A $70 million instrument designed by the University of Colorado at Boulder to probe the evolution of galaxies, stars and intergalactic matter from its perch on the orbiting Hubble Space Telescope is on schedule for its slated May 11 launch from Kennedy Space Center in Florida aboard NASA's space shuttle Atlantis.

Originally scheduled for launch in 2004, NASA's Hubble Servicing mission has been beset by delays over the years by causes ranging from the Columbia space shuttle accident to mechanical glitches.

But CU-Boulder Professor James Green of the Center for Astrophysics and Space Astronomy, principal investigator for $70 million Cosmic Origin Spectrograph, or COS, said from the Kennedy Space Center today things look very good for the launch of Atlantis next Monday at 2:01 p.m. EDT.

""There have been no hiccups this time around and everything is going very smoothly," said Green. We are right on schedule and the team is optimistic about the launch."

The telephone-booth-sized COS, built primarily by CU-Boulder's industrial partner, Ball Aerospace and Technology Corp. of Boulder, should help scientists better understand the "cosmic web" of material believed to permeate the universe, said Green.

COS will gather information from ultraviolet light emanating from distant objects, allowing scientists to look back several billion years and reconstruct the physical conditions and evolution of the early universe.

Distant quasars will be used as "flashlights" to track light as it passes through the cosmic web of long, narrow filaments of galaxies and intergalactic gas separated by enormous voids, said Green.

Astrophysicists have theorized that a single cosmic web filament may stretch for hundreds of millions of light-years, an astonishing length considering a single light-year is about 5.9 trillion miles.

Light absorbed by material in the web should reveal "fingerprints" of matter like hydrogen, helium and heavier elements, allowing scientists to build up a picture of how the gases are distributed and how matter has changed over time as the universe has aged, Green said.

The spectrograph will break light into its individual components much like a prism, revealing the temperature, density, velocity, distance and chemical composition of galaxies, stars and gas clouds, said Professor Michael Shull of CASA, a co-investigator on COS.

The team has chosen hundreds of astronomical targets in all directions of space, which will allow them to build a picture of the way matter is organized in the universe on a grand scale, Shull said.

Shull said one of the earliest COS targets will be a quasar previously looked at by Hubble that is believed to have formed about 5 billion years ago - more than one-third of the way back in time and space to the Big Bang.

"This instrument is ten times more sensitive than any previous Hubble ultraviolet instruments, so we are looking forward to studying intergalactic space at this distant epoch in detail."

While matter is thought to have been distributed uniformly throughout space just after the Big Bang, gravity has shaped it into its present filamentary structure known as the cosmic web, said Shull. "Pointing our instrument at hundreds of targets over time will allow us to take a CAT scan of the universe."

COS also will be used to detect young hot stars shrouded in the thick dust clouds they formed in, providing new information on star birth, said CASA Senior Research Associate Cynthia Froning, COS project scientist. Scientists also will point COS at gas surrounding the outer planets of the solar system to glean new clues about planetary evolution.

Green and his COS science team, which is made up of 14 CU-Boulder scientists and engineers and 10 scientists from other institutions, have been allotted 552 orbits of observation time on Hubble.

CU-Boulder's CASA is in the process of hiring several dozen postdoctoral researchers, graduate students and undergraduates to work on the project in the coming years, Green said.

Other members of the COS science team are from Ball, the Southwest Research Institute in Boulder, the University of Wisconsin-Madison, the University of California, Berkeley, NASA's Goddard Space Flight Center in Greenbelt, Md., and the Space Telescope Science Institute in Baltimore, Green said.