This pair of images of the asteroid Eros was acquired by the Near Earth Asteroid Rendezvous (NEAR) spacecraft on December 23, 1998, as the spacecraft flew by the night side of the asteroid at a distance of 2300 miles (3800 kilometers) at 1:43 PM EST. These views, taken at 1:44 PM and 2:05 PM EST as the spacecraft range increased from 2300 miles to 2500 miles (4100 kilometers), show only a tiny portion of the day side of Eros (phase angle ~119°). The smallest resolved detail is approximately 1300 feet (400 meters) across.
A firing of the main engine at 5 PM EST December 20, designed to slow the spacecraft for insertion into orbit around the asteroid, was aborted by the spacecraft. Contact with ground controllers was temporarily lost, but was regained at 8 PM EST December 21 when autonomous spacecraft safety protocols took over and transmitted a signal to the ground. All spacecraft systems were determined to be healthy and operational. Within hours, a flyby observation sequence was developed and uploaded to the spacecraft. 1026 images were acquired by the multispectral imager, to determine the size, shape, morphology, rotational state, and color properties of Eros, and to search for small moons. The infrared spectrometer measured spectral properties of the asteroid to determine what minerals are present, and the magnetometer searched for a natural magnetic field. Analysis of the spacecraft radio signal will yield bounds on the asteroid's mass and density.
The main engine was fired successfully on January 3, 1999, placing NEAR on-course for a February 2000 rendezvous. Eros is NEAR's second asteroid encountered. On June 27, 1997, NEAR flew by the main-belt asteroid Mathilde at a range of 1212 kilometers (750 miles).