EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Precise orbits for the lunar navigation system: challenges in the modeling of perturbing forces and broadcast orbit representation

Krzysztof Sośnica1, Radosław Zajdel1, Grzegorz Bury1, Mauro Di Benedetto2, Daniele Durante2, Andrea Sesta2, Agnes Fienga3, Nicola Linty4, Jacobo Belfi5, and Luciano Iess2
Krzysztof Sośnica et al.
  • 1Wroclaw University of Environmental and Life Sciences, Institute of Geodesy and Geoinformatics, Satellite Geodesy Department, Wroclaw, Poland (
  • 2Sapienza, Università di Roma, via Eudossiana 18, Rome, Italy
  • 3GéoAzur, CNRS, Observatoire de la Côte d’Azur, Université Côte d’Azur 250 Av. A. Einstein, 06560 Valbonne, France
  • 4Argotec s.r.l., via Cervino 52, 10155 Turin, Italy
  • 5Leonardo S.p.A, Viale Europa snc, IT-20014, Nerviano (MI), Italy

In the framework of the European Space Agency’s Moonlight program, a satellite navigation system is planned for positioning, navigation, timing, and communication on the Moon.  The constellation will consist of three or four lunar orbiters in eccentric orbits – with periselene above the northern hemisphere and aposelene above the southern hemisphere; the latter is of special interest in terms of future lunar missions. The eccentric orbits introduce a challenge for precise orbit determination, because large gravity perturbations due to the lunar gravity field occur in the periselene passes, whereas the aposelene passes are associated with the smallest gravity gradients and thus the largest errors in orbit determination.

We evaluate the non-gravitational and gravitational perturbing forces acting on lunar orbiters in eccentric orbits. The simulated orbits consider lunar gravity field based on the GRAIL mission, gravity perturbations from the Sun, Earth, and planets considering Earth’s oblateness, tidal deformations, direct solar radiation pressure with lunar and Earth eclipses, albedo, antenna thrust, and relativistic effects. We discuss three methods of proposed representation of the broadcast orbits: based on Keplerian parameters and a set of one-per-revolution corrections (GPS-like or Galileo-like), based on Chebyshev polynomials with a variable number of coefficients and arc-length representation, and based on a series of positions and velocities (GLONASS-like). We discuss the advantages and limitations of all three representations and accuracies provided by different approaches depending on the number of assumed coefficients and arc lengths. Finally, we discuss the impact of inconsistent treatment of the origin, scale, and orientation of the lunar reference frame on the determined positions on the Moon. 

How to cite: Sośnica, K., Zajdel, R., Bury, G., Di Benedetto, M., Durante, D., Sesta, A., Fienga, A., Linty, N., Belfi, J., and Iess, L.: Precise orbits for the lunar navigation system: challenges in the modeling of perturbing forces and broadcast orbit representation, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-5575,, 2023.