Integration and Testing of the Nanosatellite Optical Downlink Experiment
Session
Session 2: Communications
Abstract
CubeSat sensor performance continues to improve despite the limited size, weight, and power (SWaP) available on the platform. Missions are evolving into sensor constellations, demanding power-efficient high rate data downlink to compact and cost-effective ground terminals. SWaP constraints onboard nanosatellites limit the ability to accommodate large high gain antennas or higher power radio systems along with high duty cycle sensors. With the growing numbers of satellites in upcoming scientific, defense, and commercial constellations, it is difficult to place the high-gain burden solely on the ground stations, given the cost to acquire, maintain, and continuously operate facilities with dish diameters from 5 meters to 20 meters. In addition to the space and ground terminal hardware challenges, it is also increasingly difficult and sometimes not possible to obtain radio frequency licenses for CubeSats that require significant bandwidth. Free space optical communications (lasercom) can cost-effectively support data rates higher than 10 Mbps for similar space terminal SWaP as current RF solutions and with more compact ground terminals by leveraging components available for terrestrial fiber optic communication systems, and by using commercial amateur-astronomy telescopes as ground stations. We present results from the flight unit development, integration, and test of the Nanosatellite Optical Downlink Experiment (NODE) space terminal and ground station, scheduled for completion by summer of 2017. NODE’s objective is to demonstrate an end-to-end solution based on commercial telecommunications components and amateur telescope hardware that can initially compete with RF solutions at >10 Mbps and ultimately scale to Gbps. The 1550 nm NODE transmitter is designed to accommodate platform pointing errors < 3 degrees. The system uses an uplink beacon from the ground station and an onboard MEMS fine steering mirror to precisely point the 0.12 degree (2.1 mrad) 200 mW transmit laser beam toward the ground telescope. We plan to downlink to an estalblished ground terminal at the Jet Propulsion Laboratory (JPL) Optical Communications Telescope Laboratory (OCTL) ground station as well as the new low-cost 30 cm amateur telescope ground station design to reduce overall mission risk. Moving beyond our initial laboratory prototyping captured in Clements et al. 2016 we discuss recent progress developing and testing the flight electronics, opto-mechanical structures, and controls algorithms, including demonstration of a hardware-in-the-loop test of the fine pointing system, for both the space and ground terminals. We present results of over-the-air testing of the NODE system, as we advance from benchtop to hallway to rooftop demonstrations. We will present thermal and environmental test plans and discuss experimental as well as expected results.
Presentation
Integration and Testing of the Nanosatellite Optical Downlink Experiment
CubeSat sensor performance continues to improve despite the limited size, weight, and power (SWaP) available on the platform. Missions are evolving into sensor constellations, demanding power-efficient high rate data downlink to compact and cost-effective ground terminals. SWaP constraints onboard nanosatellites limit the ability to accommodate large high gain antennas or higher power radio systems along with high duty cycle sensors. With the growing numbers of satellites in upcoming scientific, defense, and commercial constellations, it is difficult to place the high-gain burden solely on the ground stations, given the cost to acquire, maintain, and continuously operate facilities with dish diameters from 5 meters to 20 meters. In addition to the space and ground terminal hardware challenges, it is also increasingly difficult and sometimes not possible to obtain radio frequency licenses for CubeSats that require significant bandwidth. Free space optical communications (lasercom) can cost-effectively support data rates higher than 10 Mbps for similar space terminal SWaP as current RF solutions and with more compact ground terminals by leveraging components available for terrestrial fiber optic communication systems, and by using commercial amateur-astronomy telescopes as ground stations. We present results from the flight unit development, integration, and test of the Nanosatellite Optical Downlink Experiment (NODE) space terminal and ground station, scheduled for completion by summer of 2017. NODE’s objective is to demonstrate an end-to-end solution based on commercial telecommunications components and amateur telescope hardware that can initially compete with RF solutions at >10 Mbps and ultimately scale to Gbps. The 1550 nm NODE transmitter is designed to accommodate platform pointing errors < 3 degrees. The system uses an uplink beacon from the ground station and an onboard MEMS fine steering mirror to precisely point the 0.12 degree (2.1 mrad) 200 mW transmit laser beam toward the ground telescope. We plan to downlink to an estalblished ground terminal at the Jet Propulsion Laboratory (JPL) Optical Communications Telescope Laboratory (OCTL) ground station as well as the new low-cost 30 cm amateur telescope ground station design to reduce overall mission risk. Moving beyond our initial laboratory prototyping captured in Clements et al. 2016 we discuss recent progress developing and testing the flight electronics, opto-mechanical structures, and controls algorithms, including demonstration of a hardware-in-the-loop test of the fine pointing system, for both the space and ground terminals. We present results of over-the-air testing of the NODE system, as we advance from benchtop to hallway to rooftop demonstrations. We will present thermal and environmental test plans and discuss experimental as well as expected results.
