Space

Dark Energy instrument snaps its first shot of the sky

Dark Energy instrument snaps i...
The "first light" image taken by the Dark Energy Spectroscopic Instrument (DESI), showing the red light of the Whirlpool Galaxy
The "first light" image taken by the Dark Energy Spectroscopic Instrument (DESI), showing the red light of the Whirlpool Galaxy
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The "first light" image taken by the Dark Energy Spectroscopic Instrument (DESI), showing the red light of the Whirlpool Galaxy
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The "first light" image taken by the Dark Energy Spectroscopic Instrument (DESI), showing the red light of the Whirlpool Galaxy
DESI's six large lenses have been installed  and tested
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DESI's six large lenses have been installed  and tested
DESI is currently being installed on the Mayall Telescope in Arizona
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DESI is currently being installed on the Mayall Telescope in Arizona

The first images from a revolutionary new telescope have been snapped this week. The Dark Energy Spectroscopic Instrument (DESI) is designed to hunt for clues about a mysterious force that permeates the universe, by building a comprehensive 3D map of the sky. On April 1 DESI achieved "first light" with a mesmerizing image of the Whirlpool Galaxy.

Taken on the first night of observations with the new telescope, this image captured the red light of the galaxy using an r-band filter. But as eye-catching as it is, it won't hold a candle to what DESI will be capable of when it's fully up and running later this year.

The instrument is still in the process of being installed on the Mayall Telescope in Arizona and this first batch of images was snapped during an early trial run designed to test out the six large lenses that were recently assembled on the telescope. These expand the viewing window by about 16 times.

DESI's six large lenses have been installed  and tested
DESI's six large lenses have been installed  and tested

The meat of DESI is still to come. Eventually, the light that streams through those lenses will be captured by an array of 5,000 robotic positioners, which can independently move their own fiber optic cables with a precision down to 5 microns. That light will then be funneled into a series of 10 spectrographs, which split it into different colors to reveal new details about the cosmological targets.

Using this method, DESI will analyze the spectra of more than 30 million galaxies and quasars, which can tell scientists a lot about how far away an object is and how fast it's moving. That in turn can help us understand dark energy, the strange force that fills the universe and appears to be causing its expansion to accelerate.

This first testing phase of the lenses and the equipment required to position them will last about six weeks. After that, the focal plane, which houses the positioners, will be installed ahead of DESI's first official data run later in the year.

The team discusses DESI in the video below.

Source: Berkeley Lab

The Making of the Largest 3D Map of the Universe

4 comments
Cryptonoetic
If the instrument is successful, I predict that the 'dark force' phenomenon (not velocity, but acceleration) will be found to be more pronounced in the vicinity of younger, highly active galaxies (exhibiting significant star formation) and less pronounced in the vicinity of older, more sedentary galaxies.
tsvieps
Missing from the video was any explanation about how this instrument can detect dark energy. It only talked about being able to individually position many glass fibers. What is it seeing that was not detectable previously? Is it just that mapping the location of more galaxies will help us learn the role of dark matter? Or is it that somehow dark matter will suddenly become visible. The latter idea seem self contradictory. If it can be seen, it is not dark. What am I missing?
Michael Irving
@tsvieps, The general idea is that objects that are moving away from us will appear more red as the wavelengths of its light shift towards the red end of the spectrum – a phenomenon known as redshift. DESI will be studying the colors of light from millions of galaxies, to figure out how fast they're all moving away from us, which helps us get a better understanding of the expansion of the universe and the force that's driving it – dark energy.
mikewax
yeah i don't get it either. higher res images of what we've already known for many decades. it's impressive to be sure, but dark energy?