BY JUSTIN RAY

Follow the countdown and launch of a Boeing Delta 2 rocket with NASA's Microwave Anisotropy Probe (MAP). Reload this page for the very latest on the mission.

SATURDAY, JUNE 30, 2001

A NASA space probe designed to map the afterglow of the Big Bang -- the fossil light from the creation of the universe 14 billion years ago -- was launched into space on Saturday atop a Boeing Delta 2 rocket. Read our full launch story.

2121 GMT (5:21 p.m. EDT)

T+plus 95 minutes. "We are very happy," NASA Launch Manager Chuck Dovale says. The MAP spacecraft successfully separated from the Delta 2 rocket and its solar arrays have been deployed.

Check back later tonight for a full wrap-up story, some pictures and a movie clip.

2119 GMT (5:19 p.m. EDT)

T+plus 93 minutes. The power-generating solar arrays on the MAP probe has been successfully deployed!

2117 GMT (5:17 p.m. EDT)

T+plus 91 minutes. NASA reports the initial health check of the MAP spacecraft is good. The satellite is in fine shape. That is the word through the Tracking and Data Relay Satellite System.

2115 GMT (5:15 p.m. EDT)

T+plus 89 minutes. The MAP spacecraft team reports its data shows a clean separation between the satellite and spent third stage.

2114 GMT (5:14 p.m. EDT)

T+plus 87 minutes, 50 seconds. SPACECRAFT SEPARATION! NASA's Microwave Anisotropy Probe has been released from the Delta rocket's third stage following launch today from Cape Canaveral. That confirmation has come via a NASA orbiting Tracking and Data Relay Satellite, which is in contact with MAP.

2113 GMT (5:13 p.m. EDT)

T+plus 86 minutes, 20 seconds. Officials are now awaiting confirmation of MAP's deployment from the third stage. They are working with other downrange stations to try and gain acquisition.

2112 GMT (5:12 p.m. EDT)

T+plus 85 minutes, 40 seconds. Engineers at the Cape have again lost live data. So they were unable to confirm spacecraft separation in real-time.

2111 GMT (5:11 p.m. EDT)

T+plus 84 minutes, 20 seconds. The Vandenberg Air Force Base tracking station in California should be picking up the rocket's signal. The vehicle has passed out of range of the Hawaii station.

2108 GMT (5:08 p.m. EDT)

T+plus 82 minutes. The vehicle is now coasting for a few minutes before the MAP spacecraft will be released from the third stage of the Delta 2 rocket.

2107 GMT (5:07 p.m. EDT)

T+plus 81 minutes. TECO. The third stage burn out confirmed, completing the powered phase of today's launch.

2106 GMT (5:06 p.m. EDT)

T+plus 80 minutes, 20 seconds. Good chamber pressure reported on the third stage as its burn continues.

2106 GMT (5:06 p.m. EDT)

T+plus 79 minutes, 40 seconds. Stage separation has been confirmed and the solid-fueled third stage has ignited.

2105 GMT (5:05 p.m. EDT)

T+plus 79 minutes. Spin rockets have fired to spin-up the vehicle like a top.

2105 GMT (5:05 p.m. EDT)

T+plus 78 minutes, 20 seconds. The second stage did restart for its planned four-second burn. There wasn't any data from the stage but telemetry from the third stage confirmed the burn.

2104 GMT (5:04 p.m. EDT)

T+plus 77 minutes, 45 seconds. Second stage restart should have occurred by now. However, engineers are still awaiting live data from Hawaii.

2102 GMT (5:02 p.m. EDT)

T+plus 76 minutes. Just under two minutes away from the planned restart of the second stage. The engine will fire for just four seconds, to be followed by spin up of the vehicle and separation between the second and third stages.

2100 GMT (5:00 p.m. EDT)

T+plus 74 minutes. We are currently awaiting aquisition of the rocket's signal by a tracking station in Hawaii.

2057 GMT (4:57 p.m. EDT)

T+plus 71 minutes. Launch officials are taking their seats again in the Mission Directors Center as activities are about to resume. The rocket is currently above the central Pacific Ocean as it nears restart of the second stage engine. The ignition is expected to occur in about six minutes.

