The Near Earth Asteroid Rendezvous (NEAR) spacecraft flew by the Earth Friday, Jan. 23, "right on schedule and right on target," says a jubilant Thomas Coughlin, Space Programs Manager at The Johns Hopkins University Applied Physics Laboratory (APL), which manages the NEAR mission. All spacecraft subsystems worked flawlessly as NEAR swooped around the Earth during a 2-hour visit for a gravity assist that put it onto the correct trajectory for a Jan. 10, 1999, encounter with asteroid 433 Eros.
The Jan. 22-23 swingby put the United States on watch for its first naked-eye glimpse of an interplanetary spacecraft. The southern states from east to west, and especially Hawaii, got the best view because of clear skies and darkness that made it easier to see sunglints off the spacecraft's four solar panels. Although closest-encounter data is still being processed, early indications are that NEAR passed within 336 miles of southwest Iran, as predicted. (Encounter data will be posted on the NEAR Web page as soon as it is available.)
The first sighting of NEAR was made at about 1:30 p.m. EST, by an astronomer in Caussols, France, using a 0.9 meter telescope, as the spacecraft approached far above the Middle East. When sighted, NEAR was 580,000 miles from Earth and within a half-mile of its expected location.
Data captured by NEAR instruments started coming in to the APL Mission Operations Center in Laurel, Md., on Friday evening, says Mark Holdridge, Mission Operations Director. Scientists released the first images from the swingby on Monday, Jan. 26. [See the NEAR web page at http://sd-www.jhuapl.edu/NEAR/].
NEAR took a series of images of Asia, Africa and Antarctica as it pulled away from Earth. The images will be combined to make a "movie" documenting the spacecraft's visit. For the next week NEAR's Multi-Spectral Imager and its Near-Infrared Spectrograph will be calibrated using proven measurements of Earth and moon geological features. On Feb. 6, the last of the instruments will be turned off. Over the next year, as NEAR closes in on Eros, scientists and engineers will be developing and testing flight and ground software for the spacecraft and finalizing procedures for the yearlong encounter with the asteroid.
NEAR's study of Eros will be the first in-depth examination of a near-Earth asteroid and is expected to yield information that will help scientists better understand the evolution of our solar system. NEAR, which is being tracked by NASA's Deep Space Network, is the first mission in the Space Agency's Discovery series.