Technical tour Hubble 25 years




The Hubble Space Telescope was launched five years ago on April 24, 1990. The plans to send in a mirror telescope space tribes already from 1946. The first serious plans to also build one, got a solid form in 1968, Hubble’s green light came in 1977.

hubble space telescope The space telescope with a mirror diameter of 2.4 meters running for a quarter century, around the earth, initially in 97 minutes at 598 km altitude. Now slightly faster in 95.6 minutes at 555 km altitude. Because the telescope has been placed outside the atmosphere of the earth, there are no problems with distortion of the incoming light, as well as in the visible to the human eye invisible part of the spectrum. This made it possible to use an optical telescope to see more than ever of the universe. But not only that. Could also using the Hubble age of the universe better be estimated: scientists came to between thirteen and fourteen billion years old. A lot more accurate than before with between ten and twenty billion years. The telescope was instrumental in the discovery of dark energy and could be proved that every galaxy has a black hole in the core.

A telescope into space, how are relatively minor, is no sinecure. The initial plan was for the 11,000 kilogram device launch in 1983, but by an accumulation of problems and the loss of the space shuttle Challenger in 1986, was postponed until 1990. During the launch, the project had already such 2.5 billion dollars, a large excess of the estimated 400 million. Eventually NASA drew it myself no more with regard to costs and asked the European Space Agency to help pay well and provide the first generation of instruments and solar cells.

That Hubble has provided stunning images of the universe, no one will have missed. This is possible because the necessary Hubble instruments on board: two cameras, two different beeldspectografen and targeting sensors. In addition, two mirrors, the large concave mirror with a diameter of 2.4 meter, and a second convex mirror, which sends back the light into a hole in the middle of the big mirror at the point of focus. As various instruments can catch the light. Shortly after the launch, NASA discovered that the large mirror had a small deviation. The mirror was 2.2 microns to be ground flat at the edges, so that there occurred spherical aberration. This created especially for problems with weak light sources, so much research could not be done. During a second space mission with a space shuttle astronauts were in December 1993 applying corrective mirror. In total, there would be four servicing missions, the last in 2009. The construction of the mirror began in 1979 and is supported by a honeycomb structure to keep everything as light as possible. The mirror was finished at the end of 1981.

hubble schematic

The corrective optical system COSTAR , Corrective Optics Space Telescope Axial Replacement, was the last space mission removed in 2009 because all instruments were replaced in the interim by new or different versions, with a built-in correction for the spherical aberration. For COSTAR in its place came a Cosmic Origins Spectrograph, COS, which ultraviolet radiation from weak point sources can be measured. This makes it possible to study the formation and evolution of galaxies and other large structures in the universe.

For it has great overview Hubble’s Wide Field Camera. Meanwhile, this is the third incarnation of installed, the WFC3. The camera takes photos in our visible spectrum. WFC3 and its predecessors made on several occasions for iconic images of the universe. The WFC3 has two different channels that can capture each other wavelengths. The channel is used for the ultraviolet wavelengths to study near galaxies or systems in which many stars are formed. The infrared-channel is to capture light from distant systems and thus a piece of history of the universe directly.

The Advanced Camera for Surveys, ACS, was installed in 2002 and can be just as WFC3 visible light and infrared capture. Currently WFC3 has a great deal of precision taken from this camera, which replaced the Faint Object Camera. FOC was Hubble’s first “zoom lens” for twelve years.

In addition to capture images of objects, is an important research tool also separating light into the base with the Space Telescope Imaging wavelengths Spectrograph, STIS. In this way, the chemical composition, density, and temperature of objects can be determined. In this way we come to know what elements exist for objects or discovering exoplanets. But STIS is also important in the discovery of black holes. The light of stars and gas that orbits around the center of a galaxy is redder when it moves away from the telescope and bluer when it comes down to. The location of a black hole is to be determined by looking at reddish material on one side, and bluish on the other side, which reveals that this material is very quickly rotates around an object.

atmospheric electromagnetic

Atmospheric absorption wavelength (source: Wikipedia)

The three sensors have been directed to the telescope in the proper direction to turn and keep at the same time and doing measurements. Two sensors keep the telescope in the proper direction, and one can do measurements. They use stars to establish themselves and to work on fixed. Because the orbit of the star is known, the sensors can thus keep the telescope constant in the right direction. The precision of the instrument is similar to a laser 800 kilometers further directed to keep a dime, and that 24 hours. Because of their high precision, since Hubble much more is known about the exact locations of celestial bodies.

It has already discussed the resolution of the telescope. Partly because there is no atmospheric disturbances, the telescope can see much more. An atmospheric disturbance from Earth example creates the familiar star-shape of stars and planets. A good telescope on Earth can see virtually no difference between two close spaced stars. The “resolution” is therefore determined in arcminutes and arcseconds. A square degree consists of 60 minutes of arc or 3600 arcseconds. A telescope on Earth sees no more than one arcsecond, which is a two star closer together than an arc second, they are indistinguishable. The Hubble telescope can see 0.1 arcsecond. The human eye sees about 60 arc seconds.

What comes next after Hubble? Even more detail. And this is a larger mirror needed. All that has been put into operation with the 6.5-meter James Webb Space Telescope. This telescope, if all goes well, the end of 2018 launched. The Webb will mainly investigate longer wavelengths to look further back in the past. The Hubble telescope is compared to light weight. Webb will also be much further from the earth on a million miles away. This will not revolve around the earth, but in an orbit around the sun.


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