2007 GMT (4:07 p.m. EDT)

T+plus 21 minutes. The Delta 2 continues in its quiet coast period. It is out of range from any ground station until it arrives in the skies over Hawaii after traveling around the globe. We will pause our coverage for the moment and will resume once we get closer to restart of the second stage, which is expected at T+plus 77 minutes, 43 seconds.

2003 GMT (4:03 p.m. EDT)

T+plus 17 minutes. The official liftoff time was 3:46:46.183 p.m. EDT.

2002 GMT (4:02 p.m. EDT)

T+plus 16 minutes. The parking orbit achieved following cutoff of the second stage is right as predicted with an apogee of 110.228 miles, perigee of 89.925 miles and inclination of 28.75 degrees to the equator. The stage did burn about six seconds longer than planned, and NASA says that was done automatically to ensure the vehicle reached the proper parking orbit.

1958 GMT (3:58 p.m. EDT)

T+plus 12 minutes. The Delta rocket is now in a coast period that will last more than an hour before the second stage restarts at T+plus 77 minutes, 43 seconds.

1958 GMT (3:58 p.m. EDT)

T+plus 11 minutes, 50 seconds. SECO 1. Confirmation that the second stage engine has shut down as planned. The Delta 2 rocket with MAP have arrive in a preliminary orbit around Earth.

1957 GMT (3:57 p.m. EDT)

T+plus 11 minutes. Coming up on cutoff of the second stage.

1956 GMT (3:56 p.m. EDT)

T+plus 9 minutes, 50 seconds. Telemetry is clearing up now. The rocket is reported stable with a good burn of second stage engine continuing. Altitude is 96 miles, downrange distance 1,230 miles, velocity of 15,000 mph.

1955 GMT (3:55 p.m. EDT)

T+plus 8 minutes, 30 seconds. The Cape has lost data from the vehicle. It appears the Antigua station is having problem locking on to the Delta 2. This is not necessarily an indication of a vehicle problem, but actually a ground problem.

1954 GMT (3:54 p.m. EDT)

T+plus 7 minutes, 30 seconds. Data from the rocket now being received from the downrange Antigua tracking station.

1953 GMT (3:53 p.m. EDT)

T+plus 6 minutes, 35 seconds. Second stage engine continues to burn as planned. Altitude 85 miles, downrange distance 585 miles, velocity over 12,000 mph.

1952 GMT (3:52 p.m. EDT)

T+plus 5 minutes, 15 seconds. The protective payload fairing enclosing the MAP satellite atop the rocket has separated with no recontact detected.

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

T+plus 4 minutes, 42 seconds. Second stage engine ignition has been confirmed.

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

T+plus 4 minutes, 35 seconds. MECO. The first stage main engine cutoff confirmed, the stage has been jettisoned.

1950 GMT (3:50 p.m. EDT)

T+plus 4 minutes. Vehicle continues on the proper trajectory. Coming up on staging.

1949 GMT (3:49 p.m. EDT)

T+plus 2 minutes, 45 seconds. The rocket continues its trek to orbit on the power of the first stage liquid-fueled main engine. The RS-27A powerplant and twin vernier steering thrusters continue to burn normally.

1948 GMT (3:48 p.m. EDT)

T+plus 1 minute, 30 seconds. Altitude 15 miles, downrange distance 31 minutes, velocity of 2,500 miles per hour.

1948 GMT (3:48 p.m. EDT)

T+plus 1 minute, 5 seconds. All four ground-start solid rocket boosters have burned out and separated.

1947 GMT (3:47 p.m. EDT)

T+plus 45 seconds. Smooth flight so far. Vehicle has passed transonic region.

1947 GMT (3:47 p.m. EDT)

T+plus 30 seconds. Solid rocket motors have passed period of maximum thrust.

1947 GMT (3:47 p.m. EDT)

T+plus 20 seconds. Vehicle has rolled to the proper trajectory.

1946:46 GMT (3:46:46 p.m. EDT)

LIFTOFF! Liftoff of NASA's MAP spacecraft to measure the afterglow of the Big Bang -- the fossil light from the creation of the universe. And the Boeing Delta 2 rocket has cleared the tower.

