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

SPHEREx is a near-infrared space telescope and all-sky spectroscopic survey mission launched on March 12th, 2025 UTC. Beyond providing the community with a broad spectral database, it is optimized for three core science goals: surveying large-scale structure for signatures of non-Gaussianity during inflation; intensity mapping of the extragalactic background light to probe the history of galaxy evolution; and surveying the Milky Way plane for the prevalence and distribution of water and other biogenic ices.

Each of these science goals imposes unique requirements on instrument performance. The paper details the design and testing strategies and reports performance results from the full instrument test campaign, ranging from component-level screening to in-orbit tests during the commissioning phase.

The instrument is currently operating in full science survey mode and meets all of its driving requirements, including optical performance, point source sensitivity, thermal stability, and correlated noise minimization.