Spying on the Stars; The Hubble Space Telescope

“Hubble isn’t just a satellite, it’s about humanity’s quest for knowledge” – John Grunsfeld, American Physicist

Article by W. S Thishakya De Silva, 2nd Year Undergraduate

In today’s rapidly expanding world of knowledge, one often hears of remarkable achievements made in astronomy.

From discovering new moons of planets to obtaining accurate estimates of the age of our universe, as well as calculating the rate of expansion of our universe, it is truly astonishing to comprehend the constant amount of discoveries made in recent decades.

To truly understand the brilliance of such discoveries, let us take a peek into an integral part of the machinery and technology that made such monumental and significant discoveries possible in the first place, namely, the Hubble Space Telescope.

Before the existence of Hubble, in the early 1900’s, scientists theorized about a telescope that could be sent to space via a rocket.

One of the main reasons that compelled scientists to aspire to send a telescope that was capable of observing the galaxy in space, as opposed to simply constructing one here on Earth, was due to the effects the Earth’s atmosphere had on observations; the turbulence of Earth’s atmosphere caused many issues with a telescope’s angular resolution, and the ability of our atmosphere to absorb both IR and UV lights, made observations using those wavelengths obsolete on earth. Thus, the thought of a telescope that could circumvent such issues was an alluring idea to the scientific community.

After two world wars, and many issues with funding and feasibility, as a result of the collaboration between the European Space Agency and NASA, the US finally began construction of this Cassegrain telescope in 1978; in 1983 it was named ‘Hubble’, in honor of Edwin Hubble, who confirmed one of the most important theories of the 20th century, namely, the expansion of the universe.

The construction of this telescope and its spacecraft would pose many significant challenges throughout the design phase, which included the optical tube assembly, spacecraft systems as well as computer systems, nevertheless, all these various components were meticulously crafted to work together in unison. Once construction was complete, in 1990 the spacecraft Discovery launched Hubble into space, in what would eventually herald in a new age of astronomical research.

*Figure 2: The Discovery Spacecraft launching with the Hubble Space Telescope in 1990.*

The beginning of this project was wrought with technical issues, mainly involving issues with the primary mirror of its telescope, but after many service attempts and upgrades, it eventually began to become one of the most important telescopes, making one groundbreaking discovery after another, furthering our understanding of the universe in many ways.

Today, it revolves 515 km above the Earth’s surface, observing the most intricate details closely. It can observe both closer objects such as asteroids in our solar system peer into the cosmos and see far-away galaxies that date way back to the beginning of the universe.

Some of the most revolutionary discoveries in astronomy due to the Hubble telescope include,

The Rate of Expansion of the Universe

In 1929, Edwin Hubble was the first to observe the rate of the expansion of the universe using a telescope, he came to that conclusion by noticing that the farther away a galaxy is from us, the faster it appears to be receding into space away from us, based on this observation, he collected data by observing 24 nearby galaxies and plotted their velocities against their distance and found out a linear relationship between the two, which revealed that the universe was expanding uniformly in all directions, using the Hubble telescope astronomers were able to refine his measurements of distance and measure a precise expansion rate, in turn utilizing that to estimate the age of our universe as well accurately. As shown in the image, scientists today utilize cyclical changes in the brightness of Cepheid stars to determine astronomical distances.

*Figure 3: The arrow shows a Cepheid star in the Andromeda Galaxy.*

The Concept of Dark Energy

Another important finding was the fact that the universe was not just expanding but was also accelerating, leading to a notion of the existence of ‘dark energy’, an invisible force that causes this acceleration by pushing galaxies apart. Current estimates predict that around 68% of the observable universe comprises dark energy, and it is currently one of the most fascinating concepts in modern astronomy.

Researching Growth of Galaxies

The deeper you look into space, the farther back you look in time. This is due to the speed of light being finite and taking a long time to reach Earth. As the universe was much smaller in the distant past, there was a higher chance of them interacting with each other gravitationally and images of distant galaxies show fascinating results, by studying galaxies of different time eras, scientists can gain a plethora of information into the evolution of the universe.

*Figure 4: Image taken by Hubble’s Deep Field Telescope, this image required a total exposure time of 11 days.*

Supermassive Black Holes

*Figure 5: The disks of dust that fuel black holes at the centers of the galaxies NGC 4261 (left) and NGC 7052 (right)*

Even before the Hubble Space Telescope was invented, scientists had a theory that supermassive black holes could exist, but there was no conclusive proof attesting to their existence. In 1994 Hubble’s Faint Object Camera was able to observe the center of the galaxy M87. By analyzing the velocity of the ionized gas that orbited the center of M87, they realized that only a supermassive black hole could have the gravitational power to create such a high velocity.

Exploring Planetary Systems

Scientists can measure the atmospheric composition of extrasolar planets, and thereby by measuring their organic components can identify planetary objects that have the potential to harbor life.

Although astronomers have been able to find more than 5000 extrasolar planets using NASA’s Kepler and TESS space observatories, Hubble has been able to further our understanding of planets which may have the potential to have some form of life. This has become an incredibly wonderful tool for humanity to continue its quest to unravel the secrets of our cosmos.

Apart from the many significant scientific achievements Hubble was able to partake in, the various technologies perfected while delving into the cosmos have found a wide range of applications outside of scientific research, aiding in the most unexpected of fields, software used by Hubble has been modified and used to track endangered sharks, read the Dead Sea scrolls and even aid in faster medical treatment. This is indicative of just how monumental and far-reaching the technologies created for Hubble are, and a humbling reminder of many facets of scientific innovation.

Although Hubble has aided in a plethora of remarkable discoveries it is estimated that it will eventually stop working optimally after 2030, nevertheless, as of today, it remains one of the most valuable astronomical tools, complimenting decades of scientific research and giving us humans an unprecedented level of access into the vast and unknown parts of the cosmos. It is a testament to the power of science and research, and its fascinating story, full of hurdles and doubt, is a reminder to us all that progress takes time, and that the path to success isn’t always linear.