The performance of the BepiColombo Laser Altimeter (BELA) prior launch and prospects for Mercury orbit operations

We explore the perspectives of the BepiColombo Laser Altimeter (BELA) onboard ESA / JAXA's Mercury mission BepiColombo and present an updated semi-analytical instrument performance model, in which we estimate signal-to-noise ratio, single shot probability of false detection, range errors and the accuracy of pulse width reconstruction. The model is generally applicable for other laser altimeters using matched filter algorithms for pulse detection and has been validated against the recently tested BELA flight model after integration on the BepiColombo spacecraft. Further, we perform numerical simulations of the instrument performance expected in orbit about Mercury. In particular, we study the measurement accuracy of topography, slopes and surface roughness, which will allow us to estimate local and global topographic coverage based on the current trajectory design. We also assess the potential for measuring the tidal Love number h2 using cross-over points, which we estimate to be constrained with an absolute accuracy of 0.14 corresponding to a relative accuracy of about 18% after two years in Mercury orbit.