Comprehensive Analysis Advances Astrometric Instrument for HWO

A recent study has outlined a detailed system analysis for an advanced astrometric instrument intended for the Habitable Worlds Observatory (HWO). This instrument aims to achieve high-precision, high-accuracy differential astrometry, primarily focused on determining the mass of Earth-like planets orbiting the nearest Sun-like stars.

The analysis encompasses multiple facets, including the mission profile, the instrumental concept architecture, and an error budget that delineates the primary contributors to the required sub-micro arcsecond precision for individual measurements. A critical part of this budget includes the estimation of the photo-center for both the target stars and the calibration stars utilized in the differential astrometry process.

Another significant contributor to the overall precision involves the control of systematics during the reconstruction of differential angle measurements. This process spans from pixel data—obtained through focal plane calibration—to the line of sight on the sky, which requires telescope distortion calibration.

To meet the end-of-mission astrometric goals, the mission necessitates approximately 100 observations of the same target over its operational lifespan. The research evaluates the mission profile to determine the percentage of survey time dedicated to astrometric studies, ensuring the scientific objectives are met.

Instrument Architecture and Technological Readiness

The proposed architectural framework for the instrument is derived from the error budget and mission constraints. It features a large visible detector array, comprised of multiple CMOS sensor chips, which collectively create a gigapixel focal plane. This design enables the instrument to capture and analyze vast amounts of astrometric data with remarkable precision.

The study also assesses the Technology Readiness Level (TRL) of the instrument, recommending a strategy to achieve TRL 5 by the Mission Consolidation Review in 2029. Achieving this level of readiness is crucial for the successful deployment and operation of the astrometric instrument within the HWO mission framework.

The collaborative effort includes contributions from a team of experts, including Jérôme Amiaux, Fabien Malbet, and several others, reflecting a broad spectrum of expertise in astrophysics and instrumentation.

This comprehensive analysis represents a significant step forward in the endeavor to explore the potential of Earth-like planets beyond our solar system. The findings are documented in the study available on arXiv, under reference arXiv:2511.07113.

As the mission progresses, further developments will likely emerge, advancing our understanding of habitable worlds and their characteristics, ultimately guiding future explorations in astrobiology and planetary science.