1946:16 GMT (3:46:16 p.m. EDT)

T-minus 30 seconds. Hydraulics and electronics reported go.

The launch ignition sequence will begin at T-minus 2 seconds when a Boeing engineer triggers the engine start switch. The process begins with ignition of the two vernier engines and first stage main engine start. The six ground-start solid rocket motors then light at T-0 for liftoff.

At launch, the rocket will produce a half-million pounds of thrust and embark on a 95-degree flight azimuth, heading east away from Central Florida.

1945:46 GMT (3:45:46 p.m. EDT)

T-minus 1 minute. The Range has given its final clear-to-launch. The Delta 2 rocket's second stage hydraulic pump has gone to internal power after its pressures were verified acceptable.

1945:16 GMT (3:45:16 p.m. EDT)

T-minus 90 seconds. At the telemetry receiving areas where data from the rocket will be transmitted, the data recording charts have gone to high speed as the liftoff nears.

1944:46 GMT (3:44:46 p.m. EDT)

T-minus 2 minutes. The first stage liquid oxygen vents are now being closed so the LOX tank can be pressurized for launch. Puffs of vapor from a relief valve on the rocket will be seen in the remainder of the countdown as the tank pressure stabilizes.

NASA's Microwave Anisotropy Probe has been declared "go" for launch today. The craft is running on internal power.

1943:46 GMT (3:43:46 p.m. EDT)

T-minus 3 minutes and counting. The safety destruct safe and arm devices are being armed.

1942:46 GMT (3:42:46 p.m. EDT)

T-minus 4 minutes and counting. Now in the final phase of the countdown as Delta launch vehicle systems begin transferring to internal power. All systems are now ready for launch of the Boeing Delta 2 rocket with NASA's MAP probe at 3:46:46 p.m. EDT from pad 17B at Cape Canaveral Air Force Station in Florida.

1941:46 GMT (3:41:46 p.m. EDT)

Now five minutes from launch! All parties reported "ready" to resume the countdown for an on-time launch. The team has received a final briefing of procedures. And weather conditions are "go" for liftoff.

1941 GMT (3:41 p.m. EDT)

The latest computer program based upon upper level winds have been uploaded to the Delta 2 rocket's guidance computer. The information tells the computer what wind conditions to expect during the climb to orbit today.

1940 GMT (3:40 p.m. EDT)

The trickle charge to the MAP spacecraft atop the Delta rocket is stopping at this point, and the satellite is switching to internal power for flight.

1939 GMT (3:39 p.m. EDT)

Boeing Mission Director Joy Bryant has polled senior officials with no problems announced.

1938 GMT (3:38 p.m. EDT)

The launch team has been polled by Boeing Launch Conductor George Stout in the "soft blockhouse" with no problems reported.

1937 GMT (3:37 p.m. EDT)

NASA Launch Manager Chuck Dovale has polled his team and verified the space agency is ready to proceed for liftoff of MAP.

1936 GMT (3:36 p.m. EDT)

Now 10 minutes away from the scheduled launch time.

1933 GMT (3:33 p.m. EDT)

At present there are no technical problems being reported. There are a series of polls of the various launch team members still to come before resuming the countdown, however.

1932 GMT (3:32 p.m. EDT)

T-minus 4 minutes and holding. The countdown has entered the final planned hold point for today's launch attempt. During this planned 10-minute, 46-second hold, officials will poll the various team members behind the scenes, in the "soft blockhouse", Range Operations Control Center and Mission Directors Center.

1930 GMT (3:30 p.m. EDT)

Boeing and NASA has concurred that the second stage yaw steering issue detected earlier was simply noisy data and not a problem with the rocket.

Also, some telemetry dropouts between the MAP spacecraft and Goddard Space Flight Center has been noted. But that is not a constraint against liftoff.

1928 GMT (3:28 p.m. EDT)

The first stage fuel tank vent is being closed and the tank is being pressurized for launch. And the third stage and spacecraft safe and arm devices are being armed.

1926 GMT (3:26 p.m. EDT)

T-minus 10 minutes and counting. The countdown is heading to T-minus 4 minutes for a 10-minute, 46-second planned hold. Liftoff the Boeing Delta 2 rocket from Cape Canaveral Air Force Station is still slated to occur at 3:46:46 p.m. EDT.

