The Ionospheric Connection Explorer - Prime Mission Review.

The two-year prime mission of the NASA Ionospheric Connection Explorer (ICON) is complete. The baseline operational and scientific objectives have been met and exceeded, as detailed in this report. In October of 2019, ICON was launched into an orbit that provides its instruments the capability to deliver near-continuous measurements of the densest plasma in Earth's space environment. Through collection of a key set of in-situ and remote sensing measurements that are, by virtue of a detailed mission design, uniquely synergistic, ICON enables completely new investigations of the mechanisms that control the behavior of the ionosphere-thermosphere system under both geomagnetically quiet and active conditions. In a two-year period that included a deep solar minimum, ICON has elucidated a number of remarkable effects in the ionosphere attributable to energetic inputs from the lower and middle atmosphere, and shown how these are transmitted from the edge of space to the peak of plasma density above. The observatory operated in a period of low activity for 2 years and then for a year with increasing solar activity, observing the changing balance of the impacts of lower and upper atmospheric drivers on the ionosphere.

Exospheric Temperature Measured by NASA-GOLD Under Low Solar Activity: Comparison With Other Data Sets.

Exospheric temperature is one of the key parameters in constructing thermospheric models and has been extensively studied with in situ observations and remote sensing. The Global-scale Observations of the Limb and Disk (GOLD) at a geosynchronous vantage point provides dayglow limb images for two longitude sectors, from which we can estimate the terrestrial exospheric temperature since 2018. In this paper, we investigate climatological behavior of the exospheric temperature measured by GOLD. The temperature has positive correlations with solar and geomagnetic activity and exhibits a morning-afternoon asymmetry, both of which agree with previous studies. We have found that the arithmetic sum of F10.7 (solar) and Ap (geomagnetic) indices is highly correlated with the exospheric temperature, explaining ∼64% of the day-to-day variability. Furthermore, the exospheric temperature has good correlation with thermospheric parameters (e.g., neutral temperature, O2 density, and NO emission index) sampled at various heights above ∼130 km, in spite of the well-known thermal gradient below ∼200 km. However, thermospheric temperature at altitudes around 100 km is not well correlated with the GOLD exospheric temperature. The result implies that effects other than thermospheric heating by solar Extreme Ultraviolet and geomagnetic activity take control below a threshold altitude that exists between ∼100 and ∼130 km.

Cloud Formation From a Localized Water Release in the Upper Mesosphere: Indication of Rapid Cooling.

Polar mesospheric clouds (PMCs) occur in the summer near 82 -85km altitude due to seasonal changes of temperature and humidity. However, water vapor and associated PMCs have also been observed associated with rocket exhaust. The effects of this rocket exhaust on the temperature of the upper mesosphere are not well understood. To investigate these effects, 220 kg of pure water was explosively released at 85 km as part of the Super Soaker sounding rocket experiment on the night of January 25-26, 2018 at Poker Flat Research Range (65°N, 147°W). A cloud formed within 18 s and was measured by a ground-based Rayleigh lidar. The peak altitude of the cloud appeared to descend from 92 to 78 km over 3 min. Temperatures leading up to the release were between 197 and 232 K, about 50 K above the summertime water frost point when PMCs typically occur. The apparent motion of the cloud is interpreted in terms of the expansion of the explosive release. Analysis using a water vapor radiative cooling code coupled to a microphysical model indicates that the cloud formed due to the combined effects of rapid radiative cooling (∼25 K) by meter-scale filaments of nearly pure water vapor (∼1 ppv) and an increase in the frost point temperature (from 150 to 200 K) due to the high concentration of water vapor. These results indicate that water exhaust not only acts as a reservoir for mesospheric cloud production but also actively cools the mesosphere to induce cloud formation.

Retrieval of Lower Thermospheric Temperatures from O2 A Band Emission: The MIGHTI Experiment on ICON.

The Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) is a satellite experiment scheduled to launch on NASA's Ionospheric Connection Explorer (ICON) in 2017. MIGHTI is designed to measure horizontal neutral winds and neutral temperatures in the terrestrial thermosphere. Temperatures will be inferred by imaging the molecular oxygen Atmospheric band (A band) on the limb in the lower thermosphere. MIGHTI will measure the spectral shape of the A band using discrete wavelength channels to infer the ambient temperature from the rotational envelope of the band. Here we present simulated temperature retrievals based on the as-built characteristics of the instrument and the expected emission rate profile of the A band for typical daytime and nighttime conditions. We find that for a spherically symmetric atmosphere, the measurement precision is 1 K between 90-105 km during the daytime whereas during the nighttime it increases from 1 K at 90 km to 3 K at 105 km. We also find that the accuracy is 2 K to 11 K for the same altitudes. The expected MIGHTI temperature precision is within the measurement requirements for the ICON mission.

Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI): Instrument Design and Calibration.

The Michelson Interferometer for Global High-resolution imaging of the Thermosphere and Ionosphere (MIGHTI) instrument was built for launch and operation on the NASA Ionospheric Connection Explorer (ICON) mission. The instrument was designed to measure thermospheric horizontal wind velocity profiles and thermospheric temperature in altitude regions between 90km and 300km, during day and night. For the wind measurements it uses two perpendicular fields of view pointed at the Earth's limb, observing the Doppler shift of the atomic oxygen red and green lines at 630.0nm and 557.7nm wavelength. The wavelength shift is measured using field-widened, temperature compensated Doppler Asymmetric Spatial Heterodyne (DASH) spectrometers, employing low order échelle gratings operating at two different orders for the different atmospheric lines. The temperature measurement is accomplished by a multichannel photometric measurement of the spectral shape of the molecular oxygen A-band around 762nm wavelength. For each field of view, the signals of the two oxygen lines and the A-band are detected on different regions of a single, cooled, frame transfer charge coupled device (CCD) detector. On-board calibration sources are used to periodically quantify thermal drifts, simultaneously with observing the atmosphere. The MIGHTI requirements, the resulting instrument design and the calibration are described.

Lead and the deafness of Ludwig van Beethoven.

OBJECTIVES/HYPOTHESIS: To reexamine the cause of Beethoven's hearing loss because of significant recent articles. DATA SOURCES: Medical and musical literature online, in print, and personal communication. METHODS: Relevant literature review. RESULTS: Evidence of otosclerosis is lacking because close gross examination of Beethoven's middle ears at autopsy did not find any otosclerotic foci. His slowly progressive hearing loss over a period of years differs from reported cases of autoimmune hearing loss, which are rapidly progressive over a period of months. He also lacked bloody diarrhea that is invariably present with autoimmune inflammatory bowel disease. The absence of mercury in Beethoven's hair and bone samples leads us to conclude that his deafness was not due to syphilis because in that era syphilis was treated with mercury. High levels of lead deep in the bone suggest repeated exposure over a long period of time rather than limited exposure prior to the time of death. The finding of shrunken cochlear nerves at his autopsy is consistent with axonal degeneration due to heavy metals such as lead. Chronic low-level lead exposure causes a slowly progressive hearing loss with sensory and autonomic findings, rather than the classic wrist drop due to motor neuropathy from sub-acute poisoning. Beethoven's physicians thought that he had alcohol dependence. He particularly liked wine that happened to be tainted with lead. CONCLUSIONS: Beethoven's chronic consumption of wine tainted with lead is a better explanation of his hearing loss than other causes.

Pain reduction by fibrin sealant in older children and adult tonsillectomy.

OBJECTIVES: Because tonsillectomy is a painful procedure in adults, this study was performed to see whether the addition of fibrin sealant (Tisseel) to the tonsillar fossa at the completion of tonsillectomy would reduce pain in adults and allow them to return to work sooner. STUDY DESIGN: Forty adult patients over the age of 12 were entered into a prospective randomized study to see whether the addition of fibrin sealant (Tisseel) to the tonsillar fossa at the completion of tonsillectomy for recurrent tonsillitis would reduce the time the patient needed to take narcotic analgesics after surgery. METHODS: Fifteen adults had a traditional complete tonsillectomy by means of a needle point Bovie and served as a control group. Twenty-five (adults had the same procedure with the addition of Tisseel to see how long they required narcotic analgesics postoperatively and when they were able to resume normal activities. RESULTS: The control group took narcotics for an average of 10.3 days, whereas the addition of Tisseel reduced the time to 8.16 days (P = .0058). This significant reduction of time allowed adults to return to work and other activities sooner. CONCLUSION: Because the time required to return to work is often of paramount interest to patients having surgery, Tisseel should be considered a safe addition to older children and adult tonsillectomy in patients who are not allergic to bovine products because it will allow an earlier return to normal activities.

Otolaryngologic manifestations of Hansens disease

A Mexican migrant farm worker whose condition was previously undiagnosed was examined at the University of Utah Medical Center. He had an unusual peripheral neuropathy, ulcerative and nodular skin lesions, and multiple head and neck complaints. Results of the history, physical examination, and multiple biopsies led to the diagnosis of lepromatous leprosy. Although an uncommon disease in the United States, leprosy remains a common cause of head and neck pathologic conditions in many parts of the world and must be considered in the appropriate clinical setting.