Advanced Camera for Surveys
The Advanced Camera for Surveys (ACS) is an instrument installed on the Hubble Space Telescope (HST) to enhance its imaging capabilities. Here are some key aspects:
History and Installation
- The ACS was developed to replace the Faint Object Camera (FOC), aiming to provide wider fields of view, higher resolution, and sensitivity in the ultraviolet, visible, and near-infrared parts of the spectrum.
- It was installed during the fourth servicing mission of HST, known as STS-109, in March 2002 by the Space Shuttle Columbia's crew.
Design and Capabilities
- **Field of View**: ACS has three channels:
- The Wide Field Channel (WFC) with a field of view of 202 x 202 arcseconds.
- The High Resolution Channel (HRC) with a smaller field of view but higher resolution.
- The Solar Blind Channel (SBC) optimized for UV observations.
- **Resolution**: ACS provides a resolution of about 0.05 arcseconds per pixel, which is critical for detailed astronomical observations.
- **Wavelength Coverage**: ACS can observe from 115 nm in the ultraviolet to 1050 nm in the near-infrared, making it versatile for a broad range of astronomical studies.
Scientific Contributions
- The ACS has been instrumental in numerous discoveries:
- It contributed to the study of the Cosmic Acceleration by observing distant supernovae, providing evidence for dark energy.
- It has mapped the distribution of dark matter in galaxy clusters through gravitational lensing observations.
- ACS has also captured detailed images of galaxies in the early universe, aiding in understanding galaxy formation and evolution.
Maintenance and Issues
- In 2007, the ACS experienced a power supply failure which affected its functionality. However, during the STS-125 servicing mission in 2009, astronauts installed a new power supply, restoring ACS to operation.
Legacy and Future
- The ACS continues to be a vital part of HST's instrument suite, providing high-resolution and wide-field imaging capabilities that are unique among space telescopes.
- Future plans include potential upgrades or replacements as part of HST's ongoing maintenance to ensure its scientific productivity.
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