Far above the desert landscape of West Texas, the Milky Way dominated the night sky.
Six astronomers huddled around a cluster of glowing monitors, wrapping up a six-day test run for a $34 million experiment that will keep the McDonald Observatory’s largest telescope busy for three years, probing the mysteries of dark energy.
“There’s a lot riding on this,” said principal investigator Gary Hill early Sunday morning.
The final version of the Hobby-Eberly Telescope Dark Energy Experiment will measure the effect of dark energy on the universe by surveying 100 million galaxies, making the largest-ever map of the universe in the process.
Other projects have searched for dark energy in the more recent past, but UT researchers using the Hobby-Eberly Telescope are the only ones examining the more distant past for data on the phenomenon that is pushing the universe apart at an accelerating rate.
“It easily is one of the biggest mysteries of all time in science,” said UT astronomy professor Karl Gebhardt, one of the principal investigators working on the project.
Dark energy is a catchall term for the force speeding up the expansion of the universe against scientists’ expectations that its growth would be slowing now, Gebhardt said.
“It may not be dark; it may not be energy,” Gebhardt said. “All it is, is just that our universe is expanding much faster than we think, and we can’t explain it.”
In 1998, two research groups, including researchers in Chile and the United States, confirmed the phenomenon. Since then, scientists have been on a race to find the source of the expansion. The UT experiment was conceived about six years ago during a hallway conversation between Gebhardt and Hill.
The idea was to use the Hobby-Eberly telescope to gather information on one million galaxies over the course of three years by using an array of 150-200 spectrographs — depending on how much funding the project receives — which lets astronomers analyze the light gathered. The galaxies are 9-11 billion light-years away, meaning the observations will be from a time in the universe when galaxies were forming.
All other experiments on dark energy will look at the more recent past, when scientists believe that dark energy began exerting a significant influence on the universe. So, the UT project is going against the scientific mainstream.
“We took a lot of flak for that early on,” Gebhardt said.
Now, Hill said, many are looking at the experiment as a cornerstone for interpreting their own data from the recent past.
“You can’t tell anything about evolution from those observations,” Hill said.
The survey is set to be finished by 2013, before any other dark energy experiments.
“We really are kicking ass right now in terms of where we think we are compared to our competition,” Gebhardt said.
Spectrographs are typically used one at a time and on one object at a time. Texas A&M University will mass produce the instruments to be used on the final experiment, an approach which has never been used before with spectrographs.
“This is the Henry Ford way of doing astronomy,” Gebhardt said. “You build one very simple thing, and you turn it into an assembly line.”
Hill said the six-day run, using one of the eventual 150-odd spectrographs on the main telescope, was a sort of pilot run for the final experiment.
Hill and Gebhardt will face pressure to get results, as the project will monopolize the telescope for the next three years.
Typically, astronomers from around the world send in proposals for observations they need from the Hobby-Eberly Telescope for things like the density of super-massive black holes or the location of planets orbiting distant suns.
While the experiment will take up a three-year window, it will also leave the facility with an improved telescope.
“This is going to be one of the most powerful telescopes in the world after we’re done with it,” Gebhardt said.
Guillermo Blanc, a UT astronomy graduate student working on the project, said the experiment would also gather data that wouldn’t necessarily go toward unraveling the mysteries of dark energy but would be immensely helpful to other scientists. There is potential for looking at near-primordial stars and dissecting nearby galaxies to better understand their inner workings.
“There’s a lot of discovery space in [this experiment],” Blanc said. “There’s a lot of room for studying objects that people aren’t really working for.”
1 comments