May 6, 2009
NASA’s Wide Field and Planetary Camera 2
Designed and built by JPL, the Wide Field and Planetary Camera 2 has been the workhorse camera on NASA's Hubble Space telescope's since it was added to the observatory in December of 1993. The camera has produced most of the stunning images that have been released by Hubble during its 15-plus years of service. Its high image resolution and quality are some of the reasons the camera became the space telescope's most requested instrument.
Throughout history, humanity has been moved by the work of the great artists of their age. Wielding brush, chisel or baton, these masters of expression have been able to interpret the environment around them in innovative ways, providing their public new avenues to explore their own senses and emotions. But as with so many career fields, the role and tools of the artisan are changing.
"I cannot tell you how many times I have heard people tell me how much this picture or that image has meant to them," said John Trauger, principal investigator of the Wide Field and Planetary Camera 2 at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "After a while, I began to realize what we have achieved reached beyond the scope of pure science and became something more."
Born as a clone, a safeguard, to be used only in the most dire circumstances, the Wide Field and Planetary Camera 2, or WFPC2, as it's known to the team, was employed under exactly those conditions. Since its arrival aboard NASA's Hubble Space Telescope 15-and-a-half years ago, the baby grand piano-sized camera has been collecting and analyzing the photons of deep space, and redefining our cosmos.
"The WFPC2 image I remember most is of the Eagle Nebula," said Ed Weiler, acting assistant administrator for NASA's Science Mission Directorate in Washington. "It has these pillars of gas and dust that are trillions of miles long. You know there are new stars and planets being formed in there, and the colors are just so intriguing. But what really got me was not my reaction to the picture, but the reaction of the American public."
Imaged by the camera on April 1, 1995, the Eagle Nebula, 7,000 light-years away, is composed of dense, towering clusters of interstellar hydrogen, oxygen and sulfur. Emerging from these towers of cosmic material can be seen newborn stars. It is, in essence, an interstellar nursery.
"After we released the image during a press conference, CNN continued to cover the story live," said Weiler. "People felt compelled to call in with their reactions to this one picture. They were seeing the faces of famous people. One person thought he saw Elvis. Others called it the pillars of creation. I mean this picture touched Americans in a way I have never seen an astronomical picture do."
Another famous portrait by the camera reached out and touched people by peering back almost to the very beginning of the universe itself.
"The original Hubble Deep Field was the deepest image mankind had ever taken out across the universe, literally back in time," said Dave Leckrone, senior project scientist at NASA Goddard Space Flight Center, Greenbelt, Md. "That was the first time we really drove the Hubble Space Telescope to its limits in terms of its ability to see extremely faint objects extremely far away."
Over 10 consecutive days in December 1995, Hubble and the Wide Field and Planetary Camera 2 stared at a speck of sky no bigger than a grain of sand held at arm's length. Soaking in the paltry traces of light (four-billion times fainter than can be seen by the human eye), the camera generated 342 separate images. When all 342 were combined, the resulting image pulled back the curtain on a part of the universe no one had seen before and few had imagined.
"You have got to appreciate that the Hubble Deep Field was taken of a part of the sky that was purposefully chosen to be as empty as people could imagine," said Leckrone. "Astronomers looked at ground-based images of that little part of the sky and said it was basically black - there wasn't anything there. And then you take this Hubble Deep Field and suddenly you see that it is not empty at all. It is filled with thousands of galaxies of every kind imaginable.
"It was just so beautiful," Leckrone added. It produced an emotional response in people saying we are part of something bigger, and more complicated and more beautiful than we ever thought before as human beings."
"One of my personal favorites is of a planetary nebula called MyCn18," said Trauger. "This image has been widely reproduced in settings as diverse as the cover of National Geographic [April 1997] and the cover of Pearl Jam's "Binaural" CD.
The hourglass-shaped nebula has an intricate pattern of "etchings" in its walls. A planetary nebula is the glowing relic of a dying, sun-like star. Scientists theorize the hourglass-shape of this particular nebula is produced by the expansion of a fast stellar wind within a slowly expanding cloud of interstellar gas, which is denser near its equator than its poles.
While the star in one of Trauger's favorite images may be dying, the camera itself is not. With more than 185,000 images of the cosmos under its belt, the Wide Field and Planetary Camera 2 is providing the kind of art astronomers, scientists and other people around the world love, right up to the end. And as much as he values his camera's time in the spotlight, the principal investigator knows when to put the brushes away.
"That camera is the grandpa, the oldest, longest-lasting instrument aboard Hubble," said John Trauger. "But with all that history comes its fair share of radiation damage and plain old obsolescence. It is tired, it is time for it to be brought home."
The camera replacing it, the Wide Field Camera 3, is equipped with state-of-the-art detectors and optics. The new imager is expected to improve Hubble's discovery efficiency and extend its outstanding imaging performance.
"We can only guess what that new camera will discover," said Trauger. "But history tells us that every increase in our reach will uncover new wonders. We will learn still more about the life cycles of galaxies, stars and planetary systems, and the unique astronomical setting of our Earth, and to me that means a lot. WFPC2 helped us see the light."
The Wide Field and Planetary Camera 2 was designed and built by NASA's Jet Propulsion Laboratory.
Image Caption: The image from NASA's Hubble Space Telescope shows the most famous of all planetary nebulae: the Ring Nebula (M57). In this October 1998 image taken with the Wide Field and Planetary Camera 2, the telescope looked down a barrel of gas cast off by a dying star thousands of years ago. This photo reveals elongated dark clumps of material embedded in the gas at the edge of the nebula with the dying central star floating in a blue haze of hot gas. The nebula is about a light-year in diameter and is located some 2,000 light-years from Earth in the direction of the constellation Lyra. The colors are approximately true colors. The color image was assembled from three black-and-white photos taken through different color filters. Blue isolates emission from very hot helium, which is located primarily close to the hot central star. Green represents ionized oxygen, which is located farther from the star. Red shows ionized nitrogen, which is radiated from the coolest gas, located farthest from the star. The gradations of color illustrate how the gas glows because it is bathed in ultraviolet radiation from the remnant central star, whose surface temperature is a white-hot 216,000 degrees Fahrenheit (120,000 degrees Celsius).
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