Liftoff came at 8:56 a.m.Eastern Daylight Time (12:38 GMT) from Cape Canaveral Air Force Station'spad 36-A and the combination Atlas first stage and Centaur upper stagesuccessfully placed the satellite into orbit 30 minutes later.

Launch was delayed 18 minuteswhile the Air Force cleared a boater from the launch danger area on theAtlantic Ocean, this despite heavy local media coverage during the pastcouple of days warning mariners to stay clear.

New signs near Port Canaveral,additional broadcasts from the Coast Guard and wide local distributionof maps outlining the danger zone all warned boaters where not to go, yetat least one boat briefly threatened the launch anyway.

Improving communications

Today's launch marks thefirst of three missions scheduled during the next four years to replacethe aging constellation of TDRS satellites, the first of which was launchedin 1983 on shuttle Challenger's first flight.

Total cost of building andlaunching the three new TDRS satellites: $830 million.

According to TDRS programmanager Tony Comberiate, the new satellite is critical to the success offuture missions involving the spaceshuttle, the InternationalSpace Station, as well as on science missions such as the HubbleSpace Telescope.

Each of these spacecraft,and many others, including U.S. military spacecraft, rely on the TDRS communicationnetwork to radio their information from orbit to ground stations on thesurface.

Without TDRS, nonstop liveradio contact between the shuttle and Mission Control in Houston wouldnot be possible. The amount of live television from the space station wouldbe reduced to a few minutes and only when the station flew over a particularground station.

Hubble astronomers rely onthe TDRS network to control where the telescope is pointing, as well asfor relaying Hubble's images back to Earth. Several other NASA scienceprobes in Earth orbit use TDRS for the same reason.

This new version of the TDRSspacecraft will be able to handle a greater number of users and move alarger volume of information between space and Earth than the previousTDRS satellites.

Seven TDRS satellites havebeen launched into orbit since 1983, all using the space shuttle as thelaunch vehicle. Six satellites are still operational, although some haveslightly degraded systems.

The seventh TDRS, the secondto be launched, was lost in the 1986 Challenger disaster.

No time to rest

With the successful launchof the Atlas 2-A rocket, International Launch Services' (ILS) -- the companyhat markets the Atlas rocket for Lockheed Martin -- attention now turnsto another ILS launch set to liftoff tonight from the Baikonur Cosmodromein Kazakhstan.

The rocket is to carry theSirius radio communications satellite into Earth orbit after launchingat 6:08 p.m. EDT (22:08 GMT).