This article about the upcoming mission to service the Hubble Space Telescope misstated the weight of two new instruments being installed. The correct weight is 1,740 pounds. The story also imprecisely described the Hubble's role in finding planets beyond the solar system. The telescope has helped discover 16 of the roughly 300 extra-solar planets identified so far.
One Last Trip to Open Hubble's Eyes Even Wider
Monday, July 7, 2008
By the end of the year, the world's greatest telescope should be able to see deeper into space and further back in time than ever. If all goes as planned, it will be able to detect events closer to the big bang, explore the "cosmic web" of galaxies and intergalactic gas that make up the large-scale structure of the universe, and reveal much more about how and when distant stars and planets were formed.
NASA scientists, engineers and astronauts are finalizing plans to fly the space shuttle this fall on a mission to the Hubble Space Telescope to repair and upgrade the orbiting observatory that revolutionized astronomy. The long-delayed servicing mission will be the last for the Hubble, NASA says, but it will allow the telescope to perform at its highest level ever for the remaining five or six years of its operating life.
"This will be the first time ever that instrument box is full," said Hubble senior scientist David Leckrone last week. "We will have the most powerful imaging capability on Hubble ever, and possibly anywhere."
It is hard to overstate the importance of the Hubble and its insights into the evolution of the universe, the presence of mysterious dark matter and dark energy, and the existence of hundreds (and probably many more) of planets orbiting distant stars.
In a briefing at the Goddard Space Flight Center, scientists said that observations by the telescope have resulted in an average of 12 published discoveries a week for years, and that almost 4,400 principal and co-investigators have produced articles based on its data.
"This is surely the most productive telescope in history," said Charles Mattias "Matt" Mountain, director of the Space Telescope Science Institute on the Johns Hopkins University campus in Baltimore.
It also has the most remarkable history. The upcoming mission, scheduled for early October, will be the fifth to the Hubble, which orbits almost 350 miles above Earth. Launched with great fanfare in 1990 after long delays, the more than $3 billion instrument (funded by NASA but with contributions from the European Space Agency) initially did not work because of a hugely embarrassing mistake in shaping its 2.4-meter mirror.
But the Hubble's developers and managers went from goats to heroes in 1993 when the first-ever repair mission in orbit succeeded in installing corrective optics that allowed the telescope to begin sending back spectacular and often awe-inspiring images. Subsequent space shuttle missions steadily upgraded the observatory and its capabilities, and the Hubble gradually achieved iconic status.
Time and the harsh environment of space take a constant toll, however, and NASA began planning one final upgrade -- until the 2003 destruction of the space shuttle Columbia. Heightened safety concerns led NASA to cancel the mission, but a public outcry ensued.
Officials then proposed sending a robotic mission to repair the telescope, but several years of work led to a finding that it could not do the job. Finally, in 2006, newly appointed NASA Administrator Michael Griffin reversed the earlier decision and gave the go-ahead to the final repair mission.
This last servicing will also deliver two new instruments -- the Cosmic Origins Spectrograph (which will explore the cosmic web in extreme ultraviolet frequencies) and the Wide Field Camera 3 (which will allow the telescope to "see" across the light spectrum from ultraviolet to optical and infrared). Over the course of five strenuous spacewalks, astronauts will also work to repair cameras and equipment that have degraded or failed, including the Advanced Camera for Surveys, which produced many of the Hubble's most dramatic images.
The two instruments -- weighing a total of 11 tons -- are now in a massive "clean room" at Goddard's Greenbelt campus, where engineers and technicians are conducting final tests and preparing to ship them to the Kennedy Space Center to be loaded onto the space shuttle Atlantis.
Last Monday, the four astronauts who will do the repairs -- including John Grunsfeld, who repaired the Hubble twice before, and Michael Massimino, who will be returning for his second mission -- joined the Goddard staff in head-to-toe white protective suits and booties required for the clean room to examine the tools they will use to do their work in space.
At Goddard, the new instruments have been exposed to intense vibration, extreme cold and heat and crushingly loud noises to make sure they can withstand the launch and the rigors of space. With the shuttles scheduled to be retired in 2010 and the schedule of flights to the international space station already very tight, the $900 million mission will almost certainly be the last to the Hubble.
Assuming the mission goes off as planned, the first new Hubble data and images are expected by early next year. Edward J. Weiler, who was the Hubble's first chief scientist and is now NASA's associate administrator of the Science Missions Directorate, said experience has taught him to be humble about predicting what the Hubble or any other new telescope will find. The major discoveries, he said, are often the ones that overthrow earlier assumptions and understandings.
Having been connected with the Hubble from its conception in the late 1970s to its 1990 launch, from its time as a multi-billion-dollar white elephant and national joke to its later repair and triumph, Weiler sees the Hubble as the ultimate "comeback kid."
"The telescope has given us spectacular science and images you can find hung up in art galleries, but I think Americans have such strong feelings about the Hubble because of its history," he said. "Our team and the instrument itself overcame enormous obstacles, but then delivered something that I think shows the best of America. One hundred years from now, people will remember Hubble and still be writing about what it did."