Hubble mission "brain surgery" in space

— -- High overhead, NASA astronauts are scheduled this week to begin repairs on the Hubble Space Telescope.

The 360-mile high "brain surgery" in space, in the words of astronaut John Grunsfeld, promises a brighter view of the cosmos for Hubble astronomers and fans alike. Sometimes the two are interchangeable.

"We are waiting on the edge of our seats for the incredible results we will get from a repaired Hubble," says cosmologist Mario Livio of the Space Telescope Science Institute in Baltimore. "We are only going to get more great science."

"Hubble will go from a VW SuperBeetle to a high-powered race car," says astronomer Julianne Dalcanton of the University of Washington in Seattle. Hubble will peer at stars and galaxies formed 500 million years after the Big Bang, armed with a new camera 30 times more sensitive to light and a chemical spectrometer 10 times more effective. "We will be able to plan observations we never could before simply because the telescope will be more efficient," Livio said in an April interview.

Hubble has delivered so many astronomical findings, that picking out a "greatest hits" list is a challenge, says Dalcanton. When she wrote a retrospective of Hubble finds for the Nature, she says, "I had to leave things out, there was just too much." Among the highlights:

Cosmic yardsticks:

Cepheids, pulsating stars thousands of times brighter than our sun, serve as ready-made distance markers in space. Measuring Cepheids in galaxies such as the Spiral Galaxy M100 allows astronomers to create a framework by which they can precisely gauge distances throughout the sky.

Stellar nurseries:

Images of the Orion Nebula, a star birth factory, revealed that the youngest stars are surrounded by dust disks buffeted by the winds from nearby exploding giant stars. These are exactly the conditions astronomers suspected would lead to solar system formation.

Star blasts:

After stars consume their hydrogen fuel, an explosion can't be far behind. Images of nearby explosions reveal the "light echoes" of blast waves shocking clouds of dust that escape from stars on the edge of eruption.