The NEAR Radio Science investigations

Abstract

Abstract. The science objectives for the Near-Earth Asteroid Rendezvous (NEAR) Radio Science team include determining the masses of asteroids 253 Mathilde (to within 10%) and 433 Eros (<0.1%). While the NEAR spacecraft is in orbit about Eros, the radiometric spacecraft tracking data, the optical landmark tracking data, and the lidar altimetry measurements will be used to determine the gravity field of Eros. Comparisons of this gravity field with one determined from Eros shape models (assuming constant density) will provide constraints upon the internal structure of this asteroid. In addition, the spin state, principal axes, and moments of inertia will be determined as part of the Radio Science activities. A campaign to meet the radio science objectives will require the close cooperation of the NEAR Navigation, Imaging, and Lidar teams.

In-Flight Calibration of the Near Earth Asteroid Rendezvous Laser Rangefinder

“…NEAR is a three-axis-stabilized spacecraft that carries a five-instrument scientific payload, composed of a multispectral imager (MSI), a near-infrared spectrometer (NIS), an X-ray/gamma-ray spectrometer (XRS/GRS), a laser rangefinder (NLR), and a magnetometer (MAG). The scientific background and expected results of planned investigations on NEAR, including a radio science investigation using the spacecraft coherent X-band telemetry system, are summarized in a special issue of the Journal of Geophysical Research (Acuna et al 1997, Trombka et al 1997, Veverka et al 1997a, Yeomans et al 1997a. The spacecraft has been renamed NEAR Shoemaker in honor of Eugene M. Shoemaker (1928Shoemaker ( -1997.…”

In-Flight Calibration of the Near Earth Asteroid Rendezvous Mission's Near Infrared Spectrometer I. Initial Calibrations

“…The reflected-light spectral data gathered by the Near Infrared Spectrometer (NIS) is a key component of an integrated strategy for the study of Eros. This strategy also includes high-resolution imaging from the Multi-Spectral Imager (MSI) (Veverka et al 1997a), elemental abundance measurements from the X-ray/γ -ray spectrometer (XGRS) (Trombka et al 1997), magnetic field data from the magnetometer (MAG) (Acuña et al 1997), topographic data from the NEAR laser rangefinder (NLR) (Zuber et al 1997), and mass and gravity data from the on-board radio science experiment (Yeomans et al 1997). NIS will conduct spectral mapping of Eros by measuring reflected sunlight in the wavelength range from 800 to 2600 nm.…”

Inflight Calibration of the NEAR Multispectral Imager

“…Its mission is to rendezvous with and orbit an asteroid, the S-type near-Earth asteroid 433 Eros . The highly focused instrument complement includes a multispectral imager (MSI) and near-infrared spectrograph (NIS) (Veverka et al 1997a), an X-ray/γ -ray spectrometer (XGRS) (Trombka et al 1997), a magnetometer (Acuña et al 1997), a laser rangefinder (NLR) (Zuber et al 1997), and a radio science experiment (Yeomans et al 1997). NEAR was launched 1 The U.S. Government's right to retain a nonexclusive royalty-free license in and to the copyright covering this paper, for government purposes, is acknowledged.…”