The space observatory and its instruments, an international cooperation effortbetween NASA and the European Space Agency, captures unprecedented views of stars, galaxies and the distant universe in visible, ultraviolet and near infrared light. These different wavelengths of light allowed Hubble to scan different regions of space that had never been observed before.
It orbits the Earth at a distance of 340 miles, well above the distorting effects of the Earth's atmosphereto observe space both near and far.
"Hubble has given us new clarity in our deep space vision," said Jennifer Wiseman, senior scientist for the Hubble project at NASA's Goddard Space Flight Center in Maryland. "And it happened just because Hubble was placed above the earth's atmosphere.
"It gave us a new point of view to see everything in the universe, from the neighboring solar system to distant galaxies and opened our eyes to the richness of the content of the universe and the dynamic activity of the universe in over time. "
The telescope was named for pioneer astronomer Edwin Hubble, who discovered in the 1920s that the distant clouds in the universe were actually galaxies. (He died in 1953.) Hubble relied on the work of the astronomer Henrietta Swan Leavitt to discover the periods of luminosity in the pulsating stars called variables of Cepheid.
Hubble's work led to the revelation that our galaxy was one of many, forever changing our perspective and our place in the universe. Hubble continued his work and discovered that distant galaxies seemed to be moving fast, suggesting that we live in an expanding universe that started with a big bang.
"One of the main reasons for building Hubble was to be able to more accurately measure the rate of expansion of the universe," said Wiseman.
"By Hubble's ability to observe activity in distant and weak galaxies, we have been able to measure this rate of expansion. We are further refining it. In recent years, Hubble, along with other observatories, has contributed to important way to find out that this rate of expansion is accelerating and that was a surprise. We now call the phenomenon behind this dark energy. "
This detection of the expansion rate of the universe contributed to obtaining the 2011 Nobel Prize in physics, awarded to Saul Perlmutter, Brian P. Schmidt and Adam G. Riess "for the discovery of the acceleration of expansion of the universe by observing distant supernovae ".
For 30 years, Hubble has allowed astronomers around the world to study black holes, mysterious dark energy, distant galaxies and galactic fusions. He observed planets outside of our solar system and where they form around stars, star formation and death, and he even spotted unknown moons around Pluto.
Hubble characterized the atmosphere of exoplanets and spotted weather changes on the planets of our own solar system. And he looked through 97% of the universe, looking back in time.
The telescope was to last 15 years and it is still as solid. But Hubble was also designed to be maintained and upgraded over time.
Between December 1993 and May 2009, the astronauts launched the space shuttle and met with the telescope to make repairs and replace the gyroscopes and instruments. The first one, in 1993, helped correct the infamous Hubble mirror defect that caused blurred images to return through the telescope. The astronauts installed corrective optics and new instruments to remedy them.
Each mission, which required years of planning and preparation, forced the astronauts to leave the shuttle and to go out into and inside a component of the telescope for repair and installation of instruments. As the telescope moved at 17,000 miles an hour at an inclination of 28.5 degrees from the equator around the Earth.
"It shows me how we can all work together to do something fantastic and rewarding for humanity," said Wiseman. She worked on Hubble in various roles for 20 years.
Discoveries, expected and unexpected
In 1994, Hubble had the chance to watch a violent event in our solar system.
Comet Shoemaker-Levy 9 was unexpectedly involved in a collision with Jupiter, and the comet was separated into fragments. Astronomers have seen 21 pieces of the comet hit Jupiter, leaving temporary black scars in the iconic clouds of the planet. They had never seen anything like it before.
"It was an amazing realization that the bodies of the solar system can interact in a very energetic way and that our solar system may not be a completely safe place," said Wiseman.
"Since then, Hubble has shown us dramatically how the planets in our solar system undergo weather changes, how asteroids can actually collide with each other, how the moons of planets in our solar system can show the activity and signs of water and basically how our solar system could actually compare to other star systems. "
Hubble also spotted four moons orbiting Pluto that had never been seen before: Nix, Hydra, Kerberos and Styx. The telescope also helped locate a distant object in the Kuiper belt named 2014 MU69, a billion miles beyond Pluto. In 2019, it became the most distant object ever visited by a spacecraft when the New Horizons mission flew over. Now the object is known as the Arrokoth.
Outside of our solar system, Hubble explored our Milky Way galaxy and neighboring galaxies. The spectacular and colorful images of Hubble are known to be largely active nebulae in our galaxy, bright clouds of gas and dust where stars form.
In 1997, a maintenance mission installed NICMOS on Hubble, the near infrared camera and the multi-object spectrometer. This new instrumentallowed the observatory to look through the thick gases and dust surrounding the star nurseries in galaxies, where the stars emit infrared light.
