Ariane 5 to place environmental satellite in orbit

Payload is the $2 billion Evisat

The Ariane 5 on the launch pad in 1999; an environmental satellite is on board for Friday's launch

LONDON, England (CNN) -- Thursday proved a tense day for Arianespace, the European launch company, as it prepared for the launch of its Ariane 5 early Friday morning.

The Ariane 5's cargo, Envisat, seen by some as the largest and most important satellite ever launched to monitor the Earth's environment.

Some $2 billion worth of hope is resting on Ariane 5's latest launch, set for about 0100 GMT Friday (8 p.m. EST Thursday) at Europe's launch site in French Guyana.

Failure for Arianespace would be devastating for both its finances and reputation, just seven months after its last launch went wrong.

"If they fail this time, you can well understand that European companies wishing to send telecommunication satellites and the like into space will look elsewhere, and that means Russia, perhaps China and indeed also the USA, which of course are the biggest satellite users," says Howard Wheeldon of Prudential-Bache.

Arianespace's credibility was heavily dented in 1996 after the midair explosion of its maiden Ariane 5 flight just 37 seconds after liftoff.

The failure delayed the rocket's planned entry into commercial service by nearly two years.

Ariane 5' s cargo, Envisat, should provide fresh information on global warming, ozone-layer depletion and the reasons behind natural disasters.

Failure this time around would be a huge blow to the European Space Agency; only $500 million of the $2 billion project is insured, there's no stand-by Envisat satellite, and a replica could not be built.

Arianespace is facing tough competition from the United States. Commercial satellite launching is a shrinking market suffering from overcapacity.

"The whole space market is under pressure at the moment," says Gareth Evans of A.T. Kearney.

"It's predicted to be worth, over a 10-year period, over $180 billion, but since the telecoms implosion as it were, on which the space market has been built up over the '90s, it's come under huge amounts of pressure to get product in the air and to justify its existence."

In these media-rich days, any failure is widely publicized. Some analysts blame the public for being too quick to criticize, saying the rate of success is actually high considering the high-risk nature of the space business.