A federal judge has dismissed two multibillion-dollar lawsuits filed by a former Morton Thiokol Inc. engineer against the aerospace firm over the shuttle Challenger accident.

Roger Boisjoly, an engineer who opposed the Challenger launch due to concerns for the rocket booster seals' ability to withstand unusually frigid weather, filed two suits totaling $3 billion against the Utah rocket maker on the first anniversary of the Jan. 28, 1986, disaster.The Willard resident claimed Thiokol's negligence led to the shuttle explosion that claimed seven lives, grounded the shuttle fleet and destroyed his health and career.

"To suggest that the recommendation or the launch were acts directed toward and for the purpose of injuring Boisjoly is ridiculous," U.S. District Judge David Winder said in a ruling released Friday.

"Furthermore, for a reasonable person to know that Boisjoly might suffer emotional injury as a result of the launch would include the requirement that the person know (emphasis by judge) that the launch would result in disaster," Winder said.

"This court cannot accept any suggestion that either MTI or NASA knew that the Challenger would explode, but yet recommended that it be launched anyway."

Winder, however, left open the possiblity two claims relating to defamation and conspiracy may be refiled. The parties earlier agreed to drop those matters.

Challenger exploded 73 seconds after liftoff from an unusually frigid Cape Canaveral, Fla. The presidential Rogers Commission that investigated the accident determined a faulty seal in a right-side solid rocket booster allowed hot gases to escape and ignite the huge external fuel tank.

The commission also found NASA and Thiokol's decision-making process was flawed and contributed to the nation's worst manned space disaster.

Boisjoly's suits, which were consolidated for pre-trial purposes, allege Thiokol officials defamed him and smeared his image, and the firm knowingly provided faulty equipment to NASA.

The ruling prohibits Boisjoly, who took a medical retirement after the accident, from refiling the claims, except in the case.

"I'm not happy," Boisjoly's Washington, D.C., attorney Robert Levin said. "But I'm not in a position to comment."

Boisjoly was out of town and could not be reached for comment.

"If indeed it (the ruling) is what the rumors say it's going to be, it vindicates us completely and it makes us very, very happy to have all of the lawsuits behind us," Rocky Raab, Morton Thiokol spokesman, said Friday.

The 35-page decision said Boisjoly's claim he was maligned "clearly fails to allege . . . a single specific defamatory statement by defendant MTI."

"While threatening an employee's job, discrediting his reputation, and removing him from a position of importance is certainly not desirable behavior, this court does not find it to be `so outrageous in character, and so extreme in degree, as to go beyond all possible bounds of decency, and to be regarded as atrocious, and utterly intolerable in a civilized society."'

Boisjoly, who sought $1 billion for the astronauts' deaths and $1 million for the loss of his health and career, based his $2 billion suit on a little-used civil conspiracy claim that allows citizens to sue and recover tax dollars used in connection with fraudulent acts.

"Boisjoly has no standing to sue and recover damages for the alleged waste of taxpayer dollars, the misdirection of the space program, the losses suffered by insurance companies, the injury to MTI stockholders, or the deaths of the astronauts," Winder wrote.