BY JUSTIN RAY

Follow the preparations and launch of the Orbital Sciences Pegasus rocket with NASA's SORCE spacecraft. Reload this page for the very latest on the mission.

Video coverage for subscribers only:
   VIDEO: WATCH ENTIRE 11-MINUTE LAUNCH OF PEGASUS QT or RV
   VIDEO: TAXI OF ORBITAL CARRIER AIRCRAFT TO RUNWAY QT or RV
   VIDEO: L-1011 CARRIER JET TAKES OFF FROM CAPE QT or RV
   VIDEO: T-38 DEPARTS THE KENNEDY SPACE CENTER QT or RV
   VIDEO: AERIAL INSPECTION BY T-38 CHASE PLANE QT or RV
   VIDEO: POST-LAUNCH COMMENTS BY NASA MANAGER QT or RV
   VIDEO: PRE-LAUNCH NEWS CONFERENCE QT or RV
   VIDEO: AN OVERVIEW OF THE SORCE PROJECT QT or RV
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SATURDAY, JANUARY 25, 2003

Cruising about 39,000 feet above the open waters of the Atlantic, an air-launched Pegasus rocket was dropped from the belly of a carrier jet Saturday afternoon to blast a science satellite into orbit to study the Sun's influence on Earth's environment. Read our full launch story.

2031 GMT (3:31 p.m. EST)

NASA Launch Manager Omar Baez confirms everything has gone successfully today.

This will conclude our live coverage of the SORCE launch. Check back later this afternoon for a collection of video clips from this mission and a full wrap-up story.

2027 GMT (3:27 p.m. EST)

The launch team is reporting that the orbit achieved today has a high point of 646 km, low point of 620 km and inclination of 40 degrees to the equator.

2025 GMT (3:25 p.m. EST)

T+plus 12 minutes. Contact has been established with the SORCE spacecraft following its launch into orbit today. All appears to have gone well.

2025 GMT (3:25 p.m. EST)

T+plus 11 minutes, 30 seconds. The third stage is performing a maneuver to move away from the SORCE spacecraft.

2024 GMT (3:24 p.m. EST)

T+plus 10 minutes, 56 seconds. SPACECRAFT SEPARATION! NASA's Solar Radiation and Climate Experiment satellite has been deployed from the Orbital Sciences Pegasus rocket's third stage to complete today's launch!

2023 GMT (3:23 p.m. EST)

T+plus 10 minutes. The vehicle has slewed around to the proper orientation for deployment of SORCE.

2022 GMT (3:22 p.m. EST)

T+plus 8 minutes, 55 seconds. The third stage has burned out, completing the powered phase of SORCE's launch. Orbit has been achieved! Coming up on payload deployment in about two minutes.

2022 GMT (3:22 p.m. EST)

T+plus 8 minutes, 25 seconds. Third stage continues to fire. Attitude is normal.

2021 GMT (3:21 p.m. EST)

T+plus 7 minutes, 47 seconds. The solid-fueled third stage motor of Pegasus is now firing, accelerating the SORCE spacecraft to its orbit.

2021 GMT (3:21 p.m. EST)

T+plus 7 minutes, 34 seconds. The spent second stage has separated. Standing by for ignition of the upper stage.

2020 GMT (3:20 p.m. EST)

T+plus 7 minutes. The vehicle is now reorienting in preparation for stage separation and third stage burn.

2019 GMT (3:19 p.m. EST)

T+plus 6 minutes. About 100 seconds from third stage ignition. Passing 500 km in altitude.

2018 GMT (3:18 p.m. EST)

T+plus 5 minutes. Attitude still nominal. Passing 400 km in altitude.

2017 GMT (3:17 p.m. EST)

T+plus 4 minutes. The rocket is passing 300 km in altitude. Third stage ignition is now calculated to occur at T+7 minutes, 41.7 seconds. The start time based upon the performance of the vehicle's first two stages.

2016 GMT (3:16 p.m. EST)

T+plus 3 minutes, 10 seconds. The Pegasus rocket is in a good attitude. No problems reported so far on the flight today.

2016 GMT (3:16 p.m. EST)

T+plus 2 minutes, 50 seconds. The solid-fueled second stage has burned out. The Pegasus rocket is now in a coast period for the next four and a half minutes or so. During this time the rocket will compute the performance of the flight thus far and adjust the third stage ignition time if necessary.

2015 GMT (3:15 p.m. EST)

T+plus 2 minute, 15 seconds. The two halves of the payload fairing enclosing the SORCE satellite on the end of the Pegasus rocket has been jettisoned. Second stage continues to burn.

