A collection of 359 stamped envelopes worth an estimated half million dollars was returned this week to three Apollo astronauts who secretly carried them to the moon in 1971 and who resigned after NASA disciplined them and seized the covers.

Stamp dealers who asked not to be identified said that each cover would bring at least $1,500 on the market.

The Justice Department confirmed yesterday that the commemorative covers were given back to Apollo 15 astronauts David R. Scott, Alfred M. Worden and James B. Irwin in an out-of-court settlement of a suit that Worden brought against the federal government in February of this year.

NASA seized the covers after the disclosure that the crew had given 100 additional covers to a German stamp dealer, who sold them to collectors for $1,500 apiece. The astronauts were to receive $21,000 in commissions from the dealer, but turned down the deal after the disclosure created an uproar in the space agency and on Capitol Hill.

The astronauts resigned from NASA after being reprimanded and transferred out of the astronaut office in 1972. The covers have been kept in the National Archives for the past 11 years.

Lawyers for Worden said the astronauts would not put the covers up for sale right away but would hold them for a time as mementos of their moon flight and reminders of their vindication.

"The three men have an agreement among themselves that they'll hold onto the covers because it took them so long to prove themselves right and blameless," said James Fleming of Fleming, Haile and Shaw in Palm Beach, where Worden lives.

"They're very happy that after 11 years they've been vindicated."

In a statement read to The Washington Post yesterday, the Justice Department said that in deciding to release 61 postal covers claimed by Worden as his property it also decided to release the rest to all three astronauts. Worden carried the 61 covers in his flight suit as he orbited the moon, and Scott and Irwin carried 298 covers in their spacesuits when they landed on the moon.

The 298 will be divided equally among the three astronauts.

The covers are imprinted with the Apollo 15 crew patch, are signed by the three astronauts and are postmarked twice, once at the Kennedy Space Center on the day of launch and the other on the aircraft carrier USS Ranger, which recovered the astronauts in the Pacific Ocean at the end of their mission.

A Justice Department source said the decision to return the covers to the astronauts was made after attorneys there told NASA that the government "did not stand a strong chance of prevailing in court" against Worden's suit. A secret memorandum sent by Justice to NASA in 1978, when NASA was contemplating return of the covers to the astronauts, said substantially the same thing.

"We reminded NASA of the 1978 memo when Worden filed his suit this year," the Justice source said.

"In effect, the 1978 memo said that the government had taken custody of the covers without going through any legal proceedings against the astronauts, which may have violated their constitutional rights."

Worden's suit was filed on grounds that NASA's seizure of the covers was a violation of the Constitution because the astronauts had been given no hearings to defend their action, the only case of its kind in space agency history. After the flight of Apollo 15, NASA issued a regulation prohibiting sale of personal items carried into space by astronauts on subsequent flights.