BY JUSTIN RAY

June 19, 2001 -- Follow the countdown and launch of the ICO global mobile communications satellite aboard a Lockheed Martin Atlas 2AS rocket. Reload this page for the very latest on the mission.

TUESDAY, JUNE 19, 2001

The orbital assembly of a new wireless telephone and data relay satellite network began Tuesday when a Lockheed Martin Atlas 2AS rocket successfully launched the cornerstone spacecraft for the ICO system. Read our full launch story.

0745 GMT (3:45 a.m. EDT)

Officials report contact has been made with ICO satellite via a tracking station at Brisbane, Australia, confirming that systems are operating normally aboard the Boeing-built craft.

Lockheed Martin says the orbit achieved was 5,458.4 by 5,456.67 nautical miles with an inclination of 44.91 degrees to the equator. That is virtually a perfect delivery of ICO F-2 by the Atlas 2AS rocket.

Today's launch begins the deployment of ICO's 12-satellite constellation. However, the London-based company has yet to firm up its launch schedule that will use Atlas, Boeing Delta 3 and Russian Proton rockets.

Check back later today for a complete wrap-up story and post-launch reaction. You can check out our mission preview for more on the ICO system, its history and the satellites.

0633 GMT (2:33 a.m. EDT)

T+plus 112 minutes. SPACECRAFT SEPARATION! The ICO global mobile telephone and data relay system has its first satellite in space. The ICO F-2 spacecraft has been released into Medium Earth Orbit following launch by the Lockheed Martin Atlas 2AS rocket. This marks the 55th consecutive successful launch by an Atlas rocket dating back to 1993.

0632 GMT (2:32 a.m. EDT)

T+plus 111 minutes. The Centaur is beginning its reorientation maneuver to prepare for releasing the ICO payload. This is all happening above the Indian Ocean southwest of Australia.

0631 GMT (2:31 a.m. EDT)

T+plus 110 minutes. Main engine cutoff confirmed. This was a guidance-commanded engine shutdown. The Centaur engine pumps spinning down following the short burn.

0630 GMT (2:30 a.m. EDT)

T+plus 109 minutes. Ignition and full thrust! Centaur is up and burning again.

0630 GMT (2:30 a.m. EDT)

T+plus 109 minutes. The thermal conditioning of the liquid hydrogen and liquid oxygen systems of the twin Centaur engines is starting to prepare for engine restart. Standing by for ignition.

0628 GMT (2:28 a.m. EDT)

T+plus 107 minutes. Small thrusters on the stage are firing to settle the propellant inside the vehicle's tanks to prepare for engine ignition.

0625 GMT (2:25 a.m. EDT)

T+plus 104 minutes. The Centaur is now maneuvering itself into the correct orientation for engine restart.

0618 GMT (2:18 a.m. EDT)

T+plus 97 minutes. A check of data from the rocket indicates everything is normal. Coming up on the second Centaur burn in about 12 minutes.

0611 GMT (2:11 a.m. EDT)

T+plus 90 minutes. The Centaur upper stage with the attached ICO spacecraft continue their coast through space. The duo is currently flying above the Indian Ocean as it heads to the apogee of the parking orbit at about 10,100 km (5,455 miles). Once reaching that point, the Centaur engines will be reignited to circularize the orbit. Deployment of the ICO satellite will follow a few minutes later.

0508 GMT (1:08 a.m. EDT)

T+plus 27 minutes. The vehicle is now coasting over northern Africa. There really isn't much to report at this point. We will resume live updates as we get closer to the second Centaur burn.

0501 GMT (1:01 a.m. EDT)

T+plus 20 minutes. Official launch time was 12:41:01.770 a.m. EDT.

0455 GMT (12:55 a.m. EDT)

T+plus 14 minutes. The vehicle is now in a lengthy coast period as it cruises up to the high point of the parking orbit. Restart of the Centaur is planned to occur at T+plus one hour, 49 minutes, 14 seconds for a 39-second burn to circularize the orbit.

Spacecraft separation is expected at T+plus one hour, 52 minutes, 43 seconds to complete this launch.

