NASA's Earth Science Program Adjusts To Loss Of Data From Japanese ADEOS Satellite

Allen KenitzerGoddard Space Flight Center, Greenbelt, MD(Phone: 301/286-2806)

Mary HardinJet Propulsion Laboratory, Pasadena, CA(Phone: 818/354-0344)

RELEASE: 97-149

NASA'S EARTH SCIENCE PROGRAM ADJUSTS TO LOSSOF DATA FROM JAPANESE ADEOS SATELLITE

"The failure of Japan's Advanced Earth Observing Satellite (ADEOS or Midori) spacecraft with the two NASA instruments aboard it is a real blow to NASA's science program," said Mike Mann, Deputy Associate Administrator, NASA's Mission to Planet Earth Strategic Enterprise, Washington, DC.

"Fortunately, much of the ozone data provided by the Total Ozone Mapping Spectrometer (TOMS) science instruments aboard ADEOS can be provided by instruments on another spacecraft. However, the sea-surface winds data provided by the NASA Scatterometer (NSCAT) will be harder to replace and were opening essentially new opportunities for research and operational users worldwide," Mann said.

The two NASA instruments were aboard the ADEOS spacecraft, which on June 30 was declared lost by the National Space Development Agency of Japan (NASDA).

"The collaboration between NASDA and NASA on this mission has been outstanding and is reflective of the great partnership that exists between Japan and the U.S in the area of global change research," Mann said.

"NASDA has performed in an exemplary and open manner in the development of the spacecraft and in dealing with us. However, space operations is a risky business; those of us involved in the business strive to limit the risk but sometimes mishaps do occur," Mann said.

"The data we have obtained to date are extremely valuable," said Jim Graf, NSCAT project manager at NASA's Jet Propulsion Laboratory, Pasadena, CA. "If we knew we were limited to just nine months of data, we would have chosen the period we actually got. We obtained coverage over the summer and winter monsoon seasons and what may be the onset of an El Nino. Perhaps the largest loss is the discontinuity of the long-term data set, which is being used to understand interannual and decadal variations in our climate."

The scatterometer measured wind speed and direction over the world's oceans. The data set is extremely valuable and versatile and is being used by climate change researchers, operational weather forecasters, and commercial ship routing firms. During its flight, the instrument gathered 42 weeks' worth of data.

Within a very few short months after launch, the value of ADEOS data was seen in U.S. weather forecasting. "NOAA had begun using ocean surface wind products, derived from NSCAT, in weather forecasting," said Helen Wood, Director, Office of Satellite Data Processing and Distribution, National Oceanic and Atmospheric Administration. "Ocean surface wind measurements are used in numerical weather prediction models and help forecasters more accurately determine the path and intensity of tropical storms and hurricanes."

Because this instrument provided measurements that will be needed over the long term, NASA was already developing a second scatterometer instrument to continue this vital data set. That instrument, called "SeaWinds," will be delivered to NASDA for integration on the spacecraft next April and is scheduled for launch in 1999 on ADEOS II.

The launch of a Total Ozone Mapping Spectrometer sensor aboard ADEOS was helping to extend the unique data set of global total column ozone measurements begun by a similar instrument carried aboard NASA's Nimbus-7 satellite in 1978 and extended until December 1994 with the Meteor-3 TOMS.

"The ADEOS spectrometer, along with the TOMS Earth Probe (EP) instruments also observed the unusual loss of Arctic polar ozone reported earlier this year," said Dr. Arlin J. Krueger, PrincipalInvestigator and Instrument Scientist for TOMS/ADEOS at NASA'sGoddard Space Flight Center, Greenbelt, MD.

Although it also provided ozone coverage, NASA's Total Ozone Mapping Spectrometer/Earth Probe instrument had also been providing high ground resolution research data to complement the global data of the spectrometer on ADEOS. As a result, its orbit is different than TOMS/ADEOS. The EP satellite has adequate fuel to raise its present 500 km orbit to an orbit near the 800 km ADEOS orbit, where contiguous Earth coverage is possible for monitoring of ozone and volcanic eruption clouds. NASA is considering raising TOMS/EP to a higher orbit.

With this adjustment, much more complete global coverage of total ozone measurements previously provided by TOMS/ADEOS could be received. However, some of the unique smaller-scale aerosols and ozone research being done by TOMS/EP would be lost. The next Total Ozone Mapping Spectrometer mission is planned for launch on a Russian Meteor-3M spacecraft in 2000.

The loss of the ADEOS platform has a particularly serious impact on oceanographic research since two instruments, the Ocean Color and Temperature Sensor and the Polarization and Directionality of the Earth's Reflectance, both capable of providing routine global estimates of phytoplankton pigment concentrations, were lost. These instruments were providing the first routine global observations of ocean color and were initiating the much-needed, long-term time series of such measurements for global change studies.

Future routine global ocean-color information will be provided by SeaWIFS, a commercial mission from which NASA will purchase data, currently scheduled for launch July 18.

The NASA Scatterometer and Total Ozone Mapping Spectrometer/ADEOS were developed under NASA's strategic enterprise called Mission to Planet Earth, a comprehensive research effort to study Earth's land, oceans, atmosphere, ice and life as an interrelated system.

NASA is cooperating with NASDA to identify the cause of the ADEOS failure and recommend a solution for future missions.

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