| 22 December 1998
For Immediate Release
NEAR Spacecraft to Fly by Asteroid Eros on Dec. 23; Rendezvous with Eros in 2000
A Dec. 20 spacecraft abort of the initial rendezvous burn of the Near Earth Asteroid Rendezvous (NEAR) spacecraft has resulted in a postponement of NEAR's orbit of asteroid 433 Eros, originally scheduled for Jan. 10, 1999. However, a flyby of the asteroid is planned for Dec. 23, 1998, at 1:43 p.m. EST, that will provide valuable information for its later study.
"While the engine burn abort was unfortunate, we still expect to accomplish the rendezvous objectives, but at a later date," says NEAR Mission Manager, Dr. Robert W. Farquhar, of The Johns Hopkins University Applied Physics Laboratory, which manages the NASA mission. "We expect that the later rendezvous date will not diminish the overall science return."
During the Dec. 23, 1998, flyby, scientists will gain a preview look at the asteroid and gain a global perspective that will provide important information in planning an orbit insertion. Mission designers are now expecting the rendezvous will take place by May 2000. Data obtained from the flyby will help determine the shape and size of the asteroid and if it has any moons.
The rescheduling of the NEAR mission was made necessary by the abort of a planned 20-minute engine burn on Dec. 20, 1998. The spacecraft aborted just seconds after initiation of the bipropellant burn, causing communications with the spacecraft to be lost for about 27 hours. Contact was reestablished early Dec. 22, after NASA's Deep Space Network locked onto a radio signal from the NEAR spacecraft at about 8 p.m. EST, on Dec. 21.
Responding to a command from the Mission Operations Center, NEAR started downloading stored data early Dec. 22, which the mission team has been analyzing to determine the cause of the abort and why the spacecraft lost attitude control.
"We've looked at the data and we believe there has been no damage to the spacecraft or the propulsion system," says spacecraft systems engineer, Andrew G. Santo. "Our fault protection software identified the problem and switched NEAR to a safe mode. Essentially, it worked as designed."
During the Dec. 23 flyby NEAR will take approximately 500 images from as close as 4,100 kilometers (2,500 miles). Although the images will be of lower resolution than those taken June 27, 1997, during the flyby of asteroid 253 Mathilde, they will provide scientists with important information about the asteroid.
NEAR will then travel in an orbit around the sun that nearly matches that of Eros. In May 2000, the spacecraft and Eros will meet, making it possible to insert NEAR into orbit around the asteroid.
NEAR was launched Feb. 17, 1996 as the first launch of NASA's Discovery Program. Updates of mission activities and science returns will be posted on the Web site (http://near.jhuapl.edu) and on the NEAR mission hot line: 240-228-5413.