For this launch, the Boeing model 7425-10 Delta 2 rocket is being used. The expendable launch vehicle consists of three stages, four strap-on solid rocket boosters and a 10-foot diameter composite payload fairing. It marks the first time a Delta 2 with four solids has flown with a 10-foot nose cone and a third stage. The rocket stands 126 feet tall. See the rocket fact sheet for more.

1923 GMT (3:23 p.m. EDT)

Inhibited checks are now under way of the Range Safety command destruct receivers that would be used in destroying the Delta rocket should a problem arise during the launch.

1920 GMT (3:20 p.m. EDT)

We are still awaiting word on the second stage engine steering tests. Engineers are working to determine if the noisy data seen during the first check was a problem with the steering actuator or just an insignificant glitch.

1916 GMT (3:16 p.m. EDT)

T-minus 20 minutes and counting. The countdown is running again. Clocks will go down to T-minus 4 minutes when the final hold is planned.

The Range reported there were some boats found in the launch danger area off the coast of Cape Canaveral. But they have just been cleared.

Also, the repeated second stage steering checks have been completed.

1915 GMT (3:15 p.m. EDT)

The launch team has been polled by Boeing Launch Conductor George Stout for a "go" to proceed with the countdown. No problems were reported. Clocks are due to resume at 3:16 p.m.

1912 GMT (3:12 p.m. EDT)

The launch team is re-performing the second stage engine steering checks because "noisy" data was receiving during the first test a short time ago. Officials want to ensure there is no problem with the vehicle.

1906 GMT (3:06 p.m. EDT)

Now half-way through this scheduled 20-minute hold in the countdown.

Launch Weather Officer Johnny Weems is sticking with a 60 percent chance of acceptable conditions for liftoff today. The weather team is watching an area of rainshowers and thunderstorms directly to west of Cape Canaveral over the Orlando Executive Airport about 30 miles away. Although the storms themselves will remain over Orlando and move to the west, the anvil clouds, or tops of the storms, are expected to move back toward the coast over the next hour because high-altitude winds above 35,000 feet at blowing to the east. At the opening of the launch window at 3:46:46 p.m., Weems says the conditions should be acceptable for liftoff. But by the end of the 12-minute window, the anvils could be within 10 miles of pad, which would violate launch weather rules.

1856 GMT (2:56 p.m. EDT)

T-minus 20 minutes and holding. The countdown has entered a planned 20-minute built-in hold. This pause is designed to give the launch team a chance to work any problems or catch up on activities that might be running behind schedule. At this point there are no technical issues being reported, the Range is clear and the weather conditions are acceptable.

Engineers have completed gimbal checks of the nozzles on the first stage main engine and twin vernier engines and second stage engine. This test is performed to ensure the engines will be able to steer the rocket during launch.

1848 GMT (2:48 p.m. EDT)

The "slew" or steering checks of the first and second stage engines are being performed at this time. And in the next few minutes RF link tests between the Range and rocket are scheduled.

1846 GMT (2:46 p.m. EDT)

The Delta rocket is fully fueled for its scheduled liftoff 60 minutes from now. The vehicle's first stage was loaded with RP-1 kerosene fuel early this morning and liquid oxygen over the past hour. The second stage was loaded with its storable nitrogen tetroxide and Aerozine 50 fuels on Thursday; and the third stage and strap-on booster rockets are solid-propellant.

The countdown currently stands at T-minus 30 minutes. There is a 20-minute hold upcoming at T-minus 20 minutes, then a 10-minute hold at T-minus 4 minutes.

1829 GMT (2:29 p.m. EDT)

The Delta 2 rocket's first stage liquid oxygen tank has been topped off at 100 percent. The tank will be replenished through the remainder of the countdown to replace the liquid oxygen that naturally boils away. It took 26 minutes, 39 seconds to load the LOX tank today, with the tanking completed at 2:28:50 p.m. EDT.

1822 GMT (2:22 p.m. EDT)

Now 20 minutes into the liquid oxygen tanking. The "rapid load" phase of filling the tank will continue over the next couple of minutes to the 95-percent level before the slower "fine load" begins to reach the 99-percent mark, which is then followed by topping off the tank to 100 percent.

