BY JUSTIN RAY

Follow the countdown and launch of the U.S. Air Force Titan 4B rocket and the Defense Support Program-21 satellite. Reload this page for the very latest on the mission.

MONDAY, AUGUST 6, 2001
1445 GMT (10:45 a.m. EDT)

SPACECRAFT SEPARATION! The U.S. Air Force has announced the Defense Support Program-21 missile warning satellite successfully arrived into its proper orbit today following a near-seven-hour launch. "The satellite is right were it is supposed to be," spokesman Lt. Warren Comer said. "We are good to go."

The $716 million mission began right on time at 3:28 a.m. EDT (0728 GMT) when the Lockheed Martin-built Titan 4B rocket lifted off from Complex 40 at Cape Canaveral Air Force Station, Florida. About nine minutes later, the satellite atop the Boeing-made Inertial Upper Stage kick motor were released into a low-Earth orbit. Over the course of the last six hours, the solid-fueled IUS fired its two stages to deliver the DSP spacecraft to a 22,000 mile orbit.

Air Force controllers will test the new DSP spacecraft -- the 21st launched in the past 30 years -- during the next month before placing it into service to replace an aging sister-satellite. Officials will not disclose which DSP is being replaced due to the classified nature of the spy satellites. The Pentagon operates a constellation of DSP satellites to detect missile launches and nuclear explosions anywhere in the world, providing early warning to the U.S. and its allies.

The next Titan 4 launch is slated for late-September from Vandenberg Air Force Base in California with a classified payload. Cape Canaveral's next Titan 4 is scheduled for no sooner than late-December to launch another Milstar military communications satellite.

1430 GMT (10:30 a.m. EDT)

The second burn of the IUS and spacecraft separation should have occurred by this time. However, we are still awaiting confirmation of these events by the Air Force.

0928 GMT (5:28 a.m. EDT)

T+plus 2 hours. Officials report the first firing of the Boeing-built Inertial Upper Stage has gone according to plan. The stage and attached DSP-21 satellite are now coasting up to the high point of its current egg-shaped orbit. Once at apogee about 6.5-hours into flight, the IUS second stage burn will occur.

0738 GMT (3:38 a.m. EDT)

T+plus 10 minutes. The Inertial Upper Stage with the Defense Support Program-21 satellite aboard is now beginning a coast that will continue until T+plus 1 hour, 13 minutes and 29 seconds into flight. At that time, the first stage of the solid-fueled IUS will be ignited to begin DSP's journey from low-Earth orbit to geostationary altitude 22,300 miles high. See our launch timeline for details on events to occur during this near-seven-hour flight.

We will pause of coverage now and report back with details thoughout the day as they become available from the U.S. Air Force. Spacecraft separation to complete the launch will not occur until 6 hours, 55 minutes after liftoff.

0737 GMT (3:37 a.m. EDT)

T+plus 9 minutes, 20 seconds. The Titan 4 rocket's second stage has shut down. The spent stage has separated from the Inertial Upper Stage.

0736 GMT (3:36 a.m. EDT)

T+plus 8 minutes, 30 seconds. Second stage engine shutdown systems enabled.

0736 GMT (3:36 a.m. EDT)

T+plus 8 minutes. About a minute left in the second stage burn. No problems reported in the Titan 4B rocket's climb to space.

0735 GMT (3:35 a.m. EDT)

T+plus 7 minutes. The second stage continues to perform as expected. The engine produces just over 100,000 pounds of thrust.

0734 GMT (3:34 a.m. EDT)

T+plus 6 minutes. Altitude 98 miles, downrange distance 340 miles

0733 GMT (3:33 a.m. EDT)

T+plus 5 minutes, 30 seconds. First stage has completed its job and the spent stage has dropped away to fall into the Atlantic Ocean. The second stage liquid-fueled engine has now ignited.

0733 GMT (3:33 a.m. EDT)

T+plus 5 minutes. First stage engine shutdown systems enabled. Coming up on engine cutoff in 25 seconds.

0731 GMT (3:31 a.m. EDT)

T+plus 3 minutes, 45 seconds. The Air Force confirms separation of the payload fairing enclosing the DSP spacecraft atop the Titan 4B rocket. First stage continues to fire.

0730 GMT (3:30 a.m. EDT)

T+plus 2 minutes, 45 seconds. The twin solid rocket boosters have burned out and separated as planned.

0730 GMT (3:30 a.m. EDT)

T+plus 2 minutes, 20 seconds. First stage main engine start. The liquid-fueled engine package up and burning to produce about 550,000 pounds of thrust.

