A week after NASA's top climate scientist complained that the space agency's public-affairs office was trying to silence his statements on global warming, the agency's administrator, Michael D. Griffin, issued a sharply worded statement yesterday calling for "scientific openness" throughout the agency.
"It is not the job of public-affairs officers," Dr. Griffin wrote in an e-mail message to the agency's 19,000 employees, "to alter, filter or adjust engineering or scientific material produced by NASA's technical staff."
The statement came six days after The New York Times quoted the scientist, James E. Hansen, as saying he was threatened with "dire consequences" if he continued to call for prompt action to limit emissions of heat-trapping gases linked to global warming. He and intermediaries in the agency's 350-member public-affairs staff said the warnings came from White House appointees in NASA headquarters.
Other National Aeronautics and Space Administration scientists and public-affairs employees came forward this week to say that beyond Dr. Hansen's case, there were several other instances in which political appointees had sought to control the flow of scientific information from the agency.
They called or e-mailed The Times and sent documents showing that news releases were delayed or altered to mesh with Bush administration policies.
In October, for example, George Deutsch, a presidential appointee in NASA headquarters, told a Web designer working for the agency to add the word "theory" after every mention of the Big Bang, according to an e-mail message from Mr. Deutsch that another NASA employee forwarded to The Times.
And in December 2004, a scientist at NASA's Jet Propulsion Laboratory complained to the agency that he had been pressured to say in a news release that his oceanic research would help advance the administration's goal of space exploration.
On Thursday night and Friday, The Times sent some of the documents to Dr. Griffin and senior public-affairs officials requesting a response.
While Dr. Griffin did not respond directly, he issued the "statement of scientific openness" to agency employees, saying, "NASA has always been, is and will continue to be committed to open scientific and technical inquiry and dialogue with the public."
Because NASA encompasses a nationwide network of research centers on everything from cosmology to climate, Dr. Griffin said, some central coordination was necessary. But he added that changes in the public-affairs office's procedures "can and will be made," and that a revised policy would "be disseminated throughout the agency."
Asked if the statement came in response to the new documents and the furor over Dr. Hansen's complaints, Dr. Griffin's press secretary, Dean Acosta, replied by e-mail:
"From time to time, the administrator communicates with NASA employees on policy and issues. Today was one of those days. I hope this helps. Have a good weekend."
Climate science has been a thorny issue for the administration since 2001, when Mr. Bush abandoned a campaign pledge to restrict power plant emissions of carbon dioxide, the main heat-trapping gas linked to global warming, and said the United States would not join the Kyoto Protocol, the first climate treaty requiring reductions.
But the accusations of political interference with the language of news releases and other public information on science go beyond climate change.
In interviews this week, more than a dozen public-affairs officials, along with half a dozen agency scientists, spoke of growing efforts by political appointees to control the flow of scientific information.
In the months before the 2004 election, according to interviews and some documents, these appointees sought to review news releases and to approve or deny news media requests to interview NASA scientists.
Repeatedly that year, public-affairs directors at all of NASA's science centers were admonished by White House appointees at headquarters to focus all attention on Mr. Bush's January 2004 "vision" for returning to the Moon and eventually traveling to Mars.
Starting early in 2004, directives, almost always transmitted verbally through a chain of midlevel workers, went out from NASA headquarters to the agency's far-flung research centers and institutes saying that all news releases on earth science developments had to allude to goals set out in Mr. Bush's "vision statement" for the agency, according to interviews with public-affairs officials working in headquarters and at three research centers.
Many people working at Goddard Space Flight Center in Greenbelt, Md., and the Jet Propulsion Laboratory in Pasadena, Calif., said that at the same time, there was a slowdown in these centers' ability to publish anything related to climate.
Most of these career government employees said they could speak only on condition of anonymity, saying they feared reprisals. But their accounts tightly meshed with one another.
One NASA scientist, William Patzert, at the Jet Propulsion Laboratory, confirmed the general tone of the agency that year.
"That was the time when NASA was reorganizing and all of a sudden earth science disappeared," Mr. Patzert said. "Earth kind of got relegated to just being one of the 9 or 10 planets. It was ludicrous."
In another incident, on Dec. 2, 2004, the propulsion lab and NASA headquarters issued a news release describing research on links between wind patterns and the recent warming of the Indian Ocean.
It included a statement in quotation marks from Tong Lee, a scientist at the laboratory, saying some of the analytical tools used in the study could "advance space exploration" and "may someday prove useful in studying climate systems on other planets."
But after other scientists at the Jet Propulsion Laboratory queried Dr. Lee on the statement, he e-mailed public-affairs officers saying he disavowed the quotation and demanded that the release be taken off the Web site. His message was part of a sequence of e-mail messages exchanged between scientists and public-affairs officers. That string of messages was provided to The Times on Friday by a NASA official.
In his e-mail message, Dr. Lee explained that he had cobbled together part of the statement on space exploration under "the pressure of the new HQ requirement for relevance to space exploration" and under a timeline requiring that NASA "needed something instantly."
The press office dropped the quotation from its version of the release, but in Washington, the NASA headquarters public affairs office did not.
Dr. Lee declined to be interviewed for this article.
According to other e-mail messages, the flare-up did not stop senior officials in headquarters from insisting that Mr. Bush's space-oriented vision continue to be reflected in all earth-science releases.
In the end, the news release with Dr. Lee's disavowed remark remained up on the NASA headquarters public affairs Web site until The Times asked about it yesterday. It was removed from the Web at midday.
The Big Bang memo came from Mr. Deutsch, a 24-year-old presidential appointee in the press office at NASA headquarters whose résumé says he was an intern in the "war room" of the 2004 Bush-Cheney re-election campaign. A 2003 journalism graduate of Texas A&M, he was also the public-affairs officer who sought more control over Dr. Hansen's public statements.
In October 2005, Mr. Deutsch sent an e-mail message to Flint Wild, a NASA contractor working on a set of Web presentations about Einstein for middle-school students. The message said the word "theory" needed to be added after every mention of the Big Bang.
The Big Bang is "not proven fact; it is opinion," Mr. Deutsch wrote, adding, "It is not NASA's place, nor should it be to make a declaration such as this about the existence of the universe that discounts intelligent design by a creator."
It continued: "This is more than a science issue, it is a religious issue. And I would hate to think that young people would only be getting one-half of this debate from NASA. That would mean we had failed to properly educate the very people who rely on us for factual information the most."
The memo also noted that The Associated Press Stylebook and Libel Manual specified the phrasing "Big Bang theory." Mr. Acosta, Mr. Deutsch's boss, said in an interview yesterday that for that reason, it should be used in all NASA documents.
The Deutsch memo was provided by an official at NASA headquarters who said he was upset with the effort to justify changes to descriptions of science by referring to politically charged issues like intelligent design. Senior NASA officials did not dispute the message's authenticity.
Mr. Wild declined to be interviewed; Mr. Deutsch did not respond to e-mail or phone messages. On Friday evening, repeated queries were made to the White House about how a young presidential appointee with no science background came to be supervising Web presentations on cosmology and interview requests to senior NASA scientists.
The only response came from Donald Tighe of the White House Office of Science and Technology Policy. "Science is respected and protected and highly valued by the administration," he said.