2015 GMT (3:15 p.m. EST)

T+plus 1 minute, 40 seconds. The first stage has separated and ignition of the Pegasus' second stage has occurred.

2015 GMT (3:15 p.m. EST)

T+plus 1 minute, 20 seconds. The solid-fueled first stage has burned out. The vehicle is now in a ballistic coast for a few seconds before the spent stage is jettisoned and the second stage ignites.

2014 GMT (3:14 p.m. EST)

T+plus 70 seconds. Altitude 120,000 feet.

2014 GMT (3:14 p.m. EST)

T+plus 50 seconds. Stage pressure reported normal.

2014 GMT (3:14 p.m. EST)

T+plus 40 seconds. The Pegasus rocket is passing through maximum dynamic pressure. Attitude of the vehicle is reported normal.

2013 GMT (3:13 p.m. EST)

IGNITION. The Pegasus rocket has begun its mission to place NASA's SORCE spacecraft into orbit to study the Sun's influence on Earth!

2013 GMT (3:13 p.m. EST)

DROP. The Orbital Sciences Pegasus XL rocket has been released from the L-1011 aircraft.

2013 GMT (3:13 p.m. EST)

T-minus 30 seconds. The batteries for the first stage flight control fins have been activated, allowing the fins to undergo a sweep test prior to launch. The fins are used to steer the rocket during its initial climb to space.

With the batteries activated there is just 90 seconds to launch today or else an abort will be called. That is due to the limited life of the batteries.

In the final moments prior to release of Pegasus, the L-1011 carrier aircraft crew will oversee the last seconds of the countdown and flip the switch that will drop the three-stage vehicle, with the SORCE spacecraft aboard, from the belly of the jet.

2012 GMT (3:12 p.m. EST)

T-minus 1 minute and counting.

2012 GMT (3:12 p.m. EST)

T-minus 90 seconds. The carrier aircraft now achieving the proper launch heading.

2011 GMT (3:11 p.m. EST)

T-minus 2 minutes.

2010 GMT (3:10 p.m. EST)

T-minus 3 minutes. The transient power bus has gone internal and the rocket's guidance computer now in free inertial mode.

2009 GMT (3:09 p.m. EST)

T-minus 4 minutes and counting. The launch team now entering the final checklist for today's flight of the Pegasus rocket with NASA's SORCE spacecraft. Drop time now reset for 3:13:26 p.m. EST.

2009 GMT (3:09 p.m. EST)

The Pegasus rocket's avionics are now switching from power provided by the L-1011 to internal battery power with no problems reported.

2008 GMT (3:08 p.m. EST)

T-minus 5 minutes, 30 seconds and counting. The final launch readiness poll by NASA Launch Manager Omar Baez has been performed and all systems remain "go" for drop the Pegasus rocket.

2007 GMT (3:07 p.m. EST)

Based on the flight time of the carrier jet, the planned drop time has been adjusted to 3:13:30 p.m. EST. So the countdown has been reset.

2006 GMT (3:06 p.m. EST)

Checks of the flight termination system are being performed. The FTS would be used to destroy the Pegasus rocket should a problem arise during the launch.

2005 GMT (3:05 p.m. EST)

The SORCE spacecraft and the rocket's flight termination system are switching to internal power.

2004 GMT (3:04 p.m. EST)

The release mechanism has been armed. And the aircraft pilot reports the "arm" light is illuminated in the cockpit.

2003 GMT (3:03 p.m. EST)

The release mechanism that will drop the Pegasus rocket from the L-1011 carrier jet is now being armed. This hydraulic system involves four main hooks holding the Pegasus to the aircraft as well as a nose hook.

1955 GMT (2:55 p.m. EST)

The "P-turn" point is now occurring for the L-1011. The aircraft is banking to the right, heading northwesterly for the start of a loop to turn around and head back to the drop point.

1951 GMT (2:51 p.m. EST)

T-minus 23 minutes and counting. The carrier aircraft has passed by the planned drop point for the Pegasus rocket at an altitude of about 37,000 feet.

1947 GMT (2:47 p.m. EST)

The Stargazer carrier aircraft has completed the U-turn and is now headed westerly to the drop box for today's launch. The plane will actually fly through the box before making another looping turn to head back and drop the Pegasus. See a map of the flight path.

1944 GMT (2:44 p.m. EST)

T-minus 30 minutes and counting.

1934 GMT (2:34 p.m. EST)

A T-38 jet from Langley has just taken off from the Shuttle Landing Facility runway at Kennedy Space Center. The jet is headed to intercept the L-1011 to fly along side as the "chase plane" for today's launch. The T-38 has cameras aboard to record the Pegasus launch.

