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Technical description

The Hubble telescope weighs approximately 11 tons, makes 13,2 meters length, has a maximum diameter of 4,2 Mètre S and cost 2 billion US Dollars. It is a telescope reflectors to two Miroir S; the primary education Miroir has a diameter of approximately 2,4 meters. It is coupled with various Spectromètre S and three cameras: with narrow field for the objects slightly luminous, another with broad field for the planetary images and for the Infra-red .

It employs two solar panels to produce electricity, which is mainly used by the large cameras and the four flying employed to direct and stabilize the telescope. The infra-red camera and the spectrometer multi-objects must also be cooled with -180 °C.

Discovered

Hubble provided, in 1994, of the images of the collision of the Comet Shoemaker-Levy 9 with Jupiter.
the proof that planets revolve around stars other than the Sun was obtained for the first time with Hubble.
the observations with Hubble also proved that the Matière sinks of our galaxy cannot consist only of small not very luminous stars.
Some of the observations leading to the current model of the Accélération of the universe were carried out using the Hubble space telescope.
the theory that the majority of the galaxies contain a Black hole in their center was partially confirmed by many observations.
In December 1995, Hubble photographed the deep Champ of Hubble, an area covering one 30-millionth sky and containing several thousands of galaxies. Another image, but of the southern sky, also was made and is remarkably similar, reinforcing the thesis which the universe is uniform with large scales and which the ground occupies an unspecified place in the universe.

Launching and initial disappointment

The telescope was launched the April 25th 1990 by the mission STS-31 of the Space shuttle Discovery. This launching had already been delayed in 1986 because of the catastrophe of the Space shuttle Challenger in January of this year.

The first images provided by the telescope were generally regarded as very disappointing by the astronomers and all those concerned with the project. These images were fuzzy and, in spite of the Image processing, did not reach the resolution envisaged. It was established that the company Perkin-Elmer in responsibility of cut the principal mirror, had slightly too much flattened the edges because of a bad calibration of the instrument of checking of Courbure. This problem could have been detected before launching but was not it for economic reasons.

Missions of maintenance

The telescope was revisited four times by astronauts operating starting from space shuttles in order to correct the malfunctions and to install new equipment. Moreover, because of atmospheric braking, the telescope loses altitude slowly (and speed gains). One thus benefits from each one of these visits of maintenance to replace the telescope with a higher orbit using the shuttle.

the mission of maintenance 1 (STS-61), in December 1993, installed several instruments and other equipment. Most important from the astronomical point of view were: COSTAR , a whole of five corrective mirrors; and WF/PC-II , a version improved of camera with broad field which also incorporated a system of optical correction. The January 13rd 1994, NASA declared that the mission was a total success and showed the first new images which were much clearer.

the mission of maintenance 2 (STS-82), in February 1997, replaced the Spectrographe high-resolution and the spectrograph for weak objects by a new spectrograph and added a new infra-red camera coupled to a spectrograph multi-objects ( Near Infrared Camera/Multi-Object Spectrograph , NICMOS).
the mission of maintenance 3A (STS-103), in December 1999, replaced gyroscopes and the sensors of precise guidance which had become defective and a new computer was installed.
the mission of maintenance 3B (STS-109), in March 2002, made it possible to repair and improve several parts, but by requiring exits prolonged and delicate in space. The operations carried out were:

the update of the generators, which was particularly difficult because those were not conceived to be replaced in orbit and required also a complete stop of the telescope for the first time since its setting in operation.
the replacement of its solar panels. The new panels are based on those conceived for the communications satellites Iridium. They have only the two-thirds of the size of the old panels which were damaged, with for result a reduction in atmospheric braking while providing 30 % of power moreover. This additional power will make it possible all the instruments on board Hubble simultaneously to function.
the replacement of the camera for weak objects ( Faint Object Camera ) by a camera of advanced prospection ( Advanced Camera for Surveys ). These two instruments have each one the size of a phone box.
the installation of a unit of cooling in the infra-red camera NICMOS which was not-functional calculus.

Replacement of a reaction control wheel .

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the achievement of this mission increased considerably the possibilities of Hubble, almost a new instrument according to certain enthusiasts.

a fifth and last mission will be made by the space shuttle following the approval of the administrator of NASA Michael Griffin. The levelling will consist in installing two new scientific instruments: the spectrograph of the cosmic origins (COS) and the third camera with large field (WFC-3).

After Hubble

NASA intended to launch the telescope of the space of new generation (NGST or James Webb Space Telescope) in 2009 and to stop Hubble the following year. Hubble, which was conceived for one 15 years duration, will be thus in service for 20 years. However, the mission of maintenance, planned for the semione, was cancelled. It was to make it possible to install a new camera with broad field and a Spectrographe with Ultraviolet ultra sensitive. But it would have required expensive investments to improve safety of the shuttle which are not necessary for its interventions on the International space station. The launching of the NGST is envisaged now as soon as possible in 2013 by a launcher ARIANE 5.

Maintaining NASA and the community of the astronomers must decide what will have to possibly succeed Hubble. The NGST could seem to be the answer to this question, but the NGST will be only one infra-red telescope, whereas Hubble of course covered the range of the close infra-red to the ultraviolet close relation while passing by the visible one.

What complicates the question, they are the amazing projections of the technology of the Télescope S operative starting from the Ground which were made since Hubble was conceived.

The Canadian Space agency (ASC/CSA), proposed to send a robot in order to maintain the telescope. At the beginning of 2005 this option was cancelled, NASA having decided that it will carry out an ultimate mission of maintenance. This mission, indicated STS-125 should be launched beginning August 2008 with the Space shuttle Atlantis

See too

Large observatories (NASA)

External bonds

Site of NASA
HubbleSite
ESA, spacetelescope.org
Gallery photographs 15 years of Hubble
Hubble: New mission of maintenance for the levelling of the instruments

Simple: Hubble Space Telescopes

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