The RF/ Optical Hybrid Antenna for Deep Space Communications

The RF/ Optical hybrid antenna (RFO) is a technology demonstration deployed at the Deep Space Network (DSN) site in Goldstone, California that has demonstrated the first simultaneous, co-located radiofrequency and optical communications with a spacecraft in deep space. As the demand for larger data volumes from planetary and exploration missions grows and the DSN’s capacity becomes increasingly constrained, upgrading and expanding the network is required to meet future mission needs. One option for this is the implementation of hybrid RF/ optical antennas which combine the advantages of optical communications for higher data rates with the reliability and weather resilience of RF communications that will be essential for maintaining mission-critical communications links. This paper presents a description of the RFO system architecture and design, consisting of a 1.5-m segmented primary mirror assembly with active mirror control installed into an existing 34-m RF beam waveguide antenna. The signal from the primary mirror is focused into an off-axis camera box mounted on the subreflector of the RF antenna, which contains optics to correct for aberration of the wavefront and control the position of the light spot. The box contains two cameras - one centered at 850 nm and one centered at 1550 nm, which are used to image calibration stars and the laser spot, respectively. The light from the 1550 nm channel is coupled by fiber to a superconducting nanowire single-photon detector (SNSPD) array and receiver subsystem. Results of data downlink demos from the DSOC payload on the Psyche spacecraft are also presented. Optical data rates of up to 41.6 Mbps from 0.12 AU were achieved, and data decoding was demonstrated at low data rates from a transmitter distance of over 1 AU.