What Is NIRSpec? The James Webb Telescope Instrument Explained

NIRSpec is a type of spectrograph which works in the near-infrared spectrum, at 0.6 to 5 microns, which is just past the wavelength of red visible light (via NASA). The special thing about NIRSpec is that it can observe many objects at the same time, observing up to 200 objects simultaneously. This is important because many of the objects that Webb will be looking at, such as distant galaxies, are very faint. So the telescope needs to observe them for a long time to get enough light to study them, but there are also thousands of objects that researchers want to observe. By having an instrument which can observe many objects at once, researchers will be able to view many objects for long enough to gather spectrum data.

It is able to observe many different objects because the instrument has 250,000 microshutters, which are tiny shutters about as wide as a human hair, each of which is controlled by a magnetic field to open or close and allow Webb to focus on a particular object. These shutters can block out the light from nearer, brighter objects in order to observe distant, dim objects like far-away galaxies.

NIRSpec won’t only be observing distant galaxies though. It will also look at objects like beautiful nebulae, which are clouds of dust and gas, or star fields, which are whole regions of the sky.