NEAR swings by Earth en route to Eros



The Near Earth Asteroid Rendezvous spacecraft (NEAR) conducted a swingby of Earth on January 23, 1998, en route to its final destination, the asteroid 433 Eros. The spacecraft, built and managed by the Applied Physics Laboratory of Johns Hopkins University in Laurel, Maryland, and launched February 17, 1996, aboard a Delta II-7925-8 rocket from Cape Canaveral, is on a mission to further our understanding of the nature of asteroids and their role in the formation of the solar system. The spacecraft is three-axis stabilized, passively cooled, and uses four fixed solar panels to power five scientific instruments and transmit data to Earth through a 1.5 m, fixed, high-gain antenna.

As the first NASA Discovery-class mission, NEAR was designed to return the maximum amount of information on a timely basis with minimal cost. Aside from the transponder that will be used to determine Eros' mass and gravity field, the science instruments are focused on understanding the geology, chemistry, and history of the target asteroid. The seven-band Multi-Spectral Imager (MSI), covering wavelengths of 0.5 to 1.1 microns, will image the entire surface of the 40 x 14 x 14 km (25 x 9 x 9 mi) asteroid, mapping its morphology and color [Hawkins et al., 1997]. The Near Infrared Spectrometer (NIS) will map out Eros' surface mineralogy using reflected sunlight in the 0.8 to 2.5 micron range [Warren et al., 1997], while the X ray/Gamma ray Spectrometers (XGRS) will determine surface elemental composition of key rock-forming species such as Mg, Al, Si, S, Ca, Fe, Ti, and K [Goldsten et al., 1997]. The NEAR magnetometer will characterize the intensity and structure of any intrinsic magnetization of Eros [Lohr et al., 1997]. Finally, the NEAR Laser Rangefinder (NLR) altimeter will measure the asteroid's topography and shape to 1 m vertical resolution with its infrared 15 mJ pulsed beam [Cole et al., 1997].