Mission Launch Research Articles

Predefined-Time Enhanced Antidisturbance Attitude Control for Rigid–Liquid Coupled Launch Vehicles

High-precision and fast-response attitude control of launch vehicles plays an increasingly important role in numerous space launch missions, ensuring the efficiency of space transportation. However, disturbances caused by liquid sloshing and external environments degrade the control performances seriously. Because of the complicated coupling with control inputs and angular acceleration, the dynamics of liquid sloshing disturbance are highly uncertain. Therefore, it is urgent to develop novel disturbance estimation methods for launch vehicles by thoroughly analyzing disturbance dynamics. In this paper, an observer-based predefined-time attitude control method aimed at achieving precise and rapid estimation of liquid sloshing disturbance and other external disturbances is proposed. More specifically, a prescribed-time reduced-order state observer is proposed for estimating the liquid sloshing disturbance and the unmeasurable system state, leveraging the specific characteristics and inherent coupling relations of liquid sloshing disturbance. Additionally, a prescribed-time extended state observer is introduced for estimating external disturbances and nonlinear terms. Subsequently, by employing a predefined-time output feedback controller, a composite control law is proposed to enhance the antidisturbance capabilities of rigid–liquid coupled launch vehicles. Finally, simulation examples are presented to illustrate the effectiveness of the proposed method.

Collision probability evaluation of SRM slag during orbital lifetime

At the end of combustion, a solid rocket motor (SRM) in orbit emits combustion products with relatively large particle sizes (slag). ISO 24113:2023 “Space debris mitigation requirements” defines criteria to limit debris emission 1 mm or larger in the LEO protected region. JAXA's “Space debris mitigation standard,” JMR-003E, sets out the same requirements. Hence, JAXA has begun an improvement study on SRM slag emissions as it develops the next generation of SRMs to conserve the orbital environment by significantly reducing SRM slag larger than 1 mm. However, ensuring the complete prevention of larger SRM slag emission is technically challenging. Thus, we are alternatively working to establish a risk evaluation method and criteria based on the collision probability (Pc) of SRM slag during its orbital lifetime. Based on ground firing tests, this study estimated the number and particle size of SRM slag in orbit emitted during the Epsilon and Epsilon S launch missions. The Pc per mission during the orbital lifetime was calculated and provisionally set to 10–3 for currently operational spacecraft. This paper discusses its acceptability to JAXA.

Galactic cosmic ray environment predictions for the NASA BioSentinel Mission, part 2:Post-mission validation

The BioSentinel CubeSat was deployed on the Artemis-I mission in November 2022 and has been continuously transmitting physical measurements of the space radiation environment since that time. Just before mission launch, we published computational model predictions of the galactic cosmic ray exposure expected inside BioSentinel for multiple locations and configurations. The predictions utilized models for the ambient galactic cosmic ray environment, radiation physics and transport, and BioSentinel geometry. Now that the nominal six-month BioSentinel mission has completed and some additional time has passed, those pre-launch predictions and additional model components can be validated. Dose-rate and linear energy transfer (LET) spectral measurements from the on-board dosimeter are presented along with a summary of the computational models used to calculate exposure quantities of interest. Sensitivity tests are performed to gauge the impact of various model choices on these quantities. Satellite data collected during the BioSentinel mission are used to provide some measure of independent validation for the galactic cosmic ray model used in the present calculations. It is shown that the combined models are in excellent agreement with the measured dose-rate. Model calculations agree well with measurement below ∼10 keV/µm and underpredict at higher LET. It is argued that the underprediction is likely due to detector response or low energy anomalous cosmic ray contributions able to reach the thinly shielded side of the on-board dosimeter.