0453 GMT (12:53 a.m. EDT)

T+plus 12 minutes. Officials report the parking orbit achieved is right on the money. The apogee altitude is 10,099 km, perigee altitude of 167.4 km and inclination of 44.55 degrees.

0451 GMT (12:51 a.m. EDT)

T+plus 10 minutes, 50 seconds. MECO 1. The Centaur main engines have cut off as planned following the first of two planned firings to deliver the ICO F-2 satellite into its Medium Earth Orbit. So far all has gone as planned with no problems reported.

0450 GMT (12:50 a.m. EDT)

T+plus 9 minutes, 15 seconds. Downrange distance 972 miles, velocity 15,200 mph.

0449 GMT (12:49 a.m. EDT)

T+plus 8 minutes. Everything continues to look good, Lockheed Martin reports. The vehicle now east of New York. Less than three minutes left in the Centaur burn.

0447 GMT (12:47 a.m. EDT)

T+plus 6 minutes, 20 seconds. The Centaur continues to burn normally as the vehicle streaks 104 miles above the Atlantic Ocean off the coast of North Carolina. Velocity is 10,100 miles per hour.

0446 GMT (12:46 a.m. EDT)

T+plus 5 minutes, 27 seconds. The sustainer engine on Atlas has shut down as planned. Separation of the Atlas stage confirmed and ignition of Centaur's two engines has occurred. The engine nozzles extensions deployed and full thrust reported for the Centaur's RL-10 powerplants.

0445 GMT (12:45 a.m. EDT)

T+plus 4 minutes, 10 seconds. The rocket's trajectory still on course with no problems reported.

0444 GMT (12:44 a.m. EDT)

T+plus 3 minutes, 30 seconds. The payload fairing has been jettisoned. It is no longer needed to protect ICO satellite during the launch. Break wires indicate good separation.

0443 GMT (12:43 a.m. EDT)

T+plus 2 minutes, 55 seconds. The booster engines have shut down and the booster package -- the bottom section of the rocket -- has been jettisoned. The sustainer engine of the Atlas vehicle still firing.

0443 GMT (12:43 a.m. EDT)

T+plus 2 minutes, 25 seconds. Altitude 25 miles, downrange distance 32 miles.

0443 GMT (12:43 a.m. EDT)

T+plus 2 minutes, 5 seconds. Having burned all their propellant, the air-lit solid rocket boosters have separated from the Atlas rocket.

0442 GMT (12:42 a.m. EDT)

T+plus 90 seconds. The two spent ground-started solid rocket boosters have jettisoned to fall into the Atlantic Ocean. Atlas liquid-fueled engines continue to fire normally.

0442 GMT (12:42 a.m. EDT)

T+plus 60 seconds. The ground-lit solid rocket boosters have burned out and the air-lit motors have ignited.

0441 GMT (12:41 a.m. EDT)

T+plus 30 seconds. Pitch and roll programs underway. The Atlas engines and solid rocket boosters performing normally.

0441 GMT (12:41 a.m. EDT)

LIFTOFF! Liftoff of the Lockheed Martin Atlas rocket launching the foundation for the ICO mobile communications constellation. And the vehicle has cleared the tower.

0440 GMT (12:40 a.m. EDT)

T-minus 31 seconds. Launch Sequence Start. The Atlas 2AS rocket's onboard computer is now controlling the remainder of the countdown.

In the next few seconds the liquid hydrogen and liquid oxygen vent valves will be locked and the flight data recorders will be readied. The engine ignition sequence will begin at T-minus 2.4 seconds.

0440 GMT (12:40 a.m. EDT)

T-minus 1 minute. Engines are being verified ready for flight. The final status checks of the propellant and pneumatic systems are upcoming to confirm the Atlas and Centaur stages are "go" for launch.

In the past minute, the inertial navigation unit was launch enabled, liquid hydrogen tanking was secured, fuel tank pressures reported stable, the solid rocket boosters were armed and the ignition enable switch was closed.

