Visual Landmark Constellation matching for spacecraft pinpoint landing Bach Van Pham * , Simon Lacroix † and Michel Devy ‡ LAAS-CNRS, University of Toulouse, 7 Avenue du Colonel Roche, Toulouse Cedex 4, 31077, France Marc Drieux § EADS-ASTRIUM, 66 Route de Verneuil, Les Mureaux Cedex , 78133, France Christian Phillipe ¶ ESTEC/ESA, Keplerlaan 1 , Postbus 299 , 2200 AG Noordwijk , The Netherlands This paper presents a vision-based approach to estimate the absolute position of a plan- etary lander during the last stages of the descent. The approach relies on the matching of landmarks detected in the descent imagery with landmarks previously detected in or- biter images. The matching process must be robust with respect to scale and radiometry differences in the image data: it mainly relies on the geometric repartition of the land- marks, rather than on radiometric signatures computed from the image signal. It must also satisfy other requirements like low memory requirement and efficient hardware imple- mentation due to spatial system’s constraints. First results using a simulator are presented and discussed. Nomenclature H, h Spacecraft or obiter’s height M,m Image’s sizes F,f Camera’s field of view R, r Image’s resolution s Scale difference br Inner circle’s radius pr Outer circle’s radius D Pixelics distance nRings Number of rings nW edges Number of wedges (sectors) p Landmark’s signature L, K Landmarks P Landmark’s warped position δ Landmarks minimum distance distV ector Vector distance ε Vector distance threshold AF Affine Transformation U Image’s 2D position M Surface’s 3D position K Camera’s intrinsic matrix R Camera’s image rotation matrix * PhD Student, Group Robotics and Interactive Systems † Research Scientist, Group Robotics and Interactive Systems ‡ Research Scientist, Group Robotics, Action and Perception § Sensors engineering and Image processing Enginneer ¶ Head of Guidance, Navigation and Control Section 1 of 13 American Institute of Aeronautics and Astronautics