Updated: Aug 5
Author: Chinmay Pala
[Physics World. https://physicsworld.com/wp-content/uploads/2020/04/PIA18165_orig.jpg.]
This article will tell you about the impact of giant telescopes, what are the challenges faced by these telescopes, why should we have large telescopes, what are the impacts made by the HST and what impact will be made by its successor JWST, which would be launched in 2021.
Space, the enormous vast nothingness that surrounds us and is beyond human imagination, needs to be studied. And we have been studying it for a long time using telescopes. Telescopes had been invented about 400 years ago by the astronomer Galileo and has been evolving since - from the old Galilean telescope to the Hubble space telescope.
Why should we launch a telescope into space rather than making one on earth? The main reason we put telescopes into space is to get around the Earth's atmosphere so that we can get a clearer view of the planets, stars, and galaxies that we are studying. Our atmosphere acts like a protective blanket, letting only some light through while blocking the rest. So launching a telescope to space can give a more clear and high-quality picture. But there is a problem.
Launching and sending a telescope to space may cost millions of dollars. And making a more efficient telescope on earth is more convenient, since it can be built bigger, and using less money. They are easier to maintain and upgrade. Practically speaking, they also have a much lower risk of being damaged. But there are problems with ground telescopes. In space, however, telescopes are able to get a clearer shot of everything from exploding stars to other galaxies. Another disadvantage of a ground-based telescope is that Earth's atmosphere absorbs much of the infrared and ultraviolet light that pass through it.
Space telescopes avoid the filtering of ultraviolet frequencies, X-rays and gamma rays; the distortion (scintillation) of electromagnetic radiation; as well as light pollution which ground-based observatories encounter.
The question that arises is that should telescopes be wandering around in space or be on a planet or moon where an atmosphere is absent. Let’s take the example of the moon. Practically speaking the quality of image in both will be the same. But looking towards the flexibility, there is a lot of difference. We can change the movement, direction and speed. This gives us a more flexible image and a wider view.
Why should we have a larger telescope? What does it give more? If this question is in your mind, here is the answer for it - larger telescopes collect more light and allow you to see images in greater detail. Telescopes make objects appear larger. Larger telescopes allow astronomers to see farther into space.
As is obvious, a telescope lets us see a lot of things which we are unable to see with our naked eyes. So why exactly do we want to observe these distant objects? Well, the first reason is curiosity. There are secondary objectives such as looking for life around with the help of Drake equation, the rehabilitation of humans after the earth becomes inhabitable and exploration of more planets to live. Also, studying and deeply observing these make us familiar with things like antimatter, which we can use for energy production.
A telescope's productivity is measured by the number of papers published which are based upon data taken with the telescope. The scientific impact of a paper can be measured quantitatively by the number of citations that the paper receives. [Crabtree, Dennis. (2008). Scientific productivity and impact of large telescopes - art. no. 70161A. 7016. 10.1117/12.787176.]
The challenges faced by the 20th century ground-based telescopes are mostly regarding connection with urban scientists, since these telescopes are made in hilltops or on the mountains away from the city. Space-based telescopes can even be controlled from earth.
There are more problems faced by the space-based telescopes. Just like the lifespan of a human, telescopes have lifespans too. They are not eternal.
Let’s first discuss about the Hubble Space Telescope (HST). It was launched into Low Earth Orbit in 1990 and remains in operation. It was not the first space telescope but it is one of the largest and most versatile space telescopes, well known both as a vital research tool and as a public relations boon for astronomy. The Hubble telescope is named after astronomer Edwin Hubble and is one of NASA's Great Observatories.
The Hubble Space Telescope has been circling the Earth for 25 years, but the iconic observatory won't last forever. The telescope's operators based in NASA express confidence that the device will keep operating through at least 2020, and maybe some more years.
But after that? We should have something similar but even more compact. So we developed a telescope that can do much more than its predecessor.
This telescope is the James Webb Space Telescope (JWST or "Webb"). It is a space telescope that should succeed the Hubble Space Telescope as NASA's flagship astrophysics mission. The JWST will provide improved infrared resolution and sensitivity over Hubble, and will enable a broader range of investigations across the fields of astronomy and cosmology, including observing some of the most distant events and objects in the universe, such as the formation of the first galaxies. And a lot more. The Webb will be the largest telescope ever placed in space; 100 times more powerful than the Hubble. So big that it has to fold origami-style to fit in the rocket. The mission will launch soon, in the near future.
These are the general-purpose telescopes which are designed to be able to observe anything and everything in the cosmos. There are many more space-based observatories, but they are launched for specific purposes unlike the general-purpose ones. Examples of such telescopes are Spitzer space telescope, Kepler space telescope etc.
Viewing the space requires a telescope. The impact of giant telescopes in future astronomy have pros and cons and it is completely a matter of discussion and experiment. We have seen the evolution of telescopes and to where we have reached from Galileo's time.