0729 GMT (3:29 a.m. EDT)

T+plus 90 seconds. A good burn of the solid rocket boosters still reported. They will fire for another minute.

0729 GMT (3:29 a.m. EDT)

T+plus 60 seconds. A smooth flight reported so far.

0728 GMT (3:28 a.m. EDT)

T+plus 15 seconds. Pitch and roll programs are underway.

0728 GMT (3:28 a.m. EDT)

LIFTOFF! Liftoff of the Air Force Titan 4B rocket with America's newest Defense Support Program missile-warning spacecraft. And the vehicle has cleared the tower.

0727 GMT (3:27 a.m. EDT)

T-minus 35 seconds. Guidance system switching to flight mode.

0726 GMT (3:26 a.m. EDT)

T-minus 90 seconds. The Inertial Upper Stage will be switching to flight mode in the next few seconds.

0726 GMT (3:26 a.m. EDT)

T-minus 2 minutes, 30 seconds. The Range recorders are running.

0725 GMT (3:25 a.m. EDT)

T-minus 3 minutes. At liftoff, the Titan 4B will be powered by the two solid rocket motors, each producing 1.7 million pounds of thrust. Once the launch tower is cleared, the vehicle will perform a roll maneuver for positioning on the 93 degree flight azimuth for this launch. Titan will head eastward away from Cape Canaveral, ultimately sending its Defense Support Program-21 satellite payload into geostationary orbit.

0724 GMT (3:24 a.m. EDT)

T-minus 4 minutes. The Boeing-built Inertial Upper Stage is switching to internal power. The two-stage IUS will propel the DSP satellite from a low-Earth orbit to geostationary orbit.

0723 GMT (3:23 a.m. EDT)

T-minus 4 minutes, 30 seconds and counting. The countdown sequence is being controlled by the PAGE -- Programmable Aerospace Ground Equipment system.

0723 GMT (3:23 a.m. EDT)

T-minus 5 minutes and counting. The countdown is once again underway at Cape Canaveral for today's launch of the Titan 4B rocket. Liftoff is slated to occur at 3:28 a.m. EDT. All systems reported go!

0722 GMT (3:22 a.m. EDT)

The launch team is preparing to pick up the countdown in one minute. The Titan 4 rocket is now six minutes away from liftoff on its 32nd flight.

0718 GMT (3:18 a.m. EDT)

Five minutes left in this scheduled hold. Now 10 minutes away from launch. Readiness polls have been successfully completed. There are no technical problems to speak of and the weather is going to cooperate for an on-time liftoff.

0713 GMT (3:13 a.m. EDT)

T-minus 5 minutes and holding. The countdown clocks have entered a planned 10-minute built-in hold. During this period, final readiness checks will be performed by the launch team to ensure all systems are go for flight today. There are still no issues being worked by the launch time and liftoff remain set for 3:28 a.m. EDT.

0708 GMT (3:08 a.m. EDT)

All continues to go well in the countdown for this morning's Titan 4B launch. The core vehicle oxidizer tanks have been pressurized and the DSP satellite is being powered up.

0650 GMT (2:50 a.m. EDT)

The Air Force still reports everything is ready for today's 3:28 a.m. EDT liftoff. No problems are being worked as the countdown continues smoothly and on schedule for this second Titan 4B launch of 2001.

0650 GMT (2:50 a.m. EDT)

The Air Force still reports everything is ready for today's 3:28 a.m. EDT liftoff. No problems are being worked as the countdown continues smoothly and on schedule for this second Titan 4B launch of 2001.

0640 GMT (2:40 a.m. EDT)

Today's launch will mark the 32nd for a Titan 4 rocket dating back to 1989 and the tenth flight of the newer Titan 4B model. And this is the 22nd Titan 4 to launch from Cape Canaveral, the 12th from Complex 40.

0620 GMT (2:20 a.m. EDT)

All systems are reported "go" for an on-time launch of the Titan 4B rocket this morning. There are no problems being worked with the rocket, payload or Range at this point. Weather conditions are also looking good, the Air Force says.

The countdown for this particular rocket is less than action-packed compared to others we cover. Unlike most vehicles, this particular rocket configuration flying today does not require fueling during the final hours of the countdown. The Titan core stages were loaded with storable propellant days ago and the Inertial Upper Stage is solid-propellant.

The Titan 4/Centaur version does feature loading the upper stage with its super-cold liquid hydrogen and liquid oxygen just prior to liftoff.

So this morning's key activities include getting the launch pad cleared and secured, arming the rocket, preparing the DSP-21 satellite for flight and then the last-minute configuring the onboard guidance computers for liftoff.

