But in the end, higher priority was given to the $250 million weather satellite a badly needed replacement for an aging spacecraft that now serves as the nations primary early warning system for hurricanes that spawn off Africas west coast before barreling across the Atlantic.

"The feeling was that its necessary to protect human life," said George Diller, a spokesman for NASAs Kennedy Space Center, which is managing the weather satellite launch for the National Oceanic and Atmospheric Administration (NOAA).

Heres the situation:

NOAA which is the parent agency of the National Weather Service -- operates a pair Geostationary Operational Environmental Satellites (GOES) as part of a federal government effort to provide coast-to-coast weather forecasting services in the U.S.

Satellite photos on TV newscasts and in newspapers come from the so-called GOES satellites. But more importantly, the spacecraft enable the National Weather Service to track severe-weather systems that can endanger towns and cities throughout the country.

Now keeping vigil over the U.S. East Coast, however, is a six-year-old GOES spacecraft that is flying along on its on its last legs, so to say. Already operating on backup systems, the spacecraft is considered highly susceptible to a mission-ending failure in the midst of the upcoming hurricane season, which extends until November 30.

Meteorologists, meanwhile, are predicting a particularly dangerous season. Noted expert William Gray of Colorado State University expects 11 named storms, seven of which could build to hurricane strength. Whats more, three of those seven are expected to be the type of "major hurricane" that could threaten millions of people and cause billions of dollars of property damage.

As it stands now, a GOES launch next Wednesday and an expedited series of tests in orbit will be needed to get the replacement spacecraft in operation by July 1.

"But that would still protect us during the most active part of the hurricane season -- late July through November," Diller said.

Another factor in the decision: Postponing the GOES launch would have prompted the removal of the spacecraft from atop the Lockheed Martin Atlas 2 rocket slated to send it aloft, triggering a lengthy flight delay.

Neither NASA nor NOAA wanted the GOES spacecraft exposed to potential damage when Lockheed Martin stages the inaugural flight of its new Atlas 3 rocket from a nearby launch pad on May 15. Historically, about 50 percent of new rockets fail explosively during their first flight.

The decision to press ahead with the GOES launch forced NASA to reschedule the Atlantis flight for May 18. The reason: Four previously scheduled rocket launches from Cape Canaveral including the Atlas 3 mission -- effectively block any Atlantis launch opportunity before that date.

Consequently, Atlantis and its crew which includes six U.S. astronauts and a Russian cosmonaut -- now are scheduled to blast off from KSCs launch pad 39-A during a five-minute launch window that will open around 6:30 a.m. or 6:45 a.m. Eastern Daylight Time (10:30 or 10:45 GMT) May 18.

An on-time launch would lead to a landing at KSCs shuttle runway about 3:15 a.m. (07:15 GMT) May 28.

The crews mission will remain the same: Repairing International Space Station electrical systems that have exceeded their warranty, mounting construction cranes outside the outpost and nudging the unfinished lab which has been sinking slightly due to increased solar activity into a higher orbit.

The Atlantis slip is not expected to trigger further delay in the planned mid-July launch of the long-awaited Russian Zvezda service module, a command and control segment that will double as initial crew quarters at the International Space Station.

Already two years behind schedule, the service module which is an upgraded version of the core lab of Russias Mir space station still is expected to launch from Baikonur Cosmodrome in Kazakhstan around July 12.

The delay, however, is expected to have a ripple effect on two subsequent shuttle missions and the arrival of the stations first full-time crew.

A planned August 19 launch of Atlantis on a mission to outfit the service module likely will fall back to around September 8, and the planned September 21 launch of Discovery on a station-construction mission probably wont fly before October 8.

The first station crew, meanwhile, probably wont board the outpost until mid-November at the earliest. The crew which includes U.S. astronaut William Shepherd and Russian cosmonauts Sergei Krikalev and Yuri Gidzenko had been scheduled to fly up to the outpost on October 30.