Lower Limits on Aperture Size for an ExoEarth-Detecting Coronagraphic Mission

TL;DR

This paper introduces a comprehensive optimization method for exoEarth detection missions, calculating the necessary telescope aperture size to maximize yield based on astrophysical and instrumental assumptions.

Contribution

It presents a novel yield maximization approach that jointly optimizes target selection, observation scheduling, and exposure times for exoEarth detection missions.

Findings

Provides lower limits on aperture size for exoEarth detection

Introduces a new completeness code for yield calculation

Suggests optimal mission parameters based on astrophysical assumptions

Abstract

The yield of Earth-like planets will likely be a primary science metric for future space-based missions that will drive telescope aperture size. Maximizing the exoEarth candidate yield is therefore critical to minimizing the required aperture. Here we describe a method for exoEarth candidate yield maximization that simultaneously optimizes, for the first time, the targets chosen for observation, the number of visits to each target, the delay time between visits, and the exposure time of every observation. This code calculates both the detection time and multi-wavelength spectral characterization time required for planets. We also refine the astrophysical assumptions used as inputs to these calculations, relying on published estimates of planetary occurrence rates as well as theoretical and observational constraints on terrestrial planet sizes and classical habitable zones. Given these astrophysical assumptions, optimistic telescope and instrument assumptions, and our new completeness code that produces the highest yields to date, we suggest lower limits on the aperture size required to detect and characterize a statistically-motivated sample of exoEarths.