 |
|
|
The Hubble's Days Are Numbered |
|
By Cristina Hernández-Espinoza*
If no new maintenance missions are sent, the useful life of the magnificent telescope-satellite will come to an end in just three years. Much depends on a renewal of space exploration efforts by the United States.
SAN FRANCISCO, USA - The decision by the U.S. space agency NASA (National Aeronautics and Space Agency) to begin shuttle flights again in 2004 is fuelling hope that the life of the Hubble Space Telescope could be extended, otherwise in three years it could stop transmitting information for deciphering the enigmas of the universe.
Often compared to the first telescope of Galileo Galilei for the magnitude of its contribution to astronomy, the Hubble was put in orbit by NASA's Discovery space shuttle in April 1990.
It was designed to operate until 2010, but has suffered a "premature obsolescence".
"If there are no additional servicing missions, it is likely that the Hubble will stop producing science sometime in 2006," Steven Beckwith, director of the Space Telescope Science Institute (STScI) and professor at Johns Hopkins University, told Tierramérica.
"The gyroscopes necessary to keep Hubble pointed accurately at the sky eventually wear out. We expect gyroscope failures to cripple the Hubble's operations within about three years," said Beckwith, whose institute is responsible for directing and coordinating the telescope's scientific operations.
The modular satellite's instruments have been kept up to date with the latest technologies thanks to four maintenance missions, the last of which took place in early 2002, by the crew of the shuttle Columbia, which was destroyed in the tragic explosion upon return to earth in February.
Weighing 12 tons, the Hubble orbits the earth every 97 minutes, 600 km above the earth's surface. Its observation capacities include the infrared and ultraviolet spectrums.
Its relative proximity to the planet and brushes with the stratosphere bring the telescope one kilometer closer to earth each month, requiring periodic adjustments in its orbit to prevent an unplanned re-entry into the atmosphere.
"With the loss of Columbia space shuttle, the fate of the Hubble Space Telescope is in jeopardy," says Mike Cressy, president of the Kennedy Space Center Amateur Astronomers Club. "The Columbia was the only shuttle that had the ability to provide service to Hubble."
The plan is that by the time the Hubble stops operating, the new James Webb telescope should be in orbit. But the launch of this next-generation model has been postponed until 2011.
In mid-August an independent group of scientists known as the Hubble-Webb transition panel recommended that NASA carry out two maintenance missions, in 2005 and 2015, to optimize the operations and lifespan of the Hubble.
But if these missions are not possible, the panel suggested sending a robot to install a propulsion module that would allow the space telescope to enter the atmosphere in a controlled manner.
"The Columbia Accident Investigation Board report and the Return to Flight report are important pieces in determining Hubble's fate," Anne Kinney, director of NASA's astronomy and physics division, told Tierramérica.
"We must wait and see how Hubble servicing fits into the return to flight," she said.
Nevertheless, Kinney added, "We are now asking the Hubble project to undertake a study on optimizing science with Hubble assuming no future servicing missions. With the right software developed, it may be possible to operate Hubble even with decreased operational capabilities."
Extending the Hubble's useful life would have to take place under restricted budgets, and take into consideration the new Webb telescope, the missions of astronauts aboard the shuttle -- and the risks implied.
One out of every four astronomers in the United States utilizes data sent from the Hubble, and every year STScI receives more than a thousand project proposals.
Its successor, the Webb, is not conceived as a replacement, but rather would be complementary in the tasks it performs. The new telescope will have a more distant orbit.
This is why it is essential to continue to have clear and detailed images and data from the Hubble, say scientists.
"Hubble's major scientific contribution has been to extend our reach into the cosmos, back to a time when the universe was only a few billion years old, less than 10 percent of its present age," explained STScI chief Beckwith.
The universe is estimated at 13 to 15 billion years old, and the age of the Sun at 4.5 billion years.
Fragments of comets hitting Jupiter, stars emerging and dying, and the formation of planetary systems are just part of the repertoire of cosmic processes the Hubble has revealed.
The telescope is named in honor of astronomer Edwin Hubble, who came up with the notion that the universe is expanding, establishing the groundwork for the Big Bang theory, the explosion of matter that gave rise to the cosmos.
The Hubble produces some 45 gigabytes of information each month, or 33 percent of the NASA output, but consuming less than two percent of its budget.
Annual maintenance of the aging telescope reaches 250 million dollars.
The chances of the Hubble's survival beyond 2010, as some astronomers are hoping, depends not only on maintenance missions, but also on the importance of astrophysics projects that compete for limited funding and for a place in the history of knowledge of the universe.
* Cristina Hernández-Espinoza is a Tierramérica contributor.
|
