The History of the Hubble Space Telescope
by Krysta CardinaleThe NASA Hubble space telescope was launched in 1990, and remains in orbit around the Earth just outside the atmosphere. This telescope has the ability to take very detailed images of even the faintest objects. It has become astronomy’s most important telescope ever. The Hubble space telescope discoveries have been ground-breaking, and have created a better understanding of astrophysics for astronomers. The NASA Hubble space telescope is a modern example of turning defeat into victory. When Hubble was launched, it was charted as the most advanced telescope of its kind; and it promised to bring the deepest reaches of the galaxy into sharp focus. But a problem in the telescope’s primary mirror called “Spherical Aberration” forced astronomers to rethink their science goals.
The First Repair Mission
Within several weeks of the Hubble Telescope’s launch there were problems with the images being received. Apparently there was some damage to the highly sensitive and important mirrors. NASA was already in the midst of planning a way out of the dilemma, a bold mission to service the telescope, replace the flawed components or figure ways to work around them. The mission called simply STS-61 was the most ambitious servicing mission of its kind. The space shuttle Endeavour was sent in December of 1993. Seven astronauts were selected and then sent through intense training sessions to learn how to operate the new technology.
Endeavour arched out over the Atlantic, and headed on a computer-guided course to catch up to the Hubble space telescope forty-eight hours later. During the next two days, the astronauts checked out Endeavour’s robot arm and the support equipment in the shuttles cargo bay in which the replacement components for Hubble were housed. Early on the morning of December 4th, Endeavour closed in on the 43-foot long observatory. Slowly but surely Endeavour crept up on Hubble and with the help of binoculars astronaut Jeff Hoffman confirmed what engineers had surmised, that Hubble had a damaged solar array after its tenure in orbit.
European Space Agency astronaut Claude Nicollier unfurled the shuttle Canadian built robot on, and at 3:47 am Eastern Time, plucked Hubble out of orbit. Nicollier gently set Hubble down onto its work platform where it was latched and placed. A power cable was connected to the telescope to provide electricity for its various systems. The robot arm then was moved back and forth around Hubble, providing the first close-up views of the telescope for engineers in more than three years. Late that night after an eight hour sleep period, payload Commander Story Musgrave and Jeff Hoffman suited up for the first of the five planned space walks. The space walkers moved around the cargo bay deftly. Hoffman perched at the end of the robot arm; Musgrave, working from the foot restraints at the side of Hubble. After installing the new Gyroscopes and electrical units, Hoffman replaced eight fuse plugs to upgrade Hubble’s power capacity. After several hours of meticulous work, Hoffman was told by flight controllers that health checks performed on Hubble’s new equipment proved successful.
In all, Hoffman and Musgrave spent seven hours and fifty-four minutes in the cargo bay, the second longest space walk in US history; but the night was not over. Engineers tried to retract Hubble’s old solar arrays in advance of the second space walk the following day. Only one array rolled up and the officials discussed their options, eventually deciding it would be manually jettisoned. On the night of December 5th the next team of space walkers emerged from Endeavour’s airlock. Kathy Thornton and Tom Akers had one objective on the 2nd space walk; to replace Hubble’s critical solar arrays. With Thornton at the end of the robot arm and Akers at fixed foot restraints, the space walkers first disconnected the damaged array. Then, with the array held over her head Thornton was maneuvered to the side of Endeavour’s cargo bay where she waited for the sun to rise to perform the manual jettison.
Over the next few hours, Thornton and Akers hooked up electrical connectors and latches to the arrays, which were designed to eliminate the jitter the old ones experienced as Hubble passed in and out of darkness. With the replacement complete, ground controllers sent commands to test the arrays. The highest priority objective of the servicing mission was declared a success. As he wrapped up the six and a half hour space walk, Akers established a shuttle record for time spent outside a crew cabin in the harsh environment of space. Later in the mission, Akers would surpass Gene Cernan for the most space walking time by an American space traveler. The astronauts pressed ahead the following night, as Musgrave and Hoffman returned to the cargo bay for the third space walk, making the transition from mechanics to optometrists to begin the installation of the new optics to improve Hubble’s vision.
