So Far, So Good

Activation of the Aura spacecraft, launched July 15, is continuing, with the mission going very well so far.

Just over an hour after launch, the spacecraft separated from the Boeing Delta II launch vehicle. This was followed shortly thereafter by deployment of the spacecraft's solar array and transition to Sun point mode. The next day, the spacecraft transitioned to Earth point mode, where it remained another day before transitioning to fine point mode, the mission's normal operating mode. S-band communications with the space network began immediately, followed by routine ground network contacts. X-band playbacks from the solid-state recorder to the ground network are now ongoing as well.

All spacecraft subsystems have demonstrated readiness to support science operations, which cannot begin until the instruments are fully activated and Aura has reached its nominal orbit altitude.

With respect to orbit altitude, four of six planned ascent burns have been completed. The fifth ascent burn is planned for Fri., August 6. The Aura ascent plan anticipates reaching a nominal altitude of 705 kilometers (about 438 miles) this month.

All four instruments are powered and are systematically being activated; the following are some of the highlights that have occurred so far. The antenna launch latch for the Microwave Limb Sounder primary reflector has been released, and the receivers are undergoing characterization activities. Good output power from the Microwave Limb Sounder THz module gas laser local oscillator has been confirmed. The Tropospheric Emission Spectrometer translator has been unlatched, as has that instrument's pointing control system gimbals. The Sun-shield door for the High Resolution Dynamics Limb Sounder has been released. Transition of the Tropospheric Emission Spectrometer, High Resolution Dynamics Limb Sounder and the Ozone Monitoring Instrument to science mode is paced by their significant outgassing requirements, which last about 30 days.

"From what we have seen so far, satellite performance appears very solid," said Rick Pickering, Aura project manager at NASA's Goddard Space Flight Center, Greenbelt (MD). "Also, the performance of the entire operations team has been tremendous. Not only are all the team members inherently sharp and well-trained, many of them have extensive experience with Aqua, which is paying great dividends."

Aura, a mission dedicated to the health of Earth's atmosphere, will help us understand and protect the air we breathe. Aura will help answer three key scientific questions: Is Earth's protective ozone layer recovering? What are the processes controlling air quality? How is Earth's climate changing? NASA expects early scientific data from Aura within 30 to 90 days.

Each of Aura's four instruments is designed to survey different aspects of Earth's atmosphere. Aura will survey the atmosphere from the troposphere, where mankind lives, through the stratosphere, where the ozone layer resides and protects life on Earth.

With the launch of Aura, the first series of NASA's Earth Observing System satellites is complete. The other satellites are Terra, which monitors land, and Aqua, which observes Earth's water cycle.

The High Resolution Dynamics Limb Sounder was built by the United Kingdom and the United States. NASA's Jet Propulsion Laboratory, developed and manages the Microwave Limb Sounder and Tropospheric Emission Spectrometer. The Ozone Monitoring Instrument was built by the Netherlands and Finland in collaboration with NASA. NASA's Goddard Space Flight Center manages the Aura mission.

The Microwave Limb Sounder is intended to improve our understanding of ozone in Earth's stratosphere, which is vital in protecting us from solar ultraviolet radiation. The Tropospheric Emission Spectrometer is an infrared sensor designed to study Earth's troposphere and to look at ozone and other urban pollutants.

FMI: www.gsfc.nasa.gov/topstory/2004/0517aura.html, www.nasa.gov/aura