When the National Aeronautics and Space Administration announced Sept. 18 that a New York firm would publish and distribute "NASA Tech Briefs Journal," everyone involved looked like a winner. The agency could save $600,000 a year, the publishers could sell ads to make a profit, and more free copies might be made available to the public.

But now the losers are rattling their statutes and preparing for a fight. The chairmen of Congress' Joint Committee on Printing have declared NASA's agreement illegal, a violation of an 1895 law that gives the Government Printing Office a virtual monopoly on government publishing.

Committee members fear this could inspire other cost-conscious agencies to seek private publishers, leaving the GPO a paperless tiger.

"We receive no appropriation . . . our costs are based on running a large system," said Michael DiMario, an assistant public printer at the GPO, which prints or supervises the printing of 16,000 publications a year, including the Federal Register and the Congressional Record.

"If you start pulling revenue away by pulling certain publications away, that impacts dramatically on the costs of everyone else," he said. "If other agencies were allowed to follow suit, you'd have the potential for the collapse of the system."

Seeking a way to cut government costs, the GPO suggested that NASA begin charging the magazine's 75,000 subscribers. But a NASA survey showed that a subscription fee -- in this case, $16 a year -- would cause wide dissatisfaction, so it opted for private publication instead. A New York-based firm, Associated Business Publications Inc., was selected this month from several competing bidders.

The law on government printing gives the joint committee the authority to grant waivers to agencies who don't want to go to the GPO. But waivers are rare; faced with probable rejection, NASA simply went ahead without one.

Last Thursday the committee struck back. Its co-chairmen, Sen. Charles McC. Mathias Jr. (R-Md.) and Rep. Frank Annunzio (D-Ill.), dispatched a letter to NASA warning that its action "runs afoul of longstanding government practice and statute. . . ."

Possible sanctions, explained committee staff director Thomas J. Kleis, range from filing suit against the agency to, in the most drastic -- and least likely -- case, withholding its appropriations.

Kleis said NASA's move also raised the question of controlling ad content. While the agency's "memo of agreement" with the publisher contained a mandate that ads be "in good taste," committee members said that was too vague.

In a May 31 letter, Rep. Augustus Hawkins (D -Calif.), then the committee co-chairman, cautioned: "Though liquor, tobacco or gambling casino advertising may be in 'good taste' by some reckoning . . . to have a respected government periodical associated with such products will surely engender some opposition."

But Frank Nothaft, executive vice president of the publishing firm, rejected that notion. "We expect most of the ads will be along the lines of something high-tech . . . . The rates $3,990 for a full-page, black-and-white ad don't make it attractive to rinky-dink advertisers."

He said the back cover of the winter edition had already been sold "to a major aerospace manufacturer." "We don't expect tobacco advertisements," he added.

NASA's Leonard A. Ault said that the space agency entered into the five-year agreement with the firm after exploring several alternatives for cutting costs.

The agency's survey found that advertising usually brought in four times the revenue of subscription payments, Ault said. Also, if the publication and distribution were handled privately, the circulation -- currently capped at 75,000 by a 1981 directive of the Office of Management and Budget -- could grow while subscriptions remained free. The Sept. 18 agreement leaves open the possibility of future royalty payments to NASA. The fight with the GPO was expected, Ault added. But a NASA lawyer has issued an opinion that the committee's jurisdiction applies only to publications intended for a government audience, not to all publications containing government-gathered information.

"Their interpretation . . . is totally specious," said Richard Oleszewski, an attorney on the committee staff. "That would leave out the larger part of the universe of government publications," he said.

Ault knows this. "I feel like the point man on a combat patrol," he said. "There are a lot of people behind me, watching."