The Hubble Marks 34th Year in Orbit: The Telescope That Changed Our View of the Universe

25th Apr 2023
The Hubble Marks 34th Year in Orbit: The Telescope That Changed Our View of the Universe

This month marks the 34rd anniversary of the launch of the iconic Hubble Space Telescope. On 24th April, 1990, the space shuttle Discovery lifted off from Earth with a very special payload: the Hubble Space Telescope, one of humanity’s greatest scientific instruments. This joint effort between NASA and the European Space Agency marked a significant milestone in the field of astronomy.

Hubble space telescope
Credit: NASA/Smithsonian/Lockheed

It’s been over three decades, and the mission continues to amaze the world with its discoveries about our universe. Now, you have a ringside seat to watch the entire universe evolve and change in front of you.

The Launch That Revolutionised Our Understanding of the Cosmos

The idea for the Hubble Space Telescope can be traced back to the early 1940s, when American astronomer Lyman Spitzer proposed the concept of placing a telescope in space. From there, it could avoid the effects of the Earth’s atmosphere, which obscure ground-based astronomers’ view of celestial objects by absorbing or distorting the light rays from them.

A telescope stationed in outer space is entirely above the atmosphere, however, and it creates images of much greater brightness, clarity, and detail than do ground-based telescopes with comparable optics. It wasn’t until the 1970s that the technology and funding necessary to build such a telescope became available.

Developed by NASA and the European Space Agency, the Hubble Space Telescope was equipped with a suite of sophisticated instruments, including cameras, spectrographs, and other detectors, that allowed astronomers to study the universe in unprecedented detail.

Tapestry of Blazing Starbirth image
Tapestry of Blazing Starbirth. Credit: NASA, ESA, and STScI

The Hubble Space Telescope was initially scheduled to be launched in 1986, but the launch was delayed until 1990 due to technical issues and the Space Shuttle Challenger disaster.

Reflecting on Imperfection: Hubble’s Flawed Mirror

It took several weeks of methodically checking Hubble’s control and communication systems before astronomers working at the Space Telescope Science Institute in Baltimore could see Hubble’s first images. The results were disappointing, images were blurred. The telescope’s mirror had been accurately ground but to the wrong shape. An incorrectly assembled test instrument had been relied upon during the manufacture, and nobody had double-checked.

Because the error was understood, a corrective device could be fitted to the telescope. A series of small mirrors would compensate for the primary mirror’s defect. It was called “COSTAR” (Corrective Optics Space Telescope Axial Replacement). A new wide-field planetary camera would be installed. The telescope solar panels with new electronic processors would be replaced.

Astronaut Kathryn C. Thornton lifts COSTAR out of the Shuttle’s payload bay. Credit: NASA

In December 1993, the mission to repair Hubble began. The work on the telescope was considerable and there were five spacewalks scheduled. On the ninth day of the mission, Hubble was released, and all the damaged parts were repaired. Fixing the Hubble telescope wasn’t about physical strength. It required finesse and technical coordination. Reflecting on those intense days, mission commander Dick Covey later shared with evident pride: “There wasn’t anybody that was chilling down on the middeck. Everybody was up top, working.”

It would take close to two months for technicians on the ground to run through a complex series of optical alignments before they could be certain that the telescope was performing correctly. When astronomers finally saw the results, they were stunned at the quality it was delivering. It was New Year’s Day 1994, and astronaut Jeff Hoffman was at home when his phone suddenly rang.

“Jeff, hi. Do you have any champagne left?”
“Yeah, I have a half-bottle in the refrigerator.”
“Well, crack it open. We’ve just had the first pictures back from Hubble. It works!”

Comparison Image of Hubble's photos before and after repairing
View of the universe before and after the first servicing mission in December 1993. The original view, taken a few days before the mirror was fixed, is on the left. Credits: ESA/Hubble & NASA.

The Best of Hubble’s Discoveries

Equipped with a suite of instruments designed to capture images across the electromagnetic spectrum, the Hubble has captured some of the most stunning and scientifically significant images of the universe. NASA says that the observatory has taken a whooping 1.6 million observations of nearly 52,000 stellar targets since its launch.

 Hubble Space Telescope image of Jupiter
The latest image of Jupiter, taken by the NASA/ESA Hubble Space Telescope on 25 August 2020.
Credit: NASA, ESA, A. Simon (Goddard Space Flight Center), and M. H. Wong (University of California, Berkeley) and the OPAL team.

Hubble has looked back into our universe’s distant past to locations dating back more than 13.7 billion light-years from Earth, discovered moons around Pluto, watched a comet crash into Jupiter, found stellar nurseries in the Milky Way that could someday become planetary systems, probed supermassive black holes and has enlightened the world about the universe. All, in just 33 years.

 Hubble Space Telescope image
Credit: NASA, ESA and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration

One of the most iconic images captured by the Hubble is the “Pillars of Creation” in the Eagle Nebula. This image, captured in 1995, shows towering columns of gas and dust where new stars are forming. The Hubble has also captured images of distant galaxies, including the “Hubble Deep Field” image, which revealed thousands of galaxies in a tiny patch of sky.

Pillars of Creation pic made by Hubble
Credit: NASA, ESA/Hubble and the Hubble Heritage Team

Hubble’s Hall of Fame: Top 7 Breakthrough Discoveries

You probably saw most of the jaw-dropping, eye-popping, gobsmacking images the Hubble Space Telescope has sent home over the years. But let’s talk more specifically. Why has Hubble given astronomers an unprecedented window into the Universe? Here is a short rundown of Hubble’s greatest achievements.

