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Apollo‐Soyuz O(³P) and N( 4 S) density measurement by UV spectroscopy
Author(s) -
Donahue T. M.,
Anderson J. G.,
Rawlins W. T.,
Kaufman F.,
Hudson R. D.
Publication year - 1977
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl004i002p00079
Subject(s) - apollo , physics , spacecraft , collimated light , spectral line , orbital inclination , spectroscopy , radiation , geology , astrophysics , optics , astronomy , laser , mathematics , zoology , binary number , biology , arithmetic
The densities of O(³P) and N( 4 S) at 225 km were determined during the Apollo‐Soyuz Test Project by a resonance absorption‐fluorescence technique in which OI and NI line radiation produced and collimated on board the Apollo was reflected from the Soyuz back to the Apollo for spectral analysis. The two spacecraft maneuvered so that a range of observation angles of ± 15° with respect to the normal to the orbital velocity vector was scanned. The measurements described here were made at night, July 19, 1975, on two consecutive orbits at spacecraft separations of 150 and 500 m. The results indicate [O] = 1.15 × 10 9 cm −3 ± 30% agreeing with mass spectrometric measurements made under similar conditions, and 5.6 × 10 6 cm −3 ≤ [N] ≤ 11.2 × 10 6 cm −3 , in good agreement with recent measurements but suggesting a smaller diurnal variation than predicted by present models.