Do transformer missions redirect values of mission-oriented projects? The case of the EU mission ‘Restore our Ocean and Waters’

Transformative mission-oriented innovation policy aims to redirect innovation, but evidence of this directional ability is limited. This paper examines whether transformer missions redirect values reflected by mission-oriented projects. We study the EU Mission ‘Restore our Ocean and Waters’ and use probabilistic topic modelling and thematic analyses to identify, conceptualize, and compare latent values described in 17 policy documents (i.e., strategic layer), 37 mission-oriented projects, and 809 mission-relevant projects (i.e., operational layer). We map how these values changed during the mission launch. The results of this study are ambivalent. On the one hand, the mission launch corresponds with an increase of funded projects of which mission-oriented projects commonly frame efforts towards mission objectives. On the other hand, there is a misalignment between policy and project-level values while the prevalence of project-level values remained largely unaffected by the mission. These mixed results provide a more nuanced understanding of transformer missions’ directional abilities.

Design and characterization of a pyroshock reduction structure based on local resonance mechanisms

In the spacecraft Pyrotechnic shock process, the explosion generated by the strong shock wave and preload force release of the vehicle structure produces a transient, high-frequency, and high-amplitude shock response, resulting in a harsh shock environment prone to failure or damage to many precision equipment or components on the spacecraft, a fatal impact on the launch mission. This paper designed a local resonance shock mitigation structure based on local resonance theory for the Pyrotechnic shock environment and optimized the parameters of the structure by the genetic algorithm. A Pyrotechnic shock simulation experimental device was built to verify the impact reduction effect of the designed shock reduction structure. This experimental device can well restore the pyrotechnic shock environment. In addition, a finite element simulation model was established, and the impact reduction effect of the protective structure was verified both numerically and experimentally. The experimental and numerical analysis results show that the impact response decays significantly in the structural band gap range with the same transfer path, and the shock response spectrum amplitude decreases 9.8 dB in the 100–10,000 Hz frequency band.

Estimating software reliability using size-biased modelling

Software testing is an important step in software development where inputs are administered repeatedly to detect bugs present in the software. In this paper, we have considered the estimation of total number of bugs and software reliability as a size-biased sampling problem by introducing the concept of eventual bug size as a latent variable. We have developed a Bayesian generalised linear mixed model (GLMM) using software testing detection data to estimate software reliability and stopping phase. The model uses size-biased approach where the probability of detecting a bug is an increasing function of eventual size of the bug which is as an index for the potential number of inputs that may eventually pass through the bug. We have tested the sensitivity of the reliability estimates by varying the number of inputs and detection probability via a simulation study and have found that the key parameters could be accurately estimated. Further, we have applied our model to two empirical data sets – one from a commercial software and the other from ISRO launch mission software testing data set. The hierarchical modelling approach provides a unified modelling framework that may find applications in other fields (e.g. hydrocarbon explorations) apart from software management.

PlatoSim: an end-to-end PLATO camera simulator for modelling high-precision space-based photometry

Context. PLAnetary Transits and Oscillations of stars (PLATO) is the ESA M3 space mission dedicated to detect and characterise transiting exoplanets including information from the asteroseismic properties of their stellar hosts. The uninterrupted and high-precision photometry provided by space-borne instruments such as PLATO require long preparatory phases. An exhaustive list of tests are paramount to design a mission that meets the performance requirements and, as such, simulations are an indispensable tool in the mission preparation. Aims. To accommodate PLATO’s need of versatile simulations prior to mission launch that at the same time describe innovative yet complex multi-telescope design accurately, in this work we present the end-to-end PLATO simulator specifically developed for that purpose, namely PlatoSim. We show, step-by-step, the algorithms embedded into the software architecture of PlatoSim that allow the user to simulate photometric time series of charge-coupled device (CCD) images and light curves in accordance to the expected observations of PLATO. Methods. In the context of the PLATO payload, a general formalism of modelling, end-to-end, incoming photons from the sky to the final measurement in digital units is discussed. According to the light path through the instrument, we present an overview of the stellar field and sky background, the short- and long-term barycentric pixel displacement of the stellar sources, the cameras and their optics, the modelling of the CCDs and their electronics, and all main random and systematic noise sources. Results. We show the strong predictive power of PlatoSim through its diverse applicability and contribution to numerous working groups within the PLATO mission consortium. This involves the ongoing mechanical integration and alignment, performance studies of the payload, the pipeline development, and assessments of the scientific goals. Conclusions. PlatoSim is a state-of-the-art simulator that is able to produce the expected photometric observations of PLATO to a high level of accuracy. We demonstrate that PlatoSim is a key software tool for the PLATO mission in the preparatory phases until mission launch and prospectively beyond.

