NASA examines shuttle; illness prompts spacewalk delay

(CNN) -- NASA engineers are assessing two small areas on the space shuttle Atlantis that may have received some damage during Thursday's launch and ascent, officials said Saturday.

In addition, a spacewalk scheduled for Sunday has been postponed until Monday, with one of the two astronauts scheduled to take it -- Germany's Hans Schlegel -- to be replaced.

The switch was being made because of a "medical issue," said John Shannon, deputy shuttle program manager, at a briefing Saturday night.

NASA sources earlier had told CNN Schlegel was ill.

It's not uncommon for astronauts to experience some nausea and sickness after being launched into space.

The issue is "not going to impact the objectives of this mission," Shannon said.

Because of privacy regulations, he could not confirm if Schlegel was the ill astronaut, but said the condition was "not life-threatening."

Schlegel, 56, is a European Space Agency astronaut on his second trip to space. He initially was scheduled for two spacewalks during the current mission.

Astronaut Stan Love will replace Schlegel, officials said.

The purpose for the spacewalk is to install the Columbus module -- a European laboratory -- on the international space station, a primary purpose of the shuttle mission. Watch the view of Earth from Atlantis »

On the potential damage, there appears to be a small rip on a thermal blanket on the right orbital maneuvering system (OMS) pod, according to NASA documents and Shuttle Lead Flight Director Mike Sarafin.

At first blush, this appears similar to the ripped blanket on the left OMS pod that happened during an Atlantis flight in June.

On that occasion, NASA managers sent astronaut Danny Olivas out on a spacewalk to put the blanket back into place using a surgical stapler -- although they thought Atlantis probably would have been able to re-enter the atmosphere without the fix.

Later Saturday or in the coming days, officials will find out more about how the current ripped blanket compares to that one, and whether they feel the need to repair it.

In addition, there is some potential damage to a tile near the right-side forward reaction control system, which is near the shuttle's nose cap and helps provide the thrust for rotational maneuvers and small velocity changes, officials said.

The potential damage is being assessed. Tile damage occurs on every shuttle flight, however, and the shuttle usually is cleared to return to Earth as-is. E-mail to a friend

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