The solid rocket motors are ignited at T-minus 0 seconds to begin the 6-hour, 55-minute flight.

0600 GMT (2:00 a.m. EDT)

Good morning and welcome to our live coverage of the Titan 4B rocket launching the Defense Support Program-21 spacecraft from Complex 40 at Cape Canaveral Air Force Station in Florida. Lockheed Martin, builder of the rocket, reports all systems are "go" for liftoff for 3:28 a.m. EDT (0728 GMT).

0100 GMT (9:00 p.m. EDT Sun.)

It is a rainy night at Cape Canaveral but Air Force meteorologists are optimistic the weather will gradually improve over the next several hours to give the Titan 4B rocket a reasonable shot at launching sometime during its four-hour window early Monday.

Launch Weather Officer Johnny Weems says although conditions are rather adverse currently, the thunderstorms should clear out by midnight and the clouds will erode during the overnight hours.

The official forecast gives a 70 percent chance of meeting the launch weather rules during the window of 3:28 to 7:28 a.m. EDT (0728-1128 GMT). The weather is expected to get better during the later portions of the window.

Weems also says weather shouldn't be a major obstacle in getting the mobile service tower retracted from around the rocket at the launch pad. There could be a slight chance of lightning, but that should be short lived.

Should the launch be delayed 24 hours for some reason, the forecast calls for an 80 percent chance of acceptable conditions.

Spaceflight Now will have complete live coverage of the final countdown and launch beginning at around 2 a.m. EDT.

SUNDAY, AUGUST 5, 2001
2018 GMT (4:18 p.m. EDT)

The countdown begins at this time for the launch of the Air Force Titan 4B rocket carrying the 21st Defense Support Program missile warning satellite.

Over the next 11 hours the launch team will ready the rocket, spacecraft and ground equipment for the planned 3:28 a.m. EDT liftoff Monday from Cape Canaveral's Complex 40.

The crucial milestone this evening will be retraction of the massive mobile service tower from around the Titan 4. Officials will receive a weather briefing at 10:33 p.m. in advance of the sliding doors being opened on the tower. The half-hour process to roll back the tower is slated to start at 11:58 p.m. EDT.

The weather at the Cape does not look overly promising. There are storms in the area courtesy of Tropical Storm Barry that is spinning in the Gulf of Mexico. But given the lengthy four-hour launch window extending to 7:28 a.m. EDT, officials hope there will be a shot at liftoff.

FRIDAY, AUGUST 3, 2001

Crews are gearing up for Monday's predawn attempt to launch a Lockheed Martin-built Titan 4B rocket with DSP-21 missile-warning satellite. The flight has been on hold due to concerns with the second stage guidance control unit.

Technicians were slated to replace the unit after it gave suspect data during pre-launch testing. However, engineers later determined the data seen was actually within tolerances for flight, proving the unit was healthy after all. The box was buttoned up and the vehicle has been cleared for launch.

Forecasters say there is a 70 percent chance of good weather during Monday's four-hour launch window of 3:28 to 7:28 a.m. EDT. Meteorologists will be watching rain and thick clouds for possible constraints against launch.

Should the launch be delayed for some reason there is a backup opportunity available on Tuesday before the Range is turned over to support Thursday's space shuttle liftoff.

TUESDAY, JULY 31, 2001

The U.S. Air Force has rescheduled the launch of the Titan 4B rocket with the Defense Support Program 21 missile-warning satellite for Monday, August 6. The launch window extends from 3:28 to 7:28 a.m. EDT (0728-1128 GMT). Officials have not yet released a progress report on repairs to the rocket's second stage guidance system. However, such an update is expected on Wednesday and we will post it here.

FRIDAY, JULY 27, 2001
1900 GMT (3:00 p.m. EDT)

Officials have made the decision to remove and replace the suspect guidance control unit on the second stage of the Titan 4B rocket. The unit failed routine checks yesterday and repeated testing today. A new launch date has not been established.

1710 GMT (1:10 p.m. EDT)

Launch of the Air Force Titan 4B rocket on a $716 million mission to place the Defense Support Program-21 missile warning satellite into space is being grounded while officials work to fix a problem with the vehicle's guidance system.

The liftoff had been scheduled for this morning but was scrubbed after pre-launch testing revealed a concern with the guidance control unit on the Titan rocket's core second stage. Technicians repeated the test this morning and found the same suspect data from the unit.

As a result the Air Force has postponed the launch indefinitely so more testing and analysis can be conducted. Officials will then determine how to correct the problem and set a new launch date.

