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“The Pillars of Creation”, one of the most famous images captured by Hubble. Giant columns of gas and dust indicate cradles of stars in the Eagle Nebula.
Not only has it dazzled millions of people in the world and lasted more than twice what was expected, it is also “a thousand times better” today than in its beginnings.
The Hubble Space Telescope, one of the most extraordinary scientific instruments in history, fulfills 30 years in space.
“The cosmological advances that Hubble has enabled are massive, legendary“Kathryn Sullivan, a former NASA astronaut, told BBC News.
Sullivan was one of five crew members on the historic space shuttle Discovery mission that took off on April 24, 1990 with the precious telescope on board and placed it in orbit a day later.
But Hubble has not only revolutionized astronomy. It has also become an icon.
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“We have all seen spectacular images captured by Hubble on our computers and cell phones. It is the only scientific instrument that I know of that has become such a beloved symbol in popular culture, ”said Sullivan.
The astronaut shared with BBC Mudo little-known stories from the history of the telescope, gathered in the book “Footprints on Hubble” (Handprints on Hubbland), who wrote on the occasion of the anniversary.
The dream of a space telescope
Placing a telescope in space was the culmination of a decades-long dream.
Already in 1946 the American astronomer Lyman Spitzer published a famous article in which he outlined the advantages of a space observatory.
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The telescope fit just as well in Discovery’s cargo section “as bread in its pan.”
But Spitzer’s vision he was ahead of his time. And making it happen took many years of engineering advancement.
Why a space telescope? “I like to quote James Odom, one of the directors of the Hubble program,” Sullivan told BBC Mundo.
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“He said that trying Seeing stars from Earth is like wanting to watch birds from the bottom of a lake.
“And it is that the atmosphere always has particles of water and dust that affect the light that reaches us. That turbulence makes the stars ‘flicker’ when in fact they don’t.
“Furthermore, the atmosphere prevents the arrival of some forms of radiation, such as ultraviolet. Only a telescope in space could open great doors for astronomy. “
Forgotten heroes
It was only in 1977 that NASA commissioned the Lockheed Martin company to design and manufacture the space telescope, which in 1983 was renamed Hubble in honor of the American astronomer Edwin Hubble.
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Hubble has been orbiting Earth for more than 500 kilometers for three decades. The telescope is operated by NASA with the participation of the European Space Agency.
The telescope was scheduled to launch in 1986, but the explosion that year of the shuttle Challenger and the death of its seven crew members forced a change of plans.
From 1986 to 1990, Sullivan and astronaut Bruce McCandless, another member of the mission that put Hubble into orbit, worked intensively with Lockheed Martin and NASA engineers.
Components and tools had to be not only adapted but invented to allow for something unprecedented: repairing an orbiting telescope.
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Each tool had to be tested by astronauts submerged in large water tanks that simulated the lack of gravity in space.
“Hubble is the only scientific satellite that has improved over time and this is thanks to the engineers who designed the telescope from the beginning so that it could receive maintenance in orbit, “said Sullivan.
For the astronaut it is crucial to understand that the fact that it could be maintained “is not something that can be added; it must be incorporated from the design ”.
And it was that vision that enabled Hubble to improve over time.
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Components and tools had to be not only adapted but invented to allow for something unprecedented: repairing an orbiting telescope.
Five shuttle missions, the so-called service missions between 1993 and 2009, replaced instruments on the telescope and upgraded its technological capabilities.
“I wanted to talk in my book about the role of engineers, those forgotten heroes, thanks to whom Today the telescope is a thousand times better than when we put it into orbit. It is a Hubble story that has not been told. ”
A catastrophic mistake
Discovery’s crew completed the delicate operation of placing the telescope in space on April 25, 1990.
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“Hubble is as big as a bus and it fit as tightly into Discovery’s cargo compartment as bread in its pan,” recalls Sullivan.
The shuttle’s robotic arm carefully lifted Hubble and placed it in its orbit more than 500 km from Earth.
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“The telescope is a thousand times better today than when we put it into orbit.”
In the following days, astronomers around the world eagerly awaited the first images of the telescope that had cost more than a billion dollars. But expectations evaporated dramatically.
“Time passed and there was no news about the images. And suddenly NASA gave a press conference in which several high officials, with faces of shock, they had to confess to the world that the telescope could not focus correctly“Sullivan recalled.
“The reason was that the main mirror, 2.4 meters in diameter, had to have a very particular curvature. It had been polished with an error of a fraction of a human hair. It was a tiny but catastrophic error for the telescope.”
