Terra Deep Space Calibration Maneuvers Flawless

Artistic render of Terra spacecraft

The Terra spacecraft successfully conducted two reverse pitch maneuvers. The first maneuver, on March 26, 2003, allowed the Terra instruments to view deep space for the first time to improve calibration of CERES, MODIS and ASTER longwave infrared channels. A second Terra Deep Space Calibration Maneuver, performed on April 14, 2003, was designed to allow MODIS, ASTER and MISR cameras to view the sunlit lunar disk primarily for radiometric characterization purposes. CERES was also able acquire additional deep space scans. The Terra Flight Operations, Instrument Operations and System Engineering Teams conducted both maneuvers flawlessly.

Evaluation of the data by the Instrument Science Teams shortly after the maneuvers confirmed that all instruments acquired data according to plan. Images of the moon acquired by MODIS, ASTER and MISR are seen below. Data analysis is proceeding to evaluate the quality of the data for meeting the maneuver objectives. A possible third maneuver will be planned and conducted based on the results of the first two, likely within the next six months.

The deep space and lunar calibration maneuvers had been studied, reviewed and planned over the past six years. The objectives for CERES were to characterize measurement accuracy in the short term and provide comparison to other similar instruments over the long term. MODIS objectives were to measure the characteristics of their scan mirror to improve accuracy of thermal measurements and use the illuminated lunar disk measurement to improve radiometric calibration. ASTER interests were mainly in using measurements of the moon for radiometric characterization. MISR will also use the data of the moon for relative radiometric calibration among the nine cameras. The calibration data acquired during these maneuvers will improve Terra's ability to monitor climate change.

For more on the Terra mission, go to:
http://terra.nasa.gov/

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Centennial of Flight Activities Gain Momentum: NASA has a special connection with the Wright Brothers' 100th anniversary. In 1915, the United States Congress created the National Advisory Committee for Aeronautics, NASA's predecessor organization. During 2003, Inventing Flight offers an outstanding opportunity for NASA to reach the public and show pride in our part of aviation's evolution. Visit the NASA Glenn Centennial Website at: http://centennial.grc.nasa.gov for information about the Inventing Flight celebration. Volunteers are needed for most of the venues and participation is open to all NASA civil service employees, contractors and retirees with supervisory approval.

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