Is it True That the James Webb Telescope can solve many mysteries?

The James Webb Telescope, the solver of mysteries, is about to start! The launch of the James Webb Space Telescope is now less than a month away.

If the god of space exploration wills it, on December 22, an Ariane launcher will bring into orbit the most perfect and expensive astronomical machine ever built by man, and then direct it to the distant Lagrange 2 region, a quiet and sheltered gravitational oasis from where it will begin to investigate the universe. While we pray that everything will go well, it will not be bad to try to understand what this technical prodigy can do for us. Research on NASA

"Webb is his given name and it will be the space telescope that is now universally considered the successor to the Hubble Space Telescope. This new instrument is also named after one of the American fathers of space exploration.

Edwin Hubble is the astronomer known for having formulated in 1929, together with Milton Humason, the empirical law on the speed of recession of galaxies, which confirmed the hypothesis of the expansion of the universe.

James Webb was the second administrator of NASA, called in 1961 to lead the Space Agency by John Fitzgerald Kennedy to make reality his historic speech "We choose to go to the moon" A dream was then crowned in 1969 with the Apollo 11 mission.

So now, the name Webb is inextricably linked to the most advanced instrument to investigate the universe that we are going to launch outside the atmosphere.

Credit to NASA

Until a few days ago, the plans included the launch of the James Webb Space Telescope on December 18, but the date has now been moved to December 22 due to minor setbacks, which NASA ensures will be of little importance.

If so, for at least 5 years, we can see the two "extraterrestrial" telescopes working together, waiting-hopefully as late as possible for the final retirement of Hubble, and at least after having blown out the thirtieth candle of its activity in orbit. The JWST is now universally considered "Hubble's heir," but it will not be a trivially modernized copy.

What are its main features and how does it differ from HST? From the standpoint of implications for astrophysics, the most important differences are twofold: First, JWST's primary mirror, which is 6.5 meters in diameter, is nearly three times larger than that of HST. This means that the photon-collecting surface on JWST will be about seven times larger than on Hubble. A telescope this large has never been launched into space.

Essentially, JWST is a telescope similar in size to large ground-based telescopes (slightly smaller than ESO's Very Large Telescope), but operating in the space environment, away from Earth, with very little light "pollution" and without the image deterioration problems due to Earth's atmosphere. JWST is optimized for infrared observations, particularly in the wavelength band between 1 micron and 27 microns. A region of the spectrum where phenomena and objects otherwise invisible in other bands are observable. Research on Weather

Phenomena and objects will be imaged with two types of digital sensors: visible to near-infrared arrays with 2,048 x 2,048 pixels and mid-infrared arrays with about 1,024 x 1,024 pixels. Webb's angular resolution, or sharpness of vision, will be the same as Hubble's, but in the near-infrared.

This means that Webb's images will appear just as sharp as Hubble's. At a wavelength of 2 micrometers, Webb will have an angular resolution of somewhat better than 0.1 arc-seconds at a wavelength of 2 micrometers (an arc-second is the 1800th part of the apparent diameter of the lunar disk).

Seeing at a resolution of 0.1 arc-second means that Webb could see details the size of a US penny at a distance of about 40 km! Only two factors that affect how sharp an image is-the diameter of the mirror and the wavelength being observed.

They are mathematically related; resolving ability is proportional to wavelength over diameter, so the shorter the wavelength and the bigger the diameter, the sharper your images will be. Webb is optimized to see deeper into the infrared than Hubble and has a much larger mirror, as well as state-of-the-art detectors.

Its imagery will be detailed and spectacular. JWST will allow a giant leap in almost all areas of astronomy. To give an idea of this improvement, just think that in some spectral bands, the sensitivity of JWST will be about one hundred to one thousand times higher than any telescope available at the time.

Credit to https://www.spiedigitallibrary.org/

Such a leap is equivalent, in terms of sensitivity, to moving abruptly from the Galileo telescope to the Very Large Telescope! The fields of investigation for JWST will therefore be vast. One of the areas for which there is the greatest excitement and expectation is the study of the atmospheres of planets in other solar systems.

JWST will allow the identification of different molecular species in the atmospheres of extrasolar planets, will allow the characterization of the physical properties of these atmospheres, and will also allow the assessment of whether some of these planets have conditions suitable for the development of life.

The sensitivity of JWST in the infrared bands will be crucial for penetrating the dense dust clouds in which new stars form in our galaxy, as well as in other galaxies, and will therefore allow us to study in detail the process that leads to the formation of stars, as well as the formation of planets in circumstellar disks.

The first scientific results will come from the Early Release Science program, based on 13 proposals chosen from over 4,000 astronomers from around the world.

About 70 percent of Webb’s observing time will be for spectroscopy. (If a picture is worth a thousand words, a spectrum is worth a thousand pictures.) In addition, 20 teams were chosen for archival research and theoretical work.