1816 GMT (2:16 p.m. EDT)

Liftoff of the Delta 2 rocket with MAP is now 90 minutes away. There are no technical problems being worked by the launch team, the weather is currently within limits, upper level winds are acceptable, the Range is clear and the countdown continues on schedule for liftoff at 3:46:46 p.m. EDT (1946:46 GMT).

1810 GMT (2:10 p.m. EDT)

The Range reports the restricted launch danger area off the coast of Cape Canaveral is currently clear of any boats. There had been concern going into today's countdown that boats intruding into the area could be a problem today since it is the weekend and liftoff is occurring in the afternoon.

1807 GMT (2:07 p.m. EDT)

Now 5 minutes into this approximate 25-minute tanking process. The normal layer of thin ice and frost is forming on the bottom half of the Delta 2 rocket's first stage where the liquid oxygen tank is located.

1802 GMT (2:02 p.m. EDT)

Super-cold liquid oxygen, chilled to Minus-298 degrees F, is now flowing from a storage tank at pad 17B, through plumbing and into the bottom of the Boeing Delta 2 rocket. The LOX will be guzzled by the first stage main engine along with RP-1 kerosene loaded aboard the vehicle early this morning.

1756 GMT (1:56 p.m. EDT)

T-minus 80 minutes and counting. Preparations are now beginning for cryogenic tanking. The launch team is verifying valves are in the correct positions before liquid oxygen begins flowing.

1753 GMT (1:53 p.m. EDT)

Boeing Mission Director Joy Bryant has performed her poll and then gave approval to begin liquid oxygen loading, which is expected to commence in about 8 minutes.

1750 GMT (1:50 p.m. EDT)

NASA Launch Manager Chuck Dovale has just polled his team for a "go" to begin loading liquid oxygen into the Delta rocket's first stage, expected to commence in about 11 minutes. No problems were reported. Dovale said there are no issues being worked with the rocket or Range.

1746 GMT (1:46 p.m. EDT)

Launch Weather Officer Johnny Weems just gave an update to officials on current conditions and the forecast. Air Force meteorologists are continuing to watch thunderstorms around Central Florida, specifically the clouds associated with the storms that could drift back toward Cape Canaveral.

At this point all the weather criteria is "go" for launch, but Weems is sticking with only a 60 percent chance of acceptable conditions at the 3:46 p.m. EDT liftoff time. The percentage is not better because of uncertainty with the clouds in the region and where they might move over the next couple of hours.

The launch time forecast calls for some scattered low-level clouds, broken upper level clouds, southeasterly winds 10 to 15 knots, a temperature of 87 degrees and a slight chance of storms within 10 miles.

1730 GMT (1:30 p.m. EDT)

The MAP spacecraft arrived in Florida on April 20 from NASA's Goddard Space Flight Center in Greenbelt, Md. It was taken to the Spacecraft and Encapsulation Facility-2 (SAEF-2) in Kennedy Space Center's Industrial Area for a series of final testing, fueling and attachment to the third stage of the Delta rocket.

Stacking of the Delta 2 at Cape Canaveral Air Force Station's launch pad 17B began on May 24 when the first stage was erected. The four solid rocket motors were added on May 25. The second stage was hoisted into the tower and mated to the vehicle on May 29.

The combined MAP/third stage was moved to the launch pad on June 19 to join the rest of the Delta 2. The protective nose cone was installed around MAP on June 26.

1700 GMT (1:00 p.m. EDT)

The Air Force has verified there are no Collision Avoidance periods, or COLAs, that would prohibit liftoff during any portion of today's 12-minute launch window. COLAs are periods when a rocket can't be launched because it would pass too close to an object already orbiting Earth.

1646 GMT (12:46 p.m. EDT)

T-minus 150 minutes and counting. The Terminal Countdown has begun for the launch of the Boeing Delta 2 rocket and NASA's Microwave Anisotropy Probe. Over the next three hours, the launch team will ready the three-stage rocket, payload and ground support systems for the planned 3:46:46 p.m. EDT (1946:46 GMT) liftoff from pad 17B at Cape Canaveral Air Force Station in Florida.

