A project of the Dark Energy Survey collaboration

DES Computing


The Cosmos: A Digital Frontier

ded_computing_compositeEver since we started looking up, we tried to picture where the lights in the night were coming from as they moved through the universe. What were these objects – fiery stones, gods?

We kept dreaming about and measuring a world that was hard and too dark to see. And then one day, we could see into its depths.

At first, we only looked out with our eyes, and then we captured light on photographic plates of glass, and then we learned to convert the photons of light into electrical signals that we can store and analyze in computers.

When you sit down at the console, the eight-panel control module first looks like a gamer’s dream. And then you look to your left and you see another multi-panel module. These two consoles alone control the hundreds-ton telescope and $50M Dark Energy Camera (DECam) that captures the light from distant galaxies and exploding stars. These two consoles initiate the process of turning the ancient light into the recorded history of the cosmos. But if you want to know what goes on inside the machines, how we cyber crunch the sky, you have to look behind the scenes at the Data Management system that turns photons into bytes.

The Dark Energy Survey (DES) acquires hundreds of images – nearly a Terabyte of data – every night, and will continue to do so for the next five years. After the light is collected and stored, it must be transferred and cleaned before we can mine it for the faint clues of dark energy. As the images are taken, they are transferred via a high-speed pipeline from the mountaintop of Cerro Tololo in Chile to the corn fields of Illinois, where computer clusters at the National Center for Supercomputing Applications (NCSA; image, upper left) perform calibrations and tests to ensure data are free of error and contamination, to prepare them for cosmological analyses.

While we can observe and measure the sky to great depths, a key partner in this endeavor is our theoretical understanding of cosmic evolution. For this, we must create fake universes, with a variety of different parameters, inside these super-computers. DES will simulate several universes, in which we will test the hundreds of thousands, millions of lines of code in preparation for working with actual data. What’s more, we can compare the simulated universe to our own, telling us which aspects we’ve simulated correctly and which parts of our theories are solid, which need revision. Super-computers, like those at NCSA shown in today’s image (top right and bottom), play a critical role in constructing these universes.

It’s amazing how productive watching the sky can be.  But, to look out, we had to bring the universe in.

(Hat tip to Tron: Legacy.)

By: B. Nord [FNAL]

Image: NCSA