The costly mislaunch of two satellites from the space shuttle a year ago is making it difficult to obtain insurance for subsequent satellite launches.

Brazil is having difficulty obtaining insurance coverage for its Feb. 8 satellite launch, and Saudi Arabia has been forced to take less than full coverage for its launch the same day. The Saudi launch, in connection with other Middle Eastern countries, is part of a series of satellite launches scheduled for this year. None of the launches currently has full insurance coverage.

Increasing numbers of clients seeking satellite and launch insurance will have to take less than full coverage and assume more of the risk themselves, or pay skyrocketing rates, according to space insurance underwriters and brokers trying to secure insurance for clients.

"The market sustained nearly $300 million in losses in 1984 and, as a result, a large number of underwriters have withdrawn from underwriting at all or cut back on coverage because of shrinking capacity," said James W. Barrett, president of International Technology Underwriters (Intec). "It is a difficult market for space risks; some satellites may very well be uninsured or underinsured."

Since Indonesia's Palapa B2 and Western Union Telegraph Co.'s Westar VI were launched into useless orbits last February, insurance underwriters, including Intec, had to absorb $180 million in losses. A satellite launched by Intelsat, the global satellite communications consortium, that was lost in June also cost the insurance industry $102 million.

While the Indonesian and Western Union satellites were successfully recovered by the space shuttle, their resale still will cover less than half the total insurance cost. Since 1979 alone, the industry has paid out close to $400 million for botched launches, said David Williams, senior editor of the newsletter Satellite News.

Adding to the financial squeeze is the withdrawal of several underwriters from the space insurance game. In recent months, London-based Orion Insurance Co., a major underwriter, and a smaller firm, Stewart Smith East Inc., the New York subsidiary of the London underwriter Stewart Wrightson, both have declined to underwrite satellite insurance.

Rates for insurance have skyrocketed from between 5 percent and 10 percent a year ago to as high as 20 percent.

"The insurance is always going to be there. It's just a question of the price you are willing to pay," said Michael Hewins, vice president of the insurance brokerage Johnson & Higgins of Washington D.C. Inc. "But I think clients will be looking for alternatives until prices come down -- the underwriter doesn't want to get killed, and the client doesn't want to pay with his first-born child."

Hewins said some alternatives include "co-insurance," in which the client assumes some of the risk, and one- or two-launch deductibles in which clients are not covered for the first or second satellite in a series of launches. Partial coverage will be the norm in the coming months, industry sources said.

An increasing number of insurance underwriters will agree to insure only "the safer portions of launches," said Intec's Barrett. The new approach has a good chance of attracting more underwriters back to the space insurance field, Barrett said. In addition, satellites will be built to make it easier to recover them in the event of a mislaunch.

Consequently, two satellites owned by the Arab Satellite Communications Organization have found only partial insurance, and Brazil's two satellites have found none yet, according to one underwriter close to the transaction, who asked not to be identified. One Brazilsat and one Arabsat satellite are scheduled for takeoff Feb. 8 on a French Ariane rocket.

"Brazilsat is having a hard time," the underwriter said. "The client doesn't want to pay the very high rates." The two Arabsat satellites are insured for $25 million each, and if a third "spare" also failed, the organization would receive $45 million. A satellite and launch are estimated to cost about $80 million, according to industry sources.

But insurance underwriters "won't make a firm commitment on the second satellite until the first goes up," he said. "People are not insuring launches way out into the future -- they can't afford to."

While launches scheduled by major companies this year are already insured, Intelsat said it may agree to absorb more of the risk should the cost of premiums on launches become prohibitive.