A project aiming to create a three-dimensional map of millions of stars in the night sky is one step closer to success. The Dark Energy Spectroscopic Instrument, or DESI, recently received formal approval from the U.S. Department of Energy to begin construction. This approval allows spending on the major components of the project. If all goes according to plan, DESI will be installed and ready for observations by January 2019.
Charting the Cosmos
DESI works using 5000 fiber optic cables, each with a corresponding robotic actuator. The 10-inch-long cylindrical robots can precisely position the fibers to capture light from stars, quasars and entire galaxies. The gathered light is then analyzed by 10 spectrographs that can determine its wavelength, which reveals how quickly the objects are moving away from us.
During its planned five-year mission, DESI’s robots will examine different sets of space objects several times each hour. Altogether, DESI will map one-third of the night sky and capture more than 10 times as much data as its predecessor, the Baryon Oscillation Spectroscopic Survey (BOSS).
DESI is currently being prototyped by an instrument called ProtoDESI, which uses only four robots to test the fiber positioning system. The two-month trial is underway at the Nicholas U. Mayall four-meter telescope at Kitt National Observatory in Arizona, where DESI will eventually be installed.
Where No Map Has Gone Before
Having a detailed 3D map of our corner of the universe will offer invaluable insight into many astrophysical questions. DESI will reveal properties of stars, quasars and galaxies, help us understand galaxy clustering and evolution, and allow us to learn more about the cosmic microwave background radiation that permeates the universe. But most exciting is the opportunity to study dark matter and energy, which is responsible for the accelerating expansion of the universe.
“DESI will be able to make a 3D map of the universe using an order of magnitude more redshifts than currently exist,” said DESI co-spokesperson Risa Wechsler of the SLAC National Accelerator Laboratory, Stanford University. “This will allow us to probe the physics of the universe and discover the true nature of dark energy.”
The recent funding approval reflects DESI’s inspiring potential and the team is excited to move forward with the project. “This brings DESI closer to its five-year mission to go where no map has gone before in the universe,” said DESI scientist David Schlegel. “I can’t wait.”
For more telescopic news, find out how the Spitzer space telescope is repurposed 13 years after launch.