Source: Google Image
The James Webb Space Telescope (JWST) is a large, infrared-optimized space telescope that is set to be the successor to the Hubble Space Telescope. Developed by NASA, with significant contributions from the European Space Agency (ESA) and the Canadian Space Agency (CSA), the JWST is set to be launched in 2021.
The JWST is designed to study the earliest galaxies, stars, and planets in the universe, as well as the formation of solar systems and the potential for life on other planets. It will do this by observing in the infrared part of the spectrum, which will allow it to see through the dust that often obscures these objects in visible light.
The JWST will be positioned at a location called the second Lagrange point, or L2, which is about 1.5 million kilometers (about 930,000 miles) from Earth. This location will allow the telescope to observe the sky without the interference of the Earth's atmosphere, and will also allow it to stay in the same position relative to the Earth and the sun, which will make it easier to point at specific objects.
The JWST will have a primary mirror that is 6.5 meters (about 21.3 feet) in diameter, which is more than twice the size of the primary mirror on the Hubble Space Telescope. This larger mirror will allow the JWST to collect more light and, therefore, see fainter objects. The mirror is made of 18 hexagonal segments that will work together as a single mirror.
The JWST will have four main scientific instruments on board: the Near Infrared Camera (NIRCam), the Near Infrared Spectrograph (NIRSpec), the Mid-Infrared Instrument (MIRI), and the Fine Guidance Sensor/Near InfraRed Imager and Slitless Spectrograph (FGS/NIRISS). These instruments will be used to study a wide range of astronomical phenomena, from distant galaxies to nearby exoplanets.
Near Infrared Camera (NIRcam)
The Near Infrared Camera (NIRCam) is Webb’s primary imager that will cover the infrared wavelength range 0.6 to 5 microns. NIRCam will detect light from: the earliest stars and galaxies in the process of formation, the population of stars in nearby galaxies, as well as young stars in the Milky Way and Kuiper Belt objects. NIRCam is equipped with coronagraphs, instruments that allow astronomers to take pictures of very faint objects around a central bright object, like stellar systems. NIRCam’s coronagraphs work by blocking a brighter object’s light, making it possible to view the dimmer object nearby - just like shielding the sun from your eyes with an upraised hand can allow you to focus on the view in front of you. With the coronagraphs, astronomers hope to determine the characteristics of planets orbiting nearby stars.
Near Infrared Spectrograph (NIRSpec)
The Near InfraRed Spectrograph (NIRSpec) will operate over a wavelength range of 0.6 to 5 microns. A spectrograph (also sometimes called a spectrometer) is used to disperse light from an object into a spectrum. Analyzing the spectrum of an object can tell us about its physical properties, including temperature, mass, and chemical composition. The atoms and molecules in the object actually imprint lines on its spectrum that uniquely fingerprint each chemical element present and can reveal a wealth of information about physical conditions in the object. Spectroscopy and spectrometry (the sciences of interpreting these lines) are among the sharpest tools in the shed for exploring the cosmos.
Many of the objects that the Webb will study, such as the first galaxies to form after the Big Bang, are so faint, that the Webb's giant mirror must stare at them for hundreds of hours in order to collect enough light to form a spectrum. In order to study thousands of galaxies during its 5 year mission, the NIRSpec is designed to observe 100 objects simultaneously. The NIRSpec will be the first spectrograph in space that has this remarkable multi-object capability. To make it possible, Goddard scientists and engineers had to invent a new technology microshutter system to control how light enters the NIRSpec.
Mid-Infrared Instrument (MIRI)
The Mid-Infrared Instrument (MIRI) has both a camera and a spectrograph that sees light in the mid-infrared region of the electromagnetic spectrum, with wavelengths that are longer than our eyes see.
MIRI covers the wavelength range of 5 to 28 microns. Its sensitive detectors will allow it to see the redshifted light of distant galaxies, newly forming stars, and faintly visible comets as well as objects in the Kuiper Belt. MIRI’s camera will provide wide-field, broadband imaging that will continue the breathtaking astrophotography that has made Hubble so universally admired. The spectrograph will enable medium-resolution spectroscopy, providing new physical details of the distant objects it will observe.
Slitless Spectrograph (FGS/NIRISS)
The Mid-Infrared Instrument (MIRI) has both a camera and a spectrograph that sees light in the mid-infrared region of the electromagnetic spectrum, with wavelengths that are longer than our eyes see.
MIRI covers the wavelength range of 5 to 28 microns. Its sensitive detectors will allow it to see the redshifted light of distant galaxies, newly forming stars, and faintly visible comets as well as objects in the Kuiper Belt. MIRI's camera will provide wide-field, broadband imaging that will continue the breathtaking astrophotography that has made Hubble so universally admired. The spectrograph will enable medium-resolution spectroscopy, providing new physical details of the distant objects it will observe.
The JWST is expected to make many groundbreaking discoveries and will be a major tool for researchers for years to ome. Its capabilities will allow us to study the earliest galaxies and stars, and will help us to understand how our own solar system formed. Additionally, its ability to study exoplanets in the infrared will allow us to search for signs of life on other worlds. Overall, the James Webb Space Telescope will be a major step forward in our understanding of the universe.
