Spaceborn laser altimeter based on the single photon diode receiver and semiconductor laser transmitter

We are reporting on a novel design of a spaceborn altimeter based on single photon detection technique and a laser diode pulser as a transmitter. The MARS 94 planetary mission1 will carry, among others, the balloon probe experiment. The balloon with the scientific cargo in the gondole underneath will drift in the Mars atmosphere propelled by winds. Its altitude will range from zero, in the nighttime, to 5 km at noon. The accurate gondole altitude will be determined by the altimeter described below.