Updated

When the initial shock and grief surrounding the space shuttle Columbia tragedy begin to subside, critics of NASA are sure to demand answers.

The nation's space program, which is partially privatized, has been plagued with shortages of key experts, tight budgets and mounting safety concerns, according to a trail of reports by congressional auditors, outside panels and NASA retirees. Less than a day after the shuttle disaster occurred, a British newspaper published a letter warning of safety shortcomings within the space program, written by a former NASA engineer and addressed to President Bush last summer.

How much of a forewarning these documents were to Saturday's space shuttle Columbia tragedy may be determined in the next several weeks.

NASA critics both in and outside the government and investigators into the accident are sure to comb the reports for anything that might explain the disintegration of the spacecraft nearly 40 miles above Texas as it screamed toward a landing in Florida at more than 12,000 miles per hour.

As President Bush took office, the investigative arm of Congress found in 2001 that NASA's shuttle work force over the years had declined significantly to the point of reducing the agency's ability to safely support the program.

Many key areas were not sufficiently staffed by qualified workers and the remaining work force showed signs of overwork and fatigue, the General Accounting Office stated.

There were other warnings, including a report to Congress last April on the shuttle program by a federally mandated safety panel of outside experts which expressed "the strongest safety concern" in 15 years.

"We just received a GAO report, I think last week, that looked at NASA's oversight of some of their private contractors and basically said it was inadequate," Sen. John Breaux, D-La., said Sunday on CNN.

Members of Congress made clear Sunday that safety and the NASA budget will come under intense scrutiny on Capitol Hill this year, beginning Monday when the White House sends lawmakers details of Bush's priorities for the agency next year.

"Inevitably, there will be a discussion out of this about how much NASA should be funded, should there be another orbiter built, and in fact, has it been so poorly funded in recent years that maybe, just maybe it wasn't as safe as it should be?" said Sen. Bill Nelson, D-Fla., a former astronaut who flew aboard Columbia.

The House Science Committee will take the lead in Congress's investigation of the tragedy, focusing on how much money has been devoted to the safety of the shuttle and other space programs and whether the disaster could have been prevented with more resources.

Last August, a retired NASA engineer, Don A. Nelson, wrote Bush about what he said was inadequate safety of the shuttle but was rebuffed by the White House's science adviser.

"Your intervention is required to prevent another catastrophic space shuttle accident," said Nelson, who is no relation to the senator. He suggested that shuttle crews be limited to four people, saying that "if this ... is ignored we can watch in horror and shame as the astronauts face certain death."

Bush science adviser John Marburger on Sunday defended the way the administration dealt with Nelson's concerns and said that even in the wake of Sunday's accident, he would still make the same decisions. Nelson advocated an escape module for the shuttle crews, a proposal that would require extensive redesign efforts, NASA official Bill Readdy wrote in 1999.

"When we looked at the way NASA was responding to those issues we decided it was not justified," said Marburger.

White House spokesman Ari Fleischer said "clearly in this case, an escape pod would not have saved the lives of the astronauts given that they were 200,000 feet above Earth and flying at 12,000 mph, they would not have been able to survive."

While many of the warnings in years past about shuttle safety were blunt, they were often tempered with qualified praise for NASA.

For example, the GAO said that to NASA's credit the agency discontinued downsizing plans for the shuttle program in December 1999 and initiated efforts to hire new staff. But even with these efforts, the training of new staff and dealing with critical losses due to retirements are "considerable challenges," the auditors said.

In last April's report to Congress, the Aerospace Safety Advisory Panel noted that "safety has not yet been compromised. NASA and its contractors maintain excellent safety practices and processes as well as a world-class level of safety consciousness."

On the other hand, the safety panel's former chairman, Richard D. Blomberg, told Congress that many engineering improvements have been cut or delayed for budget reasons and "some of these would directly reduce flight risk."

In an interview Sunday, Blomberg said that "what I was talking about was long-term safety. ... I was not predicting this or any other imminent disaster."

Blomberg said that "the space shuttle was destined to be our human flight vehicle until 2020" and "every change takes a long time to plan. We were saying you've got to get your act together and move forward now."

The Associated Press contributed to this report.