21 Jul 2026

LWe propose the Photonic Submillimeter Space Interferometer (PS2I) — a ~50-element array of spacecraft, each carrying a 4-meter deployable reflector and a heterodyne receiver. With baselines of 1-2 km and ~100 GHz of bandwidth, PS2I enables unprecedented resolution and sensitivity at submillimeter wavelengths (0.5 to 0.05 mm). The mission leverages optical frequency comb (OFC)-based photonic technology for high-throughput signal transport, correlation, phasing, synchronization, and calibration. These systems offer significant size, weight, and power (SWaP) advantages, making them ideal for space deployment. Combined with declining launch costs, lightweight antennas, and efficient front-ends, PS2I is a technically and economically viable mission within 15-20 years. PS2I enables two transformative science goals: (a) Sub-AU imaging of protoplanetary disks within 50 pc, revealing disk structure, dust evolution, and planet formation timescales. (b) Spectral imaging of [C II] 158 μm emission from galaxies at redshifts z = 1–2, probing gas kinematics and morphology during peak cosmic star formation, advancing our understanding of galaxy evolution. 

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Graphic depiction of the Transforming Submillimeter Space Interferometry concept.