0439 GMT (12:39 a.m. EDT)

T-minus 2 minutes. Pressurization of the Atlas/Centaur vehicle has started. Tanks now being brought to proper pressure levels for flight. Also, the solid rocket booster fire commands have been enabled and the vehicle's inadvertent separation destruct safety system has been armed.

Shortly, the Centaur upper stage will go to internal power and the flight termination system will be armed.

0438 GMT (12:38 a.m. EDT)

T-minus 3 minutes. The water system is being readied for activation at launch pad 36B. Water will flood the pad to suppress the sound produced at liftoff and protect the ground support systems.

And the ICO satellite is confirmed on internal power and go for launch.

0437 GMT (12:37 a.m. EDT)

T-minus 4 minutes. The Atlas booster stage and Flight Termination System are switching from ground-supplied power to internal batteries. The ground trickle charge to the satellite payload has been stopped and the spacecraft is on internal power.

0436 GMT (12:36 a.m. EDT)

T-minus 5 minutes and counting! The countdown has resumed for launch of the Lockheed Martin Atlas 2AS rocket with the ICO satellite from pad 36B at Cape Canaveral Air Force Station in Florida. Liftoff set for 12:41 a.m. EDT.

0435 GMT (12:35 a.m. EDT)

Standing by to resume the countdown in one minute.

0434 GMT (12:34 a.m. EDT)

The Lockheed Martin final readiness poll of the entire launch team was just performed by Launch Conductor Ed Christiansen in the Complex 36 Blockhouse. Everyone reported "go" for launch.

0429 GMT (12:29 a.m. EDT)

The final readiness polls of the launch team members and the senior managers are upcoming in about four minutes. All parties will be polled to determine if there are any constraints to picking up the countdown at T-minus 5 minutes for liftoff at 12:41 a.m. EDT tonight.

At this point there haven't been any reports of problems and the weather looks like it will cooperate.

0425 GMT (12:25 a.m. EDT)

The Complex 36 Blockhouse doors and escape tunnel doors are being sealed for launch.

0423 GMT (12:23 a.m. EDT)

Today will mark the 566th of an Atlas rocket; the 132nd flight of a Centaur upper stage on an Atlas; the 22nd mission of an Atlas 2AS vehicle; and first Atlas launch of 2001.

0421 GMT (12:21 a.m. EDT)

T-minus 5 minutes and holding. The countdown has entered the planned hold. This pause is slated to last 15 minutes. There are no major technical problems being worked by the launch team and weather conditions are "go". The Atlas-Centaur rocket is now fully fueled and just awaiting the final minutes before liftoff at 12:41 a.m. EDT.

0416 GMT (12:16 a.m. EDT)

T-minus 10 minutes and counting. Coming up on the planned 15-minute built-in hold at T-minus 5 minutes.

0411 GMT (12:11 a.m. EDT)

Now 30 minutes away from the scheduled launch time of the Atlas rocket. The liquid oxygen and liquid hydrogen tanks have all been brought up to flight level, and the other countdown activities continue smoothly for an on-time liftoff.

0359 GMT (11:59 p.m. EDT)

The updated weather forecast is still calling for an 80 percent chance of acceptable conditions for tonight's two-hour launch window opening at 12:41 a.m. EDT. Meteorologists predict clouds scattered at 3,000 feet and broken at 12,000 and 24,000 feet, 7 miles visibility or better, northwesterly winds from 300 degrees at 10 gusting to 17 knots and a slight chance of a coastal rainshower.

0356 GMT (11:56 p.m. EDT)

T-minus 30 minutes and counting. Countdown clocks marching down to the T-minus 5 minute mark where a 15-minute hold will occur. Fueling of the rocket's liquid oxygen and liquid hydrogen tanks is nearing completion.

And interrogation checks have been completed to verify the rocket's C-band beacon is ready for use to track the vehicle during flight.

0354 GMT (11:54 p.m. EDT)

An inhibited self test of the rocket's Flight Termination System is starting. The FTS would be used to destroy the vehicle in the event of a malfunction during launch.

0351 GMT (11:51 p.m. EDT)

The spacecraft team reports the ICO satellite is in its launch configuration and "go" for an on-time liftoff tonight.