Dynamic modeling and motion prediction of two projectiles launched successively underwater

The technology of successive underwater launching of multiple projectiles is a growing trend in military development. However, the process is complex, and the wake field formed after the launch of the first projectile can significantly impact the trajectories and attitudes of the subsequent projectiles. This can potentially lead to mutual collisions or destabilization of motion among the projectiles, resulting in mission failures. In this paper, a mathematical model incorporating unknown parameters is proposed to effectively describe the underwater motion of projectiles. To refine this model, we employed a system identification method that utilizes experimentally validated numerical simulation data to solve for the unknown parameters. The model is then used to predict the trajectory and attitude changes of the projectiles across various launching conditions. The results indicate that to ensure a successful launch mission, certain adjustments must be made. These adjustments include increasing the launching velocity within acceptable limits, extending the launch time interval, increasing the spatial distances between projectiles, and reducing the platform velocity.

Optimum Design of a Reusable Spacecraft Launch System Using Electromagnetic Energy: An Artificial Intelligence GSO Algorithm

Due to its advantages of high acceleration, reusability, environmental protection, safety, energy conservation, and efficiency, electromagnetic energy has been considered as an inevitable choicefor future space launch technology. This paper proposes a novel three-level orbital launch approach based on a combination of a traditional two-level orbital launch method and an electromagnetic boost (EMB), in whichthe traditional two-level orbital launch consists of a turbine-basedcombined cycle (TBCC) and a reusable rocket (RR). Firstly, a mathematical model of a multi-stage coil electromagnetic boost system is established to develop the proposed three-level EMB-TBCC-RR orbital launch approach, achieving a horizontal take-off–horizontal landing (HTHL) reusable launch. In order to optimize the fuel quality of the energy system, an artificial intelligence algorithmparameters-sensitivity-basedadaptive quantum-inspiredglowworm swarm optimization (AQGSO)is proposed to improve the performance of the electromagnetic boosting system. Simulation results show that the proposed AQGSO improves the global optimization precision and convergence speed. By using the proposed EMB-TBCC-RR orbital launch system and the optimization approach, the required fuel weight was reduced by about 13 tons for the same launch mission, and the energy efficiency and reusability of the spacecraft was greatly improved. The spacecraft can be launched with more cargo capacity and increased payload. The proposed novel three-level orbital launch approach can help engineers to design and optimize the orbital launch system in the field of electromagnetic energy conversion and management.

Development of a deployable mechanism for a conical optical baffle for a small satellite

Baffles in optical systems on a satellite, such as imaging payloads and star trackers, involve structures with large empty volumes that take up significant payload volume. Limiting the volume of optical systems is essential, considering the demand for small satellite platforms and rideshare launch missions. A baffle structure with empty volume can be configured to stow in a packed configuration during launch and deploy to its operational configuration once the satellite is in orbit. An analytical model for deployable conical baffles is developed to trade off various design parameters. A simple and reliable deployment mechanism with large torsion springs is designed and developed for an optical baffle. A prototype baffle is developed with representative materials, and functional testing is carried out. The deployment tests were carried out to measure the shocks and deployment accuracy. The baffle in its stowed configuration performed satisfactorily and indicated no damages when subjected to vibration testing. Further, the deployment mechanism performed adequately at a low temperature of -40°C and at 0.062 mPa during the cold functional test in a thermovac chamber. The baffle is a precursor to the flight model, which will be launched as a part of a hyperspectral imager, CyanoSat of CSIRO.

