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The neutral‐atmosphere temperature instrument
Author(s) -
Spencer N. W.,
Niemann H. B.,
Carignan G. R.
Publication year - 1973
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/rs008i004p00287
Subject(s) - atmosphere (unit) , spectrometer , body orifice , environmental science , quadrupole mass analyzer , equator , optics , altitude (triangle) , physics , computational physics , zenith , remote sensing , meteorology , mass spectrometry , geology , latitude , ecology , quantum mechanics , astronomy , biology , geometry , mathematics
The determination of the temperature of the neutral gas at the location of the satellite is based on measurement of the velocity distribution of the molecular nitrogen. Measurement of the thermal‐velocity component in the presence of the free‐stream velocity will be obtained through application of the velocity‐scan technique and, independently, through use of a baffle technique. A 3‐cm diameter spherical sampling chamber with a 0.5‐cm diameter precisely‐knife‐edged orifice is located at the satellite equator to permit free diffusion of atmosphere gases between the chamber interior and the atmosphere. The spherical chamber is connected through a high‐conductance tube to a quadrupole mass‐spectrometer sensor to permit accurate quantitative evaluation of the density of the gas. The spectrometer, tuned to N 2 for most of the measuring time, will also be tuned to other gases for exploratory purposes. The accuracy of the temperature data is expected to be better than 5%. The altitude range, determined primarily by system snr at the upper altitudes and mean‐free‐path limitations at the lower altitudes, is expected to be from 130 to 400 km.