1. The Age of the Universe

Age of the Universe
The age of the universe is determined by observing the universe’s rate of expansion. Credit: NASA

The Hubble Space Telescope has been a real game-changer in figuring out how old the Universe is. It started with the spiral galaxy M81, which was just the beginning of many galaxies observed by Hubble to help calculate the expansion rate of the Universe and, hence, its age.

“Before Hubble was launched, astronomers were really scratching their heads over whether the Universe was 10 or 20 billion years old,” explains Prof Wendy Freedman from The University of Chicago.

Freedman decided to focus on Cepheid variable stars. These stars are unique because they pulse, getting brighter and dimmer over days or months. By studying the link between how bright they get and how fast they pulse, astronomers can work out how far away they are. Cepheids are super reliable for measuring the distances to galaxies, which is crucial for figuring out how fast the Universe is expanding. Thanks to the sharp eyes of Hubble’s instruments, Freedman and her team found over 800 Cepheids across 24 nearby galaxies.

Thanks to all these observations with the Hubble Space Telescope, scientists have nailed down that the Universe is 13.8 billion years old.

2. Dark Matter

Dark Matter
Credits: NASA/ESA

This image shows a 3D dark matter map stretching from nearer to farther from Earth. While the stars and galaxies we see make up just 15% of the Universe’s matter, the remaining 85% is dark matter, which doesn’t emit or absorb light.

“With this map, we finally got a glimpse of where dark matter is located,” says Dr. Richard Massey, a physicist at Durham University. The Hubble Space Telescope and other ground-based telescopes studied half a million galaxies to create it.

The way dark matter bends the light, known as ‘gravitational lensing,’ causes the galaxies to look distorted. Observing these distortions helps scientists figure out where dark matter is and understand the Universe’s structure, as dark matter serves as a sort of ‘scaffolding’ for galaxy formation.

3. The Cause of Gamma-ray Bursts

Gamma-ray Bursts

Gamma-ray bursts are the universe’s most intense explosions, releasing more energy in a few seconds than our sun will in 10 billion years. For a long time, no one knew where these bursts came from. Then the Hubble Space Telescope provided some clues: these bursts often happen in galaxies where stars are rapidly forming and where there’s not much metallicity – meaning these galaxies have fewer elements heavier than helium. This environment is perfect for gamma-ray bursts because it’s full of massive stars that can quickly collapse to form black holes. In particular, stars with low metallicity are less likely to lose their mass, making them more likely to end up as black holes.

4. Supermassive Black Holes

Supermassive Black Holes
Credits: NASA, ESA, and G. Canalizo (University of California, Riverside)

Black holes are notoriously tricky to spot since their gravitational pull is so strong that even light can’t escape, rendering them invisible. However, scientists can infer their presence by measuring how fast material moves around them, using the laws of gravity to estimate their mass.

By the early 1990s, astronomers suspected that supermassive black holes (SMBHs) sat at the centres of several galaxies. Right after its launch, Hubble confirmed these suspicions with images five times sharper than those from ground-based telescopes. The Hubble Space Telescope earned a reputation as a ‘black hole hunter’ because it could precisely measure the speeds of gas and stars swirling around these hidden giants.

5. Pluto & Its Kin

Pluto & Its Kin
Credits: NASA, ESA, and M. Buie (Southwest Research Institute)

The Hubble Space Telescope has been quite busy with Pluto. It found two new moons, named Nix and Hydra, and also spotted seasonal changes on Pluto’s surface. Hubble’s work didn’t stop there. It also helped measure the mass of Eris, a body 27% heavier than Pluto. Discoveries like Eris suggest there are more similar objects in the Kuiper Belt and beyond, leading to Pluto reclassifying as a dwarf planet.

6. Exoplanet Atmospheres

Exoplanet Atmospheres
Credit: NASA

The Hubble Space Telescope made a groundbreaking discovery. It was the first to detect the atmosphere of an exoplanet, one of the over 4,000 planets we now know orbit stars other than our Sun. This particular planet, HD 209458-b or Osiris, is a sweltering world located 150 light-years away. It orbits extremely close to its star, only 6.4 million kilometres away, leading to surface temperatures around 1,100°C.

As Osiris passes in front of its star, Hubble uses a spectrograph to analyse the starlight that filters through the planet’s atmosphere. This tool breaks the light into its component colours, revealing details about the atmosphere’s composition.

7. Protoplanetary Disks

Protoplanetary Disks
Credits: NASA/ESA and L. Ricci (ESO) 

Our understanding of protoplanetary discs, also known as proplyds, took a huge leap forward thanks to the Hubble Space Telescope. These discs, which appear as little islands of cold dust and gas, are remnants from the birth of new stars in the Orion Nebula. Over time, some of this material may clump together to form new planets eventually.

These proplyds show us what our Solar System might have looked like when it was just starting out. While ground-based telescopes had previously spotted these objects, mistaking them for stars, it wasn’t until the late 1980s that their true nature as discs was confirmed through molecular observations. Hubble’s direct images of numerous proplyds within the Orion Nebula marked a significant breakthrough in this field.

New Hubble Findings

The telescope continues to deliver. Astronomers are celebrating its launch anniversary with a mesmerising photo of NGC 1333, a star-forming region. Located 960-light years away, the nebula is located in the Perseus molecular cloud.

NGC 1333 region image by Hubble
Credit: ESA/Hubble & NASA, K. Stapelfeldt

What it shows is “an effervescent cauldron of glowing gases and pitch-black dust stirred up and blown around by several hundred newly forming stars embedded within the dark cloud,” NASA and the European Space Agency (ESA) noted.

Wrapping Up

The Hubble Space Telescope remains one of the most important tools in astronomy today, and its impact on our understanding of the universe cannot be overstated. Each pixel helps unlock another scientific mystery.

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