Michael Mendillo

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Atomic sodium is a useful tracer of the tenuous lunar atmosphere because of its high efficiency in scattering sunlight at the D(1) (5896 angstroms) and D(2) (5890 angstroms) wavelengths. In 1988, Earth-based instruments revealed the presence of sodium at a density of less than 50 atoms per cubic centimeter at lunar altitudes below 100 kilometers. Telescopic(More)
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)
Optical diagnostic techniques have been applied to studies of equatorial aeronomy for nearly half a century. The use of scanning photometers and two-dimensional imagers to observe the spatial patterns associated with low-latitude emissions has been an increasingly used approach during the last few decades. In this paper we review the rationale for the use(More)
All planetary atmospheres respond to the enhanced x-rays and ultraviolet (UV) light emitted from the Sun during a flare. Yet only on Earth are observations so continuous that the consequences of these essentially unpredictable events can be measured reliably. Here, we report observations of solar flares, causing up to 200% enhancements to the ionosphere of(More)
 Mars' peak electron density data used to make semi-empirical global model 12  Mars ionosphere model extends from 1964 through 2019 13  Mars ionospheric model available for upcoming NASA MAVEN mission 14 15 16 17 18 19 2 Abstract 20 Observations of the ionosphere of Mars have now reached a sufficient number to 21 begin discussions on how best to create(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 the first 3-dimensional self-consistent calculations of the response of Saturn's global thermosphere to different sources of external heating, giving local time and latitudinal changes of temperatures, winds and composition at equinox and solstice. Our calculations confirm the well-known finding that solar EUV heating alone is insufficient to(More)
—Solar-terrestrial interactions produce a rich variety of optical emissions in the Earth's upper atmosphere (100–1000 km). While ground based brightness measurements (i.e., column integrated photon density) provide an important diagnostic of these processes, the more interesting physics is in the associated volume emission rate distribution (i.e., photon(More)
In this paper we present the first coordinated use of Global Positioning System (GPS) multisite and multisatellite observations with ground based radar and optical diagnostics to investigate equatorial irregularity patterns. Thirty second samples of total electron content (TEC) obtained from GPS phase differences between 1.2-and 1.6-GHz signals are used to(More)