Two instruments that played critical roles in discoveries made by NASA’s Hubble Space Telescope now are on display in an exhibit at the Smithsonian National Air and Space Museum in Washington.
“Repairing Hubble” recognizes the 24th anniversary of Hubble’s launch into space aboard space shuttle Discovery on April 24, 1990. The exhibit features Hubble’s Corrective Optics Space Telescope Axial Replacement (COSTAR) instrument and the Wide Field and Planetary Camera 2 (WFPC2).
Soon after Hubble began sending back images in 1990, scientists discovered the telescope’s primary mirror had a flaw called spherical aberration. The outer edge of the mirror was ground too flat by a depth of 4 microns, which is roughly equal to one-fiftieth the thickness of a human hair. The flaw resulted in images that were fuzzy because some of the light from the objects being studied was being scattered. After the amount of aberration was understood, scientists and engineers developed WFPC2 and COSTAR, which were installed in Hubble during the first space shuttle servicing mission in 1993.
COSTAR deployed corrective optics in front of three of Hubble’s first-generation instruments – the Faint Object Camera, the Goddard High Resolution Spectrometer, and the Faint Object Spectrograph. COSTAR could not correct the vision for the Wide Field/Planetary Camera (WFPC) currently on Hubble. So, a replacement instrument, which was already in work as an upgrade, was hastened to completion as WFPC2. WFPC and WFPC2 were built by NASA’s Jet Propulsion Laboratory in Pasadena, Calif.
WFPC2 was separately fitted with corrective optics to compensate for the scattered light from the primary mirror. This allowed the camera to record razor-sharp images of celestial objects – from nearby planets to remote galaxies — for more than 15 years. A landmark observation was the Hubble Deep Field taken in 1995. This long exposure captured the light of 4,000 galaxies stretching 12 billion years back into time.
Previously unseen details of a mysterious, complex structure within the Carina Nebula (NGC 3372) are revealed by this image of the “Keyhole Nebula,” obtained with NASA’s Hubble Space Telescope. The picture is a montage assembled from four different April 1999 telescope pointings with Hubble’s Wide Field Planetary Camera 2, which used six different color filters.
The picture is dominated by a large, approximately circular feature, which is part of the Keyhole Nebula, named in the 19th century by Sir John Herschel. This region, about 8000 light-years from Earth, is located adjacent to the famous explosive variable star Eta Carinae, which lies just outside the field of view toward the upper right. The Carina Nebula also contains several other stars that are among the hottest and most massive known, each about 10 times as hot, and 100 times as massive, as our Sun.
The circular Keyhole structure contains both bright filaments of hot, fluorescing gas, and dark silhouetted clouds of cold molecules and dust, all of which are in rapid, chaotic motion. The high resolution of the Hubble images reveals the relative three-dimensional locations of many of these features, as well as showing numerous small dark globules that may be in the process of collapsing to form new stars.
Two striking large, sharp-edged dust clouds are located near the bottom center and upper left edges of the image. The former is immersed within the ring and the latter is just outside the ring. The pronounced pillars and knobs of the upper left cloud appear to point toward a luminous, massive star located just outside the field further toward the upper left, which may be responsible for illuminating and sculpting them by means of its high-energy radiation and stellar wind of high-velocity ejected material. These large dark clouds may eventually evaporate, or if there are sufficiently dense condensations within them, give birth to small star clusters.
The Carina Nebula, with an overall diameter of more than 200 light-years, is one of the outstanding features of the Southern-Hemisphere portion of the Milky Way. The diameter of the Keyhole ring structure shown here is about 7 light-years.
WFPC2 was one of Hubble’s main cameras until the Advanced Camera for Surveys was installed in 2002. WFPC2’s 48 filters allowed scientists to study precise wavelengths of light and to sense a range of wavelengths from ultraviolet to near-infrared light.
COSTAR and WFPC2 were removed from Hubble in 2009, during the fifth and final shuttle servicing mission, and returned to Earth. COSTAR’s removal made way for the Cosmic Origins Spectrograph. WFPC2 was replaced by Wide Field Camera 3.
Development of the National Air and Space Museum exhibit was supported by NASA, including the agency’s Goddard Space Flight Center in Greenbelt, Md., and the Space Telescope Science Institute in Baltimore. The exhibit was designed and constructed by museum staff.
A reception at the National Air and Space Museum Wednesday featured presentations by NASA Administrator Charles Bolden, who was the pilot for Discovery during the Hubble deployment mission in 1990; Gen. J.R. “Jack” Dailey, museum director; John Grunsfeld, NASA’s Science Mission Directorate associate administrator and astronaut on several shuttle Hubble servicing missions; and John Trauger, former WFPC2 principal investigator at JPL. The presentations will air on NASA Television. For NASA TV streaming video, downlink and scheduling information, visit: http://www.nasa.gov/nasatv
More information about the new Hubble exhibit and the Smithsonian National Air and Space Museum.
More information about the WFPC2.
For more information about NASA’s Hubble Space Telescope, visit: http://www.nasa.gov/hubble or http://hubblesite.org/
Top image: The NASA Hubble Space Telescope has captured the sharpest view yet of the most famous of all planetary nebulae: the Ring Nebula (M57). In this October 1998 image, the telescope has 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; 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 with the Hubble telescope’s Wide Field Planetary Camera 2. 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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Filed under: Space Telescopes
