The space shuttle Discovery's commander said Friday that she didn't think the orbiter sustained any serious damage when foam fell off the external fuel tank during this week's launch.
"We were actually quite surprised to hear that we had some large pieces of debris fall off the external tank," Commander Eileen Collins said.
Collins admitted that "it wasn't what we had expected."
"I don't think we should fly again unless we do something to prevent this from happening again."
The space agency has said it would suspend shuttle flights until it re-evaluated why the foam still falls from the tank.
Collins said NASA has a good plan to inspect the shuttle and its delicate system of heat-resistant tiles that protect it upon re-entry to Earth.
At a NASA status briefing Friday, shuttle operations manager John Shannon said the orbiter was "extremely" clean but had sustained 25 small dings to heat tiles. (Inspections after previous shuttle missions show an average of 150 dings in thermal protection tiles during launch and re-entry, a NASA official said earlier.)
The crew used Discovery's robot arm Friday to inspect six areas that may have been damaged.
The astronauts looked at the nose landing gear, leading edges of the shuttle's wings and the belly of the orbiter.
Discovery's flight is the first space shuttle mission since the 2003 Columbia disaster, and NASA deployed an array of new equipment and procedures to check for damage, including a boom on the shuttle to inspect the spacecraft with cameras and lasers.
"I am completely blown away at the quality of the data we get from the orbital boom sensor system and the lasers and the cameras. It is a wonderful tool," Shannon said.
Mission extension?
Shannon expressed confidence the shuttle would be safe to return to Earth on
August 7.
"We surely think we'll come back in on late Saturday or Sunday with a clean bill of health for Discovery," he said.
Discovery docked with the international space station Thursday and is scheduled to be stationed there until August 5.
But NASA officials said they are considering extending Discovery's mission by one day to help out space station crew members, who may have to go without another shuttle visit for some time to come.
The shuttle's crew plans to test tile repair techniques during three spacewalks by astronauts Steve Robinson and Soichi Noguchi of Japan. The two also will service the international space station.
The first of three spacewalks is set for 4:44 a.m. ET Saturday.
On Friday, the crew also attached the Raffaello Multi-Purpose Logistics Module to the space station, bringing cargo of food, tools and replacement parts.
In the next few days, the crew will begin transferring the cargo to the station, mission operations manager Phil Engelauf said.
Discovery's two solid rocket boosters also were recovered in perfect condition, Shannon said, enabling them to be reused for future missions.
Foam may have struck wing
NASA officials said Thursday that analysis of camera footage from the launch
showed a small piece of foam may have struck the wing of the orbiter -- a scenario
eerily similar to the accident that doomed the shuttle Columbia. That chunk
of foam left a crack in Columbia's wing, causing it to disintegrate during the
heat of re-entry and killing seven astronauts aboard.
Wayne Hale, NASA's deputy shuttle program manager, said analysts have differing views about whether the piece of foam actually struck Discovery's orbiter -- and, even if it did, it did not strike with enough force to cause any "damage of concern" the data indicates.
The manager of NASA's orbiter program office, Steve Poulos, said an examination of the orbiter has turned up nothing that might present a safety issue for Discovery or its seven astronauts.
Problem of falling foam persists
Shortly after Tuesday's launch, NASA officials said that camera footage shot
of the external fuel tank showed a large piece of foam -- believed to be 24
to 33 inches long, 10 to 14 inches wide and 2.5 to 8 inches thick -- sheared
away from the tank.
Though the piece of foam fell away into space and didn't strike Discovery's orbiter, NASA decided to suspend future shuttle missions and take another look at why foam was falling off the tank, a problem engineers thought they had solved after Columbia's demise.
By Thursday evening, NASA determined that a much smaller piece of foam may have struck the orbiter's right wing.
Additional analysis showed three small pieces of foam separated from the tank at an altitude of about 200,000 feet, and one went in an upward trajectory that took it toward the wing, Hale said.
While the size of the foam piece is unknown, a gap in the area where the pieces are believed to have originated was about 7 inches long and 2 inches wide, he said.
Hale said detection sensors on the leading edge of the wing did not show any impact and an examination of the wing panels did not turn up any damage. Calculations of the force of the impact also showed it would have had about 1/10th of the energy necessary to cause damage, he said.
Officials: Damage appears slight
As Discovery got to within 600 feet of the space station Thursday, Collins and
pilot Jim Kelly executed a "pitch maneuver" in which the shuttle flipped
onto its back so that the space station's crew could photograph the underbelly
to check for possible damage.
Poulos said photography of the underbelly showed slight damage to a tile near the doors that cover the nose landing gear. The area of damage is less than one-half inch.
Footage also showed what appeared to be a piece of tile flying off the orbiter from the same area, around the time it separated from the external fuel tank.
Poulos also said a thermal blanket under one of the orbiter's windows appears to have been slightly damaged.
