accurate prediction can be made in a short time by using the proposed procedure.

Modelization of Low-Cost Maneuvers for an Areostationary Preliminary Mission Design

The aim of this paper is to analyze the determination of interplanetary trajectories from Earth to Mars to evaluate the cost of the required impulse magnitudes for an areostationary orbiter mission design. Such analysis is first conducted by solving the Lambert orbital boundary value problem and studying the launch and arrival conditions for various date combinations. Then, genetic algorithms are applied to investigate the minimum-energy transfer orbit. Afterwards, an iterative procedure is used to determine the heliocentric elliptic transfer orbit that matches at the entry point of Mars’s sphere of influence with an areocentric hyperbolic orbit imposing specific conditions on inclination and periapsis radius. Finally, the maneuvers needed to obtain an areostationary orbit are numerically computed for different objective condition values at the Mars entry point to evaluate an areostationary preliminary mission cost for further study and characterization. Results show that, for the dates of the minimum-energy Earth–Mars transfer trajectory, a low value for the maneuvers to achieve an areostationary orbit is obtained for an arrival hyperbola with the minimum possible inclination and a capture into an elliptical trajectory with a low periapsis radius and an apoapsis at the stationary orbit. For a 2026 mission with a TOF of 304 for the minimum-energy Earth–Mars transfer trajectory, for a capture with a periapsis of 300 km above the Mars surface the value achieved will be 2.083 km/s.

Evolution of Shock Waves during Muzzle Jet Impinging Moving Bodies under Different Constrained Boundaries

A recently developed launching device called the gun–track launch system is affected by its constrained track, such that the form of the muzzle jet changes from the state of free development in the entire space to a constrained state, where this lends unique characteristics of development to its flow field. In this study, the authors establish the corresponding model for numerical simulations based on the dynamic mesh method. We also considered a model of simulation of the muzzle jet with an “infinitely” constrained track to analyze its performance under real launch conditions to explore the mechanism of development and the disturbance-induced propagation of the shock wave when the muzzle jet impinges on moving bodies. The results showed that the muzzle jet exhibited a circumferential asymmetric shape that tilted toward the area above the muzzle and generated transverse air flow that led to the generation of a vortex on it. Because the muzzle was close to the ground, the jet was reflected by it to enhance the development and evolution of the shock waves and vortices and to aggravate the rate of distortion and asymmetry of the jet. The wave reflected from the ground was emitted once again when it encountered the infinitely constrained track. No local low-pressure area or a prominent vortex was observed after multiple reflections. Because the track in the test model was short, the waves reflected by the ground were not blocked, and vortices were formed in the area above the ground. Significant differences in the changes in pressure were also observed at key points in the domain. The results of a comparative analysis showed that the infinitely constrained track increased the Mach number of the moving body from 1.4 to 1.6. The work provides a theoretical basis and the requisite technical support for applications of the gun–track launch system.

Lunar ejecta origin of near-Earth asteroid Kamo’oalewa is compatible with rare orbital pathways

Near-Earth asteroid, Kamo’oalewa (469219), is one of a small number of known quasi-satellites of Earth; it transitions between quasi-satellite and horseshoe orbital states on centennial timescales, maintaining this dynamics over megayears. The similarity of its reflectance spectrum to lunar silicates and its Earth-like orbit both suggest that it originated from the lunar surface. Here we carry out numerical simulations of the dynamical evolution of particles launched from different locations on the lunar surface with a range of ejection velocities in order to assess the hypothesis that Kamo‘oalewa originated as a debris-fragment from a meteoroidal impact with the lunar surface. As these ejecta escape the Earth-Moon environment, they face a dynamical barrier for entry into Earth’s co-orbital space. However, a small fraction of launch conditions yields outcomes that are compatible with Kamo‘oalewa’s orbit. The most favored conditions are launch velocities slightly above the escape velocity from the trailing lunar hemisphere.