The Hubble Space Telescope : Humanity’s Eye On The Stars

The Hubble Space Telescope is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versatile, renowned both as a vital research tool and as a public relations boon for astronomy.

Hubble photographed in outer space, floating above our atmosphere

It is named after astronomer Edwin Hubble and is one of NASA's Great Observatories. Orbiting high above the Earth, the Hubble Space Telescope has a clear view of the universe free from the blurring and absorbing effects of the atmosphere. In addition to observing visible and near-infrared light, It detects ultraviolet light, which is absorbed by the atmosphere and visible only from space. The telescope has beamed hundreds of thousands of celestial images back to Earth during its time in space.

Hubble is a Cassegrain reflector telescope. Light from celestial objects travels down a tube, is collected by a bowl-like, inwardly curved primary mirror and reflected toward a smaller, dome-shaped, outwardly curved secondary mirror. The secondary mirror bounces the light back to the primary mirror and through a hole in its center. The light is focused on a small area called the focal plane, where it is picked up by its various science instruments. Hubble’s science instruments, the astronomer’s eyes to the universe, work together or individually to provide the observations. Each instrument is designed to examine the universe in a different way. It holds two main varieties of instruments: cameras, which capture Hubble's famed images, and spectrographs, which break light into colors for analysis. Its current suite of instruments includes the Wide Field Camera 3 (WFC3), Cosmic Origins Spectrograph (COS), Advanced Camera for Surveys (ACS), Space Telescope Imaging Spectrograph (STIS) and Fine Guidance Sensors (FGS).

An overview of the scientific instruments on Hubble

Many objective measures show the positive impact of Hubble data on astronomy. Over 15,000 papers based on Hubble data have been published in peer-reviewed journals, and countless more have appeared in conference proceedings. Looking at papers several years after their publication, about one-third of all astronomy papers have no citations, while only two percent of papers based on Hubble data have no citations. On average, a paper based on Hubble data receives about twice as many citations as papers based on non-Hubble data. Of the 200 papers published each year that receive the most citations, about 10% are based on Hubble data. In addition to its scientific results, Hubble has also made significant contributions to aerospace engineering, in particular the performance of systems in low Earth orbit (LEO). These insights result from Hubble's long lifetime on orbit, extensive instrumentation, and return of assemblies to the Earth where they can be studied in detail.

Among its many discoveries, Hubble has revealed the age of the universe to be about 13.8 billion years, much more accurate than the old range of anywhere from 10 to 20 billion years. It played a key role in the discovery of dark energy, a mysterious force that causes the expansion of the universe to accelerate. The telescope has shown scientists galaxies in all stages of evolution, including galaxies that were around when the universe was still young, helping them understand how galaxies form. It found protoplanetary disks, clumps of gas and dust around young stars that likely function as birthing grounds for new planets. It discovered that gamma-ray bursts — strange, incredibly powerful explosions of energy — can occur in far-distant galaxies when massive stars collapse.

The Pillars of Creation, as photographed by Hubble

As evident, Hubble is one of NASA’s most successful and long-lasting science missions. It has beamed hundreds of thousands of images back to Earth, shedding light on many of the great mysteries of astronomy. It is truly awe inspiring thinking about the brilliant minds who have contributed in some shape or form to the resounding magnificence of the Hubble Space Telescope, and when future generations look back fondly to their past, they will be thankful for the knowledge they have then, all due the hardwork and toil of our people now.

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