Barry Lyu, Vaibhavi Manjarekar, Nathaniel Bleier

Maintaining long-term wavefront stability is critical for the Habitable Worlds Observatory (HWO), which targets contrasts approaching $10^{-10}$ and therefore requires continuous dark-zone maintenance using high-order wavefront sensing and control (HOWFSC). Prior work has advanced HOWFSC algorithms and profiled candidate implementations on radiation-hardened processors, highlighting a substantial gap between the computational demands of LUVOIR-scale HOWFSC and the capabilities of current onboard spacecraft hardware. In this paper, we argue that this gap can be closed by offloading the HOWFSC pipeline to a dedicated co-flying compute satellite at Sun-Earth L2. This approach enables the use of modern, radiation-tolerant high-performance processors without increasing risk to the primary observatory. We show that such an architecture can increase the end-to-end control cadence from the sub-hertz regime typical of radiation-hardened onboard processing or ground-in-the-loop operation to tens and even hundreds of hertz. We evaluate commercial hardware platforms in terms of performance and feasibility, and we propose custom architectures that enable higher control frequencies with significant power consumption reductions. Finally, we outline system-level considerations for co-flying compute, including reliability, satellite integration, and inter-satellite communication constraints.