Altogether, this initial series of observations will cover a vast range of astronomical targets and subjects. We’ll look at the solar system, including Mars, Jupiter, Saturn, Uranus, Neptune, Pluto, Eris, Sedna, Enceladus, Titan (where NASA is sending a helicopter), and Europa (where NASA is sending a probe to look for organic molecules in the moon’s warm water geysers). We’ll look at Proxima Centauri itself about the size of Jupiter with at least one planet of its own, as well as Alpha Centauri, which also might have planets. Research on Guardian

We’ll look at transiting worlds around red dwarf stars like TRAPPIST-1 and hunt for signs of planetary atmospheres. We’ll look into the famous Deep Fields pioneered by Hubble to peer further back in time and see, we hope, signs of the first galaxies being born.

We’ll look through nature’s telescopes: gravitational lenses, which are clusters of galaxies whose gravitational pull magnifies the images of even more distant galaxies behind them.

Some of these lenses magnify their backgrounds by a factor of 10,000, which gives us a chance to see individual stars in the early universe. Closer to home, we’ll look at the Trapezium, the star cluster that makes up the middle "star" of Orion’s sword. Where Galileo saw three stars by pressing his eye to his tiny telescope, our infrared camera will reveal a thousand newborn stars. And close to home, when another interstellar interloper like ‘Oumuamua comes by, we’ll be ready to see if it’s a solid nitrogen pancake.

An artist's concept of a galaxy with a brilliant quasar at its centre.Credit to NASA, ESA and J. Olmsted [STScI]

But what might we find that is completely unexpected? Dark matter, dark energy, and the black holes at the centers of most galaxies stand out as truly special and have won their discoverers a rash of Nobel Prizes in the last decade.

Webb cannot directly see "dark matter," the unseen matter that makes up a large fraction of the mass of galaxies and clusters of galaxies, but he can measure its effects. One of the best ways to measure mass is through the gravitational lens effect.

As described by Einstein's General Relativity theory, a light beam passing near a large mass will be slightly deflected because space-time is disturbed by the presence of mass. By taking pictures of distant galaxies from behind nearby galaxies, astronomers can calculate the total amount of mass in the foreground galaxies by measuring the disturbances in the background galaxies.

Because astronomers can see how much mass is present in stars in the foreground galaxies, they can then calculate how much of the total mass is missing, which is presumed to be in dark matter.

Also, Webb will observe many statistics of galaxy evolution, and scientists can compare these observations to theories of the role that dark matter plays in that process, leading to some understanding of the amount and nature of the dark matter in galaxies. I’m guessing that perhaps some kinds of objects formed in the early universe have all disappeared, so we can’t find them now.

Maybe there were immense stars, thousands or millions of times the mass of the Sun, but they were burning out and turning into black holes and flying debris. Maybe dark matter was turning directly into black holes. Or maybe these strange objects are still here, but masquerading as something else. Or perhaps it’s something about exoplanets.

Today, we know of thousands of them. Planets the size and temperature of Earth are known to be common, with up to 20% of all stars containing one. With the Webb, we will search these planets for evidence of water, which we suspect is a requirement for life. Searching for oxygen is harder and we probably won’t see it, but it would be a strong sign of photosynthesis.

The timeline of the universe.Credit to https://scitechdaily.com/

The Webb will be able to detect the presence of planetary systems around nearby stars from their infrared light (heat). It will be able to see directly the reflected light of large planets the size of Jupiter orbiting around nearby stars. It will also be possible to see very young planets' information while they are still hot.

Webb will have the coronagraphic capability, which means blocking out the light of the parent star of the planets. This is needed as the parent star will be millions of times brighter than the planets orbiting it. Webb will not have the resolution to see any details on the planets; it will only be able to detect a faint light speckle next to the bright parent star. Webb will also study planets that transit across their parent star.

When the planet goes between the star and Webb, the total brightness will drop slightly. The amount that the brightness drops tells us the size of the planet.

Webb can even see starlight that passes through the planet's atmosphere, measures its constituent gases, and determine whether the planet has liquid water on its surface. When the planet passes behind the star, the total brightness drops, and we can again determine more of the planet's characteristics.

But what’s next? Just as Webb was conceived before Hubble even left Earth’s surface, astronomers and engineers are already planning for the next generation of telescopes in space and on the ground. The European Space Agency’s 1.2-meter Euclid telescope is scheduled to launch in 2022 and will survey much of the sky to hunt for evidence of dark matter and dark energy.

NASA’s larger Nancy Grace Roman Space Telescope, with a 2.4-meter mirror (the same size as Hubble’s), is planned for launch around 2026 and will take in 100 times as much sky in one bite as Hubble's.

On the ground, the 8.4-meter "Vera Rubin Observatory" and its 3-gigapixel camera will survey the whole observable sky from its location every three nights, finding millions of short-lived transient events on every sweep, like supernovae, near-Earth objects, and matter falling into black holes.

Also, JWST is ready and able to serve as a follow-up telescope for these finds: If a discovery needs an immediate response, we can do it within two days or less. Even larger ground-based telescopes the 24-meter Giant Magellan Telescope, the Thirty-Meter Telescope, and the 39-meter Extremely Large Telescope—are under construction.

They are perfect for spectroscopy, which requires more light than taking images, and will be capable of imaging exoplanets (though not quite as small as Earth) around nearby stars.

None will be easy to build, but all are possible. In my opinion, each project is worthy of astronomers’ time and effort. Together, they could keep us fully occupied for at least half a century.