A look at the deep universe reveals a strange phenomenon – it seems the universe is expanding and galaxies are accelerating away from us. Scientists have hypothesized that this expansion is due to an invisible, unknown force called "dark energy" that accounts for about 70% of the total energy in the universe.
As part of an effort to understand this amazing power, scientists have built an instrument that will eventually look over the sky at 40 million galaxies ̵
The Dark Energy Spectroscopic Instrument (DESI) can be viewed as an upgrade to the 46-year-old Mayall Telescope, located at the Kitt Peak National Observatory in Tucson, Arizona. After being equipped with six new lenses, on Monday, April 1, DESI recorded the first light of the red-purple spiral of the Messier 51 galaxy.
"It was an incredible moment to first see these images on the control room monitors," said Connie Rockosi, a DESI astrophysicist in a press release.
The six lenses in the package are housed in a special corrector-tagged device attached to the Mayall Telescope. This allows DESI to see around one-third of the visible sky over its five-year mission.
The sensitive lenses have been manufactured in several factories around the world, including the Japanese glass manufacturer Ohama Group. NASA's Goddard Space Flight Center and University College London. The fact that the lenses ricocheted around the world did not mean that this first light test could be a success.
"We had half a dozen salesmen involved in the manufacture and polishing of the glass," explains Peter Doel, who led the design of the optical system. "One mistake would have ruined everything, it's exciting to know that they survived the trip and work so well."
The lens inspection will take six weeks, but is only the first part of a series of attempts to get DESI up and running. DESI itself is still being assembled, so the images generated during the test are actually the result of a fake DESI double attached to the Mayall Telescope to make sure the lenses work as planned. The year looks at 12 Billions of light years back. If everything goes as planned, the new instrument will provide our most accurate measure of the expansion of the universe, and will enhance our understanding of how dark energy contributes to this phenomenon.
The complete instrument will use a series of "5,000 robots", each of which can target a single galaxy in the sky and observe its light, creating one of the best 3D reconstructions in the universe. It can even measure the mass of a neutrino, one of the most abundant subatomic particles in the Universe, and provide insight into the Milky Way's gravity dynamics.