By Paul Rincon
BBC News science reporter, at the Kennedy Space Center
Nasa is investigating two cases of apparent debris seen falling from the space shuttle Discovery as it blasted off for Earth orbit.
The events were captured in onboard video and the agency says it now needs to consider their significance.
In one case, a heatshield tile seems to have been affected on the underside of the shuttle.
Discovery's astronauts are to use a 15m-long robotic arm to inspect the orbiter's exterior.
The arm is equipped with sensor and camera attachments. A full sweep of the shuttle's key surfaces will take several hours.
It appears the tip of the shuttle's external fuel tank also hit a bird as it launched from Kennedy Space Center on Tuesday.
John Shannon, STS-114 mission operations representative, pointed out video frames apparently showing a piece of heatshield tile breaking off from the underside of the shuttle.
This has left a one-and-a-half inch white spot near the nose landing-gear doors.
SHUTTLE RETURN TO FLIGHT
Mission known as STS-114
Discovery's 31st flight
17th orbiter flight to ISS
Payload: Raffaello Multi-Purpose Logistics Module
Lift-off: 1039 EDT, 26 July
Location: Kennedy Space Center, Launch Pad 39B
Discovery crew: Collins, Kelly, Noguchi, Robinson, Thomas, Lawrence and Camarda
"We're very interested in that," he told reporters. "That's something we're going to get better pictures of on flight-day three."
Mr Shannon said it could simply be that part of the black covering on the orbiter's underside was damaged exposing the heatshield tile.
But he added that it was equally possible the tile itself had been dented or sheared.
The missions operations representative also showed journalists video footage of a dark object falling from the external tank.
Experts cannot yet determine its size, but it did not appear to hit the shuttle, they said.
News outlets had reported details of this piece of debris falling off the tank earlier in the day.
Parts and supplies
Tuesday's successful launch was Nasa's second go at a lift-off in the current launch window.
An earlier attempt on 13 July had to be scrubbed because of the failure of a fuel sensor; but the problem did not recur and the countdown proceeded without interruption.
PERFECT FLORIDA DAY
Everything seemed to go right for Nasa and the cheering spectators
Nasa says it has learnt the safety lessons of the Columbia disaster, which cost the lives of seven astronauts, and has made this the most scrutinised shuttle flight ever.
Columbia broke up as it attempted to re-enter Earth's atmosphere.
Super-heated gases entered a hole punched in the wing during take-off by a suitcase-sized chunk of foam from the external tank, tearing the vehicle apart.
Nasa has been considering the issue of bird-strike on launch
Nasa had positioned more than 100 cameras, both on the ground and in the air, to capture as much detail as possible on Discovery's ascent into orbit.
Discovery will take parts and supplies to the ISS and test new safety features such as a repair-kit for heatshield tiles and a 15m-long robotic arm that will inspect the shuttle for damage in orbit.
Discovery is due to touch down at Kennedy Space Center on 7 August at 0546 EDT (0946 GMT; 1046 BST).