0341 GMT (11:41 p.m. EDT)

Now inside the final 60 minutes of the countdown to launch of a Lockheed Martin Atlas 2AS rocket from Cape Canaveral Air Force Station at 12:41 a.m. EDT.

0336 GMT (11:36 p.m. EDT)

Fueling of the Atlas rocket and its Centaur upper stage goes on. The Atlas liquid oxygen tank has reached the 98 percent level. It will be topped off to flight level shortly. The Centaur liquid hydrogen tank is at the 10 percent level and Centaur liquid oxygen tank is being topped off to flight level.

0333 GMT (11:33 p.m. EDT)

The liquid hydrogen chilldown is now complete and the super-cold fuel is flowing to fill the Centaur upper stage. The cryogenic propellant will be consumed with liquid oxygen by the stage's Pratt & Whitney-made RL-10 engines to propel the ICO satellite into its Medium Earth Orbit.

Meanwhile, the Atlas liquid oxygen tank is now 80 percent full.

0329 GMT (11:29 p.m. EDT)

The liquid oxygen tank inside the Atlas booster stage is now half-full.

0326 GMT (11:26 p.m. EDT)

The rocket's shiny exterior is now turning a frosty white as a thin layer of ice forms from the super-cold liquid oxygen.

Meanwhile, Centaur liquid oxygen topping to flight level has started. As the countdown proceeds, the tank will be replenished to replace the cryogenic liquid oxygen that naturally boils away.

And the final alignment of the Atlas rocket's inertial navigation guidance computer has been completed, and the flight control system final preps are now beginning.

0317 GMT (11:17 p.m. EDT)

The Centaur liquid oxygen tank has reached 95 percent full level where it is being maintained. Topping to 100 percent will be completed later. And now loading of liquid oxygen into the Atlas booster stage is beginning.

The countdown is proceeding on schedule for launch at 12:41 a.m. EDT. There are no major technical snags threatening tonight's liftoff and officials remain hopeful the weather will be acceptable. There are thunderstorms west and north of the Cape, but no rain near the complex. Meteorologists are watching the clouds associated with the surrounding storms, which would be the constraint against launch.

0314 GMT (11:14 p.m. EDT)

Loading of liquid oxygen into the Centaur upper stage continues with the tank having reached 80 percent full.

0312 GMT (11:12 p.m. EDT)

Now inside 90 minutes from the planned 12:41 a.m. EDT (0441 GMT) liftoff time.

The chilldown conditioning of liquid hydrogen propellant lines at pad 36B is now starting. This process is like the one performed on the liquid oxygen side whereby a small amount of the liquid is released from the pad's storage tank to prepare the plumbing for transferring the Minus-423 degree F fuel into the rocket.

Also at this time the doors of the Complex 36 Blockhouse are being sealed. The 120-member launch team is inside the blockhouse controlling the countdown just a few hundred yards away from pad 36B.

0307 GMT (11:07 p.m. EDT Mon.)

The Centaur upper stage's liquid oxygen tank is now 30 percent full in this early portion of fueling operations.

0256 GMT (10:56 p.m. EDT Mon.)

Chilldown conditioning of the liquid oxygen transfer lines at pad 36B has been completed and the launch team is now beginning to fill the Centaur upper stage with its its supply of super-cold cryogenic oxidizer. The liquid oxygen is chilled to Minus-298 degrees F, and will be consumed by the Centaur's twin RL-10 engines along with liquid hydrogen to be pumped into the start a little later in the countdown.

0251 GMT (10:51 p.m. EDT Mon.)

The latest weather update from Launch Weather Officer Jim Sardonia indicates a promising forecast for tonight's window. There are a lot of thunderstorms off to the west of Cape Canaveral. But conditions here at Cape Canaveral are still favorable. Overall, Sardonia is giving an 80 percent chance of launching.

0246 GMT (10:46 p.m. EDT Mon.)

The "chilldown" procedure will soon start to thermally condition the liquid oxygen propellants lines at pad 36B in advance of loading the Centaur upper stage. Chilldown is a process in which a small amount of the super-cold liquid oxygen is released from the pad's storage tank into the feed lines that lead to the rocket.

