Context: James Webb Space Telescope lifts off on historic mission:
The world’s most powerful space telescope blasted off into orbit, headed to an outpost 1.5 million kilometers (930,000 miles) from Earth, after several delays caused by technical hitches.
The James Webb Space Telescope, some three decades and billions of dollars in the making, left Earth enclosed in its Ariane 5 rocket from Kourou Space Centre in French Guiana.
Named after a former NASA director, Webb follows in the footsteps of the legendary Hubble — but intends to show humans what the Universe looked like even closer to its birth nearly 14 billion years ago.
About James Webb Space Telescope (JSWT):
- JWST is a joint venture between the USA (NASA), European (ESA) and Canadian space agencies (CSA).
- It is an orbiting infrared observatory that will complement and extend the discoveries of the Hubble Space Telescope, with longer wavelength coverage and greatly improved sensitivity.
- Webb was formerly known as the “Next Generation Space Telescope” (NGST) and it was renamed in 2002 after a former NASA administrator, James Webb.
- It will be a large infrared telescope with an approximately 6.5 meter primary mirror.
What is the James Webb Space Telescope (JWST) significance?
- It is widely expected to unveil many secrets of the universe, particularly those related to the formation of stars and galaxies in the early period the first few hundred million years after the Big Bang.
- Powerful space telescopes, like JWST or the Hubble Telescope, are often called time-machines because of their ability to view very faraway objects.
- The light coming from those objects, stars or galaxies, which is captured by these telescopes, began its journey millions of years earlier.
- Essentially, what these telescopes see are images of these stars or galaxies as they were millions of years ago. The more distant the planet or star, the farther back in time are the telescopes able to see.
- JWST is much more powerful and has the ability to look in the infrared spectrum, which will allow it to peer through much deeper into the universe, and see through obstructions such as gas clouds.
- As electromagnetic waves travel for long distances, they lose energy, resulting in an increase in their wavelength.
- An ultraviolet wave, for example, can slowly move into the visible light spectrum and the infrared spectrum, and further weaken to microwaves or radio waves, as it loses energy.
- Hubble was designed to look mainly into the ultraviolet and visible regions of the electromagnetic spectrum. JWST is primarily an infrared telescope, the first of its kind.
- It can also analyze the atmospheres of exoplanets that pass in front of their stars.
- It will look at a large number of things in the universe including icy moons, distant exoplanets and galaxy clusters.
James Webb Space Telescope (JWST) use the phenomenon of “gravitational lensing”:
- Launch of the James Webb Space Telescope (JWST), will use a natural phenomenon called “gravitational lensing” to carry out astronomical observations.
- The phenomenon of gravitational lensing occurs when a huge amount of matter, such as a massive galaxy, cluster of galaxies or a black hole, creates a gravitational field that distorts and magnifies the light from objects behind it.
- Gravitational lensing is based on Einstein’s theory of general relativity (Mass bend light).
- Normal lenses such as the ones in a magnifying glass work by bending light rays that pass through them in a process known as refraction, in order to focus the light somewhere else.
- Similarly, the gravitational field of a massive object causes light rays passing close to that object to be bent and refocused somewhere else.
- The more massive the object, the stronger its gravitational field and hence the greater the bending of light rays – just like using denser materials to make optical lenses results in a greater amount of refraction.
- In effect, gravitational lenses act like natural cosmic telescopes.
Webb vs Hubble Telescope:
- Unlike the Hubble telescope that orbits the Earth at an altitude of around 570 km, the Webb will instead sit 1.5 million kilometres away from the Earth to stay in a stable, predictable orbit around the Sun.
- Furthermore, Webb is capable of viewing the Universe in longer-wavelength infrared light while Hubble studies it primarily at optical and ultraviolet wavelengths.
- With a much bigger mirror than Hubble, Webb can peer farther back into time than Hubble as it has a larger light-collecting area.
- Webb has over 1200 skilled scientists, engineers and technicians from 14 countries and more than 29 US states with the District of Columbia building it.
- It is a joint NASA/ESA/CSA mission. The assembly and testing of the mirror and instruments occurred at NASA Goddard.
JWST will study every phase in the history of our Universe, ranging from the first luminous glows after the Big Bang, to the formation of solar systems capable of supporting life on planets like Earth, to the evolution of our own Solar System, etc.
Scientists hope this set-up can detect the light from the very first population of stars in the Universe to switch on more than 13.5 billion years ago.
Among the tensest moments, astronomers say, will be the unfolding of a giant sunscreen, the size of a tennis court, designed to keep the telescope in the dark and cold enough so that its own heat doesn’t swamp the heat from distant stars.