With three weeks left before NASA's next shuttle launch window opens, the space agency has still not yet met the full letter of recommendations made by Columbia accident investigators, an independent group overseeing the return to flight effort said Monday.

The Stafford Covey Return to Flight Task Group, led by former astronauts Thomas Stafford and Richard Covey, said NASA has only partially fulfilled the final three recommendations it pledged to meet before resuming space shuttle flights.

It is now up to NASA Administrator Michael Griffin to decide whether the space shuttle Discovery, the first orbiter to fly since the Columbia tragedy, will launch next month as planned.

In a statement released just after the task group's announcement, Griffin said the independent panel had performed a "valuable public service."

"As an engineer, I know that a vigorous discussion of these complex issues can make us smarter," Griffin said in the statement. "I anticipate, and expect, a healthy debate in our upcoming Flight Readiness Review for the Space Shuttle Return to Flight mission, STS-114."

Sitting atop Launch Pad 39B at KSC, Discovery is slated to launch its STS-114 astronaut crew spaceward no earlier than July 13. Shuttle program and mission managers are expected to meet between June 29 and 30 for a flight readiness review meeting at Kennedy Space Center (KSC) in Cape Canaveral, Florida.

CAIB Recommendations

"They have a sound plan to go forward, to finish up their analysis and hopefully resolve all of their open issues," said Joseph Cuzzopoli, technology panel leader, during the press conference at NASA's Washington, D.C. headquarters.

Orbiter hardening, external tank debris mitigation and in-flight repair methods rounded out the last three of 15 recommendations from Columbia investigators to be met before NASA launches its next shuttle flight.

While NASA has made great strides in strengthening its orbiter fleet and minimizing harmful debris such as foam and ice - efforts which the task group conceded - it did not meet the full intent of Columbia Accident Investigation Board (CAIB), the task group members said. The task group also accepted that while the five repair methods devised by NASA to orbiter damage in-flight could be used in a contingency situation, they are not far enough along to meet the CAIB recommendations.

"All of these options show promise for future flights, but we didn't feel they were tested and vetted enough to be called a capability," said James Adamson, operations lead for the task group. "Our hats are off to NASA in the tremendous effort they put forth on a system that was never intended to be repaired...it was a tough job."

Task group members will deliver their findings in an executive summary to Griffin Tuesday, Covey told reporters during the press conference.

"We're going to continue writing our final report and hope to get that done as soon as we can," Covey said, adding that despite the task group's findings, he would not have a concern about flying aboard Discovery's next flight.

Discovery's spaceflight is the first of two scheduled test missions to verify new hardware and procedures developed to increase shuttle safety. It is also expected to ferry much-needed supplies, spare parts and science equipment to the International Space Station (ISS), which has depended on Russian spacecraft for cargo deliveries and crew changes since the Columbia accident.

NASA grounded its three remaining space shuttles following the loss of Columbia and its STS-107 astronaut crew on Feb. 1, 2003. The orbiter broke apart over Texas while reentering the Earth's atmosphere. Investigators later found that wing damage, caused by external tank foam debris at launch, caused the accident.