Particle monitoring capability of the Solar Orbiter Metis coronagraph through the increasing phase of solar cycle 25

Context. Galactic cosmic rays (GCRs) and solar particles with energies greater than tens of MeV penetrate spacecraft and instruments hosted aboard space missions. The Solar Orbiter Metis coronagraph is aimed at observing the solar corona in both visible (VL) and ultraviolet (UV) light. Particle tracks are observed in the Metis images of the corona. An algorithm has been implemented in the Metis processing electronics to detect the VL image pixels crossed by cosmic rays. This algorithm was initially enabled for the VL instrument only, since the process of separating the particle tracks in the UV images has proven to be very challenging. Aims. We study the impact of the overall bulk of particles of galactic and solar origin on the Metis coronagraph images. We discuss the effects of the increasing solar activity after the Solar Orbiter mission launch on the secondary particle production in the spacecraft. Methods. We compared Monte Carlo simulations of GCRs crossing or interacting in the Metis VL CMOS sensor to observations gathered in 2020 and 2022. We also evaluated the impact of solar energetic particle events of different intensities on the Metis images. Results. The study of the role of abundant and rare cosmic rays in firing pixels in the Metis VL images of the corona allows us to estimate the efficiency of the algorithm applied for cosmic-ray track removal from the images and to demonstrate that the instrument performance had remained unchanged during the first two years of the Solar Orbiter operations. The outcome of this work can be used to estimate the Solar Orbiter instrument’s deep charging and the order of magnitude for energetic particles crossing the images of Metis and other instruments such as STIX and EUI.

Trajectory optimization of rocket recovery based on Neural Network and Genetic Algorithm

After the completion of the launch mission, the soft landing recovery and reuse of the carrier rocket’s first-stage can effectively control the landing area to ensure safety and significantly reduce the cost of space launch transportation. The trajectory optimization of the whole process from the first section to the landing site is significant to fuel saving. In the entire process, the first-stage needs to go through three startup ignitions of course adjustment, power deceleration, and vertical landing. For this segmented fuel optimization problem, optimizing the thrust size and direction during three sections and the switching time between each section is necessary. Optimizing the vertical landing section is essential to ensure the accuracy of landing position and speed, which greatly complicates the whole process’s optimization. Therefore, the optimization process of the vertical landing is substituted by a neural network predictor, which is used to obtain the mapping relationship between the initial state of the vertical landing section and the fuel consumption of the segment. Besides, the thrust profiles of the first two startup sections are reasonably handled based on physical cognition. The combination of convex optimization and neural network successfully converted the multi-stage optimal control problem into a parameter optimization problem and solved it by a genetic algorithm. Optimization results were compared with the conventional method, which indicated its superiority.

Review of Launch Vehicle Engine PHM Technology and Analysis Methods Research

The reliability and safety of launch vehicle launch missions might be effectively increased thanks to the fault prediction and health management (PHM) technology of engines, which could also improve with problem diagnostics and decrease the cost of operation and maintenance overhaul. This paper combines the equipment characteristics and the current state of safeguarding for large, complex space systems, introduces the intelligent launch vehicle engine PHM technology methods that are being gradually implemented in space systems, and discusses and compares fault detection and health assessment techniques. Subsequently, analysis of the measurement signals from a rocket engine was performed using an example, and it was shown that the established comprehensive health assessment structure, which is based on the fault prediction algorithm method and the fuzzy comprehensive assessment method, could successfully realize the effectiveness of the rocket engine system health assessment, which had an outstanding application value.