1929 GMT (2:29 p.m. EST)

T-minus 45 minutes and counting. The flight path of the L-1011 today takes the jet east away from the Cape. After reaching a point well off the coast, Stargazer then will make a U-turn to head west, back toward Florida, allowing the aircraft to fly through the predetermined drop box where the Pegasus rocket will be released, albeit traveling in the wrong direction. The pass through the box, however, allows the aircraft crew to verify weather conditions in the area.

After flying through the box, the aircraft will make another looping turn to head back for the box. About 90 seconds before the drop the flight crew will turn the L-1011 to the proper heading for launch.

See a map of the flight path.

1917 GMT (2:17 p.m. EST)

Right on time, the "Stargazer" carrier aircraft with the Orbital Sciences Pegasus XL rocket attached to its belly just took off from the Skid Strip at Cape Canaveral Air Force Station in Florida for today's launch to place NASA's SORCE spacecraft into orbit.

1916:45 GMT (2:16:45 p.m. EST)

Stargazer is in motion!

1914 GMT (2:14 p.m. EST)

After polling the ground launch team, Orbital Sciences has given the aircraft crew a "go" for takeoff pending clearance from the runway tower.

1910 GMT (2:10 p.m. EST)

Takeoff of the L-1011 is now being targeted for 2:17 p.m. EST for a drop of Pegasus 57 minutes later.

1908 GMT (2:08 p.m. EST)

NASA Launch Manager Omar Baez has given his approval for takeoff following a poll of the space agency team.

1859 GMT (1:59 p.m. EST)

The aircraft crew reports Stargazer is now positioned on the end of the 10,000 foot runway at the Cape.

1851 GMT (1:51 p.m. EST)

The L-1011 carrier jet is now taxiing from the Hot Pad staging zone to the runway for takeoff. The "Stargazer" aircraft with a 7-person crew aboard will be taking to the skies in about 25 minutes from Cape Canaveral's Skid Strip runway. Drop of Pegasus is targeted for 3:14 p.m. EST about 100 miles off the coast.

1815 GMT (1:15 p.m. EST)

NASA officials at Kennedy Space Center report preparations are going well for today's launch of the Pegasus rocket. We will begin our live play-by-play reports on the countdown and launch beginning at 2 p.m. EST.

1530 GMT (10:30 a.m. EST)

It is launch day for NASA's Solar Radiation and Climate Experiment satellite and the Orbital Sciences Pegasus XL rocket. Countdown activities are now underway at Florida's Cape Canaveral Air Force Station in support of today's mission. The L-1011 carrier aircraft is due to take off from the Skid Strip at around 2:15 p.m. EST, heading east over the Atlantic to a planned drop point where the air-launched Pegasus will be released at 3:14 p.m. EST.

The weather conditions remain favorable, Launch Weather Officer Lt. Mike Jennings said this morning.

"Broad Surface High Pressure Center continues provide northerly flow to central Florida this morning dropping temperatures to around 34 F at the Cape and KSC. Wind Speeds will continue to decrease today along the space coast in sharp contrast to the past 24 to 48 hours. Expect some scattered low clouds to move in off shore today. Isolated rain showers will remain off the space coast today and south where the stratocumulus cloud field remains well defined.

"Weather today looks good for launch, with light northeasterly winds at the Skid Strip for takeoff of the L-1011. Skies are expected to be partly cloudy along the entire flight path of the L-1011 at flight level prior to Pegasus Drop. A very strong Jet Stream aloft will provide a strong westerly wind at Flight level (39,000 ft) and a chance of light to moderate turbulence for the L-1011.

"The only concern for launch day will be the chance of light with occasional moderate turbulence during L-1011 climb out and at flight level (39,000 ft)."

FRIDAY, JANUARY 24, 2003
1845 GMT (1:45 p.m. EST)

The Pegasus rocket and SORCE spacecraft remain ready to fly Saturday.

"This morning we completed our Launch Readiness Review successfully. We are ready to proceed with launch tomorrow," NASA launch manager Omar Baez told reporters a short time ago.

The weather forecast is still favorable with a 90 percent chance of acceptable conditions. Lt. Mike Jennings, the launch weather officer, issued this overview today:

"The strong cold front has exited the area and moved well south of the Florida into Cuba. A vigorous High Pressure Center drops into the South East U.S today inducing gusty surface winds and very cold temperatures over central Florida. Temperatures dropping below freezing this morning and near freezing again on Saturday morning in the local area.

