Morphology of the Venus ultraviolet night airglow
122
Citation
24
Reference
10
Related Paper
Citation Trend
Abstract:
Images of the nightside of Venus in the (0,1)δ band of nitric oxide have been obtained by the Pioneer Venus orbiter ultraviolet spectrometer (OUVS). The emission, which is produced by radiative association of N and O, shows a bright spot reaching ∼5 kR and located at 2 a.m. local solar time just south of the equator. The emitting layer is at 111±7‐km altitude. A one dimensional vertical transport model shows that the hemispheric average brightness of 0.8 kR is consistent with the orbiter neutral mass spectrometer (ONMS) measurements of N and O near 167 km, and that the altitude of the emitting layer is consistent with the eddy mixing model proposed to explain the dayside helium profile measured by the bus neutral mass spectrometer. In the model, N reaches a peak of 7 × 10 8 cm −3 at 114 km, and O reaches a peak of 2.6 × 10 11 cm −3 at 106 km. There is a fair degree of consistency between the ONMS, OUVS, and other airglow measurements, except as regards the local time dependence.Keywords:
Airglow
Orbiter
Atmosphere of Venus
Mixing ratio
During the last orbital sequences of the Pioneer‐Venus spacecraft prior to final encounter and atmospheric entry, data were obtained by the Orbiter Ion Mass Spectrometer (OIMS) at the lowest periapsis altitudes of the mission. These data verified OIMS observations of the nightside ionospheric peak reported earlier in the mission, and revealed additional details related to composition, energetics and maintenance of the nightside ionosphere. OIMS observations of the ion peak during the final encounter sequence are compared with radio occultation data and OIMS peak observations obtained earlier. OIMS ion density and Orbiter Electron Temperature Probe (OETP) electron density are found to correlate near the peak. Coupling of mass channels 30 and 32 during nightside passes is observed and its interpretation considered. Changes in high altitude composition of the nightside ionosphere, especially the relative changes in O + and H + , are described.
Orbiter
Atmosphere of Venus
Radio occultation
Atmospheric entry
Cite
Citations (5)
Airglow
Line (geometry)
Cite
Citations (7)
From the Pioneer Venus, as well as the Venera 11 and 12 spacecrafts, data on the chemical composition of the Venus atmosphere from about 700 km to the surface were obtained. In general, reasonable consistency can be found among the results from the seven gas analyzers that encountered Venus in December 1978. One of the more significant findings is the large excess abundance of primordial gases on Venus. The O 2 abundances below 30 km must be very small, since none of the instruments detected O 2 there. In and near the clouds the O 2 mixing ratio may be as much as a few tens of parts per million. The CO mixing ratio is 20–30 ppm. The existence of COS, originally reported to be a major sulfur compound in the lowest part of the atmosphere, is doubtful there, and its mixing ratio at higher altitudes does not exceed a few parts per million. On the other hand, SO 2 may exist below the clouds at a mixing ratio of the order of 100 ppm. In the clouds it is less than 10 ppm. A serious discrepancy in the data still exists for the case of the water vapor abundance. As a result of the cross‐checks provided by the number and types of instruments flown to Venus, confidence in the validity of these results on its atmospheric composition has progressed to a reasonable degree of certitude.
Atmosphere of Venus
Mixing ratio
Cite
Citations (87)
Airglow
Atomic oxygen
Cite
Citations (2)
Further results from the Venus orbiter radiometric temperature experiment (VORTEX) on the Pioneer orbiter are presented. These are used to characterize the three-dimensional temperature field, the cloud structure, and the dynamics of the 60-to 130-kilometer altitude region of the Venus atmosphere. One of the new discoveries is a "dipole" structure at high latitudes, with two hot spots rotating around the pole, surrounded by banks of cold cloud.
Orbiter
Atmosphere of Venus
Cite
Citations (51)