Hubble: The Telescope, The Science and The Legacy

Hubble Telescope: The Science and The Legacy

Look at this picture.

Beautiful, isn’t it? But however long you stare at the night sky or use one of those fancy DSLRs that you might own to take a picture, you’re never going to get an image as detailed as this one. Even with a telescope, you might end up missing certain duller stars, or if the weather is bad, not even get a proper image.

The Hubble Telescope (Credits: Source)

Maybe that’s why many astronomers wanted a telescope that was free from all the interference by clouds, dust, light, and pollution in general. And that’s how the subject of this blog was conceptualized.

Yes. That is the Hubble Space Telescope or the HST. Launched on the 24th of April and deployed on the 25th of April, 1990, the telescope has provided us invaluable data about the stars and the cosmos. It may not be the largest of telescopes, with a 2.4-meter radius primary mirror,  but since it is in space – it orbits at an average altitude of around 600 kilometers, it is free from all the distortions of the atmosphere. This makes it an invaluable boon to astronomers around the world!

Working of the Hubble Telescope…

Hubble is a joint mission by the American space agency NASA and the European Space Agency. It was deployed from the cargo bay of space shuttle Discovery on April 25, 1990, as part of STS-31. Its four main instruments can capture signals from the UV, visible and near-infrared. Since the range of its possible observation is such, the amount of data it sends back to us, 120 gigabytes of data every week, is quite large. The telescope is solar-powered, with two twenty-foot solar panels that you can see in the picture. 

The Hubble telescope is a Cassegrain reflection telescope. A schematic diagram of its mechanism is given below.
The Hubble Telescope is a Cassegrain reflection telescope. A schematic diagram of its mechanism is given below. (Credits: Source)

Let’s talk about how a Cassegrain reflection telescope works for a few minutes now. This kind of telescope usually involves two mirrors, a primary, larger, paraboloid mirror and a secondary, smaller, hyperboloid mirror. Light or electromagnetic radiation (let’s call it a signal) enters through the aperture of the telescope. First, it hits the primary mirror and is reflected to the secondary mirror. The secondary mirror focusses this signal onto the detector through a hole in the primary mirror. The detector transfers the signal and the associated data to the various instruments present, which converts it into a form that shows us what the signal looks like and from where in the sky it came from – an image!

Perhaps from the image and explanation, we may not be able to appreciate the level of accuracy and precision that is required to make this telescope as effective as it is. To illustrate this point, let us look at one instance of an error. After the launch in 1990, NASA realised that there was a small aberration on the primary mirror of the Hubble space telescope. The defect itself was tiny, close to 1/50th the width of a human hair. But this caused such a significant distortion to the image formed, that astronauts had to add corrective optics to compensate, during the December 1993 Servicing Mission 1. 

A Note on the Important Discoveries

Of course, considering how long the telescope has been around, and also considering how much data it has sent back to us, there has been a lot of new science and discoveries that have been made possible thanks to the HST. Here are a few of them described in no particular order. 

Dark Matter

For a long time, dark matter has remained a mystery to many scientists. Even now, we don’t quite understand what exactly it is. But thanks to the HST, we know a little bit of its distribution in space. By analyzing the distortions of the light, Hubble could make a map of the presence of dark matter in space.

Dark matter map in galaxy cluster Abell 1689
Dark Matter Map in Galaxy Cluster Abell (Credits: Source)

The Moons of Pluto

The Hubble Space Telescope has given us insight about the ex-last planet of our solar system. First, it helped us identify two of its moons, Nyx and Hydra

It also showed seasonal variations on the surface of Pluto.

(Credits: Source)

But the discovery that really changed our solar system was the discovery of the mass of the body Eris. HST helped show that Eris was 27% more massive than Pluto. The realization that there were bodies that were bigger than Pluto, and that many of them were orbiting the Sun close to the Kuiper belt and beyond, resulted in the demotion of the status from a planet. 

The beginnings of Planetary Systems

Hubble caught protoplanetary discs, which is basically a rotating disc of dense gas and dust that surrounds a young, newly formed star while exploring the Orion Nebula. This points in the direction of the existence of exoplanets.

(Credit: Source)

Gamma-Ray Bursts

Gamma-ray bursts are high energy explosions from the universe. They release more energy in a second than our Sun will in its entire lifetime. For a long time, we didn’t know how they originated. But thanks to Hubble, we now know that they originate from galaxies with actively forming stars and are low in metalicity. Such galaxies are more likely to contain massive stars that collapse quickly, and low metallicity stars are more likely to retain their mass and form black holes.

Gama Ray Bursts captured by Hubble Telescope
Gama Ray Bursts captured by Hubble Telescope (Credits: Source)

On the topic of black holes…

Speculation of Black Holes

A black hole is a region in space where gravity pulls so much that nothing, not even light, can escape. They are usually formed when stars collapse at the end of their lifetime. The Hubble telescope showed that super-massive black holes are probably found in galaxies that have a large clump of stars at its center. It also showed that there exists a link between the size of the galaxy and the size of the black hole. Such data that reveals how our universe began was also collected by studying this. 

Of course, there are more discoveries that are made, including finding comets, dark energy, and also revealing precious information regarding the formation of the universe. If we had to talk about everything that the telescope found, we’d be here all day! The contribution of this telescope to astronomy is immense. 

The legacy we remember…

The impact of the telescope to astronomy has been immense. It has provided us with a new perspective with which to look at the sky. This April 25th, when we celebrate 30 years of the Hubble telescope, let us remember the people and celebrate the science and the people that have made it possible for us to reach to the horizons of both space and time. Of course, the road was not very easy.

This is the video version of this article

Great people made unbelievable blunders. Unknown geniuses remained unknown despite groundbreaking discoveries. In the end, they have taken humanity one step forward to understanding the cosmos, and still continue to push the boundaries of what is known. The Hubble Space Telescope has been our eyes to the stars for thirty years now and will continue to show us visions of what we could never achieve with a similar telescope on Earth. 

The Hubble Space Telescope is an important tool and a memorial to one of the most important scientists of the 20th century, Edwin Hubble. A legacy of 30 years of the Hubble Telescope, and an even longer legacy of the universe itself. It is estimated that Hubble will continue its quest for new things in the cosmos until 2025 and 2025 will mark the end of its service.

Perhaps the biggest testament to the success of the telescope is the hundreds of pictures found across the internet. Google for HST pictures, and you’re greeted with a barrage of what can only be described as otherworldly sights of gas clouds and stars like diamonds. And it is not just one or two pictures; hundreds of them have been sent to us to study. And I’ll leave you with one picture of the Eskimo Nebula to finish. 

The eskimo galaxy
The eskimo galaxy (Credits: Source)
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