Live In Orbit 1st Hubble Spacewalk On Tap Today

Two American astronauts will venture outside shuttle Atlantis today on the first of five consecutive spacewalks aimed at elevating the Hubble Space Telescope to the apex of its scientific capability.

Wearing cumbersome spacesuits to protect them from the deadly vacuum in low Earth orbit, Atlantis lead spacewalker John Grunsfeld and fellow mission specialist Andrew "Drew" Feustel are scheduled to exit the shuttle's airlock at 8:16 a.m.

For Grunsfeld -- an accomplished astronomer-turned-astronaut -- it will be his third close encounter with the telescope. A self-described "Hubble hugger," Grunsfeld flew on telescope servicing missions in 1999 and 2002.

"I'm looking forward to seeing our old friend, the Hubble Space Telescope, and seeing if it's changed at all -- I know I have," Grunsfeld told crewmate Mike Massimino in a video the crew downlinked late Wednesday.

At first glance, the telescope looked pretty good out flight deck windows.

"It's an unbelievably beautiful sight," Grunsfeld said earlier in the day. "Amazingly, the exterior of Hubble, an old man of 19 years in space, still looks in fantastic shape."

Now looming four stories tall in the cargo bay of Atlantis, NASA's flagship observatory was snatched out of orbit Wednesday after a high-flying rendezvous that drew audible gasps from Hubble scientists gathered at NASA's Mission Control Center in Houston.

The 12.5-ton telescope gleamed against pitch black space as veteran mission commander Scott Altman eased Atlantis up to Hubble while both craft flew 350 miles above the planet.

Atlantis mission specialist Megan McArthur grabbed the telescope with the shuttle's robot arm, and views of Hubble with the blue planet Earth behind it were awesome.

"I was really blown away with seeing the telescope up close on the screen," said Jon Morse, director of the astrophysics division at NASA Headquarters in Washington, D.C.

"It really shows you how big the telescope is - the size of a bus," he said. "It takes your breath away."

The rendezvous and capture set the stage for five consecutive days of spacewalking work aboard Atlantis.

Two spacewalking teams plan to outfit Hubble with two new science instruments and then attempt unprecedented repairs on two others.

The astronauts also aim to equip Hubble with six new nickel-hydrogen batteries, six new gyroscopes for its precision pointing system and other gear that should extend orbital observations by another five to 10 years.

First up: Grunsfeld and Feustel. Today the two plan to tackle the two highest priority objectives of the mission:

++Install a next-generation planetary camera that will replace one that has delivered 135,000 images - including the majority of Hubble's most iconic images -- since late 1993.

The new Wide Field Camera 3 will enable scientists to image light emitted from galaxies just 600 million years after the Big Bang, the primordial explosion that birthed the universe.

Sized and shaped like a baby grand piano, the new camera will replace the Wide Field Planetary Camera 2, the optical instrument that corrected the debilitating flaw detected in the telescope's primary mirror two months after its 1990 launch.

"What will they Wide Field Camera do?" Grunsfeld asked crewmate Feustel last night.

"Unlock the secrets of the universe," Feustel said.

The old planetary camera to be removed from Hubble will be returned to Earth and displayed in the Smithsonian Air & Space Museum in Washington, D.C.

++Install a refurbished Science Instrument Control and Data Handling unit, which routes commands to the telescope and scientific data back to Earth.

Hubble's prime unit broke down two weeks before a planned Atlantis launch last October Failure of the back-up unit would shut down science observations, so NASA delayed the Atlantis mission until a replacement for the prime unit could be fielded.

Grunsfeld and Feustel also will install a docking mechanism so that Hubble can be safely guided on a destructive plunge back through the atmosphere at the end of its useful life.

NASA's plan is to develop a robotic spacecraft that would latch on to the mechanism and propel the observatory toward a remote part of the Pacific Ocean. Doing so would ensure no surviving debris will threaten populated areas.

"I'm excited," Feustel said last night. "I'm ready to go."

"You guys are going to do great," mission specialist Mike Massimino said.

"You all set? Ready to go? Tools are ready?" he added. "Wish you the best of luck. we're going to be there, talking with you from the inside, and here we go. Our spacewalking is starting (today)."