The collision between the exhaust from the Primary Reaction Control System (PRCS) engines (870 pounds thrust) of the space shuttle and the ambient atmosphere has been observed from the Air Force Maui Optical Station (AMOS). Spectra have been obtained in the wavelength region near 630 nm. The temporal, spatial, and spectral distribution of the emission in this region has been recorded. The results reported here indicate that when the exhaust of the space shuttle interacts with the atmosphere in the ram direction, an intense, long-lasting emission at 630 nm due to O(1D --> 3p) is generated. A substantial amount of O(1D) is swept back onto the orbiter. Two processes are proposed for the formation of O(1D): (1) excitation of atmospheric O(3p) by collisions with the exhaust of the space shuttle engines; and (2) charge exchange between ambient O + and exhaust H20. Calculations using the SOCRATES code show excellent agreement with the data. 19,501

Ground‐based video photography of firings of Space Shuttle Primary Reaction Control System (PRCS) engines show optical emissions extending nearly 4 km from the vehicle after steady state is reached. The total intensity and spatial distribution of these emissions depend on the angle between the spacecraft velocity vector and the engine exhaust axis. Candidate sources for this radiation are reviewed and the conclusion is reached that it is most likely due to vibrationally excited OH, formed by the reaction of fast ambient O atoms and H2O molecules in the exhaust.

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Sixty-two temperature sections were taken to depths of 800 m by aircraft along Geosat ground tracks within 1-2 days of the satellite orbit. The sections are 500-700 km long and cross the Gulf Stream and its rings. From pairs of sections that repeat on the same ground track, collinear differences of geopotential anomaly (0/25 MPa) and the depth of the 16øC isotherm were collected as along-track signals of the change of baroclinic conditions. The corresponding collinear differences of sea elevation were collected from the Geosat orbits. These difference signals, from aircraft and altimeter, were fit to one another along common ground track segments by removing residual orbit error as a tilt and bias and proportionally scaling the magnitudes of the signals. The ratio of geopotential anomaly to sea elevation by this method is 0.84 -0.10 dyn m m -1 . That is, fluctuations of geopotential anomaly which correlate to sea elevation across the Gulf Stream are smaller by this proportional value. The difference of this ratio from unity is consistent with a barotropic signal of about 0.10 m, as estimated from reported measurements of abyssal velocity under the stream. Because the uncertainties in the aircraft data are of the same order as the scatter in the calibration, it is unclear whether greater precision is impeded primarily by these uncertainties or by random barotropic signals. The ratio of the displacement of 16øC to sea elevation is 480 +--75. ß ß ß ß ß e e ß ß ß ß ß ß ß e e ß ß ß ß I ß ß 0 0o 0-0 0 0 ß ß ß ß o ß ß ß ß ß ß ß ß •••ooooooooo,-•,-000000000000 TRACK Fig. 13. (a) Computations of Az16/Aqba using collinear combinations of aircraft sections. (b) Computations of z16/qba using individual sections from Table 1.

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