(11/18/1999) --- Workers at Vandenberg AFB, Calif., help prepare NASA's Terra spacecraft (right) for encapsulation in the rocket faring (left). Terra is expected to be launched aboard a Lockheed Martin Atlas IIAS rocket Dec. 16 from Space Launch Complex 3 East at Vandenberg. Terra comprises five state-of-the-art sets of instruments that will collect data for continuous, long-term records of the state of Earth's land, oceans and atmosphere. Together with data from other satellite systems launched by NASA and other countries, Terra will inaugurate a new self-consistent data record that will be gathered over the next 15 years. From an altitude of 438 miles, Terra will circle the Earth 16 times a day from pole to pole (98 degree inclination), crossing the equator at 10:30 a.m. The five Terra instruments will operate by measuring sunlight reflected by the Earth and heat emitted by the Earth