How many microshutters does NIRSpec’s micro-shutter array contain? It contains 248,000 microshutters. These tiny, individually controlled openings are part of JWST’s Near-Infrared Spectrograph, or NIRSpec.
Each microshutter works like a microscopic door. It can open to admit light from a selected astronomical target or close to block unwanted light. By choosing many targets at once, NIRSpec can collect multiple spectra during a single observation, making it far more efficient than a conventional single-object spectrograph.
The array uses microelectromechanical systems, or MEMS, technology. A magnetic scanning process helps activate the shutters, while the telescope’s pointing and instrument optics align selected objects with open shutters. NIRSpec can study galaxies, stars, and exoplanet atmospheres by separating their light into component wavelengths.
A common source of confusion is the rounded figure. NASA gives the array’s count as 248,000, while technical descriptions often round it to approximately 250,000. Those figures refer to the same huge grid, not to the number of shutters opened for every observation.