Rodger Thompson, head of NICMOS and professor of astronomy at the Steward Observatory at the University of Arizona, began work on the instrument's proposal in 1984. It shaped the future of infrared astronomy , from the revelation of the secrets of star formation to going back to the earliest. galaxies in the universe.
"We could see in those dusty regions where stars are formed in all the exquisite detail with Hubble," said Thompson. "And we were able to trace the formation of stars in the history of the universe, going back to the earliest galaxies, which only represented a few percent of the age of the universe when they formed."
In the near infrared, seemingly pristine parts of the sky seemed to light up with evidence of distant galaxies, and no one expected it, Thompson said.
Astronomers have discovered that many young stars have disks of dusty debris swirling around them, where planets form.
"When Hubble was launched (in 1990), no one knew a single planet outside of our solar system," said Tom Brown, Hubble chief of mission at the Space Telescope Science Institute in Maryland.
Astronomers found exoplanets in the 1990s using other telescopes, but Hubble was able to do revolutionary science by following these observations and studying the atmospheres of exoplanets.
Hubble's early experiments in exoplanet science included measuring the atmosphere of another planet, confirming the oldest known exoplanet, detecting the first organic molecule on an exoplanet, and first changes in the atmosphere of 'an exoplanet. Today, the science of exoplanets represents20% of the observation time of the telescope.
The telescope made it possible to map dark matter, even if the dark matter is invisible.
"Dark matter is a mysterious substance which constitutes most of the matter in the universe, but we do not know what it is and cannot observe it because it does not emit observable radiation", a said Wiseman. "But we know it's there because of the gravitational effects."
"Hubble is used to map the location of dark matter and its effects through the gravitational lens."
The gravitational lens also allowed Hubble to deepen the early days of the universe. It occurs when clusters of galaxies create a distorting gravitational field that acts like a natural giant magnifying glass for distant galaxies beyond Hubble's ability to observe.
Hubble has also allowed astronomers to realize that galaxies tend to merge with each other, capturing spectacular images of these mergers taking place across the universe. This is how our own milky waythe galaxy has reached its current size, merging with smaller galaxies.
And Hubble is known for helping astronomers realize that supermassive black holes are ubiquitous with giant galaxy centers. Hubble was able to observe the fall of gas in the galactic centers near the speed of light, which is now considered a fundamental understanding, said Brown.
"Thinking about the universe as a whole, I believe that Hubble opened our eyes to the recognition that galaxies have radically changed over the course of cosmic time," said Wiseman.
The future of Hubble
Hubble scientists believe the telescope will continue to operate at least until 2025, if not longer. This offers astronomers a great opportunity because Hubble may overlap with new space telescopes coming online soon, such as NASA's James Webb space telescope which is slated to launch in 2021.
Webb is an infrared observatory. Together, their combined abilities can provide a more complete picture of the targets they are observing. Webb will provide a more detailed overview of exoplanets and their atmospheres and examine the early days of the universe more deeply than ever.
Hubble continues to contribute to incredible discoveries and tracks detections and observations from other telescopes. For years, Hubble has been the perfect complement to other major NASA observatories, including Chandra's X-ray observatory and the recently retired Spitzer infrared space telescope, as well as ground-based observatories.
It was used to track the detections of gravitational waves and the explosions of collisions of neutron starsby LIGO and VIRGO, which are gravitational wave detectors.
And Hubble has actively followed the journeys of interstellar visitors through our solar system, such as the interstellar asteroid 'Oumuamua in 2017 and the interstellar comet 2I / Borisov, which is still there.
"We are getting better scientific feedback now than ever before," said Wiseman. "I am excited about how it will be used in the years to come for new discoveries and to complement new observatories."
But when Hubble's mission ends, its optical and ultraviolet capabilities will not be reproduced anytime soon. The only similar thing is LUVOIR, the great UV / optical / IR surveyor. The concept is for a multi-wavelength space observatory which, if developed, could be launched in the late 2030s or 2040s, said Brown.
Depending on when Hubble concludes, this could leave a huge void for scientists who depend on Hubble observations to do their job.
And when it comes to Hubble's sightings and incredible images, "there is no other game in town," said Brown.
Hubble has provided 1.4 million observations over 30 years, feeding more than 17,000 peer-reviewed scientific publications with its data, "making it the most prolific space observatory in history," according to NASA. . And Hubble's archival data will offer a multitude of scientific opportunities in the decades to come.
For now, they hope the telescope will continue for years, and perhaps even decades, to come.
"It ages very gracefully and well understood and still functions as powerfully," said Brown.