Uplink beacon laser for Mars laser communication demonstration (MLCD)

Abstract

The requirements and design concepts for a ground-based laser assembly for transmitting an uplink beacon to a Mars bound spacecraft, carrying a laser communications terminal, are reported. The effects of the atmosphere are analyzed and drive the multi-beam design.

Deep-Space Optical Communications: Future Perspectives and Applications

“…Increased additive background noise when SPE angles are small further limits beacon-assisted acquisition, tracking, and pointing. Current studies that have analyzed beaconassisted acquisition and tracking from Mars farthest range with SPE angles of 2 -3 using 22-30-cm diameter space terminal aperture diameters suggest this to be viable [28], [29]. In these cases, the beacon is modulated and temporal acquisition is utilized in order to discriminate against background noise (see Section IV).…”

“…Since the ground transmitted lasers propagate through the atmosphere without adaptive optics corrections, multi-beaming [28], [77] is used to mitigate scintillation effects. Multibeaming is accomplished by transmitting multiple mutually incoherent, coaligned beamlets.…”

Safe laser–beam propagation for interplanetary links

“…Ground-to-space laser uplinks to Earth-orbiting satellites and deep space probes serve both as a beacon and an uplink command channel for deep space probes and Earth-orbiting satellites. 1 An acquisition and tracking point design to support a high bandwidth downlink from a 20-cm optical terminal on an orbiting Mars spacecraft typically calls for 2.5 kW of 1030-nm uplink optical power in 40 microradians divergent beams. 2 The NOHD (nominal ocular hazard distance) of the 1030nm uplink is in excess of 2E5 km, approximately half the distance to the moon.…”