Incorporating Wavefront Error, Wavefront Sensing and Control, and Sensitivities into Exposure Time Calculations for Future Space Missions with the Error Budget Software (EBS)

TL;DR

This paper introduces the Error Budget Software (EBS), an open-source tool that integrates wavefront error, sensing, and control effects into exposure time calculations, aiding future space mission planning and yield estimation.

Contribution

The paper presents EBS, a novel software that incorporates wavefront and sensitivity parameters into exposure time calculations, filling a gap in mission error budgeting tools.

Findings

EBS effectively models the impact of wavefront errors on exposure times.

EBS demonstrates the relationship between contrast, wavefront error, and detector noise.

Application to USORT design showcases EBS's utility in mission planning.

Abstract

A primary goal of NASA's Habitable Worlds Observatory (HWO) mission concept is to explore the Habitable Zones (HZ) of ~100 stellar systems and acquire spectra of ~25 terrestrial-type planets (with planet/star flux ratios on the order of 1E-10) which places tight constraints on the performance of observatory systems. In particular, coronagraph instrumentation needs to be matured for higher throughput, deeper contrasts, and better broadband performance, while also considering their sensitivity and ability to mitigate the impact of telescope instability and wavefront error (WFE), which can have a profound impact on exo-Earth imaging. The success of various proposed HWO mission architectures is often represented by the estimated exo-Earth candidate yield. Computation of the minimum exposure time to achieve the required signal-to-noise on a given target, using an exposure time calculator (ETC), is a key part of yield estimation. The impacts of coronagraph sensitivity, WFE, and wavefront sensing and control (WFS&C) have been well studied in the context of developing error budgets for missions and instruments such as the Roman Coronagraph Instrument, but there is currently no easily accessible way to incorporate the effects of these key parameters into calculating exposure times for HWO. To address this, we developed the Error Budget Software (EBS) - an open-source tool that synthesizes sensitivity, WFE, and WFS&C information for a variety of temporal and spatial scales and directly interfaces with the open-source yield code EXOSIMS to produce exposure times. We demonstrate how EBS can be used for mission error budgeting using the example of the Ultrastable Observatory Roadmap Team (USORT) observatory design. This includes both single and multi-variate parameter explorations using EBS where we identify trends between raw contrast and wavefront error, and detector noise and energy resolution.