On April 24, 1990, one of the most important events in the history of astronomy took place. The space shuttle Atlantis was launched from the Cape Canaveral launch site and carried the Hubble Space Telescope into orbit. In honor of this unique project’s 35th anniversary, the editorial staff of Universe Space Tech tells the story of its creation, its main discoveries, and its importance for science.
A brief history of the Hubble telescope
In the late 1960s, NASA began exploring the concept of a large optical telescope that could be placed in Earth’s orbit. Its transfer outside the atmosphere would greatly improve the accuracy of observations and provide the opportunity to collect data not only in the visible but also in the ultraviolet and infrared ranges.
Initially, the space observatory was planned to be equipped with a 3-meter mirror, but due to budget constraints, its diameter later had to be reduced to 2.4 meters. The telescope was named Hubble in honor of astronomer Edwin Hubble, who proved that the Universe is expanding and extends far beyond the Milky Way.
The project was officially approved by NASA in the late 1970s. Originally, Hubble was scheduled to be launched in 1983. However, due to various technical problems, its creation was delayed. Eventually, the launch was scheduled for the summer of 1986. But after the Challenger disaster in January 1986, shuttle flights were halted for nearly three years. As a result, Hubble was placed in long-term storage in a hangar with a nitrogen atmosphere. This downtime led to a significant cost increase in the project.
After all the postponements, Hubble went into space on April 24, 1990. The telescope was put into a 610-kilometer orbit around the Earth.
Hubble repair
After astronomers received the first images of Hubble, they were in for a big blow. It turned out that its mirror had a defect that made the images much less clear than expected. This cast doubt on whether the telescope’s science program could be carried out. As a result, NASA decided to repair Hubble.
The first option was to return Hubble to Earth and replace the mirror with a spare. But this was abandoned because it was too expensive. Instead, NASA decided to take advantage of the fact that Hubble was originally built with the expectation that it could be repaired in space. It was decided to put on the telescope block of corrective optics, which would play the role of “glasses”.
This task was assigned to mission STS-61, which was launched in December 1993. It is still considered one of the most challenging missions in the history of astronautics. During five spacewalks, the astronauts successfully installed a correction unit and also replaced some of the telescope’s instruments. The repairs were successful. After the installation of the block, the clarity of Hubble images reached the expected.
Hubble was subsequently visited by four more manned shuttle missions. The last of these took place in 2009. Their crews repaired the telescope and replaced its instruments with more modern ones. Because of this, Hubble is still in service, and its scientific capabilities have grown significantly since the early 1990s.
Hubble’s technical structure
It is believed that externally, Hubble resembles the KH-11 optical reconnaissance satellites, which are also equipped with a 2.4-meter mirror. The telescope is 13.2 meters long, 4.2 meters in diameter, and has a mass (at the time of launch) of 11.1 tons.
Hubble is powered by two solar panels. The scientific stuffing has been changed several times so that none of the “original” instruments remain on board. It is now equipped with four operational instruments: the WFC3 and ACS cameras, as well as the COS and STIS spectrographs.
The Hubble telescope does not have its own engines. Shuttles used to be used to raise the altitude of its orbit. After they stopped flying, Hubble’s orbit gradually declined due to the braking effect created by the upper layers of the Earth’s atmosphere.
Hubble’s major discoveries
The Hubble telescope has rightfully earned fame as the instrument that revolutionized astronomy. Since its launch, it has made over 1.6 million scientific observations, based on which scientists have written 21,000 peer-reviewed scientific papers. For many years now, Hubble has been at the top of the list of the most cited telescopes in the world.
Hubble was able to look to the edge of the Universe and photograph galaxies that existed just a few hundred million years after the Big Bang, as well as clarify the value of the Hubble constant. One of the most sensational findings of the telescope was that our Universe is expanding not with deceleration, but with acceleration. Its authors were awarded the Nobel Prize in Physics.
Source: NASA, ESA, Hubble Heritage Team
In 1995, Hubble took one of the most important images in its history. It was called Hubble Deep Field. For ten days, the telescope photographed a small and, as previously thought, almost deserted area of the sky. The results astounded astronomers. It turned out that there were thousands of distant galaxies. The experiment proved that the Universe contains orders of magnitude more galaxies than previously thought.
In addition, Hubble has been used extensively to study galaxies, supernovae, regions of active star formation, and black holes. Astronomers have also used it to observe exoplanets.
Hubble has also found work in the solar system. Thus, in 1994, it captured the consequences of the fall of the Comet Shoemaker–Levy 9 debris on Jupiter. Hubble studied the atmospheres of giant planets, found their previously unknown satellites and Kuiper Belt objects, and photographed the consequences of the collision of the DART probe with the asteroid Dimorphos.
Source: NASA/ESA/STScI/Hubble
And that’s just the tip of the iceberg. It is extremely difficult to find any category of celestial bodies that would have escaped Hubble’s attention. Over the 35 years of its work, it has become the very real “patriarch” of modern astronomy.
Source: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
And, of course, the telescope’s many stunning images of deep space – from the Pillars of Creation to the Sombrero Galaxy – are not to be overlooked. They have made a huge contribution to the popularization of astronomy, inspiring a new generation of researchers.
The future of the Hubble telescope
Like any other spacecraft, Hubble won’t last forever. It has been 16 years since the last repair mission. During this time, many components of the telescope thoroughly worn out, if not broken. So last year, engineers had to transfer Hubble into the mode of operation with a single gyroscope. Because of this, the productivity of the apparatus decreased by almost a quarter.
Another very serious problem is the gradual decrease in the Hubble orbital altitude. It is now 491 kilometers. According to engineers’ calculations, by the end of this decade, Hubble will enter the atmosphere and burn up.
A few years ago, billionaire Jared Isaacman offered to organize at his own expense a mission to raise the Hubble orbit. Now, Isaacman is close to heading NASA; however, the overall cuts to science initiated by the current U.S. administration may well put an end to any attempts to save the telescope.
But even if Hubble’s work cannot be extended, it has long since written itself into the history of science. The telescope has allowed us to look into corners of space, the existence of which no one suspected before, and demonstrated all the advantages of extra-atmospheric astronomy. The experience gained during its operation was and still is actively used in the creation of new space observatories. So, even after Hubble is no longer in operation, its “DNA” will continue to live on in the next generation of space explorers for a long time to come.
