The Iris Deep-Space Transponder for the SLS EM-1 Secondary Payloads

Abstract

The Jet Propulsion Laboratory (JPL) is supporting several deep-space CubeSat missions selected as secondary payloads on the Space Launch System Exploration Mission One (SLS EM-1) launch of the Orion spacecraft. Seven secondary payload CubeSat missions (Lunar Flashlight, Near-Earth Asteroid Scout, BioSentinel, Lunar IceCube, CubeSat for Solar Particles, Lunar Polar Hydrogen Mapper, and ArgoMoon) have baselined the Iris deep space transponder as the main telecommunications and navigation transponder for their missions. Iris, first developed for JPL's interplanetary nanospacecraft pathfinder in relevant environment mission, and further developed for JPL's Mars Cube One mission, is a software-defined radio based on various JPL flight heritage designs. The transponder operates at X-band frequencies (7.2-GHz uplink, 8.4-GHz downlink) for compatibility with NASA's Deep Space Network, but the modular hardware design allows for further expanded capabilities into other frequency bands such as UHF, S-, and Ka-band. The transponder has a maximum power consumption of 35 W at 4-W radio frequency output, with uplink sensitivities down to −150 dBm. Various encoding schemes are available for the user to choose, from traditional convolutional coding with Reed Solomon concatenation to Turbo codes, and support for low-density parity-check coding is in the plan for future support. This paper will discuss the current capabilities and specifications of the Iris deep space transponder, as well as current hardware, firmware, and software implementations, and provide a short overview of future capabilities currently in the works.