By Lori Stiles

Astronomers say the grand goal of astronomy has now become a realistic one. That goal is tracing how the universe evolved after the supposed "Big Bang" and formed galaxies, stars, planets and, at least in our case, life.

For astronomers chasing that goal, the timing of the LBT couldn't be better.

"The LBT is going to be the world's largest optical/infrared telescope, and it is going to do exciting science," said LBT Project Director John Hill. "If you ask any three astronomers what they want to do with the LBT, they'll propose eight different projects. The projects range from studying the outer parts of our solar system to nearby star formation to the farthest reaches of the universe."

Some topics that LBT astronomers will explore include:

The Early Universe
Astronomers now look across the vast distances of intergalactic space and detect the first galaxies as they were forming about 13 billion years ago.

These distant galaxies are faint, fuzzy blobs of light, and the structures within them are both small and faint. The earliest galaxies are so far away that their visible light has been stretched into infrared wavelengths, making observations even more difficult.

The LBT will be a virtual time machine for astronomers studying galaxies out to the edge of the cosmos.

"The deepest problems we are attempting to solve today require higher angular resolution than we normally have available," said telescope designer and UA astronomy Professor Nick Woolf. (Angular resolution is a measure of how well a telescope can resolve close objects as separate images.)

"We need to see the detailed structure of the most distant, youngest galaxies to know what was happening in the early universe," Woolf said. "The LBT helps by combining the light collecting power of a 12-meter telescope with the angular resolution of a 23-meter telescope."

Quasars
"The LBT will be a fantastic tool to study quasars," said Steward Observatory's Xiaohui Fan.

Fan leads the Sloan Digital Sky Survey team that has been finding the most distant quasars in the universe. Astronomers now estimate the age of the universe at 13.7 billion years. The most distant, primeval quasars yet found are 13 billion light years away. That is, they formed when the universe was merely 6 percent of its current age, or about 700 million years after the Big Bang.

"So far we have been using Keck (a 10-meter segmented-mirror telescope on Mauna Kea, Hawaii) and VLT (Europe's series of 8-meter telescopes in Chile) to obtain the most detailed observations of these quasars. LBT will be an even more powerful tool, especially with its good infrared instrumentation," Fan said.

"Plus, I am hoping to use LBT to search for more very high redshift quasars," he said.

(Redshift is a shift of the light from celestial objects toward the red end, or longer wavelengths of the spectrum, as those stars, galaxies or other objects move outward at increasing speed. The most distant objects recede from Earth at the highest velocities, so the farther away an object is, the greater its redshift.)

"We can't cover as much sky with LBT as with SDSS, but it goes very deep, so we can use it to look for fainter, and more typical quasars, while SDSS is only sensitive to the rarest and most luminous ones," Fan said.

The Search for Life on Other Planets
LBT will give astronomers sharper images of the universe much closer to home. They'll see the details of individual forming stars and solar systems nearby in the Milky Way.

The hunt for nearby planetary systems is daunting, because although these systems are a billion times closer than the earliest distant galaxies, they are likewise extremely faint. Worse, planetary systems have a 10-million to 10-billion times brighter star parked on the doorstep.

Astronomers have discovered more than 100 planets beyond our solar system since 1996. So far, exoplanets have been detected by the tugs their gravity give their parent stars. No one yet has taken a picture of an exoplanet ­ but it could happen at the LBT on Mount Graham in the near future. The telescope is ideal for solar system searches.

Steward Observatory's Phil Hinz leads a team that is developing a new technique called nulling interferometry that will directly image planets in other solar systems. The technique suppresses light from a star while enhancing light from dust and planets orbiting the star.

"Nulling interferometry is very exciting because it is one of only a few technologies that can directly image environments around stars," Hinz said.

Hinz has a $5 million NASA grant to build the Large Binocular Telescope Interferometer, or LBTI, specifically to image dust disks and exoplanets around 80 nearby stars.

Astronomers will use LBTI to detect planets younger than 500 million years old and at least five times as massive as Jupiter orbiting stars within 30 light years of Earth. They also will hunt for dust disks around those stars, which are like the zodiacal dust disk around our sun. Zodiacal dust shows that rocky debris, "and, with luck, Earth-like planets," are in the galactic neighborhood, Hinz said.

While other big telescopes also undertake extrasolar system searches, the LBT is "one of the few, or perhaps the only one, looking for planets at longer infrared wavelengths," he added.

"The combination of the (binocular) telescope design and having adaptive optics built right into the secondary mirrors is unique in the world right now," Hinz said. "There's no other system like this. It will be an exciting instrument when it comes on line."

Infrared Laboratories, a Tucson firm founded and headed by astronomy Regents' Professor Emeritus Frank Low, began fabricating LBTI hardware this year. "Our hope is to take the instrument to the telescope in spring 2006," Hinz said. "We plan to spend a year getting the bugs out and to begin seriously looking for planets with the system in 2007."

Hinz' LBTI project helps set the stage for NASA's Terrestrial Planet Finder (TPF), a space mission to detect Earth-size planets in other solar systems planned for the coming decade. TPF relies on scientific discoveries and technological advances made by projects like LBTI, said UA astronomy Professor Nick Woolf, who helped plan both the LBT and the Terrestrial Planet Finder.

Woolf now leads the Tucson node of the NASA Astrobiology Institute. Astrobiology is the scientific study of biological processes on the Earth and beyond.

"The search for the origin of life, and the related question of how often life occurs in our galaxy and the universe are potentially the most interesting and challenging topics in all of 21st century science," he said.