The NIRSpec Micro-Shutter Array: Operability and Operations After Two Years of JWST Science

TL;DR

Since its launch in December 2021, NIRSpec on JWST has demonstrated robust performance in multi-object spectroscopy, with ongoing engineering efforts ensuring hardware health and addressing challenges like electrical shorts.

Contribution

This paper reports on the operational status, health, and recent developments of the NIRSpec micro-shutter array after two years of JWST science operations.

Findings

NIRSpec continues to perform without significant degradation.

Electrical shorts have been identified and managed.

Operational improvements have enhanced instrument efficiency.

Abstract

The Near Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope affords the astronomical community an unprecedented space-based Multi-Object Spectroscopy (MOS) capability through the use of a programmable array of micro-electro-mechanical shutters. Launched in December 2021 and commissioned along with a suite of other observatory instruments throughout the first half of 2022, NIRSpec has been carrying out scientific observations since the completion of commissioning. These observations would not be possible without a rigorous program of engineering operations to actively monitor and maintain NIRSpec's hardware health and safety and enhance instrument efficiency and performance. Although MOS is only one of the observing modes available to users, the complexity and uniqueness of the Micro-Shutter Assembly (MSA) that enables it has presented a variety of engineering challenges, including the appearance of electrical shorts that produce contaminating glow in exposures. Despite these challenges, the NIRSpec Multi-Object Spectrograph continues to perform robustly with no discernible degradation or significant reduction in capability. This paper provides an overview of the NIRSpec micro-shutter subsystem's state of health and operability and presents some of the developments that have taken place in its operation since the completion of instrument commissioning.