Hubble, our eyes on the unknown

Since its launch on April 14, 1990, on board the Space Shuttle Discovery, the Hubble Space Telescope (HST) has revolutionized our understanding of the universe and impressed the world with its breathtaking images and groundbreaking discoveries.

Lockheed Martin personnel located at NASA's Goddard Space Flight Center. Credits: Lockheed Martin — *Lockheed Martin personnel located at NASA’s Goddard Space Flight Center. Credits: Lockheed Martin*

Called after the renowned astronomer Edwin Hubble, with a mirror 2.4 meters in diameter and five main instruments, the telescope is one of NASA’s Large Orbital Observatories.

A clear view

Placing a telescope in Earth’s orbit has strong advantages as it allows to obtain extremely high-resolution photos; it is, in fact, possible to remove the noise due to the atmosphere, which afflicts telescopes on Earth.

Hubble has recorded some of the most detailed visible-light images ever taken. From vibrant nebulae and swirling galaxies to distant star clusters and planetary systems, the HST has provided humanity with unprecedented views of the cosmos. Its high-resolution cameras and precise optics have revealed the intricate details and charming beauty of objects billions of light-years away.

*Hubble space telescope launch on board of Space shuttle Discovery during STS-31. Credits: spacefacts*

Eye in the lens

Equipped with a suite of powerful scientific instruments, the HST has not only captured stunning visuals but has also allowed astronomers to make groundbreaking discoveries in various fields. In years of activity, over 9,000 reports based on data from the space telescope were published. By observing distant supernovae, the Telescope has provided evidence for the accelerating expansion of the universe, leading to the discovery of dark energy, an enigmatic force shaping the fate of the cosmos.

*Hubble in Low Earth Orbit. Credits: NASA*

The HST has also played a crucial role in refining the measurement of the Hubble constant, a fundamental value that determines the universe’s age and rate of expansion. Nowadays, the HST is estimated to have generated 15 times the data obtained from a 4-meter ground-based telescope, underscoring its efficiency.

Severe issues on the horizon

Once launched in 1990, a problem was discovered with the primary mirror, which had been incorrectly excavated, compromising the telescope’s capabilities as images were blurry. The importance of the defect was very high as it made a million-dollar project practically unusable. So, the idea of the most ambitious repair mission performed by hand in space.

Astronauts of the repair mission STS-61 working on the telescope. Credits: Spacefacts — *Astronauts of the repair mission STS-61 working on the telescope.*
*Credits: Spacefacts*

The Repair Mission flew onboard Space Shuttle Endeavor in December 1993 and involved several specialized tools and equipment being installed over more than 10 days of hard EVAs (extravehicular activities). In this way, the 7 astronauts of STS-61 saved Hubble’s life. Hubble is the only telescope designed to be modified in orbit by astronauts. After the launch of Space Shuttle Discovery in 1990, 5 Space Shuttle missions repaired, upgraded, and replaced systems on the telescope, including all 5 of its primary instruments.

Comparison image of the core of the galaxy M100 shows the improvement in Hubble Space Telescope's view after STS-61. Credits: NASA — *Comparison image of the core of the galaxy M100 shows the improvement in Hubble Space Telescope’s view after STS-61. Credits: NASA*

Searching for life

The HST has significantly contributed to the study of exoplanets and planets orbiting stars beyond our solar system. By observing the slight lowering of a star’s light as an exoplanet passes in front of it, known as the transit method, the HST has helped identify and characterize numerous exoplanets. With this method, it is possible to analyze the gases that make up the atmospheres of these fascinating planets, thus evaluating the possible presence of organic material. These observations have provided valuable insights into the diversity of planetary systems and the conditions necessary for life to exist elsewhere in the universe.

NASA's Hubble Space Telescope has revisited the famous Pillars of Creation, Credit: NASA, ESA, — *NASA’s Hubble Space Telescope has revisited the famous Pillars of Creation, Credit: NASA, ESA*

Far far and even farther

The Hubble Deep Field, Hubble Ultra-Deep Field, and Hubble Extreme Deep Field constituted three unique windows on the Universe; exploiting the visible sensitivity of the HST, images of small samples of the sky were obtained – the deepest ever obtained in this wavelength. The frames included galaxies billions of light years away and generated a wealth of scientific data about the creation of the universe.

*Hubble Extreme Deep Field. Credits: ESA*

A tool for the community

As we reflect on its extraordinary achievements, it is important to note that the Hubble Space Telescope’s impact extends far beyond its scientific contributions. It has become a symbol of human curiosity and our insatiable desire to explore and understand the cosmos. Especially, for public use, anyone can uses the telescope; there are no nationality or academic restrictions. The competition for the telescope is intense, as only a fifth of the proposals for where to point its gaze are ultimately accepted.

*Messier 66 galaxy located at a distance of about 35 million light-years in the constellation of Leo by Hubble Space Telescope. Credits: NASA*

A worthy heir

The Hubble Space Telescope’s legacy will continue to inspire future generations of astronomers and space enthusiasts. The telescope is currently fully operational, and according to estimates, it will be able to operate until 2030-2040, or perhaps even longer. In 2022 a non-exclusive agreement was signed between NASA and SpaceX to reposition the telescope at a height of 600 km, avoiding atmospheric re-entry. The James Webb Space Telescope was launched on December 25, 2021, and many consider it its successor. We can celebrate the remarkable achievements and profound impact of this iconic telescope. The Hubble Space Telescope has genuinely transformed our view of the universe, and its contributions to humanity’s quest for knowledge will endure for generations to come.