The Hubble Space Telescope has scored a "perfect 10"--or at least an image looking like the number "10"--with its fully restored capabilities after a data formatting instrument failure delayed a Space-Shuttle serving mission. Just a couple of days after the orbiting observatory was brought back online, Hubble aimed its prime working camera, the Wide Field Planetary Camera 2 (WFPC2), at a particularly intriguing target, a pair of gravitationally interacting galaxies called Arp 147.
The image demonstrated that the camera is working exactly as it was before going offline, thereby scoring a "perfect 10" both for performance and beauty.
In late September, NASA delayed a space-shuttle mission to service the Hubble telescope because of a malfunction on the observatory. The glitch meant that Hubble could not format or store data from its instruments, nor transmit the information to Earth.
NASA had planned to send the Atlantis orbiter to repair and upgrade the telescope in October. But the flight was delayed for several months to allow time to prepare to fix the additional problem--with a box known as the Science Instrument Command and Data Handling (SIC&DH) Unit. The unit affects the functions carried out by its Science Data Formatter - Side A. The anomaly prevented Hubble from formatting the data gathered by its instruments ready for sending to scientists on the ground. The malfunction also stopped that data being stored locally on the telescope's solid state recorders for later transmission.
But NASA was able to switch over Hubble operations to its back-up - Side B. So the observatory has returned to normal operations.
The two galaxies in the latest image happen to be oriented so that they appear to mark the number 10. The left-most galaxy, or the "one" in this image, is relatively undisturbed apart from a smooth ring of starlight. It appears nearly on edge to our line of sight. The right-most galaxy, resembling a zero, exhibits a clumpy, blue ring of intense star formation.
The blue ring was most probably formed after the galaxy on the left passed through the galaxy on the right. Just as a pebble thrown into a pond creates an outwardly moving circular wave, a propagating density wave was generated at the point of impact and spread outward. As this density wave collided with material in the target galaxy that was moving inward due to the gravitational pull of the two galaxies, shocks and dense gas were produced, stimulating star formation.
The dusty reddish knot at the lower left of the blue ring probably marks the location of the original nucleus of the galaxy that was hit.
Arp 147 appears in the Arp Atlas of Peculiar Galaxies, compiled by Halton Arp in the 1960s and published in 1966. This picture was assembled from WFPC2 images taken with three separate filters. The blue, visible-light, and infrared filters are represented by the colors blue, green, and red, respectively.
The galaxy pair was photographed on October 27-28, 2008. Arp 147 lies in the constellation Cetus, and it is more than 400 million light-years away from Earth.
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John Wallace | Senior Technical Editor (1998-2022)
John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.