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Harvard Astrophysicists Help Develop Galaxy-Mapping Telescope

The Department of Astronomy at Harvard University, located within the Harvard-Smithsonian Center for Astrophysics.
The Department of Astronomy at Harvard University, located within the Harvard-Smithsonian Center for Astrophysics. By Kathryn S. Kuhar
By Haemaru Chung and Benjamin L. Fu, Contributing Writers

Harvard astrophysicists are among researchers from 13 countries who have designed the Dark Energy Spectroscopic Instrument, a telescope that will soon map the locations of galaxies across the universe and explore dark energy.

DESI is a scientific device with 5000 fiber-optic “eyes” that work to estimate and project the distance between Earth and millions of galaxies as well as other remote celestial objects across the universe, according to a press release from the Harvard Center for Astrophysics. The tool also studies dark energy, an unknown force that comprises approximately 68 percent of the universe and increasingly expands it.

Each sensor on DESI is approximately the width of a human hair, according to the release. It is intended that DESI will be able to conduct measurements involving 5000 galaxies every 20 minutes with each sensor being able to track a new galaxy every two seconds.

Harvard Astronomy professor Daniel J. Eisenstein, a spokesperson for the initiative, estimated that DESI will begin operating in 2020. It is currently housed at the Kitt Peak National Observatory near Tucson, Ariz.

“The installation began about 18 months ago,” Eisenstein said. “The project started in 2012 or 2013, and that was the first approval sequence. The project was really several years in design and then several years in active construction, and now will be about a year-and-half in installation.”

DESI will improve upon technology from similar devices used in the past to measure light in space, according to Eistenstein.

“The technological capability of DESI is to be able to measure those spectra at a much faster rate than what was done in the past, something like 20 times faster than the previous survey instrument,” Eisenstein said.

Eisenstein noted that DESI will enable researchers to study the history and composition of the universe in more detail because of the new maps it can create.

“It’s not just mapping out the universe as it is now, it’s actually making a map of what the fluctuations must have been in the first million years after the Big Bang or even the first fraction of a second after the Big Bang,” Eisenstein said.

“There’s an empirical aspect of DESI, which is to measure velocities and make maps from those velocities,” he added. “But then there’s the application side of DESI, which is studying dark energy and general cosmological clustering by understanding the patterns in those maps and using those patterns to infer things about the expansion history.”

Eisenstein said it was a “very exciting time” for the project that brought together researchers across the globe. Harvard astrophysicists are among the 500 researchers at 75 international institutions who contributed to designing DESI.

“We have been working on it for a long time, and we are now starting to see this very capable and compelling new instrument come into life,” Eisenstein said. “It is an ongoing process but it is a really fun process to be able to collaborate with so many talented people from around the world and a wide range of skill sets that come together to make something like this happen.”

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