Within Sloan's planned five-year lifetime, the survey will contain more spectra than have been published in the history of science. Astronomers will take their first peek through the telescope in May, and they expect to be collecting useful data in about a year, said James Crocker, director of program management for the survey and associate research director of the Center for Astrophysical Sciences at Hopkins. Spectra and images from the telescope will reveal the distances and locations of galaxies, enabling astronomers to build the largest three-dimensional map of the cosmos ever created. Such a map will provide important clues to the overall structure and evolution of the universe. For example, scientists are puzzled about how the cosmos developed into its present, clumpy structure from the evenly distributed mixture of gas and dust that existed originally, following the Big Bang.
Galaxies seem to be grouped on the outside edges of the voids.
They will be mounted at the back of the telescope. For each observation, a round aluminum plate larger than a pizza will be placed between the spectrographs and the telescope. The plates are riddled with tiny holes that line up precisely with the positions of galaxies and other objects being observed. As light comes through each hole, it will be picked up by an individual optical fiber and carried to the spectrographs, which have a combined 640 fibers. Astronomers expect to survey about 100 million objects overall, collecting 20 to 40 trillion bytes, or terabytes, enough data to fill 20 million floppy disks.