Hubble became ridiculed by congressmen, commentators and even comedians.
“It was really devastating and many at NASA questioned their self-confidence. They wondered how such a fundamental error could go unnoticed despite all the controls.
“And let’s not forget that this happened after the Challenger tragedy, so some questioned even NASA’s own competition questioning if he had lost his way and had been able to put man on the Moon but now he can’t even build a telescope. “
The most famous contact lenses
It took NASA three years to find a response to Hubble’s blurred vision.
And the solution was to put the equivalent of contact lenses in the telescope.
Replacing the large mirror in the bowels of Hubble was not an option. The solution was instead to intercept the blurred light emitted from the mirror and correct it before it reached the scientific instruments inside the telescope.
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Techniques similar to those applied by an optometrist were used to correct the blurred vision of the telescope.
The company subcontracted to build the mirror (Perkin-Elmer) made a big mistake, “but it was a very precise mistake, so it was possible to calculate exactly how to correct the defect,” says Sullivan.
“It is basically what an optometrist does when we need glasses.”
Hubble’s first service mission in 1993 replaced the main camera for capturing images with a new one with correction mirrors.
But the big question was how to place mirrors in front of all other instruments.
Sullivan reported that the inspiration to find a solution to this problem occurred in the least expected place, a shower.
“This was confirmed to me by the engineer who found the solution, Jim Crocker of Lockheed Martin. He was taking a shower during a trip to Europe, where they have shower heads on movable bars that can be raised or lowered depending on the height of person”.
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“That was the time for the eureka. ‘There is the solution,’ said Jim Crocker, who then designed a movable arm with different correction mirrors that extended to position itself precisely in front of each of the instruments.”
The mirrors conceived by Crocker were also installed on the 1993 mission.
Hubble achievements
Since he regained his vision, Hubble It has exceeded all expectations.
“It has allowed us to look deeper and further back in time than ever before,” said Sullivan.
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The resolution of the telescope has exceeded all expectations.
“Just to give a few examples, it has allowed us to explore stellar cradles, those large clouds of gas where stars form. He has also found dwarf planets and protoplanetary disks, the clouds of matter in which planets form around stars. “
Hubble also provided the first evidence for the existence of a black hole.
“It also made it possible for the first time to accurately measure how rapidly our universe is expanding and allowed us to discover the first planet to orbit a star other than our Sun.”
Technicolor show
Of all the images captured by Hubble, one of Sullivan’s favorites is the one known as Hubble’s Ultra Deep Field or Ultra Deep Field.
It is one of the images that most symbolizes the power of the veteran telescope.
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Kathryn Sullivan
Sullivan was one of five crew members on the historic space shuttle Discovery mission that took off on April 24, 1990.
“Astronomers decided to focus Hubble, in a long exposure, on a part of space that according to observations on the ground was empty,” said the former astronaut.
“What Hubble revealed was a technicolor show. And what we see is not stars but thousands upon thousands of galaxies outside our Milky Way, thousands of galaxies where we thought before that there was nothing.
“Hubble has taught us that no place is empty in the universe.”
The future of the telescope
What will happen to the beloved Hubble? NASA ended the space shuttle program in 2011, so there will be no missions that can repair future flaws in the telescope.
The agency plans to launch in 2021 a new, more powerful space telescope, the James Webb.
“In my opinion, NASA will face a tough decision one day: whether to continue operating Hubble or whether due to the cost of operating the two telescopes, choose to focus all efforts on the James Webb,” Sullivan said.
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For Kathryn Sullivan, engineers are the “forgotten heroes” who made Hubble’s glorious story possible.
The last mission to Hubble placed an external device, a kind of handle on the telescope.
“If NASA decides to stop Hubble from operating, a robotic probe could in principle grab the telescope and lower it in a controlled manner so that it falls in a precise and safe place, like the middle of the ocean.”
Footprints on Hubble
But Hubble is currently exploring space.
The last astronaut to touch the telescope was John Grunsfeld on the 2009 service mission.
“I want to wish Hubble its own adventures and that with the new instruments we have installed it will continue to reveal mysteries of the universe,” Grunsfeld said after patting Hubble affectionately, as if saying goodbye to a friend.
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The tracks of Grunsfeld and other astronauts can still be seen in the telescope.
For Kathryn Sullivan, those footprints are just the tip of the iceberg: They represent the work of hundreds of scientists and engineers who made it possible for 30 years after the launch of the great Hubble, their eyes continue to scan the universe.
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