Meanwhile, gaseous helium chilldown of the Centaur engines and pneumatic bottle charge for the stage have started. Also, checks of the wind damper arm and launcher pyrovent arm connecting the Atlas 2AS rocket with the launch tower will be getting underway.

0241 GMT (10:41 p.m. EDT Mon.)

T-minus 105 minutes and counting. The countdown is running again following the planned half-hour built-in hold. Activities remain on track for liftoff in two hours at 12:41 a.m. EDT (0441 GMT).

0237 GMT (10:37 p.m. EDT Mon.)

Lockheed Martin Launch Conductor Ed Christiansen has just polled his launch team for a readiness to begin fueling the Atlas rocket. All parties reported "go" status. Approval was then given to start loading super-cold liquid propellants into the vehicle. Countdown clocks are due to resume at 10:41 p.m. EDT from the T-minus 105 minute mark and the initial stages of fueling will get underway moments later.

At launch pad 36B the tower securing work, final checks and removal of stabilization shims have been completed. The technicians are now ready to depart the complex.

0226 GMT (10:26 p.m. EDT Mon.)

Now half-way through this 30-minute scheduled hold at T-minus 105 minutes.

The 219-foot tall mobile service tower has been retracted to the launch position. The tower is used to erect the rocket on the launch pad, provide access for workers to all areas of the vehicle and protection from the weather. It is electrically driven on four-wheel assemblies.

0211 GMT (10:11 p.m. EDT Mon.)

T-minus 105 minutes and holding. Clocks have entered a planned 30-minute hold period for the countdown tonight at Cape Canaveral Air Force Station for launch of the Lockheed Martin Atlas 2AS rocket. Launch remains scheduled for 12:41 a.m. EDT (0441 GMT).

The count has 45 minutes of built-in holds scheduled over the course the evening that will lead to liftoff. A second and final hold is planned at T-minus 5 minutes for 15 minutes. The holds are designed to give the launch team a window of time to work any problems that could arise without delaying other pre-flight preparations.

Two minor nits are being discussed by the launch team, but neither appear serious at this point.

The Air Force reports there are no Safety Collision Avoidance periods, or COLAs, that would prohibit liftoff during any portion of tonight's two-hour launch window. Also, computer analysis shows that should a explosion occur, debris would fall in the cleared impact areas based on current wind conditions tonight.

0141 GMT (9:41 p.m. EDT Mon.)

The mobile service tower at launch pad 36B is beginning to roll away from the Atlas 2AS rocket. Also, the launch team is starting the final alignment of the vehicle's guidance computer following the completion of a navigation test.

Over the past couple of hours, the launch team at Complex 36 have worked through propulsion launch preps for the Atlas and Centaur stages, powered up the rocket's flight control system, conducted Atlas hydraulic system and Atlas and Centaur pneumatic preps and Centaur main engine igniter checks were also started.

0126 GMT (9:26 p.m. EDT Mon.)

"Man stations for Integrated Launch Operations." That is the call to the launch team for members to take their positions at Cape Canaveral as the countdown shifts into high gear for tonight's liftoff of the Lockheed Martin Atlas 2AS rocket on a mission to place ICO's first cellular telephone and data relay satellite into orbit.

Night has fallen here on the east-central coast of Florida but the tension level is rising with three hours and 15 minutes remaining in the countdown to the 12:41 a.m. EDT launch time.

The countdown is being controlled from the Complex 36 Blockhouse where the 120-member launch team has assembled to oversee the activities leading up to liftoff of the Atlas rocket designated AC-156.

Lockheed Martin is not reporting any technical problems and the weather looks generally favorable for launch during tonight's two-hour window.

MONDAY, JUNE 18, 2001
2035 GMT (4:35 p.m. EDT)

Launch Weather Officer Jim Sardonia has just released his latest forecast for tonight's planned 12:41 a.m. liftoff of the Lockheed Martin Atlas 2AS rocket. He is giving an 80 percent chance of meeting the weather rules at some point during the available two-hour launch window.