With the countdown underway, the Complex 17 area will be cleared of workers as a safety precaution. A warning horn will be sounded at the seaside complex to alert personnel to depart and head back to road blocks.

Upcoming in the next few minutes, launch team members in the Delta Operations Building, or "soft blockhouse", located about eight miles west of the pad will oversee the pressurization of helium and nitrogen storage tanks inside the rocket's first and second stages, along with the second stage fuel and oxidizer tanks. In addition, the Delta's onboard guidance computer -- called the Redundant Inertial Flight Control Assembly or RIFCA -- will be turned on and configured for the mission.

The local weather conditions are currently acceptable. There are some thunderstorms firing up to the west, just as expected, but the launch team has been told that meteorologists don't expect the storms to be a problem.

1546 GMT (11:46 a.m. EDT)

T-minus 150 minutes and holding. Clocks have entered a planned 60-minute pause in advance of starting the Terminal Count at 12:46 p.m. EDT.

1345 GMT (9:45 a.m. EDT)

The 12-story mobile service tower enclosing the Boeing Delta 2 rocket at Cape Canaveral's pad 17B has been retracted as final hours tick down for launch at 3:46:46 p.m. EDT (1946:46 GMT) today.

The metal cocoon-like structure is used to assemble the Delta 2 on the seaside pad, as well as providing access for workers and shielding the vehicle from the weather. Rollback of the tower is a major milestone on the road to prepare for launch.

Workers will now get the tower secured into its launch position and configure the pad for liftoff. The Terminal Countdown remains scheduled to begin at 12:46 p.m. EDT.

Earlier this morning the launch team loaded the rocket's first stage with RP-1 fuel as planned.

The weather forecast remains the same with a 60 percent chance of acceptable conditions.

1310 GMT (9:10 a.m. EDT)

It is a beautiful morning here in Central Florida as preparations continue for today's launch of Delta 286 with NASA' MAP spacecraft. The weather looks good right now, but the key will be a little later in the day when thunderstorms are expected to begin developing.

At launch pad 17B workers are getting ready to roll the mobile service tower away from the Boeing-built rocket. That process is due to start later this hour.

Some unplanned work on the rocket was performed last night, but without impact the launch. A device associated with sending signal to start second stage attitude control system had to be removed and replaced. The decision to swap out the hardware was made after testing reveal a concern on Friday afternoon.

FRIDAY, JUNE 29, 2001
2350 GMT (7:50 p.m. EDT)

A Boeing Delta 2 rocket is ready to launch NASA's Microwave Anisotropy Probe on Saturday to measure the afterglow from the universe's creation 14 billion years ago, but officials will be keeping a close eye on thunderstorms and pesky boats intruding the restricted waters around Cape Canaveral that could delay the liftoff.

Launch is planned for 3:46:46 p.m. EDT (1946:46 GMT), the opening of a 12-minute window extending to 3:58:46 p.m. EDT (1958:46 GMT).

Air Force meteorologists are giving a 60 percent chance weather conditions will allow liftoff to occur. The main concern will be typical summertime thunderstorms over Central Florida that are experienced almost daily.

"Having launch windows in the middle of the afternoon at the end of June/early July is not exactly ideal conditions weather-wise around here. Tomorrow won't be any exception," Launch Weather Officer Joel Tumbiolo said.

The forecast on Saturday calls for thunderstorms to develop a few miles west of the launch pad and then move inland. Storms directly over launch pad 17B isn't expected. But the tops of the storms, called anvil clouds, can drift back toward the east. Launch rules state the clouds must be at least 10 miles away from the pad for the Delta 2 rocket to be cleared for liftoff.

Tumbiolo said the same conditions are expected for the next several days.

The launch time is determined by the MAP payload, which will set sail on a three-month voyage to reach a point one million miles from Earth where it will orbit to map the cosmic background radiation across the entire sky.

The other potential hurdle on Saturday will be keeping the restricted launch hazard area in the Atlantic Ocean clear of boats (see map). After all, it is the weekend and the launch will occur during the afternoon when pleasure boaters will be out on the waters.

The usual military support for surveying the area and clearing any wayward vessels has been beefed up, and planes from the commercial AirScan company are being used.

