No CubeSat-compatible, Deep Space Network (DSN)-compatible communications and navigation transponder exists at the time of this reporting. In order for CubeSats and other small spacecraft to go into deep space, a DSN-compatible capability is needed.

Iris is such a communications and navigation X-band deep space transponder consisting of an exciter board (26 dBm output at X-band), a receiver board (–120 dBm sensitivity), a power supply board, two antenna boards featuring four patch antennas (a transmit and receive in each of two directions), and a Marina-2 board for digital signal processing on a Virtex 5 FPGA (field-programmable gate array).

Existing transponders such as the Small Deep Space Transponder (SDST) or Universal Space Trans ponder (UST) are neither small enough nor of sufficiently low power for use on a CubeSat or other nano-spacecraft platform. The INSPIRE CubeSats are 10×10×30 cm in volume. The transponder is restricted to 10×10×5 cm volume, 500 g, and power input, in full transpond operation, of 10 W DC, all of which are about an order of magnitude less than currently available hardware.

The Radio Science Transponder Instrument consists of RF components and an analog phase locked loop backend supporting Doppler and ranging navigation data types only. Iris combines the RF portions with FPGA processing inherited from UST that allows uplink communication with subcarrier, downlink communication with or without subcarrier, Doppler and ranging navigation data types, CCSDS protocol compliance in cooperation with spacecraft C&DH, and an architecture that will support future improvements including more data rates on uplink and downlink, and other navigation data types such as PN regenerative ranging and DOR tones. The architecture will also support proximity operations with RF hardware for different bands (UHF, S-band, Ka-band, or Cband) to provide communications and navigation from mother ships to Irisequipped daughter ships on larger deep space missions.

Numerous CubeSat missions are contemplated that will require high data rates from Earth orbit. Iris firmware can be extended to support Near Earth Network (NEN), and Tracking and Data Relay Satellite System (TDRSS) frequencies and protocols, among others.

This work was done by Courtney B. Duncan, Masatoshi M. Kobayashi, Amy E. Smith, Paula J. Pingree, Maxwell B. Bryk, Fernando H. Aguirre, Igor Kuperman, Edgar H. Satorius, Alfred Khashaki, and Dmitriy Bekker of Caltech for NASA’s Jet Propulsion Laboratory. In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. This software is available for commercial licensing. Please contact Dan Broderick at This email address is being protected from spambots. You need JavaScript enabled to view it.. Refer to NPO-49284.

This Brief includes a Technical Support Package (TSP).
Iris DSN-Compatible, CubeSat-Compatible Transponder

(reference NPO-49284) is currently available for download from the TSP library.

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This article first appeared in the December, 2015 issue of NASA Tech Briefs Magazine.

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