BY JUSTIN RAY
December 20, 1999 -- Follow the countdown and launch of a Lockheed Martin Atlas 2AS rocket and NASA's Terra spacecraft. Reload this page for the very latest on the mission.
SATURDAY, DECEMBER 18, 1999
See our launch photo gallery.
Terra is the first in a series of Earth-studying satellites NASA plans to launch over the next decade. The next, Aqua, is scheduled for liftoff late next year aboard a Boeing Delta 2 rocket from Vandenberg Air Force Base.
"This program is focused on developing an understanding of the total Earth system including the extent, causes and consequences and the regional consequences of global climate change," said Michael King, the EOS series senior project scientist.
Formerly known as EOS AM-1, Terra carries a suite of five sophisticated instruments from the U.S., Japan and Canada that will examine how Earth's oceans, atmosphere and land interact with each other.
"Terra will simultaneously study clouds, water vapor, aerosol particles, trace gases, terrestrial and oceanic properties, the interaction between them and their effect on atmospheric radiation and climate," said Dr. Yoram Kaufman, the mission's project scientist.
"Terra's objective is to start the first comprehensive and well-deserved check up of the planet."
The spacecraft was released from Centaur upper stage less than 14 minutes after the 1857:39 GMT (1:57:39 p.m. EST) launch. Terra's control computer then oriented the craft so the instrument deck was facing the Earth. The power-generating gallium arsenide solar array was deployed and the high gain communicaitons antenna was slated to be released Saturday evening. Controllers will put Terra through a testing and checkout period for 8 to 9 days prior to Y2K. As a safe guard, the craft will be put into safe mode during the transition to the new year. In early January, work to commission Terra will resume. Its science instruments should begin returning data in about three months.
"We're extremely pleased with the launch," said Kevin Grady, Terra's project manager. "The spacecraft is in good shape with all systems performing nominally. The mission is right on plan."
Terra's launch was delayed several times in the last two years by spacecraft-related problems, the need to double-check the rocket's upper stage engines, and more recently by ground software troubles on Thursday and high altitude winds today.
But in the end, the 46th consecutive success for Atlas was achieved.
This launch also wrote a bit space history. It was the first time a Centaur upper stage was used by an Atlas rocket from the Vandenberg Air Force Base launch site, the first time liquid hydrogen rocket fuel - consumed by Centaur - had used at Vandenberg, the first launch from Space Launch Complex-3 East since it was rebuilt to support Atlas 2-series rockets, Terra became the heaviest payload ever carried by Atlas and the liftoff ended the longest time a commercial Atlas rocket had waited on the launch pad - some 27 months.
"The vehicle had been on the pad for so long. It was almost surrealistic to see it actually in flight after 27 months on the pad," said Mike Benik, acting director of NASA's Expendable Launch Vehicle program.
The next launch for Atlas is scheduled for January 20 from Cape Canaveral Air Station, Florida. AC-138 will carry the U.S. Air Force's Defense Satellite Communications System B8 spacecraft into orbit.
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Today's launch was the 46th consecutive success for the Lockheed Martin Atlas rocket fleet.
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The Atlas booster stage is now going to internal power.
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NASA commentator George Diller says upper level winds appear acceptable for launch.
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The Atlas booster and Centaur upper stage are now fully fueled for launch, work that has been on going over the past 90 minutes. But given the super-cold temperatures of the liquid oxygen and hydrogen aboard the vehicle, the cryogenics will be replenished as the countdown continues. The Atlas was loaded last Saturday with its RP-1 fuel, a highly refined kerosene.
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Also, Range Safety is verifying the rocket's flight termination system ready for launch.
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Terra is a $1.5 billion mission to study the Earth's environment with a suite of five science instruments. Read an overview of Terra.
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Today's launch will occur from Space Launch Complex-3 East at Vandenberg Air Force Base in California. Since its last launch in May 1995, the pad has undergone complete reconstruction to support the larger, more complex Atlas 2-series of rockets and their Centaur upper stages. The renovation contract was signed in late 1992 to build the new pad so Atlas 2 rockets could launch secret spy satellites for the National Reconnaissance Office from the U.S. West Coast, placing the craft into orbits that cannot be reached with launches from Cape Canaveral in Florida.
The old tower was demolished and rebuilt from the ground up. Construction was completed in September 1996 and the first Atlas rocket, the one flying today, was stacked on the pad in September 1997.
SLC-3E consists of the 230-foot tall mobile service tower that enclosed the rocket when it is at the pad, providing access and weather protection; the 170-foot tall fixed umbilical tower that supports lines connected to the rocket through which propellants are pumped to the rocket, as well as electrical power and conditioned air; the launch support building is a two-story structure contains support equipment; and the launch operations building where the countdown is controlled, located about 7 miles from the pad.
