On Monday, the Dark Energy Survey announced that it will be kicking off season two of its five-year investigation into the nature of dark energy on Sept. 1. Given that the first season produced hundreds of thousands of unique images, the DES sequel has a lot to live up to.
For example, how do you top the discovery of a superluminous supernova 7.8 billion light years away? Or five new Kuiper Belt objects, one of which takes a thousand years to orbit the Sun? Or the ultra-close tracking of the hazardous asteroid 2014 BE63?
Each of these studies was only tangentially related to the stated mission to study dark energy. But that just goes to show that when you go hunting for the mysterious substance that makes up 70 percent of the universe, you catch a lot of weird game in the process.
The galaxy at the bottom is 385 million light-years from Earth. Image: Dark Matter Survey.
"The first season was a resounding success, and we've already captured reams of data that will improve our understanding of the cosmos," said DES Director Josh Frieman in the group's announcement. "We're very excited to get the second season under way and continue to probe the mystery of dark energy."
In popular culture, dark energy has become a kind of open-ended shorthand for the limits of astronomical knowledge. Science fiction writers love it for its inherent vagueness and malleability. It even got a nod in The Avengers as the propulsion technique for traveling between Asgard and Earth, because why wouldn't Norse gods be using a dark energy as an intergalactic express train? We know so little about the stuff that every fictional use its put to seems legit.
The DES aims to finally nail down these outlying questions about dark energy's origins and behavior—mysteries that have eluded scientists since the term "dark energy" was coined by cosmologist Michael Turner in 1998. The DES is particularly interested in determining whether dark energy is a cosmological constant that counteracts the attractive forces of gravity, or whether it is something much more complex and unruly.
The team's biggest ally is the Dark Energy Camera (DECam), the most powerful digital camera in the world. Originally designed and built by Fermilab, the DECam is now mounted on the Victor M. Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile. It is decked out with 74 CCDs, which are the instruments that spin photons into pixels; the total array captures 570 megapixel images.
Cerro Tololo Inter-American Observatory in Chile. Image: Reidar Hahn/Fermilab
All of those fancy features add up to a camera that can capture light from over 100,000 galaxies, up to eight billion light years away. Since the first season of the survey geared up on Sept. 1, 2013, the DECam has captured hundreds of thousands of images of these distant clusters, which have helped pinpoint the architecture of dark energy across the observable universe. A bevy of Fermilab supercomputers are currently analyzing the first season’s images, and are likely to belch up some interesting results in the coming months.
The DES has also attracted a lot of attention from the public, especially with its Tumblr, Dark Energy Detectives. Though the Tumblr appears to have broken its promise of sharing a new image from the DECam with its 46,000 followers every Monday, it gets extra points for trying to live up to its forensic name.
One post is called CSI: Early Universe, with "CSI" referring to "Cosmic Scene Investigation." It conjures up images of astro-detectives debating whether a red giant blew itself up, or was pushed over the edge by some sketchy stellar interloper. Call in the matter splatter analysts.
Criminal cosmology aside, it will be interesting to see if the DES will solve some of the more persistent mysteries about dark energy within its five-year timeframe. But if the second season is anything like the first, we’ll be treated to a lot of bizarre discoveries either way.