The National Aeronautics and Space Administration says it must more than double the price of carrying commercial satellites into Earth orbit aboard the space shuttle for the three years starting Oct. 1, 1985.

NASA spokesmen said the shuttle would remain competitive with the West European Ariane rocket and offer more services, however.

Dr. Stanley I. Weiss, associate administrator for space transportation, said that the space agency will charge commercial shuttle users the equivalent of $90 million a flight to occupy the shuttle's 65,000-pound capacity cargo bay in the three fiscal years ending Sept. 30, 1988. This is compared with the $42 million per flight it now charges commercial users, which was set back in 1977 for the three years from Oct. 1, 1982, to Sept. 30, 1985.

"Inflation has something to do with it but the severe decline in our flight rate has been a dramatic factor in allocating our costs," Weiss said. "Back when we set our original price schedule we were looking at a flight rate of more than 500 missions through 1992. We now anticipate 300 missions or even less through 1992." NASA officials also said the original rate was unrealistically low.

The $90 million price for the full cargo bay, however, means that most commercial users will pay less than $30 million since most commercial satellites will occupy less than one-third of the space, with Defense Department satellites taking up the rest. Weiss said this means the shuttle's use price will still be competitive with any other launch service, including the European Space Agency's unmanned Ariane rocket launcher, and the United States' unmanned Delta and Atlas-Centaur rockets.

"The figure we have for a 2,800 pound class communications satellite for Ariane in 1986 is $27 to $30 million, maybe a little higher," Weiss said. "That includes a very favorable down payment and financing policy which we have not yet tried to match."

Weiss said the shuttle offers other advantages that Ariane does not have. Satellites carried in the wide-body shuttle bay can be made shorter, which presumably means they can be built so they do not take up 30 percent of the shuttle bay. This would allow users to pay less.

While announcing a new price schedule for commercial users, Weiss said NASA is negotiating with the Defense Department to bring its price more in line with the commercial user price. The Pentagon had signed an agreement with NASA that gave it a preferential price from 1982 to 1988-- two-thirds of the commercial price.

"We are in the final stages of this negotiation, which will establish a new price out through 1986 and another new price out to 1988," Weiss said. "While the Pentagon will continue to pay less than commercial users, their new price will be far more equitable than their old price."

Weiss said NASA will continue to charge the Pentagon less than commercial users because it is a federal agency and because it supplies NASA, free of charge, with launch services at Vandenberg Air Force Base in California.