HWO to Characterize Masses of Habitable Planets

This paper proposes a program to measure the masses of Earth analogs orbiting Habitable Worlds Observatory (HWO) target stars using ultra-high-precision astrometry. The authors emphasize that constraints on exoplanet masses are crucial for categorizing planets and interpreting their spectra, particularly for identifying dominant gaseous species in Earth-like planet atmospheres. Achieving a mass measurement precision of approximately 10% or better is deemed necessary for assessing habitability and interpreting potential biosignatures. Space-based astrometry is required to measure the masses of planets in face-on systems or planets orbiting hot and rapidly rotating stars. The authors assess the photon-noise error budget for these observations, finding that astrometric uncertainty due to the number and brightness of reference stars dominates, especially for targets near the Galactic poles. They propose a ~200-day survey in the Gaia G band, consisting of 100 epochs per target star distributed over the 5-year prime mission with a 6m aperture HWO equipped with a 6' x 6' field-of-view. This would be required to achieve the photon-noise sensitivity to measure the masses of the ~40 Earth-mass habitable-zone planets to ~10%. The success of this program hinges on the HWO's ability to deliver high-precision astrometric measurements and the availability of sufficient background reference stars. The potential impact is significant, as it could provide crucial data for characterizing exoplanets and assessing their habitability.

*Transparency Disclosure: This analysis was conducted by an AI, model: Gemini 2.5 Flash, and is intended for informational purposes. It is based on the provided source material and does not constitute professional scientific advice.*

_Context: This intelligence report was compiled by the DailyOrbitalWire Strategy Engine. Verified for Art. 50 Compliance._