Hoffman slowly removed the old WF/PC, a high-resolution imaging device primarily intended for optical observations. He then placed this old camera in a parking fixture on the side of the cargo bay. He then hauled the new camera back to the telescope. Musgrave had to perform the single most delicate task of the mission; the removal of the cover protecting WF/PC’s perfectly ground mirror, and then expose it to star light for the first time. The mission was a success. As engineers conducted successful health checks on the WF/PC, Hoffman and Musgrave headed for the top of the Hubble Space Telescope to install a pair of new magnetometers designed to help Hubble better sense its position in relation to earth’s magnetic field. The job was tedious, but Hoffman and Musgrave completed the task, bringing back with them a pair of covers off the old magnetometers, which peeled away during the installation of the new units.
The next night December 7th belonged once again to Thornton and Akers, their second space walk and the fourth of the mission. The prime objective this time was the installation of the second corrective optical device the COSTAR. It was an ingenious instrument designed to make Hubble’s vision more vivid by bending star light into sharp focus through a series of small mirrors on extendable mechanical arms. Near the end of their six hour fifty minute space walk, Thornton and Akers installed a new data processing system in Hubble, designed to expand the memory capacity for the telescope, and to compensate for the loss of two of the six memory units used by Hubble to process scientific information.
Finally, late on the night of December 8th, Musgrave and Hoffman began the fifth and final space walk. Their job was to install a new electronics package for Hubble’s new solar arrays, and hardware, to improve the performance of the Goddard High Resolution Spectrograph. In all, Musgrave, Hoffman, Thornton, and Akers spent more than 35 hours in the void of space using skills honed over than a year to accomplish every objective planned for this ambitious flight.
NASA officials hailed the mission as a remarkable success on January 13, 1994, and the astronauts received high praise from President Clinton and Vice President Gore, and a phone call from the Oval office of the Whitehouse.
President Clinton: “The Vice President and I wanted to call you and congratulate you on one of the most spectacular space missions in our history. We are also proud of you and we have been able to see you do all those things, it’s just been wonderful. And I want to thank each and every one of you for what you have done. You made it look easy.”
Other Repair Missions
The other service mission were not as long or detailed, but each one improved the telescope’s abilities. The second mission was the “Discovery” done in February of 1997 to add a new imaging spectrum and near infrared camera, replace an engineering and science tape recorder, repair thermal insulation, and boost Hubble’s orbit. The third service mission was also done by the “Discovery” in December of 1999. This mission consisted of replacing all six gyroscopes, a guidance sensor, thermal insulation blankets, and install a voltage/temperature improvement kit. The third service mission was done by the “Columbia.” This flight took place in March of 2002 and installed a new advanced camera for surveys and a new cooling system.
The Hubble Space Telescope Discoveries
The Hubble Telescope has so far had many ground-breaking discoveries in astronomy. One of these discoveries includes the measuring of distances between the “Cepheid variable” stars more accurately than ever before, and thus give a better rate of universe expansion. The telescope was also able to capture images of the collision between Comet Shoemaker-Levy 9 with Jupiter in 1994. Other date discovered by the Hubble would be on proto-planetary disks in the Orion Nebula, which suggests the presence of extra-solar planets around sun-like stars. This telescope has been able to take such images and reveal galaxies that are billions of light years away.
The Future of the Hubble Telescope
The future of the Hubble is left unknown. There has been several repair missions already, but none since the Columbia Space Shuttle disaster. The stabilizing gyroscopes need to be replaced, and if not the telescope will re-enter the Earth’s atmosphere some time in 2010. If the NASA Space Shuttle program can overcome the design flaws that caused the failure of the Columbia mission than a final servicing mission may take place. The James Webb Space Telescope (JWST) is planned to be launched in 2013 and replace the Hubble. The JWST has superior technology, but will only be able to observe infrared light in comparison to the Hubble’s ability with the visible spectrum.
