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We present an instrumentation plan for spectral imaging of MercuryÏs extended atmosphere. The approach depends upon simultaneous short-exposure images in white light and sodium, with the former used to select the frames for postintegration of the sodium images. The e †ects of atmospheric seeing are thus minimized by the combination of high-speed exposures(More)
We describe and compare two methods of short-exposure, high-deÿnition ground-based imaging of the planet Mercury. Two teams have recorded images of Mercury on diierent dates, from diierent locations, and with diierent observational and data reduction techniques. Both groups have achieved spatial resolutions of ¡ 250 km, and the same albedo features and(More)
We present observations of the lunar sodium atmosphere during four lunar eclipses between 1993 and 1997. With the Moon inside the magnetosphere, and therefore shielded from solar wind impact, we find its Na atmosphere to be comparable in abundance to cases near first and third quarter, implying that solar wind ion sputtering is not a significant source of(More)
On Jupiter's moon Io, volcanic plumes and evaporating lava flows provide hot gases to form an atmosphere that is subsequently ionized. Some of Io's plasma is captured by the planet's strong magnetic field to form a co-rotating torus at Io's distance; the remaining ions and electrons form Io's ionosphere. The torus and ionosphere are also depleted by three(More)
[1] Observations of sodium emission from Mercury can be used to describe the spatial and temporal patterns of sources and sinks in the planet's surface-boundary-exosphere. We report on new data sets that provide the highest spatial resolution of source regions at polar latitudes, as well as the extraordinary length of a tail of escaping Na atoms. The tail's(More)
Dramatic changes in the brightness and shape of Jupiter's extended sodium nebula are found to be correlated with the infrared emission brightness of Io. Previous imaging and modeling studies have shown that varying appearances of the nebula correspond to changes in the rate and the type of loss mechanism for atmospheric escape from Io. Similarly, previous(More)
[1] Trans-ionospheric radio propagation effects resulting in ranging errors are examined for a potential orbital network of communications and navigational satellites at Mars. Using recent results from the radio science experiment on board the Mars Global Surveyor (MGS) spacecraft and a photochemical model of Mars' ionosphere, we study the total electron(More)
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