Habitable World Discovery and Characterization: Coronagraph Concept of Operations and Data Post-Processing

TL;DR

This paper assesses how the COPP working group will enable habitable world discovery and characterization by evaluating coronagraph concepts of operations and post-processing strategies to reach contrasts exceeding $10^{-10}$. It reviews RDI/ADI, PDI, ODI, CDI, spectral processing, and telemetry-aided PSF subtraction, highlighting hardware needs, modeling requirements, and the role of integrated simulations and testbeds to quantify gains. The document presents an OS1 ConOps baseline inspired by NGRST OS11 and a programmatic path to mature techniques through Exploratory Analytic Cases (EACs) and TRL 5 testbeds. A master observing-scenario template and high-fidelity end-to-end modeling are proposed to estimate post-processing impact on exoplanet yields and mission efficiency.

Abstract

The discovery and characterization of habitable worlds was the top scientific recommendation of the Astro2020 decadal survey and is a key objective of the Habitable Worlds Observatory. Biosignature identification drives exceedingly challenging observations, which require raw contrasts of roughly 10$^{-10}$ contrast and ultimately, 1$σ$ photometric precision of roughly 3$\times 10^{-12}$ contrast. Despite significant advances for the Nancy Grace Roman Space Telescope's Coronagraph Instrument, technological gaps still exist in a wide range of technologies such as starlight suppression, deformable mirrors, wavefront control, low noise detectors, and high-contrast spectroscopy. Even with these new technologies matured, the Habitable Worlds Observatory must carefully obtain the observations and rely on post-processing of the data to achieve its science objectives. During the START and TAG efforts, a working group was convened to explore the Coronagraph Concept of Operations and Post Processing (COPP) in the context of the Habitable Worlds Observatory. This COPP working group evaluated coronagraphic concept of operations to enable different post processing approaches, such as reference differential imaging and angular differential imaging, polarization differential imaging, orbital differential imaging, coherent differential imaging, spectral processing, and point-spread function subtraction algorithms that incorporate ancillary telemetry and data. Future integrated modeling simulations and testbed demonstrations are needed to determine the achievable post processing gains for each approach. We report a summary of this working group's activities and findings, as well as an outlook for maturation of these techniques and infusion into the Habitable Worlds Observatory technology portfolio.

Figures (2)

• Figure 2: While the ngrst cgi will work at far higher contrasts than existing facilities, habitable world discovery and characterization require operating more than an order of magnitude deeper. hwo sample Earth twins contrast at quadrature at 550 nm are plotted for reference. This plot made use of Vanessa Bailey's GitHub repository (https://github.com/nasavbailey/DI-flux-ratio-plot).
• Figure 3: Left:The HWO OS1 ConOps uses a reference star for wavefront sensing to expedite the wavefront control sequence. Center: After the dark hole is created, the observatory is slewed to a science target with an angular roll of $+$22$^{\circ}$, waits for stabilization, and then an imaging sequence is executed. Right: The observatory is rolled to $-$22$^{\circ}$, a 40$^{\circ}$ roll in total, waits for stabilization, and then an imaging sequence is executed. Subsequent rolls and periodic wavefront control maintenance visits to the reference star complete the observing scenario. Simulated data based on HWO integrated modeling results provided by John Krist.