ESA UNDAUNTED BY ARIANE ROCKET DISASTER

When an Ariane 4 rocket carrying two Japanese satellites exploded in February, shortly after takeoff from its launch-pad in Guyana, worries grew that Ariane would suffer a setback to its successful commercial launch program. Less than a week after the explosion, however, European space officials breathed a sigh of relief when an American company, Hughes Communications, signed a contract for two Ariane launches in 1992 and 1993.

Officials with the European Space Agency, which developed Ariane, and Arianespace, which builds and commercializes the rocket, now say the February explosion is the kind of accident that satellite manufacturers and owners expect in the still-imperfect realm of space launches. A full report on the cause of the accident was expected over last weekend, but officials foresee little damage to Ariane's launch docket, which is virtually booked for three years.

That doesn't mean there are no worries for the Europeans over the long term. Ariane, which has captured 50 percent of the commercial launch market since the Challenger explosion in 1986, faces new competition from private United States companies.

Another source of concern is the Chinese, who are offering launches at low prices - a kind of ``dumping,'' the Europeans charge - to make a place for themselves on the international market. The Chinese are expected to launch the Arab League's telecommunications satellite Arabsat, and that has Europe crying foul. Nor were Europeans happy when the US government gave permission for private US satellites to be launched by the Chinese.

``Our objective is to hold on to our share of the launch market, but we're not prepared to battle unfair practices,'' says Daniel Sacotte of France's National Center for Space Studies. ``If it's a level playing field, we have nothing to fear.''