James Webb Space Telescope: A New Eye on the Universe
The James Webb Space Telescope (JWST) is a space telescope currently conducting infrared astronomy. As the largest optical telescope in space, it is equipped with high-resolution and high-sensitivity instruments, allowing it to view objects too old, distant, or faint for the Hubble Space Telescope.
The JWST is a joint project of NASA, ESA and CSA. It was launched on 25 December 2021 on an Ariane 5 rocket from Kourou, French Guiana, and arrived at the Sun–Earth L2 Lagrange point in January 2022. The first JWST image was released to the public on 11 July 2022.
The JWST’s primary mirror consists of 18 hexagonal mirror segments made of gold-plated beryllium, which combined create a 6.5-meter-diameter (21 ft) mirror, compared with Hubble’s 2.4 m (7 ft 10 in). The mirror can collect more light and observe fainter objects than Hubble. The JWST also has a large sunshield that protects the telescope from the heat and light of the Sun and Earth. The sunshield is made of five layers of thin material that reflect most of the sunlight and infrared radiation away from the telescope. The sunshield also helps keep the telescope at a very low temperature of about -223°C (-370°F), which is necessary for its infrared sensors to work properly.
The JWST has four main scientific instruments: 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 cover a wide range of wavelengths from 0.6 to 28.3 micrometers (orange to mid-infrared) and can perform various types of observations, such as imaging, spectroscopy, coronagraphy, and interferometry. The instruments are designed to work together to achieve the scientific goals of the JWST mission.
The JWST mission aims to address some of the most fundamental questions in astronomy and cosmology, such as:
● How did the first stars and galaxies form in the early universe?
● How did galaxies evolve over cosmic time?
● How do stars and planets form in our own and other galaxies?
● What are the physical and chemical properties of planetary systems, including our own solar system?
● Are there habitable worlds beyond our solar system, and what are their atmospheres like?
To answer these questions, the JWST will observe a variety of objects and phenomena in the universe, such as:
● The first light: The JWST will look back in time to see the first stars and galaxies that formed after the Big Bang, about 13.5 billion years ago. These objects are so distant that their light has been stretched by the expansion of the universe into infrared wavelengths that are invisible to Hubble but detectable by JWST. By studying these ancient sources of light, astronomers hope to learn how they formed and how they influenced the evolution of the universe.
● Galaxy formation and evolution: The JWST will study how galaxies grow and change over time, from their infancy to their maturity. It will observe how galaxies merge, interact, form stars, produce heavy elements, and host supermassive black holes at their centers. It will also measure how much dark matter and dark energy are present in different types of galaxies and how they affect their structure and dynamics.
● Star and planet formation: The JWST will peer through dusty clouds of gas and dust where stars and planets are born. It will reveal how stars form from collapsing clumps of gas, how they evolve over their lifetimes, and how they end their lives as supernovae or planetary nebulae. It will also investigate how planets form around young stars, how they migrate within their systems, and how they interact with their host stars and other planets.
● Exoplanets: The JWST will explore the diversity of worlds beyond our solar system, from giant gas planets to rocky Earth-like planets. It will use various techniques to detect and characterize exoplanets, such as direct imaging, transit spectroscopy, microlensing, and astrometry. It will measure their sizes, masses, orbits, temperatures, compositions, atmospheres, climates, and habitability potential.
● Solar system: The JWST will observe our own solar system with unprecedented detail and sensitivity. It will study the Sun and its effects on space weather and planetary environments. It will examine the surfaces, interiors, atmospheres, magnetospheres, rings, moons, asteroids, comets, and Kuiper belt objects of our neighboring planets. It will also search for signs of life or prebiotic chemistry on some of these bodies.
The JWST is expected to operate for at least five years after its commissioning phase is completed in mid-2022. It may last up to 10 years or more depending on its fuel consumption and technical performance. The JWST is designed to be serviceable by future robotic or crewed missions if needed.
The JWST is a remarkable achievement of human ingenuity and scientific curiosity. It is a powerful tool for exploring the wonders of the universe and expanding our knowledge of our cosmic origins and destiny.
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