Techniques and Instrumentation for Space-based Laser Communications, Ranging, and Metrology
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tomio-tomio-phd-aeroastro-2026-thesis.pdf
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23.19 MB
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8cb0dc400a4c924865ec692b55b7fb2e
Author(s)
Tomio, Hannah
Advisor(s)
Cahoy, Kerri
Date Issued
February 2026
Publisher
Massachusetts Institute of Technology
Abstract
Within the past two decades, space-based optical communications have advanced from the realm of one-off technology demonstrations to become an operational (and increasingly, commercial) capability. Due to the high directionality of the laser that serves as the carrier, very high data rates (on the order of hundreds of Gbps) can be achieved, and with smaller, lighter, and less power-intensive terminals than comparable radio frequency (RF) systems. This has driven their adoption in diverse mission configurations, ranging from intersatellite optical crosslinks for nanosatellites to highly efficient space-to-ground links in cislunar and interplanetary spacecraft. Nonetheless, existing efforts have yet to broadly incorporate additional metrology capabilities, such as ranging and time transfer via the optical link. Over this same period, precision laser instruments have also been realized in space, such as the Laser Ranging Interferometer (LRI) instrument of the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission. This heterodyne laser interferometer measures the relative range between two spacecraft with nanometer-level precision in order to map the Earth’s gravity field, from which insights into the planet’s mass variations can be inferred. The technological achievements of GRACE-FO are now being leveraged for the Laser Interferometer Space Antenna (LISA) mission, which will launch a laser interferometry-based gravitational wave observatory. Despite these advances, optical frequency combs, a relatively new tool for terrestrial precision metrology and spectroscopy experiments, have yet to be ruggedized and demonstrated in space. An optical frequency comb is a laser system that is stabilized such that its output can be utilized as a reference that connects the optical frequency domain (in THz) to the microwave or RF domain (MHz to GHz). There are numerous applications for frequency combs in space missions, including high-resolution spectrograph calibration for exoplanet detection and the generation of very stable radio frequency (RF) and microwave signals from optical references for coherent sensing applications such as very long baseline interferometry (VLBI). This dissertation focuses on experimental demonstrations to advance space-based optical ranging, time transfer, and metrology, and seeks to address gaps in simultaneous ranging and time transfer over optical communication links and space-qualified optical frequency combs. For ranging and time transfer, the integration of ranging capabilities into an existing optical communications terminal, the Laser Communication Relay Demonstration (LCRD) mission, is described and analyzed. The results from the simultaneous ranging over optical communications link experiment are reported, demonstrating cm-level ranging between a satellite in geosynchronous orbit and ground. For space-qualified optical frequency combs, we conduct experiments to characterize a spaceflight-compatible fiber frequency comb and describe the comb stabilization approach and residual comb noise performance. We experimentally demonstrate the use of an optical frequency comb to photonically generate an ultra-stable 100 MHz frequency reference from a cavity-stabilized laser. This reference achieves a very high short-term stability (a few parts in 10⁻¹⁴ at 1 s averaging time), making it highly applicable to serve as a frequency reference for a space-based VLBI mission.
MIT Department
Massachusetts Institute of Technology. Department of Aeronautics and Astronautics
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