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

✍ Scribed by Noam R. Izenberg; James F. Bell III; Jeffery W. Warren; Scott L. Murchie; Keith Peacock; E.Hugo Darlington; Brian Carcich; Clark Chapman; Beth E. Clark; Ann Harch; Gene Heyler; Jonathan Joseph; Patrick Martin; Lucy McFadden; Bill Merline; Mark Robinson; Joseph Veverka; Dennis Wellnitz

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 558 KB
• Volume: 148
• Category: Article
• ISSN: 0019-1035
• DOI: 10.1006/icar.2000.6541

✦ Synopsis

The Near Infrared Spectrometer (NIS) instrument on the Near Earth Asteroid Rendezvous (NEAR) spacecraft performed a comprehensive series of in-flight tests to validate its preflight radiometric characteristics and to characterize instrument stability, pointing, and co-alignment with other instruments under flight conditions. The results of these tests form the basis of the NIS data reduction and calibration procedure and will support the ability of NIS to achieve its science goal of spectrally mapping NEAR's target asteroid, 433 Eros. Key results include the following: (i) Radiometric calibration of NIS has been confirmed to be accurate to within 4-10%, based on NIS measurements of the Earth and Moon and comparisons to radiances derived from other (NEAR and non-NEAR) optical instruments; (ii) The radiometric response has been demonstrated to be stable on the scale of months; (iii) Gradual, expected detector sensitivity decay of 1-3% over 2 years of operations in space has been characterized; (iv) Temperature dependencies of detector response are identified and characterized; (v) The co-alignment of NIS with the Multi-Spectral Imager (MSI) and with respect to other NEAR instruments has been determined; (vi) A calibration program (NISCAL) that applies appropriate functions and algorithms to convert raw instrument data to analyzable spectra has been developed; (vii) Remaining unresolved instrument calibration and characterization issues have been identified, to be resolved with the help of approach and orbital observations from the main mission.