NASA Sticks to July Shuttle Launch Plan

NASA grounded its shuttles after a piece of foam came off the shuttle Discovery in July 2005, which had been the first flight since the Columbia disaster on February 1, 2003.

A piece of foam that came off an external fuel tank and pierced the protective skin caused Columbia to burn up and disintegrate as it reentered the Earth's atmosphere.

Hale said that debris coming off the external tank remains "a serious concern" for NASA engineers.

He told a press conference that changes had been made to the fuel tanks but that experts had then found a new way that foam could be lost.

NASA has carried out the "largest aerodynamic change" to the shuttle since it first started flying and Hale admitted that the agency remains anxious about future flights.

The problem is with ice frost ramps on the fuel tank.

"There was a strong, concerted opinion from several folks that we should wait until we have a good design on the ice frost ramps and then change them before we go flying," Hale said.

But engineers have concluded that it is still safe to fly until more major changes are made, he added