The SPHEREx Instrument: Calibration, testing and performance measurements of the NIR 2 spectroscopic surveyor from the laboratory to in-orbit commissioning

TL;DR

The paper details the design, testing, and performance of the SPHEREx near-infrared space telescope, which aims to conduct an all-sky spectroscopic survey to address key cosmological and galactic science goals.

Contribution

It provides comprehensive calibration, testing procedures, and performance results of the SPHEREx instrument from laboratory to in-orbit commissioning, demonstrating it meets all key requirements.

Findings

Instrument meets optical performance and sensitivity goals.

Thermal stability and noise minimization achieved.

Full survey mode operation confirmed readiness.

Abstract

The SPHEREx near-infrared space telescope is an all-sky spectroscopic survey mission launched on March 12th, 2025 UTC. In addition to providing the community with a spectral database applicable to a wide range of investigations, it is optimized to address three core science goals: to survey the large scale structure of the Universe for signatures of non-Gaussianity during inflation; to conduct intensity mapping studies of the extragalactic background light for probing the history of galaxy evolution; and to survey the plane of the Milky Way for the prevalence and distribution of water and other biogenic ices. Each of these science goals imposes unique requirements on the performance of the instrument. We detail the design and testing strategies and report the performance results for the full instrument test campaign, ranging from component-level screening to in-orbit tests during the commissioning phase. The instrument, currently operating in full science survey mode, meets all of its driving requirements including optical performance, point source sensitivity, thermal stability and correlated noise minimization.