Hubble’s Most Used Camera Celebrates 20 Years of Incredible Discoveries

Hubble ACS Camera

The Hubble Space Telescope recently celebrated its 20th year using the Advanced Camera for Surveys (ACS), which was installed on Hubble in March of 2002 and became its most used camera.

The ACS wavelength range extends from the ultraviolet, through the visible spectrum, and out to the near-infrared. The ACS is able to map large areas of the sky in great detail, and following its installation, the ACS became Hubble’s most heavily used instrument.

Hubble ACS
The light echo around the star V838 Monocerotis as seen by the Hubble Space Telescope in November 2005.

125,000 Photos and Counting

In its 20 years aboard Hubble, the ACS has captured 125,000 pictures. These observations have been the source of numerous discoveries, several of which are outlined on the European Space Agency (ESA) website.

Hubble ACS
Astronauts Andrew Feustel (left) and John Grunsfeld, both STS-125 mission specialists, participate in the mission’s third session of extravehicular activity (EVA) as work continues to refurbish and upgrade the Hubble Space Telescope. During the six-hour, 36-minute spacewalk, Grunsfeld and Feustel removed the Corrective Optics Space Telescope Axial Replacement and installed in its place the new Cosmic Origins Spectrograph. They also completed the Advanced Camera for Surveys electronic card replacement work, and completed part 2 of the ACS repair, installing a new electronics box and cable.

“We knew the ACS would add so much discovery potential to the telescope, but I don’t think anybody really understood everything it could do,” Former astronaut — and one of the two who installed the ACS on Hubble — Mike Massimino says. “It was going to unlock the secrets of the Universe.”

The ACS Camera

The ESA explains that the ACS is made up of three subinstruments: the Wide Field Channel, the High Resolution Channel, and the Solar Blind Channel. The Wide Field Channel is a high-efficiency, wide-field, optical, and near-infrared camera that is designed to look for galaxies and galaxy clusters, the ESA explains.

Hubble ACS
The Advanced Camera for Surveys (ACS) aboard the NASA/ESA Hubble Space Telescope has used a natural ‘zoom lens’ in space to boost its view of the distant universe. Besides offering an unprecedented and dramatic new view of the cosmos, the results promise to shed light on galaxy evolution and dark matter in space. Hubble peered straight through the center of one of the most massive galaxy clusters known, called Abell 1689. For this observation, Hubble had to gaze at the distant cluster, located 2.2 billion light-years away, for more than 13 hours. The gravity of the cluster’s trillion stars ” plus dark matter ” acts as a 2-million-light-year-wide ‘lens’ in space. This ‘gravitational lens’ bends and magnifies the light of galaxies located far behind it, distorting their shapes and creating multiple images of individual galaxies.

The High Resolution Channel was designed to take detailed photos of the light from galaxies that featured massive black holes. This particular mode is not currently operational. Finally, the Solar Blind Channel blocks visible light to allow faint ultraviolet radition to be seen. This channel can be used to study weather patterns on other planets; for example, aurorae on Jupiter.

Hubble ACS
A colliding galaxy dubbed the “Tadpole” (catalog name UGC10214) is set against a rich tapestry of 6,000 galaxies. The Tadpole, with its long tail of stars, looks like a runaway pinwheel firework, unlike the textbook images of stately spiral galaxies. Its distorted shape was caused by a small interloper, a very blue, compact galaxy visible near the more massive Tadpole. The Tadpole resides about 420 million light-years away in the constellation Draco. Seen shining through the Tadpole’s disk, the tiny intruder is likely a hit-and-run galaxy that is now leaving the scene of the accident. Strong gravitational forces from the interaction created the long tail of debris, consisting of stars and gas that stretch out more than 280,000 light-years.

The ESA says that amongst its many accomplishments, the ACS helps map the distribution of dark matter, detects the most distant objects in the Universe, searches for massive exoplanets, and studies the evolution of clusters of galaxies.

“Two decades into its mission, the ACS continues to deliver ground-breaking science and some of the most incredible images of the distant Universe, and everything in between,” Dan Coe, an ESA/AURA astronomer who was part of the ACS team as an instrument scientist, says. “Looking back through the archive of ACS images reminds us of the vast diversity of galaxies, colors, and stories that have been shared with the world.”

Header image caption: This collection of images features those taken by the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys (ACS), which is marking 20 years of operation in March of 2022.  

Image credits: NASA, ESA