The Hubble Space Telescope
By Yagyasha Rastogi
Named in the honor of revolutionary astronomer, Edwin Hubble, the Hubble Space Telescope is a large, space-based observatory. It was deployed by the space shuttle Discovery in 1990. Since then, it has helped scientists and astronomers alike in exploring the deep, hidden, and mysterious corners of the Universe. It has revolutionized the field of astronomy since its launch and continues to do so for the last 30 years!
Hubble has witnessed the birth of many stars and has also been a witness to the death of many. It has seen the prettiest galaxies and several mysterious nebulae. It has seen comets crash into the gases above Jupiter. Hubble has made about 1.4 million observations to date.
How Does The Hubble Space Telescope Work?
The earth’s atmosphere interferes with an astronomer’s vision of celestial objects by absorbing or distorting light rays from them. Hubble, however, is stationed in space and thus is above the layer of atmosphere. This allows Hubble to receive images of much better brightness and clarity than any other ground-based telescope with comparable optics.
The HST is a large reflecting telescope whose mirror optics gather light from celestial objects and direct it into two cameras and two spectrographs (which separate radiation into a spectrum and record the spectrum). All telescopes have a certain range of light that they can detect. Hubble’s domain extends from the ultraviolet, through the visible spectrum (the light that we can see), into the near infra-red region. Hubble uses a digital camera similar to the ones in a cell phone. It then uses radio waves to send these images back to earth
The HST is equipped with a variety of high-tech gadgets. One of the most important ones being, the wide-field planetary camera. This camera is engineered to take pictures with about 10 times more clarity than even the largest telescope here on earth.
The History of Hubble
After the U.S congress approved its construction, Hubble was built under the supervision of National Aeronautics Space Administration (NASA). The HST was put into an orbit about 600 km above the earth by the crew of space shuttle Discovery on April 25, 1990
A month after its deployment, it was brought to notice that Hubble’s large primary mirror was ground to the wrong shape due to faulty test procedures by the mirror’s manufacturer. This error resulted in spherical aberration and caused Hubble to produce blurry images rather than sharp ones. Adding to the problems, the gyroscope and solar-power arrays in the telescope also began to malfunction. These problems were at last fixed, in December 1993, by NASA’s space shuttle Endeavor, which aimed to correct the telescope’s optical system and other problems.
Further space shuttle missions in 1997,1999 and 2002 repaired the telescope’s gyroscopes and also added new instruments, including a near-infrared spectrometer and a wide-field camera.
HST’s Contribution To Astronomy
Since the light takes time to travel the long distances from the objects it came from, Hubble acts as our very own window to the past. Even light from our nearest galaxy takes about 2.5 million years to reach us.
The HST has made the following contributions to astronomy:-
Helped pin down the age for the universe now known to be 13.8 billion years, roughly three times the age of Earth.
Discovered two moons of Pluto, Nix, and Hydra.
Helped determine the rate at which the universe is expanding. (Hubble constant)
Discovered that nearly every major galaxy is anchored by a black hole at the center.
Created a 3-D map of dark matter.
HST has widened our knowledge of the universe and it's working to a great extent. Despite its modest size, it outperforms many large ground-based telescopes.
To continue HST’s legacy, NASA is building another space telescope called the James Webb Telescope. The James Webb telescope will be even bigger than Hubble and continue Hubble’s legacy of helping us explore the universe.