BepiColombo Laser Altimeter - BELA

Science

A fundamental task of exploratory space missions is to characterize and measure the figure, topography, and surface morphology of the target planet. A state of the art tool for this task is a laser altimeter because it can provide absolute topographic height and position with respect to a object-centred co-ordinate system. The technology of laser altimetry for interplanetary spaceflight is new in Europe. The BepiColombo Laser Altimeter (BELA) will be the first such instrument developed for a European space mission. It will fly on the European Space Agency's BepiColombo mission to Mercury and will measure the

  1. figure parameters of Mercury to establish accurate reference surfaces
  2. topographic variations relative to the reference figures and a geodetic network based on accurately measured positions of prominent topographic features
  3. tidal deformations of the surface
  4. surface roughness, local slopes and albedo variations, also in permanently shaded craters near the poles

BELA will form an integral part of a larger geodesy and geophysics package, incorporating radio science and stereo imaging. Although stand-alone instruments in their own right, the synergy between these instruments will dramatically enhance the scientific capability. The synergy will cover the problems of planetary figure and gravity field determination, interior structure exploration, surface morphology and geology, and extend into the measurements of tidal deformations.

You can go directly to our science pages on laser altimetry studies and BELA testing by following the links to the web site of the Planetary Imaging Group (PIG).

Current research

Currently we are studying the in-orbit performance of BELA instrument. Based on the data from latest BELA laboratory tests, we use an accurate in-orbit modelling of BELA instrument, where we consider the impact of local slopes and roughness, Sun incidence angle, pointing uncertainties, degradation effects and systematic noises modelling on the noise characteristics and on also the probability of false detection model.

The goal of this study is to determine the expected accuracy of the measurements of surface properties (local slopes/roughness and albedo) and the expected DTM resolution based on BELA data. We will determine the science performance of the instrument on different types of terrains and inside permanently shaded craters.

We are also studding the impact of BELA altimetry on the spacecraft orbit reconstruction. The main goal of BELA is to improve Mercury topography and its surface characteristics. However, when combined with Doppler tracking data, it is also possible to use the altimetry data to improve MPO orbit reconstruction and also contribute to the determination of Mercury geophysical parameters (e:g:, tidal deformations and rotational parameters). For this study we use the planetary extension of the Bernese Software (BSW). The latter is an advanced space data processing software develop at the Astronomical Institute of the University of Bern (AIUB).

Publications

  • Kallenbach, R., E. Murphy, B. Gramkow, M. Rech, K. Weidlich, T. Leikert, R. Henkelmann, B. Trefzger, B. Metz, H. Michaelis, K. Lingenauber, S. DelTogno, T. Behnke, N. Thomas, D. Piazza, and K. Seiferlin, (2013), Space-qualified laser system for the BepiColombo Laser Altimeter, Applied Optics, 52, 8732-8746 doi:10.1364/AO.52.008732.
  • Chakraborty, S., N. Thomas, M. Affolter, J. Neubert, S. Graf, D. Piazza, T. Beck, M. Gerber, G. Roethlisberger , K. Seiferlin and K. Gunderson, (2012), High accuracy alignment concept for receiver and transmitter in a laser altimeter system, Applied Optics, 51, 4907, doi: 10.1364/AO.51.004907.
  • Beck, T., A. Bieler, and N. Thomas, (2012), Numerical thermal mathematical model correlation to thermal balance test using adaptive particle swarm optimization (APSO), Applied Thermal Engineering, accepted, doi:10.1016/j.applthermaleng.2012.01.027.
  • Beck, T., B.S. Luethi, G. Messina, D. Piazza, K. Seiferlin, and N. Thomas, (2011), Thermal Analysis of a Reflective Baffle Designed for Space Applications, Acta Astronautica, 69, 323-334, doi:10.1016/j.actaastro.2011.03.014.
  • Thomas, N., T. Beck, S. Chakraborty, M. Gerber, S. Graf, D. Piazza, G. Roethlisberger, (2011), A wide‐beam solar simulator for simulating the solar flux at the orbit of Mercury, Measurement Science and Technology, Meas. Sci. Technol., 22, 065903, doi: 10.1088/0957-0233/22/6/065903.
  • Gunderson, K. and N.Thomas, (2010) BELA receiver performance modeling over the BepiColombo mission lifetime, Planetary and Space Science, 58, 309-318.
  • Gunderson, K.S., N.Thomas, T.Spohn, and K.Seiferlin, (2004),A tradeoff investigation for the BepiColombo Laser Altimeter design, Instruments, Science, and Methods for Geospace and Planetary Remote Sensing. Edited by Nardell, Carl A.; Lucey, Paul G.; Yee, Jeng-Hwa; Garvin, James B. Proceedings of the SPIE, 5660, 117-127.