"We have a Coast Guard cutter and we have added additional Coast Guard cutter. So we will have two boats in the area. We have two Jolly 1 and 2 helicopter systems, as well as two plane systems that will be doing the search and identification in the area," Boeing Mission Director Joy Bryant explained. "It is a concern due to a fish tournament this Saturday. So we do have some concerns there, as well as the time of day -- (the fisherman) will be returning to port."

The Air Force, which runs the Range and is responsible for keeping the danger areas cleared for safety reasons, stepped up its information campaign last year to inform the public about scheduled launches because intruding boats were delaying so many rocket flights.

The MAP probe has until July 5 to launch, or else wait until July 16 when a four-day window opens. If the probe isn't off the ground by July 19, the launch will have to be delayed until the end of July. See our launch window chart. The craft will use a lunar flyby as a slingshot to get the final thrust toward its final destination a million miles from Earth, and so the launch must occur when the moon is in the right position.

"We are tied to the lunar cycle," said Elizabeth Citrin, the MAP project manager. "The six launch days we have now are very good in terms of the three phasing loops in getting the moon into position. There is a dropout where the moon's gravity would perturb our spacecraft too much. Then we move into the next block, which is four days. During that block we actually have five phasing loops because of the position of the moon when we launch, it takes a little longer for the moon to get into (the right) position. That pattern continues...every month we two blocks -- generally six days and four days."

The phasing loops are highly elliptical, egg-shaped orbits of Earth that will range from about 600 miles on the low end to 240,000 miles on the high end, Citrin said.

Launch day activities will get underway at 4:30 a.m. EDT with a weather briefing for officials. Preparations to retract the mobile service tower from around the Delta 2 rocket at launch pad 17B are due to begin at 5 a.m. The rocket's first stage will be loaded with RP-1 fuel, a highly refined kerosene, at 6 a.m. The fueling is being performed early instead of during the Terminal Countdown because of the threat of thunderstorms later in the morning, as well as to weight down the relatively light rocket that has only four solid rocket motors vs. the usual nine. The exact weight will give the vehicle more stability when it is exposed on the launch pad once the protective service tower is rolled back after 9 a.m.

Launch officials will take their positions on console at 11:30 a.m., and the countdown clock will pause for 60 minutes at the T-minus 150 minute mark at 11:46 a.m. The clocks are scheduled to begin ticking down at 12:46 p.m. EDT, signaling the start of the Terminal Countdown. The loading of cryogenic liquid oxygen into the first stage is expected to commence at 2:01 p.m. EDT.

Two built-in holds are planned during Terminal Count. The first will occur at T-minus 20 minutes for a duration of 20 minutes; the second happens at T-minus 4 minutes and should last 10 minutes, 46 seconds to synch up with the opening of the launch window at 3:46:46 p.m. EDT.

Watch this page throughout the day for updates and our live coverage during the Terminal Countdown and 85-minute flight of the Delta 2 rocket.

1450 GMT (10:50 a.m. EDT)

Senior officials held the Launch Readiness Review this morning. The meeting concluded with the decision to proceed with tomorrow's scheduled launch attempt. There are no significant problems being worked that would threaten an on-time liftoff.

Late last night the fueling of the rocket's second stage was completed. The work had been delayed due to unacceptable local weather conditions.

1400 GMT (10:00 a.m. EDT)

Launch Weather Officer Johnny Weems from the U.S. Air Force has issued his latest forecast for tomorrow's planned liftoff of the Delta 2 rocket carrying NASA's MAP spacecraft. Weems is sticking with a 60 percent chance the weather will allow launch to occur during the 12-minute window opening at 3:46:46 p.m. EDT.

"Forecast guidance continues to strengthen the low and upper level high pressure ridge axis across North Florida over the weekend. The general trend over the weekend will be late morning thunderstorms which will gradually move inland during the afternoon. Upper level winds will remain relatively light with anvils not moving far from parent storms. Greatest concern will be the effect the storms have on countdown activities during late morning/ early afternoon development near the east coast. After moving inland, proximity of anvils will become increasing concern."

