Instrument Aboard NASA's Aqua Satellite Joins Twin to Begin Comprehensive Global Coverage

Smoke from multiple large wildfires in Québec, Canada, drifted far to the south of the border, as seen in this Moderate Resolution Imaging Spectroradiometer (Aqua MODIS) image from July 7, 2002.

Roughly 438 miles above the Earth, the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard NASA's Aqua satellite opened its Earth-view door on June 24 and took its first look at our planet. This event, called "first light," marks a milestone in Earth observation, allowing scientists to conduct the most comprehensive daily examination of our planet by combining ata from two MODIS instruments on sister satellites in Earth orbit.

Like its twin flying aboard NASA's Terra satellite -- launched in 1999 -- Aqua MODIS sees almost the entire surface of our planet every day in 36 channels ranging from visible to thermal infrared wavelengths. On a daily basis, Terra descends across the equator at 10:30 a.m. in every time zone, while Aqua ascends across the equator at 1:30 p.m. in every time zone. The different timing of the satellites' pole-to-pole orbits enables scientists to focus on different aspects of the Earth's climate system and to see changes within the system during the course of a day.

"With the launch of Aqua," said MODIS Team Leader Vince Salomonson, of Goddard, "we are able to observe land, ocean and atmosphere phenomena in the afternoon with Aqua and in the morning with Terra. This is especially important for observing rapid, time-varying phenomena like clouds and water vapor."

For the complete article on the Aqua mission, go to: http://www.gsfc.nasa.gov/topstory/20020815aquafirst.html