A Laser Altimeter Performance Model and Its Application to BELA

The BepiColombo laser altimeter (BELA) is among the instruments that have been confirmed for flight aboard BepiColombo, which is the European Space Agency's cornerstone mission to the planet Mercury. The harsh environmental conditions around Mercury, accompanied by stringent spacecraft resource limitations, impose challenging constraints on BELA's architecture. To assist with the convergence upon an instrument configuration that can meet experiment requirements within the allocated resource budgets, we have developed a predominantly analytical model of the BELA system performance. The model draws on a diverse set of instrument and environmental parameters to predict signal-to-noise ratios, false detection probabilities (PFDs), and range-measurement uncertainties
$(sigma_ z)$
. The model shows that the baseline instrument is capable of meeting the performance requirements of
$hboxPFD ≪ 0.1$
and
$sigma_ z ≪ 10 hboxm$
out to altitudes of 1050 km. The PFD is shown to be the critical figure of merit for design considerations. PFD-conserving resource minimization favors transimpedance amplifier bandwidths as low as tens of megahertz. The instrument, the model, and a set of model outputs are described. The BepiColombo payload is scheduled for launch in 2013.