Advanced Camera for Surveys

Advanced Camera for Surveys is a sophisticated third-generation scientific instrument installed on the Hubble Space Telescope. Designed to significantly enhance Hubble's imaging capabilities, it replaced the Faint Object Camera during Servicing Mission 3B in 2002. The instrument was built by a team led by Ball Aerospace & Technologies Corp under the direction of principal investigator Johns Hopkins University's Holland Ford.

Overview

As a primary wide-field camera for Hubble, it was engineered to survey large areas of the sky with high sensitivity and resolution. Its development was driven by the desire to observe faint objects in the early universe, such as distant galaxies and quasars. The instrument's suite of detectors and filters allows it to capture data across a broad spectrum, from ultraviolet to near-infrared wavelengths, making it a versatile tool for astrophysics.

Design and capabilities

The instrument comprises three independent CCD camera channels, each optimized for specific observational tasks. The Wide Field Channel provides a large field of view for surveys, the High Resolution Channel offered extremely detailed imaging before its failure, and the Solar Blind Channel is sensitive to ultraviolet light while blocking visible wavelengths. Key optical components include corrective optics and a suite of filters and grisms for spectroscopy. This design enabled unprecedented studies of dark matter distribution via gravitational lensing and detailed imaging of planetary nebulae and supernova remnants.

Scientific discoveries

It has been instrumental in many landmark Hubble projects, including the Hubble Ultra-Deep Field, which revealed some of the most distant galaxies ever observed. Observations contributed critical data to the Hubble constant debate, refining measurements of the expansion of the universe. The camera provided definitive evidence for dark energy through studies of Type Ia supernovae and mapped the structure of protoplanetary disks in regions like the Orion Nebula. Its data were also vital in characterizing extrasolar planet atmospheres and studying objects within our Solar System, such as Pluto and Eris.

History and deployment

Launched aboard Space Shuttle Columbia on mission STS-109 in March 2002, it was installed on Hubble by NASA astronauts during a series of spacewalks. The instrument operated flawlessly until a critical power supply failure in January 2007 rendered it inoperable. During Servicing Mission 4 in 2009, astronauts on STS-125 performed a complex repair, restoring the Wide Field Channel. This servicing mission, which also installed the Cosmic Origins Spectrograph, extended the operational life of Hubble and this camera significantly.

Technical specifications

The instrument's detectors are CCD arrays, with the Wide Field Channel utilizing a 4096 x 4096 pixel sensor. Its wavelength range spans 115 to 1050 nanometers. The field of view is approximately 202 x 202 arcseconds for the Wide Field Channel, with an angular resolution of about 0.05 arcseconds per pixel. It communicates via Hubble's Science Instrument Command and Data Handling system, and its operations are managed by the Space Telescope Science Institute in Baltimore.

Category:Hubble Space Telescope instruments Category:Space cameras Category:NASA