"Thunderstorms are forming as expected this afternoon along the east-coast seabreeze and interior portions of Florida. The steering flow however is extremely light from the southeast, which should slowly carry the storms inland and away from CCAFS by 2000 local (8 p.m. EDT). These storms are producing Anvil Clouds however, that are spreading towards Cape Canaveral due to the light winds aloft. These storms are expected to diminish after sunset but there is the chance that some residual Anvil Clouds and Thick Cloud layers may be in the area during the launch window.

"There are two concerns for tonight's launch; the slight chance of afternoon thunderstorms forming within 5 nm of SLC 36 during the early portion of the launch countdown, and the chance of stratified Thick Cloud layers and enhanced Cumulus Clouds on station during the launch window."

The launch time weather conditions are forecast tolude scattered cumulus clouds at 3,000 feet with 3/8ths sky coverage, a broken deck of altostratus clouds at 12,000 feet with 5/8ths sky coverage, cirrus clouds at 24,000 feet with 6/8ths sky coverage, visibility of 7 miles or better, light and variable winds at 5 knots, a temperature of 75 to 77 degrees F and relative humidity of 70 percent.

Should the launch slip 24 hours for some reason there is an 80 percent chance of acceptable conditions during Wednesday's window of 12:43 to 2:43 a.m. EDT. The main threat will be the possibility of enhanced cumulus clouds in the area.

Our next update on this page should come with the start of the Integrated Launch Operations portion of the countdown at 9:26 p.m. EDT.

1951 GMT (3:51 p.m. EDT)

The countdown begins at this time for tonight's launch of an Atlas rocket carrying an ICO mobile communications satellite from Complex 36 at Cape Canaveral Air Force Station in Florida. Liftoff remains targeted for 12:41 a.m. EDT at the opening of a two-hour launch window.

Throughout the evening crews in the blockhouse and at pad 36B will proceed through their standard countdown chores needed to ready the Atlas booster and its Centaur upper stage for launch.

And in the next few minutes the ICO satellite is scheduled to be powered up so technicians can perform the final work to configure the spacecraft for its journey to space.

Highlights of activities planned tonight include starting Centaur propulsion launch preps at 5:06 p.m.; powering up the rocket's flight control system at 5:11 p.m.; starting Atlas propulsion and hydraulic systems preps at 5:36 p.m.; starting preps of the pad's tower and mobile service structure at 6:06 p.m.; performing the flight control operational test at 6:11 p.m.; starting the internal power test of Atlas/Centaur at 6:46 p.m.; performing a navigation test of rocket's guidance computer at 6:56 p.m.; starting Centaur engine ignitor checks at 7:06 p.m.; starting Centaur helium purges at 8:16 p.m.; and starting liquid hydrogen and liquid oxygen system final preps at 9:21 p.m.

The Integrated Launch Operations -- the formal portion of the countdown -- begins at 9:26 p.m. with all the launch team members at their respective positions.

The mobile service structure should start rolling away from the Atlas rocket at 9:41 p.m., weather permitting. The tower can be retracted via remote control later in the countdown if weather conditions force a delay.

Countdown clocks will enter a planned 30-minute hold at 10:11 p.m. at the T-minus 105 minute mark. During this time the launch team will have a chance to catch up on any work that might be running behind schedule.

Fueling of the rocket with super-cold liquid oxygen and liquid hydrogen cryogenics commences after the countdown is restarted. Centaur liquid oxygen tanking starts at 10:55 p.m.; followed by loading liquid oxygen into the Atlas stage at 11:16 p.m.; and lastly liquid hydrogen fueling of Centaur 11:32 p.m.

A final planned hold is scheduled at T-minus 5 minutes for 15 minutes in duration. If there are no problems standing in the way of liftoff, the countdown will resume 12:36 a.m. for an on-time launch at 12:41 a.m.

SUNDAY, JUNE 17, 2001

The foundation upon which the ICO global telephone and data relay satellite system will be built is awaiting a late-night liftoff atop a Lockheed Martin Atlas 2AS rocket.