1620 GMT (12:20 p.m. EDT)

The launch of a U.S. Air Force Titan 4 rocket is now on indefinite hold following yesterday's discovery of a problem with an onboard guidance control unit. We are awaiting further word from the Air Force on the exact reasons for the extended delay and when we might expect the launch to be rescheduled. We will post news to this page as soon as we have it.

0239 GMT (10:39 p.m. EDT Thurs.)

The U.S. Air Force says the launch was scrubbed after suspect data was received during routine checks of the guidance and navigation system on the rocket's second stage. Liftoff has been pushed back at least 24 hours to early Saturday. However, the delay could be longer.

More testing will be re-performed on the guidance control unit in the morning. Officials will then meet to determine how to resolve this glitch. Further information is expected by mid-day Friday.

If the Titan doesn't fly by Sunday then it will have to wait until after the scheduled Monday launch of a Delta 2 rocket from Cape Canaveral carrying NASA's Genesis solar wind sample return spacecraft. The reason is both launches require tracking and safety services from the Air Force-control Eastern Range, which can only support one launch ever 24 hours.

The weather forecast for the weekend is favorable.

0212 GMT (10:12 p.m. EDT Thurs.)

SCRUB! The early morning launch of the Titan 4B rocket has been postponed. Details on what caused the delay and when the launch will be rescheduled hasn't been released by the Air Force yet. We'll update this page as soon as more information becomes available.

THURSDAY, JULY 26, 2001

America's most powerful unmanned rocket is ready to launch the next space sentry that will stand guard in orbit to spot enemy missile launches and nuclear explosions.

The $460 million Titan 4B rocket is slated for blastoff at 4:08 a.m. EDT on Friday from Complex 40 at Cape Canaveral Air Force Station in Florida carrying the $256 million Defense Support Program-21 satellite. The launch window extends for four hours.

"The Defense Support Program has been the cornerstone of our early warning for our nation for about 30 years. DSP-21 is going to be the continuation of this legacy, continuing the tradition," said Col. Charles Cornell, the deputy system program director of the Air Force's Space Based Infrared Systems Directorate.

There is a constellation of DSP satellites in space to give the U.S. and its allies early notice of enemy missile and space-based launches and nuclear detonations.

The spacecraft carry a sophisticated infrared telescope that see the heat from missile and booster exhaust plumes against the Earth's background. They are parked in geostationary orbit, fixed over one region of the world: Europe, Asia or the West.

The first DSP satellite was launched 30 years ago to monitor the Soviet Union and China for land-launched missiles and the waters around the U.S. for submarine ballistic missiles.

The 33-foot tall satellites, built by TRW, were used extensively during Desert Storm, expanding their utility by detecting missiles flown within the region of a conflict instead of the intercontinental ballistic missiles in which the satellites were designed to spot.

Throughout the Persian Gulf War, the DSP network detected the launches of Iraqi Scud missiles and warned civilians and troops in Israel and Saudi Arabia.

The launch countdown for this second Titan 4 flight of 2001 begins at 4:58 p.m. EDT today. Retraction of the launch pad's massive mobile service gantry from around the Lockheed Martin-built rocket is scheduled for about 12:30 a.m. EDT Friday.

"The entire team is positive we are ready to go. We look forward to picking up the count," said Lt. Col. Dave Jones, the Air Force launch director.

The weather forecast calls for an 80 percent chance of acceptable conditions. There's only a slight concern for coastal rainshowers, Launch Weather Officer Johnny Weems said.

When liftoff occurs the two Alliant Techsystems-built solid rocket boosters strapped to either side of the Titan 4B will be ignited, producing 3.4 million pounds of thrust to propel the vehicle off the planet.

Just over two minutes into flight the Titan's core vehicle will be started as the SRBs burn out and separate. The two liquid-fueled stages will fire to place the Boeing-built Inertial Upper Stage kick motor and DSP-21 satellite into a low-Earth orbit within the first nine minutes of launch.

The IUS and DSP duo will then coast for an hour before the first stage of the solid-fueled upper stage is ignited to begin the journey toward geostationary orbit 22,300 miles up.

Following the IUS' first burn, an extended cruise starts that will last until about 6 1/2 hours into the launch. Then the spent IUS first stage will be jettisoned and the second stage will fire to deliver DSP into its intended circular orbit above the Earth's equator. Spacecraft separation from the upper stage to signify completion of the launch is expected 6 hours, 54 minutes and 51 seconds after liftoff.

Spaceflight Now will provide complete live coverage on this page of the final countdown and launch of the Titan 4B rocket.