The legendary Hubble telescope is 30 years old

Text by: Simon Rozé Follow

This Friday, April 24, the Hubble Space Telescope celebrates 30 years in orbit. Thousands of photos later, it revolutionized our knowledge of the universe. This longevity is exceptional for a space telescope, because Hubble had another peculiarity: it was repairable in orbit. Five missions aimed to restore it and improve it during its career. Jean-François Clervoy, astronaut from the European Space Agency (ESA) participated in the third, in 1999.

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RFI: What is your first memory of the telescope during your maintenance mission in December 1999?

Jean-François Clervoy: When you approach the Hubble space telescope in orbit, the sun gives a golden glow to the solar panels. Hubble looked like a butterfly it was beautiful. I was accompanied by three astronauts also astrophysicists and I felt that for them it was the pinnacle of their career. Go touch Hubble! After having captured it and fixed it in the hold of the shuttle, I served as a driver for my colleagues with the robotic arm. The very first was John Grunsfeld. As I approached the telescope, he asked me to take a break. He touched Hubble with his finger, much like in the film ET. For him, it was a great moment in his career as an astrophysicist.

Hubble by Jean-François Clervoy during his mission in 1999. Jean-François Clervoy / ESA / NASA

Hubble is a mythical instrument that revolutionized the knowledge we had of the universe. It is said that there is a before and an after Hubble, as there was a before and an after the telescope of Galileo. It is a great pride to have been appointed to this mission, to have approached it and to have worked on it to give it life as surgeons. When we released it on Christmas Day, the control center told us after a few orbits: "  It is 100% operational  ". 20 years after this mission, he continues to give us extraordinary information about our universe.

This longevity is exceptional for such a complicated satellite

As Hubble is outside the atmosphere, it can receive signals that are impossible to receive on Earth because the atmosphere stops some of those emitted by stars and galaxies. Hubble is also not attached to Earth, so it allows very long exposure times. In photography, this is necessary to observe an object that is very dim. This is how Hubble was able to observe things in the depths of the universe.

Above all, Hubble sees in the visible spectrum while all the other space telescopes observe X-rays, gammas, infrared, ultraviolet…

But above all, it can be visited by humans who have allowed it to be refurbished. Even if he is thirty years old today, it is as if he had modern instruments, which are perhaps 1 million times more efficient than those launched on board in 1990.

If you were to remember only one Hubble snapshot?

Right after our mission, we were invited to the Space Science Institute, the telescope control center in Baltimore in the United States. They offered us on a large poster the first image taken by the telescope after our repair. He was completely down before that. This photo is therefore the witness of renewal. It is the Eskimo nebula, a star explosion: a supernova.

The Eskimo Nebula. ESA / NASA

On this occasion, I ask a question: "  What are the great discoveries made by Hubble?  The scientists answer me that it helped to refine the age of the universe, to demonstrate the existence of black holes. He showed that the galaxies in the observable universe, which is only 5% of our universe, number in the hundreds of billions. When we know that each galaxy is 100 to 200 billion stars… This means that Hubble can see 40,000 billion billion stars (40,000,000,000,000,000,000,000 [NdRFI]. It's an extraordinary eye on our universe which allows us to go back in time, to see that the stars are born and die.

You as an astronaut, Hubble and his shots; who most popularizes space and astronomy with the general public?

The profession of astronaut is a profession of operator. We are technicians, electricians, plumbers ... When I was on board the shuttle with three astrophysicists, I had the most beautiful astronomy lessons! When we were on the night side of the orbit, after having successfully dropped the telescope on December 25, they explained to me what we saw. We turned off all the lights in the cockpit to see the universe, the Milky Way. It was fantastic. Hubble is truly the legendary telescope. We all know Hubble's photos: the deep field, the star nursery, the Eskimo galaxy, the cat's eye, the crab, the horse's head ... and gravitational lenses! Hubble took photos where we can see the phenomenon of general relativity which curves space-time. This makes you see a star in several places at once, because the trajectory of its rays are curved by a massive object.

the deep field of Hubble: each luminous point is in fact a galaxy. This photo covers a tiny part of the sky. ESA / NASA

The telescope made it possible to take images of the universe which speak to someone who knows nothing about it. While astrophysicists study with computer data, with 0s and 1s, Hubble shows images such that you could see them with your eyes if you had very powerful binoculars while floating in space. Hubble is therefore like an extension of the human body. Seeing colored interstellar gases with small dots showing stars being born, or stars exploding, that speaks to everyone. Hubble did popularize interest in the universe. He helped make astronomy more popular. It is still the first science! The first thing that fascinates humans is observing the sky.

► Read also: The Hubble telescope is 25 years old, interview with one of its creators

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