On December 24, the James Webb Space Telescope (JWST) will launch from the Kourou space center (French Guiana). After successive delays in the launch date (initially scheduled for 2007), it will mark a milestone in the history of space observation.
It owes its name to James E. Webb, the second administrator of NASA and responsible for the Apollo project that would put the human being on the moon.
With an estimated cost of 10 billion dollars, it is a project led by NASA in collaboration with the European (ESA) and Canadian (CSA) Space Agencies.
It will orbit the Earth at a distance of 1.5 million kilometers (farther than the Moon, about 380,000 km) at a point where the gravitational interaction between the Earth and the Sun is balanced (called Lagrange point L2).
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Therefore, the JWST will maintain a stable orbit aligned with our planet.
Before delving into the potential discoveries of the new space telescope, it is convenient to look back in time and review how astronomical observation has evolved to this day.
From Galileo’s telescope to the James Webb
Until the invention of the telescope, observation of the sky was with the naked eye. That is, without the help of an optical instrument capable of collecting the light emitted by the stars and generating an enlarged image of them.
Any optical telescope (sensitive to the wavelengths of visible light) consists of two fundamental components: objective and ocular.
Depending on the objective of the telescope, these can be classified into two large groups:
1. Refractors or glasses: Your objective is made up of a lens or lens coupling. To this type belongs the Galileo telescope with which lunar craters and the four Galilean satellites of the planet Jupiter were detected.
2. Reflectors: the objective is a mirror or mirror coupling. His forerunner was Isaac Newton, who designed a telescope more compact than the refractor, correcting image defects such as the chromatic aberration. Most later telescopes have been based on this Newtonian model.
As early as the 18th century, the astronomer and musician William Herschel designed a reflecting telescope that allowed him to discover a planet farther away than Saturn (to date, the last in the Solar System). Later christened the planet Uranus, this discovery took place just 173 years after Galileo’s first observations.
The largest telescope in the world (until 1917) was the de Rosse The Parsonstown Leviathan. It was a reflector with a primary mirror size of 1.8 meters capable of observing, among other objects, spiral galaxies such as the one in Whirlpool (M51).
In the 20th century, Hooker’s telescope (with a diameter of 2.5 meters of the objective) managed to observe galaxies like the one in Andromeda (M81).
He took over hale’s telescope, which challenged the Hooker’s design with a 5 meter diameter mirror. With these characteristics, the astrophysicist Edwin hubble managed to measure the radial velocity of the galaxies reaching a surprising conclusion: the galaxies are moving away from us and the more distant they are, the faster they are. It was the first experimental confirmation of the expansion of the universe.
The idea of placing a telescope in space was conceived at the end of the 20th century and materialized with the launch into orbit in 1990 of the hubble space telescope. In this way, atmospheric turbulence and light pollution are eliminated during astronomical observations.
It is a 2.4 meter primary mirror reflector with a mass of about 11 tons. In his thirty years of service, he has captured unprecedented images of nebulae, galaxies, explosions of supernovas and images of the high resolution solar system planets.
Potential discoveries from the James Webb
The James Webb telescope will be the most powerful to date. It will have a 6.5 meter diameter primary mirror (made up of 18 hexagonal beryllium segments, coated in gold) and will obtain images in the range of infrared.
What is special about this feature?
On the one hand, to capture details of astronomical objects that could not be recorded with a telescope operating in the visible.
As an example, the lower image represents the same astronomical object (the Lagoon Nebula, M8) taken in the visible spectrum (left, with a high concentration of cosmic dust) and infrared (right). It is notable that the concentration of cosmic dust makes it difficult to distinguish (in the visible range) the set of stars present in M8.
NASA
But its greatest strength will be the observation of the most distant and ancient galaxies in the universe. Due to the effect known as redshift, the light emitted by these primitive galaxies (and that are moving away at greater speed from us) will be detected by the new space telescope in the infrared range, something unthinkable for ground-based observatories (including the Hubble space telescope).
Furthermore, since the objects colder of the universe also emit in the infrared, the James Webb Space Telescope will allow the observation of extrasolar planets with unprecedented resolution.
If the Galileo telescope showed a sky unknown until then, the James Webb space telescope will open another window to the first moments of the universe, when the most distant galaxies began to form. It will undoubtedly be an exciting trip to the past.
Oscar del Barco Novillo, Associate professor in the area of Optics, University of Murcia
This article was originally published on The Conversation. read the original.
Reference-www.eleconomista.com.mx