By Siddhartha Bhatnagar
Since the earliest days of astronomy, since the time of Galileo, astronomers have shared a single goal to see more, see farther, see deeper.
The Hubble Space Telescope’s launch on April 24, 1990 aboard the Space Shuttle Discovery sped humanity to one of its greatest advances in that journey. Hubble is a telescope that orbits Earth. Its position above the atmosphere, which distorts and blocks the light that reaches our planet, gives it a view of the universe that typically far surpasses that of ground-based telescopes. 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. Its gaze has helped determine the age of the universe, the identity of quasars, and the existence of dark energy. The telescope carried five instruments: The Wide Field/Planetary Camera, the Goddard High Resolution Spectrograph, the Faint Object Camera, the Faint Object Spectrograph and the High Speed Photometer.
CHANGING ASTRONOMY
Hubble’s discoveries have transformed the way scientists look at the universe. Its ability to show the universe in unprecedented detail has turned astronomical conjectures into concrete certainties. It has winnowed down the collection of theories about the universe even as it sparked new ones, clarifying the path for future astronomers.
Among its many discoveries, Hubble has revealed the age of the universe to be about 13 to 14 billion years, much more accurate than the old range of anywhere from 10 to 20 billion years. Hubble played a key role in the discovery of dark energy, a mysterious force that causes the expansion of the universe to accelerate. Hubble has shown scientists galaxies in all stages of evolution, including toddler 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 occur in far-distant galaxies when massive stars collapse.
The policies that govern the telescope have contributed to its incredible productivity. The telescope is an instrument for the entire astronomical community any astronomer in the world can submit a proposal and request time on the telescope. Teams of experts then select the observations to be performed. Once observations are completed, the astronomers have a year to pursue their work before the data is released to the entire scientific community. Because everyone gets to see the information, the observations have given rise to a multitude of findings many in areas that would not have been predicted by the telescopes original proposals. Hubble’s success with these policies has helped spread them throughout the astronomical community, and they are becoming common with other observatories.
NEED FOR A SPACE TELESCOPE
The Hubble Space Telescope is the direct solution to a problem that telescopes have faced since the very earliest days of their invention: the atmosphere. The quandary is twofold: Shifting air pockets in Earth’s atmosphere distort the view of telescopes on the ground, no matter how large or scientifically advanced those telescopes are. This “atmospheric distortion” is the reason that the stars seem to twinkle when you look up at the sky. The atmosphere also partially blocks or absorbs certain wavelengths of radiation, like ultraviolet, gamma- and X-rays, before they can reach Earth. Scientists can best examine an object like a star by studying it in all the types of wavelengths that it emits.
Newer ground-based telescopes are using technological advances to try to correct atmospheric distortion, but there’s no way to see the wavelengths the atmosphere prevents from even reaching the planet. The most effective way to avoid the problems of the atmosphere is to place your telescope beyond it. Or, in Hubble’s case, 353 miles (569 km) above the surface of Earth.
HOW IT WORKS
Every 97 minutes, Hubble completes a spin around Earth, moving at the speed of about five miles per second (8 km per second) fast enough to travel across the United States in about 10 minutes. As it travels, Hubble’s mirror captures light and directs it into its several science instruments.
All of Hubble’s functions are powered by sunlight. Hubble sports solar arrays that convert sunlight directly into electricity. Some of that electricity is stored in batteries that keep the telescope running when it’s in Earth’s shadow, blocked from the Sun’s rays.
A quartet of antennae on the telescope sends and receives information between Hubble and the Flight Operations Team at the Goddard Space Flight Center in Greenbelt, Md. Engineers use satellites to communicate with the telescope, giving it directions and commands. The telescope has two main computers and a number of smaller systems. One of the main computers handles the commands that point the telescope and other system-wide functions. The other talks to the instruments, receives their data, and sends it to satellites that in turn transmit it to the ground.
Once the ground station transfers the data to Goddard, Goddard sends it to the Space Telescope Science Institute (STScI), where staff translate the data into scientifically meaningful units such as wavelength or brightness and archive the information on 5.25-inch magneto-optical disks. Hubble sends the archive enough information to fill about 18 DVDs every week. Astronomers can download archived data via the Internet and analyze it from anywhere in the world.
THE END
Eventually, Hubble’s time will end. As the years progress, Hubble’s components will slowly degrade to the point at which the telescope stops working. But Hubble’s legacy its discoveries, its trailblazing design, its success in showing us the universe in unparalleled detail will live on. Scientists will rely on Hubble’s revelations for years as they continue in their quest to understand the cosmos a quest that has attained clarity, focus, and triumph through Hubble’s rich existence.
Siddhartha Bhatnagar: He is currently pursuing MBA in Energy and Infrastructure from School Of Petroleum Management, Pandit Deendayal Petroleum University Gandhinagar, Gujarat. He has completed B.Tech (I.T.) from Jaypee University of Information Technology, H.P. and was engaged with Infosys as Senior Systems Engineer. He believes India is energy scarce country and it needs personnel who can understand the complexity in this secto. A deep research mindset, voracious reading, and ability to simplify things will prove handy and that is where his contributions incline.