A school bus-sized space observatory that will monitor the health of Earth's atmosphere in unprecedented detail rocketed into polar orbit today, finally darting away from its California launch pad atop a Boeing Delta 2 booster after several frustrating delays.

The Delta 2 rocket launches with Aura. Credit: U.S. Air Force photo by Master Sgt. Rodney Jones

Rumbling into the predawn sky at 1002 GMT (6:02 a.m. EDT; 3:02 a.m. PDT), the two-stage rocket creating a dazzling light show for spectators at Vandenberg Air Force Base and beyond. Ten minutes later, NASA's Aura satellite reached an initial orbit above the planet while still riding the rocket's second stage motor.

Aura was originally supposed to launch June 19, but multiple technical concerns conspired to postpone the mission six times, keeping the satellite earthbound for an extra month.

Today's launch shot came after two back-to-back countdowns were scrubbed.

"I guess the third time was the charm for Aura," NASA launch director Chuck Dovale said.

"We worked through a couple of hard days and unfortunately couldn't get off the ground the last few days. But the team stuck together and worked a lot of issues, actually in the last week. This one provided tough to get off."

Nearly an hour after liftoff, the rocket restarted its second stage engine over east-central Africa to propel Aura into an orbit 370 nautical miles high. Sixty-four minutes into flight, the second stage opened its latches and then gently backed away from Aura, successfully delivering the 6,600-pound craft into space for the start of its six-year mission.

"We wish the Aura team well," Dovale said.

An artist's illustration shows Aura deploying its power-generating solar array soon after launch. Credit: NASA-GSFC

"Aura, the first comprehensive laboratory in space to help us better understand the chemistry and composition of the Earth's atmosphere, is fundamentally a mission to understand and protect the very air we breathe," said Ghassem Asrar, NASA's associate administrator for Earth science.

Our planet's atmosphere "is one of the most important life-sustaining resources. In fact, every breath we take reminds us of this importance," said Phil DeCola, Aura program scientist from NASA Headquarters.

"However, it is not the oxygen or even the nitrogen, which make up 99 percent of Earth's atmosphere, that is the focus of the Aura mission. Aura is focused on a fraction of the remaining one-percent -- the trace gases and aerosol particles that are almost as important as oxygen itself in sustaining life on Earth."

Aura's $785 million mission will attempt to answer three specific questions:

• Is the stratospheric ozone layer recovering? The satellite's ability to study ozone chemistry should improve predictions of ozone change, scientists say.
  
  
• What are the processes controlling air quality? Aura's tracking of atmospheric chemistry will provide a daily view of global air pollution, and researchers say the satellite will help distinguish between industrial and natural sources.
  
  
• How is the Earth's climate changing? The spacecraft will measure greenhouse gases in the upper troposphere and lower stratosphere, aerosols in the lower stratosphere and lower troposphere and water vapor inside high tropical clouds. Scientists say this information will help climate forecasting.

An artist's concept of Aura. Credit: Northrop Grumman

The scientific return from Aura's view of Earth has the potential to impact environmental policies around the world.

"We are faced with many important decisions both nationally and internationally. This kind of information is a national and worldwide treasure to make sound decisions and form good policy for managing important resources," DeCola said.

"NASA is not in the business of making any regulations. We are in the business of providing the sound scientific understanding and information for our government and in partnership with governments around the world in making these decisions.

"Having said that though, it will be interesting to see how international treaties might be formed in the future. Right now, there are no international treaties that address the issue of air quality in that sense. Of course, there have been attempts at getting international treaties related to climate change, and we've had success in treaties for stratospheric ozone. But nothing really is in place right now or even really in a major way in the works to address the issue of global air quality.

The Aura satellite is seen here during pre-flight preparations. Credit: Northrop Grumman

"So in the future one might imagine that the kind of information that Aura is delivering could be used in that way."

Aura is the third of three large satellites in NASA's Earth Observing System -- a program aimed at taking the pulse of the planet's environment. The flagship Terra was launched in late 1999 to study the land; and Aqua followed two years ago to monitor Earth's water cycle.

"(Aura is) a perfect complement to our other Earth Observing System satellites that, together, will aid our nation and our neighbors by determining the extent, causes and regional consequences of global change," Asrar said.

The Aura platform was built by Northrop Grumman. The craft is fitted with four sophisticated instruments:

• The joint U.K./U.S. High Resolution Dynamics Limb Sounder instrument will measure trace gases, temperature and aerosols in the upper troposphere, stratosphere, and mesosphere.
  
  
• The Microwave Limb Sounder will measure important ozone-destroying chemical species in the upper troposphere and stratosphere and measure trace gases in the presence of ice clouds and volcanic aerosols. NASA's Jet Propulsion Laboratory built MLS.
  
  
• Ozone Monitoring Instrument is Aura's primary sensor for tracking global ozone change and will continue the record of space-based ozone monitoring that began in 1970. OMI was built by the Netherlands and Finland in conjunction with NASA.
  
  
• Tropospheric Emission Spectrometer will measure tropospheric ozone directly and other gases important to tropospheric pollution. JPL also made TES.

An artist's concept of Aura. Credit: Northrop Grumman

Aura should complete its in-space tests and begin science operations by mid-October. Researchers expect to release first results by year's end.

Today's launch was the 114th flight of a Delta 2 rocket and fourth this year. The launcher is riding a string of 59 consecutive successes dating back to 1997.

"Aura will provide invaluable information on the condition of our atmosphere," said Will Trafton, vice president and general manager of Boeing Expendable Launch Systems. "Our Delta launch team knows that mission success in deploying satellites that enable important research such as this to continue, will benefit the people of the world today and for future generations."

The next Delta 2 launch is scheduled for August 2 when NASA's MESSENGER probe embarks on its voyage to orbit the planet Mercury. Workers are busy assembling the rocket on pad 17B at Cape Canaveral, Florida.

"We are looking forward to that," Dovale said. "There is about a two-week window we have to get (MESSENGER) off in. So we are looking forward to that challenge."

Additional coverage for subscribers:
VIDEO: THE DELTA ROCKET LAUNCHES AURA QT
VIDEO: AURA IS DEPLOYED FROM THE DELTA ROCKET QT
VIDEO: POST-FLIGHT INTERVIEW WITH NASA LAUNCH DIRECTOR QT

VIDEO: WEDNESDAY'S LAUNCH ATTEMPT IS SCRUBBED QT
VIDEO: LAUNCH DIRECTOR EXPLAINS WEDNESDAY'S PROBLEMS QT
VIDEO: TUESDAY'S LAUNCH ATTEMPT IS SCRUBBED QT
VIDEO: AURA'S LAUNCH CAMPAIGN SHOWN WITH NARRATION QT
VIDEO: DELTA 2 ROCKET IS ASSEMBLED ON THE LAUNCH PAD QT
VIDEO: MOBILE SERVICE TOWER IS ROLLED BACK MONDAY EVENING QT
VIDEO: ANIMATION SHOWS DELTA LAUNCHING AURA INTO ORBIT QT
VIDEO: AURA SCIENTIST EXPLAINS WHAT MISSION AIMS TO DO QT
VIDEO: WATCH FRIDAY'S PRE-LAUNCH NEWS CONFERENCE QT
VIDEO: ANIMATION OF AURA STUDYING THE ATMOSPHERE QT
VIDEO: FLASHBACK TO THE AQUA LAUNCH IN 2002 QT
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