The TeraByte InfraRed Delivery (TBIRD) system is a 3U payload on a 6U CubeSat launched in May 2022 which has now demonstrated space to ground links of >1 Terabyte (TB) per pass at a max data rate of 200Gbps. As a CubeSat mission, the development of the TBIRD payload was focused on low SWaP and a “rapid prototyping” approach which accepted higher risks to accelerate the schedule and reduce costs. The optomechanical design process followed standard in-house processes to develop a system that would be robust to LEO environmental loads, with a focus on the stability of the transmit (Tx) and receive (Rx) channel performance metrics. The driving requirement of maintaining 20μrad pointing error between the TX and Rx channels forced specific attention to thermal and mechanical load changes over operational conditions, which drove major design decisions. This paper describes some of engineering challenges overcome and approaches used to make TBIRD a successful program, as well as some of the tradeoffs of rapid prototyping precision optical payloads. TBIRD successfully met and exceeded the total downlink requirements listed above, with a bandwidth of 200Gbps and a total downlink of 4.8TB of information in a single pass.
The potential of lasercom could often be much more attractive to system designers if the terminals could be made very
small. In particular, in systems where one end of the link is allowed to be somewhat more capable than the other, the
lesser of the two terminals could take advantage of the asymmetry and shrink as much as possible. We have investigated
how such asymmetry factors into the requirements for a small terminal and have designed a terminal with a very small
aperture (35-75 mm) and an inertial stabilization scheme. The space-worthy terminal has applicability to Moon-to-Earth
as well as near-Earth lasercom missions.
With the advent of efficient fiber laser and amplifiers, low noise photon-counting detectors, turbo-codes, and low-cost ground receiver architectures, it is now feasible to consider very high rate data links from deep space. A set of options leading to a 10-100 Mbps link from Mars to Earth is described.
This paper describes a novel packaging design for a lithium niobate Mach-Zehnder interferometric modulator. The modulator is mounted to the bottom of a miniature carrier using elastic supports to minimize transmission of bending, random vibration and shock loads. Optical fibers are threaded from the modulator ends to the outside world via tubular feed- throughs located to allow for thermal expansion of the carrier without inducing stress on the fibers. An electric current board is attached to the carrier, and wire bonds from the board to the modulator provide the required voltages. The total package envelope is less than 0.41 in3 in volume. A major design goal was to achieve a hermetically sealed package, using all-metallic seals wherever possible. The package cover is resistance-seam-welded over the carrier top. However, as an intermediate step in the development process, the optical fibers are sealed with epoxy at the feed-through locations, rather than with solder seals to metallized fibers, which would provide a true hermetic seal. The paper provides supporting analysis performed to demonstrate the effectiveness of the design, including the epoxy seals, as well as experimental test results which validate the design.
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