Effectiveness Evaluation of Medium-sized Carrier Rockets Based on ADC Method

Using scientific evaluation methods to evaluate the mission effectiveness and cost-efficiency of rockets is one of the important topics in the development of rocket models. Aiming at the problem that the effectiveness evaluation of carrier rockets cannot be quantitatively analyzed, this paper takes the medium-sized carrier rockets, covering both new and old generation ones in service, as the object of establishing a simplified inherent capability index system. The ADC method is utilized to quantitatively evaluate the availabilities, dependabilities, and capabilities of various types of rockets and calculates the corresponding effectiveness and cost efficiencies when performing launch missions in LEO, GTO, and SSO orbits. The results show that Model II has excellent mission effectiveness, which is particularly suitable for medium and high orbit missions; the cost-efficiency of Model III is as good as that of the former, and it can complete many tasks; but Model I is outdated.

Convex optimization for post-fault ascent trajectory replanning using auxiliary phases

For ascent trajectory replanning after non-fatal dynamic faults, the terminal orbital constraints and optimization indexes under different replanning strategies usually have very strong nonconvexity, which brings significant challenges to real-time guidance. This paper introduces auxiliary phases to convexify the terminal constraints and objective functions losslessly, significantly improving the convergence and injection accuracy. After lossless and successive convexification, the original problems are converted into a series of convex subproblems. The replanning algorithm is then presented, including the fault detection module, the residual carrying capacity determination module, and the task degradation module. Two typical launch missions are simulated to verify the proposed method's pmethoderformance. Numerical results show that the method can always converge efficiently and reliably in different scenarios and has great potential for real-time onboard applications.

Ascent adaptive energy management method for solid rocket‐powered hypersonic vehicle under uncertainties

SummaryThe solid rocket booster is widely used in the launch mission for hypersonic vehicles nowadays, whose ascent energy management is still a challenging problem due to the inherent dynamic nonlinearity. This paper casts the problem into an equivalent ascent guidance one and proposes a model predictive static programming (MPSP) based solution. The MPSP‐based method is a computationally efficient solver that adapts to different energy demands while guaranteeing the satisfaction of terminal constraints. To further improve the performance of MPSP in this problem, a Bézier spline guidance method is proposed to generate high‐quality reference trajectories such that the MPSP can converge with high accuracy while satisfying the real‐time requirement. Additionally, an online parameter estimation based on the extended Kalman filter is employed to avoid large terminal state deviations incurred by parametric uncertainties during the Bézier curve computation and linearization in MPSP. Numerical simulations with different hard terminal constraints and uncertainties are conducted to demonstrate the effectiveness and robustness of the proposed algorithm. The simulation results show that our proposed algorithm can guide the hypersonic vehicle to a given terminal state under uncertainties and outperforms several existing ascent energy management methods.

Ionospheric correction of S-band tracking radar data using NavIC S-band signals in missile test range applications

AbstractIn missile test ranges, complex missions demand precise trajectory generated by radar. Both the radar and Global Navigation Satellite System (GNSS) signals are affected by atmospheric effects, degrading their accuracy and performance. The Indian Regional Navigation Satellite System/Navigation with Indian Constellation (IRNSS/NavIC) transmits signals in the S-band together with the L-band. This paper presents a novel experimental technique to improve the tracking accuracy of S-band radars using the concurrent NavIC S-band signal. The ionospheric delay using the NavIC S-band signal is calculated first, and the results are used to improve the trajectory data of simultaneously operating S-band radars. This is a unique application of the NavIC S-band signals apart from its conventional usage. During a launch mission, for low elevation angles, the ionospheric error is found to be ~130 m while at higher elevation angles the error values are found to be ~1–3 m. The concept is validated using data from a missile test mission. This report on the use of S-band GNSS signals for the correction of S-band radar range data offers a clear advantage of simplicity and accuracy.