To date, there are three scheduled launches from the new pad: Terra today and two NRO payloads next summer and one about a year later.
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Weather conditions, specifically winds, are acceptable for launch. The main threat is for winds to gradually increase with the passage of a weather front around launch time today.
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The Atlas rocket to be launched today was assembled at SLC-3E in September 1997 to support pathfinder exercises at the newly rebuilt pad. Those tests to check the pad, ground support equipment and launch team were completed in April of 1998. However, the Terra satellite was grounded due to software problems, forcing the Atlas rocket to be placed in extended storage.
Lockheed Martin officials decided the best place to keep the Atlas was on the launch pad enclosed in the mobile service tower. The MST at Vandenberg is unlike the more open towers at Cape Canaveral Air Station's Complex 36 Atlas pads. The Vandenberg tower is often referred to as a building, fully enclosed and environmentally controlled. In addition, workers closed off the base of the tower and erected a tent around the base of the Atlas to protect the engines. Dry, warm air was also pumped into the tent.
Throughout the past two years the rocket has been coated with WD-40 to prevent corrosion. WD-40 was originally created 40 years ago for the Atlas ICBMs. X-ray tests were also performed every 90 days to check the structural integrity of the rocket's fuel tanks.
In May of this year when the decision was made to resume the launch campaign for Terra, Lockheed Martin reperformed tests and checkout of the pad and rocket for for today's mission, said Mark Ware, manager of launch operations at SLC-3. Launch pad validations were completed as if the rocket was never there. "It was like starting fresh."
When the work resumed the launch was planned for late July. However, when the Boeing Delta 3 rocket failed on May 4, another delay for Terra was triggered. The upper stage engine that caused the Delta 3 mishap is a similar version to the engines on the Atlas rocket's upper stage - Centaur. To ensure the engines on Centaur were safe to use, a pair of ultrasonic inspections were performed at the launch pad to check the engines' combustion chambers to see if the problem that doomed Delta 3 would affect Terra's ride. The inspections and later analysis concluded that the Centaur was ready for flight. The launch was rescheduled for today.
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Countdown clocks began ticking backwards at 1018 GMT (5:18 a.m. EST) today with the activation of the launch system computers at the launch pad. Later work has included a checkout of the Atlas rocket's flight termination system, a communications test with the orbiting Tracking and Data Relay Satellite System and tests of the Atlas' flight controls. Work is currently continuing to closeout of the payload fairing for launch.
Upcoming the launch team will review a weather briefing for rolling the mobile service tower away from the rocket. MST retraction is expected in about an hour. Also, an alignment will begin of the rocket's guidance computer.
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If the launch does not occur on Saturday for some reason, it is unclear when the next attempt would be made. "We will cross that bridge when we come to it," NASA spokesman George Diller said. Sunday is not expected to be an option for the Atlas because the Western Range will use that day to reconfigure communications and tracking systems to support Monday night's (local time) launch of an Orbital Sciences Taurus rocket.
The main concern for Saturday will be ground-level winds. The forecast calls for a 60 percent chance weather will delay the launch.
Read our earlier countdown coverage.
Flight data file
Vehicle: Atlas 2AS
Launch date: Dec. 18, 1999
Launch window: 1833-1858 GMT (1333-1358 EST)
Launch site: SLC-3E, Vandenberg Air Force Base, Calif.
The Lockheed Martin Atlas 2AS rocket launches with NASA's Terra spacecraft from Vandenberg AFB, Calif.
PLAY (496k QuickTime file)
The first countdown for the launch of NASA's Terra spacecraft aboard an Atlas 2AS rocket is cutoff in the final minute.
PLAY (103k QuickTime file)
Download QuickTime 4 software or the Real Player to view these files.
Atlas vehicle data - Overview of the rocket that will launch Terra into space.
Terra spacecraft - Facts and information about NASA's Terra satellite.
Launch timeline - Chart with times and descriptions of events to occur during the launch.
Pre-launch photo gallery - Follow the rocket and satellite preparations for launch in pictures.
Terra's mission - A NASA release detailing the objectives and science goals of Terra.
Atlas index - Listing of our previous Atlas coverage.
Explore the Net
International Launch Services - Lockheed Martin-led consortium which globally markets the U.S. Atlas and Russian Proton rockets.
Lockheed Martin Astronautics - U.S. company which builds and launches the Atlas family of rockets.
Terra - NASA's flagship mission for the Earth observing system.
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