"Weather on Saturday looks good for launch, with northerly winds at the Skid Strip for takeoff of the L-1011. Skies are expected to be partly cloudy along the entire flight path of the L-1011 prior to Pegasus Drop. A very strong Jet Stream aloft will provide a strong westerly wind at Flight level (39,000 ft) and a chance of light to moderate turbulence for the L-1011.

"The only concern for launch day will be the chance of light with occasional moderate turbulence during L-1011 climb out and at flight level (39,000 ft)."

The conditions at the Skid Strip runway at about 2 p.m. EST Saturday for takeoff include scattered to broken stratocumulus clouds at 3,000 feet with tops at 3,500 feet, visibility of 7 miles or better, northerly winds from 350 to 020 degrees at 8 gusting to 15 knots, a temperature of 58 to 60 degrees.

The flight path and drop point should see scattered stratocumulus clouds at 3,000 feet and tops at 3,500 feet and scattered cirrus clouds at 25,000 and tops at 26,000 feet.

At the 39,000-foot flight level, meteorologists are predicting unlimited visibility, westerly winds from 260 degrees at 125 knots, a temperature of - 56 degrees C and a chance of light to occasional moderate turbulence.

The forecast for Sunday calls for an 80 percent chance of favorable weather due to a slight chance of rainshowers over the Gulf Stream along the flight path of the L-1011.

THURSDAY, JANUARY 23, 2003

A spacecraft designed to study how the Sun affects the Earth's atmosphere and climate will ride an air-launched Pegasus XL rocket into orbit Saturday afternoon in a mission originating at the Cape Canaveral Air Force Station's runway.

The Orbital Sciences-built rocket will be dropped from the belly of an L-1011 carrier jet 39,000 feet above the Atlantic Ocean about 100 miles east-southeast of the Cape. The launch window extends from 3:10 to 4:08 p.m. EST (2010-2108 GMT) with a preferred drop time of 3:14 p.m. EST.

It will take about 10 minutes for the three-stage launcher to deliver NASA's Solar Radiation and Climate Experiment satellite into a perch about 400 miles high at an inclination of 40 degrees.

SORCE carries five instruments for its five-year, $122 million mission as part of NASA's constellation of Earth Observing System satellites.

"This mission will help to distinguish between natural and human-induced influences in climate change. Incoming light energy from the Sun is ultimately what powers our climate system. Past NASA missions showed the amount of solar radiation is not constant, but rather varies over time. SORCE will help us understand these variations, and the role of solar variability in climate change," said Dr. Ghassem Asrar, NASA's associate administrator for Earth Science.

"The SORCE spacecraft specifically will study solar variability and its influence on climate change," said Gary Rottman, the SORCE principal investigator. "We are interested in understanding the Sun's influence on Earth's atmosphere and climate so that we can more reliably determine how humans are changing the environment."

"Everything about climate, from droughts and ozone loss to human health problems like eye cataracts and skin cancer revolve around our understanding of the Sun," added Tom Sparn, the SORCE project manager. "We need to integrate our long-term solar data with supercomputers that model Earth's climate system to see what is occurring in the big picture."

The SORCE project is managed by NASA's Goddard Space Flight Center, the spacecraft is built by the Orbital Sciences and the instruments are provided by the University of Colorado's Laboratory for Atmospheric and Space Physics in Boulder.

The weather forecast for Saturday is favorable with a 90 percent chance of acceptable conditions for the launch attempt. There is an 80 percent chance of good weather on Sunday, if the launch is delayed for some reason.

"Weather on Saturday looks good for launch, with light northerly winds at the Skid Strip for takeoff of the L-1011. Skies are expected to be partly cloudy along the entire flight path of the L-1011 prior to Pegasus Drop. A very strong Jet Stream aloft will provide a strong westerly wind at Flight level (39,000 kft) and a chance of light to moderate turbulence for the L-1011. The only slight concern for launch day will be the chance of light with occasional moderate turbulence during L-1011 climb out and at flight level (39,000 ft)," Launch Weather Officer Lt. Mike Jennings reported.

Officials will hold the Launch Readiness Review on Friday to verify all systems are "go" to begin the countdown early Saturday.

We will provide live updates on this page starting at 2 p.m. EST Saturday as the L-1011 prepares for takeoff.

WEDNESDAY, JANUARY 22, 2003

An Orbital Sciences Pegasus XL rocket, with its NASA satellite cargo aboard, was rolled out of Kennedy Space Center's Multipurpose Payload Processing Facility and driven to Cape Canaveral's Skid Strip runway this morning. The winged rocket was then attached to the L-1011 carrier aircraft. The rocket is due to launch the Solar Radiation and Climate Experiment spacecraft around 3:14 p.m. EST (2014 GMT) Saturday off the Florida coast.