Making its first flight of 2001, the Atlas booster is poised to place ICO's first communications spacecraft into a unique orbit around Earth. Launch is planned for 12:41 a.m. EDT (0441 GMT) Tuesday from pad 36B at Cape Canaveral Air Force Station, Florida. Duration of the flight of AC-156 is one-hour, 52 minutes, 43 seconds from liftoff through spacecraft separation.

The Atlas has a two-hour launch window in which to lift off.

The weather forecast calls for an 80 percent chance of acceptable conditions. Launch Weather Officer Jim Sardonia provided this summary in his forecast issued Sunday:

"On Monday, a weak surface trough is expected to move into central Florida triggering early afternoon thunderstorms along the east-coast seabreeze and interior portions of Florida. The steering flow however is expected to be very light from the southeast, which should slowly carry the storms inland and away from CCAFS by 8 p.m. With the weak surface trough remaining over central Florida during the countdown, there will be a slight chance of residual Thick Cloud layers and enhanced Cumulus clouds in the area during the launch window.

"There are two concerns for launch day: The chance of afternoon thunderstorms on station during the early stages of the launch countdown on Monday, and the chance of stratified Thick Cloud layers and enhanced Cumulus Clouds on station during the launch window."

If thunderstorms and lightning move too close to the launch pad, workers will be forced to clear the tower for safety reasons. Officials are concerned that countdown activities could fall behind schedule if crews are chased off the pad for any significant period of time Monday evening.

A backup launch opportunity will be available early Wednesday with the window opening at 12:43 a.m. EDT. The forecast calls for an 80 percent chance of good weather.

It will be ICO's second try to begin deploying its satellite constellation. The first craft was lost in a failed flight of a Sea Launch Zenit 3SL rocket in March 2000.

ICO plans to launch 10 primary satellites and two spares for its network that will circle 6,456 statute miles (10,390 kilometers) above the planet in a so-called Medium Earth Orbit (MEO). The spacecraft will be separated into two orthogonal planes, with each group having five main satellites and one backup. The planes will be inclined 45 degrees to the equator, allowing complete, overlapping coverage of the Earth.

Known as ICO F-2, the satellite to fly Tuesday will serve as a testbed for ICO to ensure the spacecraft and ground systems can operate together properly.

"This launch achieves one of our most important milestones," said Greg Clarke, ICO chief executive officer. "It sets us on a course to build out this system and offer a range of unique services to the market."

In addition to voice and digital data transmissions, the ICO system will also provide users with wirlesss Internet and packet-data services. ICO could be ready for commerical service in 2003.

Boeing Satellite Systems is building 15 satellites for ICO -- the 10 primaries, two in-space spares, two ground spares and the one lost on Sea Launch.

The 6,000-pound ICO satellites are modified versions of Boeing's popular 601-model design. They are 25 percent taller, standing 16 feet high due to the transmit and receive antennas. Each craft features integrated C- and S-band payload with 5,100 watts of power and a peak effective isotropic radiated power of 58 dBW. They can support 4,500 simultaneous telephone calls. An onboard narrow band digital processor will perform channelization, routing and beam-forming of the S-band payload.

"This satellite design incorporates a number of unique design features," said Randy Brinkley, president of Boeing Satellite Systems. "The satellites carry more computing power than 600 Pentium III-based computers. They feature innovative transmit and receive antennas allowing direct air link to users and use a 'smart processor' capable of adapting beam configuration to match demand. These features give ICO unprecedented flexibility to meet ever-changing market demands on a global basis."

ICO was formed in 1995, but experienced financial troubles and went into bankruptcy. Life was restored in the system with a $1.2 billion acquisition by Craig McCaw in a deal completed last May. The revamped ICO concept was enhanced to provide more data relay capability over the original focus of providing cellular telephone service.

Spaceflight Now will be your source for comprehensive live coverage of this Atlas mission with a running commentary of the countdown and launch. Our coverage will originate from the vantage point of Lockheed Martin's new Atlas 5 Space Operations Center -- a state-of-the-art facility under construction at Cape Canaveral's Complex 41. The ASOC will serve as the launch control center for the next generation Atlas 5 rocket, as well as Atlas 2 and 3 rockets starting later this year.