Artist's concept of NASA's Terra spacecraft orbiting Earth. Photo: NASA

After more than three weeks of the spacecraft being on-orbit, NASA controllers report Terra Mission operations are going extremely well, with no significant problems at this time.

"We are extremely pleased with the mission to date," said Kevin Grady, Terra Project Manager at NASA's Goddard Space Flight Center, Greenbelt, Md. "All of the instruments have now been turned-on, with outgassing occurring over the next couple weeks. We are anticipating collection of the first images by the end of this month and we could not be more pleased with the performance of the spacecraft and the Operations Team to date."

During the week of December 30, the first two instruments, the Multi-angle Imaging SpectroRadiometer (MISR) and the Clouds and the Earth's Radiant Energy System (CERES), were turned on and the outgassing process initiated. Early last week, the spacecraft was placed back in the normal control mode with communications via the high gain antenna. The spacecraft had been in a planned Earth sensor based acquisition mode during the Y2K rollover, which the spacecraft passed with flying colors. The Moderate-resolution Imaging Spectroradiometer (MODIS) and the Measurements of Pollution In The Troposphere (MOPITT)instruments were then activated. On Friday and continuing over this past weekend, the final instrument, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), was powered-on. Controllers are now monitoring the performance of all five instruments as the outgassing process continues and the temperatures of the instruments reach equilibrium.

Also last week, the critical Terra X-band and Ku-band science data links were successfully checked. It is over these communications links, that the vast amount of Terra science data will be delivered, enabling the earth system scientists to better understand the drivers of global climate change.

Finally, Terra's propulsion system was checked in preparation of the first of four orbital maneuvers. Terra was placed in a slightly elliptical on December 18, when it was launched by an Atlas/Centaur rocket. The four planned maneuvers using Terra's propulsion will place it in a 438 mile (705 kilometer) circular orbit.

Terra was launched from Vandenberg Air Force Base, Calif., on December 18, 1999, at 1:57 p.m. EST, and is the "flagship" to the Earth Observing System series of satellites, part of a precedent setting program designed to provide daily information on the health of the Planet.

The Terra satellite was built by Lockheed Martin assembled and tested the Terra spacecraft at its production facility in Valley Forge, Pa., under management from NASA's Goddard Space Flight Center, Greenbelt, Md.

The primary objective of the Terra Mission is to simultaneously will study clouds, water vapor, small particles in the atmosphere (called "aerosol" particles), trace gases, land surface and oceanic properties, as well as the interaction between them and their effect on the Earth's energy budget and climate.

Terra is managed by NASA's Goddard Space Flight Center, Greenbelt, Md., for NASA's Office of Earth Science, Washington, DC. A goal of the Earth Science Enterprise is to expand knowledge of the Earth System, from the unique vantage point of space. Earth Science Enterprise data, which will be distributed to researchers worldwide at the cost of reproduction, is essential to people making informed decisions about their environment.