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David Gondelach

Postgraduate research student
M.Sc., B.Sc.

Academic and research departments

Surrey Space Centre.



Research interests

My publications


Armellin R, Gondelach D, San Juan J (2018) Multi-Revolution Perturbed Lambert?s Problem, Proceedings of 28th AIAA/AAS Space Flight Mechanics Meeting AIAA
The solution of multiple-revolution perturbed Lambert problems is a challenging task due
to the high sensitivity of the final state to variations of the initial velocity. In this work two
different solvers based on high order Taylor expansions and an analytical solution of the J2
problem are presented. In addition, an iteration-less procedure is developed to refine the
solutions in a dynamical model that includes J2 ? J4 perturbations. The properties of the
proposed approached are tested against transfers with hundreds of revolutions including those
required to solve the Global Trajectory Optimisation Competition 9.
Gondelach D, Armellin R, Lidtke A (2017) Ballistic coefficient estimation for re-entry
prediction of rocket bodies in eccentric orbits
based on TLE data,
Mathematical Problems in Engineering 2017 7309637 Hindawi Publishing Corporation
Spent rocket bodies in geostationary transfer orbit (GTO) pose
impact risks to the Earth's surface when they re-enter the Earth's at-
mosphere. To mitigate these risks, re-entry prediction of GTO rocket
bodies is required. In this paper, the re-entry prediction of rocket bod-
ies in eccentric orbits based on only Two-Line Element (TLE) data
and using only ballistic coefficient (BC) estimation is assessed. The
TLEs are preprocessed to filter out outliers and the BC is estimated
using only semi-major axis data. The BC estimation and re-entry pre-
diction accuracy are analyzed by performing predictions for 101 rocket
bodies initially in GTO and comparing with the actual re-entry epoch
at different times before re-entry. Predictions using a single and mul-
tiple BC estimates and using state estimation by orbit determination
are quantitatively compared with each other for the 101 upper stages.
Armellin Roberto, Gondelach David, San Juan J (2018) Multi-revolution Perturbed Lambert Problem Solvers, Journal of Guidance, Control, and Dynamics American Institute of Aeronautics and Astronautics
Lidtke Aleksander A., Gondelach David J., Armellin Roberto (2018) Optimising filtering of two-line element sets to increase re-entry prediction accuracy for GTO objects, Advances in Space Research Elsevier
Predicting re-entry epoch of space objects enables managing the risk to
ground population. Predictions are particularly difficult for objects in highlyelliptical
orbits, and important for objects with components that can survive
re-entry, e.g. rocket bodies (R/Bs). This paper presents a methodology to
filter two-line element sets (TLEs) to facilitate accurate re-entry prediction
of such objects. Difficulties in using TLEs for precise analyses are highlighted
and a set of filters that identifies erroneous element sets is developed. The
filter settings are optimised using an artificially generated TLE time series.
Optimisation results are verified on real TLEs by analysing the automatically
found outliers for exemplar R/Bs. Based on a study of 96 historical
re-entries, it is shown that TLE filtering is necessary on all orbital elements
that are being used in a given analysis in order to avoid considerably inaccurate

Additional publications