Slowly and carefully, the automatic arm of space shuttle Discovery put into orbit the Hubble Space Telescope. It was April 25, 1990. The telescope had been built for more than a decade at a cost of several million dollars.
They had never made a mirror as careful or as expensive as its main mirror of 2.4 meters, having a central opening through which passes the light that comes from the secondary mirror. Its development had been an impressive scientific achievement (or so it seemed).
You can see in the image the aperture and the technicians in an enlarged image due to the parabolic shape of the mirror. Credit: NASA
Shortly after the launch, the scientists discovered that there was a problem with the mirror. The light that reached its end was focused about 4 centimeters behind the light that reached the center and the images produced by the telescope were blurred. A minuscule error in the design measures was the cause of the problem.
The mirror during its polishing. Credit: NASA
The company responsible for constructing the mirror had made a mistake in polishing the mirror, its edges were too flat at 2.2 micrometers, which caused spherical aberration, that it was a distortion in Hubble's main mirror, which means that instead of concentrating on a point in the mirror, it spreads throughout the mirror, causing blurry images.
The hubble was repaired during the first service mission in December 1993. Fortunately, this telescope was built to be repaired in space. The scientists created a tool called COSTAR that basically was a lens that could counteract the error.
THE COSTAR (Corrective Optics Space Telescope Axial Replacement)-- Credit:NASA
Produced blurry images similar to a myopic vision (left image). After the installation of COSTAR (right image). Credit: NASA
In December of 1993, the telescope began to send its first impressive images of the universe. Now you can bring us photos of the universe with which we could only dream.
Yet it is a warning to scientists, and for those who aspire to be, that precise and careful measurements can be the difference between success and scientific defeat.
Hubble 3D is a spectacular documentary about these maintenance missions
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References website
https://en.wikipedia.org/wiki/Hubble_Space_Telescope
https://elpais.com/diario/1990/08/11/sociedad/650325609_850215.html
http://www.microsiervos.com/archivo/ciencia/el-dia-que-le-pusieron-gafas-de-miope-al-hubble.html
http://www.geocities.ws/edug2406/hubble_graf.htm
http://danielmarin.naukas.com/2011/03/11/ov-103-discovery/
http://www.imagenoptica.com.mx/pdf/revista30/hubble.htm