SPACE.com -- $1.3 Billion Terra Satellite Reaches Final Orbit

Math Problem Bedevils $1.3-billion NASA Satellite

Terra Back on Track

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	$1.3 Billion Terra Satellite Reaches Final Orbit By Andrew Bridges Chief Pasadena Correspondent posted: 06:33 am ET 25 February 2000

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Terra, a NASA satellite scientists say will allow them to study the Earths land, oceans and atmosphere as a complete interrelated system, has reached its final orbit more than two months after its launch.

The missions flight team at NASAs Goddard Space Flight Center in Greenbelt, Maryland completed the last of eight burns on Wednesday to raise Terra to its final 437-mile (705-kilometer) polar orbit.

The $1.3 billion Terra now trails another Earth-observing satellite, Landsat 7, by 35 minutes, allowing the two to work in near unison.

Terra, or EOS AM, is the flagship and first to launch of a series of 10 satellites that will make up NASAs Earth Observing System. The flotilla should contribute at least 15 years worth of data on the planet, providing a literal checkup of its health, including the effects of human activity.

Terra will collect spectral data from the visible to the infrared from the entire surface of the globe every 16 days, amassing on a daily basis 850 gigabytes 100,000 encyclopedia volumes worth of measurements.

It will look at everything from cloud types to leaf density in forests to changes in land cover.

The school bus-sized Terra carries five instruments to do so. Canada and Japan supplied two of the instruments.

On Thursday, mission controllers opened the covers on two of the satellites instruments. Another will be opened on Friday. On Saturday, the last of the bunch -- the Japanese contribution -- will point at Tokyo and take its first images.

"Its a day weve been waiting for for 10 years," said Kevin Grady, Terras project manager at Goddard. "Were extremely pleased at the outcome."

Over the weekend, Terra will also image Mayon, an erupting volcano in the Philippines, Grady said.

Terras first 68 days in orbit have not been without problems, however.

The first attempt at raising Terra to its final orbit failed on January 11 when the spacecraft went into a roll. Grady said engineers later determined a clutch of issues caused the problem, including the force produced by thruster plumes striking the satellites mammoth solar array.

And in other incidents, stray radiation caused repeated glitches with the satellites main antenna and an unexpected math problem caused the spacecraft to go into standby mode during the winter solstice.

Grady said Thursday that software patches uploaded to Terra since then should prevent any further mishaps.

Terra was launched December 18, 1999 aboard an Atlas/Centaur 2-AS rocket from Vandenberg Air Force Base, California.

Its follow-on mission, Aqua, or EOS PM, will be launched this winter.