Live in Orbit: Atlantis inspections continue

Atlantis astronauts are finishing up inspections of heat shields on the leading edge of the shuttle's left wing as they speed closer the Hubble Space Telescope.

Earlier, they completed scans of the right wing and nose cap, and tiles underneath the shuttle, using a boom equipped with cameras and lasers.

No glaring signs of damage have appeared during the process, which began around 9 a.m., but analysts at Johnson Space Center in Houston will continue to pore over pictures through Wednesday to determine if any areas warrant a closer look.

Tony Ceccacci, the mission's lead flight director, is scheduled to provide an update on the mission at 2:30 p.m. EDT. You can watch it live by clicking on the NASA TV image on the right side of the page to launch a viewer.

Another briefing is scheduled at 5 p.m. EDT following a meeting by the Mission Management Team.

While the heat shield inspections were in progress, astronauts also thoroughly examined four spacesuits stowed on Atlantis to make sure they're in good shape for the five consecutive spacewalks scheduled to start Thursday. Each spacewalk should last 6.5 hours.

In another step to prepare for the spacewalks, the crew soon will begin lowering the air pressure inside Atlantis from a sea level pressure of 14.7 pounds per square inch down to 10.2 psi, roughly the pressure at a 10,000-foot elevation.

The procedure reduces the amount of time the four spacewalkers will need to pre-breath pure oxygen before they step out into space from about four hours to just 45 minutes.

On missions to the International Space Station, the air pressure is only reduced in the Quest airlock, where astronauts "camp out" the night before their spacewalk. But the shuttle isn't set up to pressurize individual compartments at different levels.

In both cases, the lower pressure and breathing of pure oxygen is intended to reduce the chance of an astronaut experiencing decompression sickness, or "the bends," as divers commonly call it.

Once Atlantis is done inspecting heat shields, the crew will return the 50-foot boom extension to the payload bay. Then around 5:30 p.m., they'll use the shuttle's robotic arm to check out the rear maneuvering engines.

After 6 p.m., the Hubble observatory's aperture door will be commanded to close as it is readied for a rendezvous with Atlantis early Wednesday afternoon.