The launch time conditions are predicted to include low-level clouds at 3,000 feet with 2-3/8ths sky coverage, upper-level clouds at 28,000 feet with 3-4/8ths sky coverage, visibility of 7 miles, southeasterly winds from 120 degrees at 10 to 12 knots, a temperature of 87 degrees F, relative humidity of 68 percent and a slight chance of storms within 10 miles.

Should the launch slip to Sunday or Monday, the forecast calls a 60 percent chance of meeting the weather rules each day.

THURSDAY, JUNE 28, 2001

The second stage of a Boeing Delta 2 rocket is being fueled at Cape Canaveral Air Force Station's launch pad 17B today. The fueling process was delayed until this afternoon due to bad weather at the Cape. The operation was expected to last until around midnight.

The stage uses Aerozine 50 propellant -- which is made of 50 percent unsymetrical dimethyl hydrazine and 50 percent hydrazine -- and nitrogen tetroxide oxidizer. The storable fuel is consumed by the stage's Aerojet AJ10-118K engine in two scheduled firings during launch.

The rocket's first stage will be loaded with a highly refined kerosene and super-cold liquid oxygen in the final hours before liftoff. The third stage is solid-fueled.

Also today the launch team held a countdown dress rehearsal for a final tune-up practice run before Saturday's big event.

Officials will hold the Launch Readiness Review on Friday to verify all systems are ready to proceed with the countdown.

Other activities on Friday include powering up the rocket, updating the vehicle's the guidance system with launch azimuth data, performing closeouts of the rocket and sealing the payload access port on the nose cone.

Liftoff remains scheduled for 3:46:46 p.m. EDT (1946:46 p.m. EDT) on Saturday. The weather forecast remains unchanged with a 60 percent chance of acceptable conditions.

WEDNESDAY, JUNE 27, 2001

Boeing's Delta 2 rocket is slated for launch Saturday to propel a NASA spacecraft on a journey to detect the afterglow of the Big Bang, which scientists hope will shed light on age-old questions about the content, shape, history and the ultimate fate of the universe.

The $145 million Microwave Anisotropy Probe is designed to paint a full-sky picture of the oldest light, looking back in time before there were any stars, galaxies or quasars. The spacecraft will orbit about one million miles from Earth at a position known as the second Lagrange (L2) point.

MAP's charter is to answer the questions: What happened during the first instant after the Big Bang? How did the Universe evolve into the complex patterns of galaxies that we see today? Will the Universe expand forever or will it collapse?

Liftoff from pad 17B at Cape Canaveral Air Force Station in Florida is scheduled for precisely 3:46:46 p.m. EDT, the opening of a 12-minute window.

Air Force weather forecasters are calling for a 60 percent chance of acceptable conditions for launch. The main threat will come in the form of thunderstorms and anvil clouds moving too close to the launch pad.

"Low and upper level high pressure ridge axis is gradually positioning itself across North Florida during the week. General trend will produce late morning thunderstorms which will gradually move inland during the afternoon. Upper level winds will remain relatively light with anvils not moving far from parent storms. Greatest concern will be the effect the storms have on countdown activities during late morning/early afternoon development near the east coast," Launch Weather Officer Johnny Weems said.

The launch time conditions are predicted to include low-level clouds at 3,000 feet with 2-3/8ths sky coverage, upper-level clouds at 28,000 feet with 1-2/8ths sky coverage, visibility of 7 miles, southeasterly winds from 120 degrees at 5 to 8 knots, a temperature of 87 degrees F, relative humidity of 68 percent and a slight chance of storms within 10 miles.

Should the launch slip to Sunday, the forecast is similar with a 60 percent chance of meeting the weather rules. The forecast worsens on Monday with only a 40 percent chance of good weather due to precipitation and the proximity of thunderstorms.

Launch pad crews installed the two-halves of the 10-foot diameter composite rocket nose cone around MAP on Tuesday. Officials held the Flight Readiness Review today. With no significant problems reported, officials gave technicians approval to load the rocket's second stage with storable propellant on Thursday as planned. Also Thursday the launch team will take part in the countdown dress rehearsal from 8 a.m. to 12 p.m.

Stay with Spaceflight Now for continuing updates leading up to Saturday's launch. And we will have comprehensive live coverage throughout the countdown and 85-minute flight of the Delta 2 rocket!