Although, Hubble did not discover this comet, it was able to track its many fragments with unprecedented clarity well before impact (Chaisson, 1998 p. 3). Farther out, Uranus and Neptune have been periodically studied by Hubble at different wavelengths. Data acquired in mid-1990s have allowed astronomers to examine various layers in these giant planets atmospheres, enabling us to watch the hazy clouds of mixed gases come and go. The HST is the largest, most complex, and most powerful observatory ever deployed in space.
It is a project of the National Aeronautics and Space Administration (NASA), which built the telescope in cooperation with the European Space Agency (ESA) and numerous industrial contractors. The discovery of HST is one of mans breakthroughs in order to obtain scientific knowledge far beyond the scope of Earths ordinary eyes. HCT has revolutionized the concepts of meteorology and astronomy, and more importantly, human body of knowledge. The contributions of HCT have caused the arousal of various developmental queries and new perspectives involving the outside world.
The study involves mainly the mechanics, characteristics, historical perspective and scientific contributions of the HST. The study shall incorporate factual discussions in order to address the subject criteria of the problem imposed. Mainly, the study shall scrutinize the details of the review of related literature patterned to the primary components imposed in the latter of the studies. Analysis and interpretation of data present shall involve clear and accurate depiction of the study utilizing the present and gathered data of the review of literatures. Discussion Historical Background
It was Edwin Hubble in the early 1920s who showed that the apparently small spiral nebulae others had thought were inside our Galaxy were themselves similar star systems at great distances. The Andromeda Galaxy, two million light years (a light year is the distance light travels in a year: nearly 10 million kilometers) away, is the nearest of these. It closely resembles our Galaxy and like ours, it has dwarf companion galaxies hovering nearby. It appears to the naked eye as a faint smudge but its structure can be seen with a good pair of binoculars (Zirker, 2005 p. 104; Day, 1997 p. 65).
It was Edwin Hubble who found that the clusters of galaxies were receding from us, in such a way that everything in the Universe was moving apart from everything else in proportion to distance: the further away the galaxy cluster, the faster it is receding (Day, 1997 p. 65). During its pre-launch way back 1946, the American astronomer, Lymann Spitzer produced a classified report of RAND outlining possible scientific programs that could be undertaken using space satellites containing optical telescopes of up to 200 to 600 inches (5. 1 to 15. 2 m) diameter (Zirker, 2005 p. 104; Heck, 2000 p. 11; Leverington, 2000 p. 420).
To say that this was ambitious was something of an understatement, as this report was written before the 200 inch ground-based Palomar telescope had been completed and some eleven years before the launch of Sputnik. The American attitude to the possibility of building such space satellites gradually changed in the 1950s, however, and in 1968, the year after Sputnik, Lloyd Berkner, chairman of the Space Board of the national Academy of Sciences, solicited suggestions for space-based projects to follow those undertaken in the International Geophysical Year (Zirker, 2005 p. 104; Leverington, 2000 p. 420).
The two hundred proposal received were then used to aid NASA and lots advisory committees to define a space-based observatory program. The interest of the public grew to the extent that the proposal of Spitzer was put into attention (Leverington, 2000 p. 420). Detailed design studies for a space telescope began in the mid-1960s, and by 1971, a NASA committee chained by Spitzer recommended the construction of the large Space Telescope. In 1977, the U. S government agreed to fund a Space telescope with a 2. 4-m mirror.
In 1983, NASA renamed it the Hubble Space Telescope, after an American astronomer who, as we shall see, played a pivotal role in developing our understanding of the size of the universe (Webb, 1999 p. 80). Hubble Space Telescope: Characteristics and Features The HST is potentially the best instrument we have for making precise astronomic measurements. In principle, we can use it to measure the parallax of stars that are several hundred of light years away. In practice, there are problems with the stability of the platform that limit its use in astrometry.
Besides, the universe is large and filled with interesting objects to study (Webb, 1999 p. 80). HST is a high-resolution optical astronomical facility in low Earth orbit (28. 5 degrees inclination, 600 km altitude). It is equipped with a Ritchey-Chretien optical system including 2. 4 meter primary mirror and a secondary mirror. A cluster of four axial scientific instruments (three only at this time mid 2002) and one radial scientific instrument provides the Telescopes scientific capability.
Optical fine guidance sensors are located in the remaining three radial bays. Electrical power is provided by a set of two solar arrays and six NiH2 batteries (Heck, 2000 p. 11). The HST named after the American astronomer Edwin Hubble is 43. 5 ft or 13. 1 meters long and 14 feet or 4. 27 meters wide. The telescope weighs 25,500 pounds or 11,000 kilograms. The HST was constructed on Earth and deployed into space by the space shuttle in 1990. Two solar panels, one on either side of the telescope, provide power for the telescopes equipment.
Astronomers on Earth control the telescope. Images are relayed by satellites down to the control center in Baltimore, Maryland (Grice, 2002 p. 3-4). Additional systems include a data management system, the heart of which is presently a radiation-hardened 486 computer, a pointing control subsystem using reaction wheels, rate sensing units, magnetic torquers, three optical fine guidance sensors (no propulsive attitude control), an instrumentation and communication subsystem, and a thermal control subsystem (Heck, 2000 p. 11).
Hubble images are 5 to 20 times sharper than those obtained with standard ground-based telescopes, in effect bringing the universe that is much closer. Image sharpness and the absence of light pollution in orbit help Hubble to see objects 10 times fainter than even the largest ground-based telescopes. Moreover, Hubbles images are extremely stable, in contrast to those obtained with ground telescopes, whose view is continually distorted by changing atmospheric clarity and turbulence (Lanzerotti, 2005 p. 3).
It takes about 95 minutes for the HST to complete one orbit around the Earth. Only part of this time is spent observing with the remainder spent on housekeeping functions. These functions include receiving command loads and sending data on Earth, turning the telescope to find a new target or avoid the Sun or Moon, and similar activities. To keep the telescope operating efficiently, commands are sent to the HST several times a day (Koupelis, 2007 p. 154).