Wide-eyed: An artist’s rendering shows the proposed Thirty-Meter Telescope mirror inside the observatory dome.
The scientists discovered that the distant galaxy was spinning, just as galaxies spin today, but that it had not yet formed the spiral arms that our own Milky Way galaxy displays. For Ellis, who’s trying to understand how the universe evolved and is one of the paper’s authors, the observation is significant. “It’s telling us the universe was really fairly organized when it was only 10 to 15 percent of its current age,” he says.
Although the concept of adaptive optics has been around for decades, it’s only in the past few years that it’s become sophisticated enough and easy enough to use to become a routine part of astronomy. The system was installed on the Keck II telescope in 2004, and it was the first for a telescope that big. It has since been used to provide clearer views of astronomical objects, but nothing as distant as the galaxy seen last week. The Keck II’s adaptive-optics system, however, pales in comparison to what’s planned for the new Thirty-Meter Telescope (TMT), which a U.S.-Canadian team that includes Caltech, the University of California, and the Association of Canadian Universities for Research in Astronomy will build over the next decade. A decision on whether to place it on Mauna Kea, in Hawaii, where the Keck is, or in Chile is expected next year.
The TMT will have nine times the light-collecting area of the Keck II, whose primary mirror is 10 meters across. And according to Brent Ellerbroek, the adaptive-optics group leader for the TMT, the new telescope’s optics system will be far more sophisticated. It will use about six lasers to measure atmospheric turbulence. While a single laser measures turbulence at only one small spot in the telescope’s line of sight, an array of lasers can provide a three-dimensional picture of distortions over a wider area and at different heights in the atmosphere. The wave-front sensors will also have smaller apertures, to make more-precise measurements, and there will be thousands of actuators, up from hundreds in the Keck, to control the larger number of mirrors. All that measuring and moving presents a computing challenge. “We have to use more-complex algorithms,” Ellerbroek says.
“It’s a great engineering challenge,” says Scott Uebelhart, a postdoctoral associate studying space policy in MIT’s Program in Science, Technology, and Society. But he thinks that the effort is worthwhile. “TMT pretty much puts everything else to shame,” Uebelhart says.
With the advanced system in the TMT, Ellis says, astronomers won’t have to get lucky and find a cosmic lens in order to see far away. Exactly how close to the birth of the universe they’ll get is a question that’s yet to be answered, he says. “We’re almost at the very beginning.”