FGS, a multi-mission space gamma-ray spectrometer: Design optimization and first results

Following the failure of the TARANIS (Tool for the Analysis of RAdiation from lightNIng and Sprites) mission launch[1], the French space agency (CNES) funded a R&D program with APC and LESIA laboratories to develop a new gamma-ray spectrometer. The first studies started in 2021 and lead to a new design called FGS (Fast Gamma-ray Spectrometer) based on new GAGG scintillators readout by SiPM and analysed by the IDEAS/APOCAT fast ASIC. This program’s main objective is to build a space qualified FGS prototype before 2024. FGS scientific specifications are based on Terrestrial Gamma-ray Flashes (TGF) science studies but this spectrometer could also be used or optimized for other missions: solar science, astrophysical observations (Gamma-Ray Bursts) or planetology studies. The main instrumental objectives are to detect gamma rays in the [20keV–20MeV] energy range with high count rate abilities and a large detection surface. In this paper, we will present our FGS concept and the first spectroscopic results we obtained, consistent on ground with our scientific requirements.

НАЗЕМНА ПІДТРИМКА КОСМІЧНОЇ МІСІЇ PARKER УКРАЇНСЬКИМИ НИЗЬКОЧАСТОТНИМИ РАДІОТЕЛЕСКОПАМИ

Subject and Purpose. The sporadic radio emissions coming from the Sun in a broad frequency range contain a lot of important information concerning the solar corona, parameters of the radio frequency sources therein, and the parameter variations resulting from active processes on and about the Sun. These have been the reasons for recent launches of the space missions intended for stud- ying the Sun and its corona, such as the Parker Solar Probe (PSP) and the Solar Orbiter. The present work is aimed at demonstrating effectiveness of the ground-based support for the space missions, the PSP before all, which is provided by the large Ukrainian radio telescopes of the decameter wavelength range. Another purpose has been cross-calibration of the space-borne radiometer against calibrated data from a ground-based instrument. Methods and Methodology. One of the remote diagnosis techniques widely used with respect to the solar corona is to analyze parameters of the radio frequency emissions from sources lying at a variety of altitudes within the corona. The methodology of such joint, space-borne/terrestrial investigations suggests simultaneous observations of certain individual events during closest approach of the space probe PSP to the Sun, with analysis over a widest possible frequency range. The data obtainable within overlapping fre- quency bands are proposed for calibrating the on-board radio receivers of the space probe. Results. The methodology proposed for joint, space-based / terrestrial observations has been substantiated. Data from the UTR-2 and URAN-2 radio telescopes and the space probe PSP have been used to plot the dynamic and the polarization spectra of the June 9, 2020 solar bursts, with identification and comparison of the relevant individual events. A joint dynamic spectrum of these bursts has been obtained for the frequency band of 0.5 to 32 MHz. The calibrated data from the ground-based radio telescopes have allowed performing cross-calibration of the HF receiver in the FIELDS-PSP data taking module within the frequency band of 10 to 18 MHz. Conclusions. The paper has provided evidence of an effective ground-based support for the space mission PSP on the part of large Ukrainian radio telescopes. Examples of joint observations have been given, and a methodology described which is employed for cross-calibrating the HF receivers of the FIELD-PSP module. Prospects are outlined of further ground-based support for solar space research missions.

Evaluation of the Metrological Integrated Support Capability of Launch Site Based on FUZZY-AHP

The metrological integrated support capability is an important part of the equipment support capability of the launch site. To realize the quantitative description and scientific evaluation of the metrological integrated support capability, the FUZZY-AHP method is introduced. Based on the study of the factors affecting the capability, the evaluation index system is constructed from four aspects of personnel capability, equipment capability, technical support capability, and comprehensive management capability. A multilevel evaluation model of the metrological support capability is established by using the analytic hierarchy process. Then, with the fuzzy mathematics method, the rules of the fuzzy evaluation for the quantitative and qualitative indicators are formulated. Finally, combined with a launch mission, the FUZZY-AHP method is used to evaluate the metrological integrated support capability. The method is scientific and feasible, which provides an effective reference for the subsequent evaluation of the metrological integrated support capability.