Quantcast
Last updated on April 17, 2014 at 1:21 EDT
NEARs Eros Flyby Movie
263 of 267

NEAR's Eros Flyby Movie

October 22, 2009
This movie shows the asteroid Eros as seen from the Near Earth Asteroid Rendezvous (NEAR) spacecraft on December 23, 1998, when NEAR flew within 2320 miles (3830 kilometers) of the asteroid. Eros, a very elongated, cratered object about 18 by 8 miles (30 by 14 kilometers) across, is seen rotating with a period of just over 5 hours.

The movie shows about two-thirds of a rotation of Eros. The first view, taken at 10:44 AM EST from a range of 7150 miles (11,890 km), shows about half of the dayside of Eros (phase angle 87°). The movie ends at 2:05 PM EST, just after closest approach, when only a tiny portion of the dayside of Eros is seen (phase angle 119°). During the movie, the spacecraft's view of the asteroid changed dramatically. As is the case with most asteroids, Eros is rotating uniformly about a fixed axis, and is not tumbling randomly through space.

A firing of NEAR's main engine at 5 PM EST December 20, designed to match the spacecraft's velocity with Eros's 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 during the flyby yields 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).