arXiv subjects

Stijn Lemmens

Publications and source records attributed to Stijn Lemmens.

6 recordsLinked to original sources

arXiv2026

Uncertainty Quantification Study of a Re-entry Breakup

The uncertainty associated with breakup events that occur during atmospheric re-entry is severe. Limited attempts to gain a better knowledge of this environment have included the use of breakup recorder-type sensor capsules that are designed to escape the demising debris cloud and survive in order to transmit data. This work models a breakup recorder undergoing this process as a rigid body experiencing hypersonic aerothermodynamic loads alongside collision dynamics with components of the demising container vehicle. The re-entry of the Edoardo Amaldi Automated Transfer Vehicle (ATV3) and the recorder placed on board, the Re-Entry Breakup Recorder 4 (REBR4) is studied in the present work. After a deterministic exploration of the nature of the dynamics of the problem, uncertainty quantification is performed to investigate the effects of initial spacecraft state, REBR detachment conditions and spacecraft fragmentation states. From this data, inferences about the nature of the real re-entry event indicate that detachment of the recorder from the cargo bay prior to main breakup events is more likely than the alternate hypothesis of the container vehicle experiencing high rotation rates.

cs.CE↗

arXiv2024

The space environment particle density in Low Earth Orbit based on two decades of in-situ observation

Currently the only method to establish the prevalence of particles, space debris or meteoroids, sized between 1 micrometre and a few centimetres, in Earth orbit is by instruments or witness plates dedicated to in-situ detection. Derived usable datasets are remarkably scarce and generally only cover a short period of time and a single orbital region. Nonetheless, space environment models use those limited datasets as anchor points to extrapolate results to the entirety of Earth orbit, from the beginning of the space age to decades into the future. Here we present a readout of over 20 years of DEBris In orbit Evaluator 1 (DEBIE-1), an in-situ detector that was launched in October 2001, providing the longest continuous set of measurements available to date. The dataset has not been used in the generation of space environment models and hence provides a first independent source for the detection of environment changing events and for the calibration of long term evolution models.

astro-ph.EP↗

arXiv2021

Medium-term predictions of F10.7 and F30 cm solar radio flux with the adaptive Kalman filter

The solar radio flux at F10.7 cm and F30 cm is required by most models characterizing the state of the Earth's upper atmosphere, such as the thermosphere and ionosphere to specify satellite orbits, re-entry services, collision avoidance maneuvers and modeling of space debris evolution. We develop a method called RESONANCE ("Radio Emissions from the Sun: ONline ANalytical Computer-aided Estimator") for the prediction of the 13-month smoothed monthly mean F10.7 and F30 indices 1-24 months ahead. The prediction algorithm includes three steps. First, we apply a 13-month optimized running mean technique to effectively reduce the noise in the radio flux data. Second, we provide initial predictions of the F10.7 and F30 indices using the McNish-Lincoln method. Finally, we improve these initial predictions by developing an adaptive Kalman filter with the error statistics identification. The root-mean-square-error of predictions with lead times from 1 to 24 months is 5-27 sfu for the F10.7 and 3-16 sfu for F30 index, which statistically outperforms current algorithms in use. The proposed approach based on Kalman filter is universal and can be applied to improve the initial predictions of a process under study provided by any other forecasting method. Furthermore, we present a systematic evaluation of re-entry forecast as an application to test the performance of F10.7 predictions on past ESA re-entry campaigns for payloads, rocket bodies, and space debris that re-entered from June 2006 to June 2019. The test results demonstrate that the predictions obtained by RESONANCE in general also lead to improvements in the forecasts of re-entry epochs.

astro-ph.SR↗

arXiv2019

Extension of the King-Hele orbit contraction method for accurate, semi-analytical propagation of non-circular orbits

Numerical integration of orbit trajectories for a large number of initial conditions and for long time spans is computationally expensive. Semi-analytical methods were developed to reduce the computational burden. An elegant and widely used method of semi-analytically integrating trajectories of objects subject to atmospheric drag was proposed by King-Hele (KH). However, the analytical KH contraction method relies on the assumption that the atmosphere density decays strictly exponentially with altitude. If the actual density profile does not satisfy the assumption of a fixed scale height, as is the case for Earth's atmosphere, the KH method introduces potentially large errors for non-circular orbit configurations. In this work, the KH method is extended to account for such errors by using a newly introduced atmosphere model derivative. By superimposing exponentially decaying partial atmospheres, the superimposed KH method can be applied accurately while considering more complex density profiles. The KH method is further refined by deriving higher order terms during the series expansion. A variable boundary condition to choose the appropriate eccentricity regime, based on the series truncation errors, is introduced. The accuracy of the extended analytical contraction method is shown to be comparable to numerical Gauss-Legendre quadrature. Propagation using the proposed method compares well against non-averaged integration of the dynamics, while the computational load remains very low.

astro-ph.EP↗

arXiv2018

Radar-based Re-Entry Predictions with very limited tracking capabilities: the GOCE case study

The problem of the re-entry predictions of GOCE has been deeply investigated in the literature, due to the large amount of data, mainly radar and GPS, available until re-entry. The accurate GPS and attitude measurements are used to compute a precise reference orbit for the three weeks of decay, and to extrapolate the ballistic coefficient evolution of the object. In previous works, the capabilities of radar-based solutions for the re-entry predictions of GOCE and of similar objects were investigated, focusing on the german TIRA radar. In this work we have performed additional analysis, focusing on the northern european radar EISCAT-UHF, located in Tromsø, Norway. This sensor, conceived for atmospheric studies, has recently been considered for space debris applications. Due to its limited tracking capabilities, we are interested in testing its effectiveness in supporting re-entry predictions. We have simulated reliable re-entry prediction scenarios, with different availability of data from EISCAT and TIRA. The main conclusion is that, provided a suitable amount of observations, EISCAT-based re-entry predictions are comparable to TIRA-based, but also to GPS and TLE-based, corresponding ones. In general, EISCAT is not able to determine an orbit with the same accuracy of TIRA, but the results are equivalent in terms of re-entry predictions, if we consider the relevant parameters involved and their effects on the re-entry time. What is very important is the difficulty in predicting atmospheric and attitude significant variations in between the current epoch and the actual re-entry. Thus, it is not easy to keep the accuracy of predictions much lower than 10% of the residual lifetime, apart from cases with constant area to mass ratio, and low atmospheric variations with respect to the models. An experiment with real data is presented for the object 2012-006K, with consistent results.

astro-ph.EP↗

arXiv2017

The observing campaign on the deep-space debris WT1190F as a test case for short-warning NEO impacts

On 2015 November 13, the small artificial object designated WT1190F entered the Earth atmosphere above the Indian Ocean offshore Sri Lanka after being discovered as a possible new asteroid only a few weeks earlier. At ESA's SSA-NEO Coordination Centre we took advantage of this opportunity to organize a ground-based observational campaign, using WT1190F as a test case for a possible similar future event involving a natural asteroidal body.

astro-ph.EP↗