Analysis of Anechoic Chamber Testing of the Hurricane Imaging Radiometer

The Hurricane Imaging Radiometer System (HIRAD) is a new airborne passive microwave remote sensor developed to observe hurricanes. HIRAD incorporates synthetic thinned array radiometry technology, which use Fourier synthesis to reconstruct images from an array of correlated antenna elements. The HIRAD system response to a point emitter has been measured in an anechoic chamber. With this data, a Fourier inversion image reconstruction algorithm has been developed. Performance analysis of the apparatus is presented, along with an overview of the image reconstruction algorith

The NASA CYGNSS Mission; A Pathfinder for GNSS Scatterometry Remote Sensing Applications

ABSTRACT Global Navigation Satellite System (GNSS) based scatterometry offers breakthrough opportunities for wave, wind, ice, and soil moisture remote sensing. Recent developments in electronics and nano-satellite technologies combined with modeling techniques developed over the past 20 years are enabling a new class of remote sensing capabilities that present more cost effective solutions to existing problems while opening new applications of Earth remote sensing. Key information about the ocean and global climate is hidden from existing space borne observatories because of the frequency band in which they operate. Using GNSS-based bi-static scatterometry performed by a constellation of microsatellites offers remote sensing of ocean wave, wind, and ice data with unprecedented temporal resolution and spatial coverage across the full dynamic range of ocean wind speeds in all precipitating conditions. The NASA Cyclone Global Navigation Satellite System (CYGNSS) is a space borne mission being developed to study tropical cyclone inner core processes. CYGNSS consists of 8 GPS bi-static radar receivers to be deployed on separate micro-satellites in October 2016. CYGNSS will provide data to address what are thought to be the principle deficiencies with current tropical cyclone intensity forecasts: inadequate observations and modeling of the inner core. The inadequacy in observations results from two causes: 1) Much of the inner core ocean surface is obscured from conventional remote sensing instruments by intense precipitation in the eye wall and inner rain bands. 2) The rapidly evolving (genesis and intensification) stages of the tropical cyclone life cycle are poorly sampled in time by conventional polar-orbiting, wide-swath surface wind imagers. It is anticipated that numerous additional Earth science applications can also benefit from the cost effective high spatial and temporal sampling capabilities of GNSS remote sensing. These applications include monitoring of rough and dangerous sea states, global observations of sea ice cover and extent, meso-scale ocean circulation studies, and near surface soil moisture observations. This presentation provides a primer for GNSS based scatterometry, an overview of NASA's CYGNSS mission and its expected performance, as well as a summary of possible other GNSS based remote sensing applications

Vicarious Calibration of Global Precipitation Measurement Microwave Radiometers

The vicarious cold calibration method of Ruf has been used to assess the calibration of the TMI, WindSat, SSM/I F13 and SSM/I F14 microwave radiometers using data from the GPM Inter-Calibration Working Group. Significant scan position dependent biases are seen for TMI (as large as 1 K) and for WindSat (as large as 5 K) – scan position dependent biases in SSM/I data were removed prior to processing. These biases are thought to be due to obstructions in the edge of scan field of view from the given instrument and its spacecraft. WindSat vertically polarized data also show a linear decrease in vicarious cold calibration brightness temperatures with scan position. SSM/I F13 and F14 vicarious cold brightness temperatures differ by an amount consistent with a ~.2 ° offset in their relative Earth incidence angles

Nanosat Technology And Managed Risk; An Update Of The CYGNSS Microsatellite Constellation Mission Development

Existing and forecasted budget constraints continue to drive innovative solutions for space-based mission applications. NASA’s Earth science mission, the Cyclone Global Navigation Satellite System (CYGNSS) was selected as part of NASA\u27s Earth Venture program with a total mission cost cap (excluding launch vehicle) of $103M. Performing valuable science at low cost is only possible given technology innovation and a development risk posture higher than typically accepted for NASA missions. CYGNSS is being designed to address present tropical cyclone intensity forecasting deficiencies. These deficiencies are thought to be the root cause for essentially no improvement in the accuracy of the storm’s intensity prediction (Classification and Category levels) since 1990 while tropical storm track forecasts have improved in accuracy by ~50%. The mission will combine the all-weather performance of GNSS bi-static ocean surface scatterometry with the sampling properties of a satellite constellation to provide science measurements never before available to the tropical cyclone operational and research communities. The mission cost cap dictates that the CYGNSS flight segment of 8 Observatories, each carrying a 4-channel GPS-based scatterometer, all be launched on a single launch vehicle. The mission will demonstrate how recent developments in nano- and micro-satellite technology integration, including recent developments in star trackers and reaction wheels, when combined with a managed risk approach, can be applied as cost effective solutions to fill capability voids of large-scale observatories. CYGNSS will also demonstrate low cost science mission operations, how to safely deploy a constellation from a single launch vehicle without collision, and a low-cost method for constellation configuration management. The CYGNSS SmallSat 2014 paper will provide an update of the mission system development status, an overview of how a synergistic approach between flight and ground segments enables a cost effective science mission solution, and a description of our approach to constellation configuration control

The GRSS standard for GNSS-reflectometry

In February 2019 a Project Authorization Request was approved by the Institute of Electrical and Electronics Engineers (IEEE) Standards Association with the title “Standard for Global Navigation Satellite System Reflectometry (GNSS-R) Data and Metadata Content”. A Working Group has been assembled to draft this standard with the purpose of unifying and documenting GNSS-R measurements, calibration procedures, and product level definitions. The Working Group (http://www.grss-ieee.org/community/technical-committees/standards-or-earth-observations/) includes members, collaborators, and contributors from academia, international space agencies, and private industry. In a recent face-to-face meeting held during the ARSI+KEO 2019 Conference, the need was recognized to develop a standard with a wide range of operations, providing procedure guidelines independently of constraints imposed by current limitations on geophysical parameters retrieval algorithms. As such, this effort aims to establish the fundamentals of a potential virtual network of satellites providing inter-comparable data to the scientific community.Peer ReviewedPostprint (author's final draft

IEEE 4003-2021

27 páginasThe scope of this effort is to develop a standard for data and metadata content arising from spaceborne global navigation satellite system-reflectometry (GNSS-R) missions, which uses GNSS signals as signals of opportunity, as described in “The IEEE SA Working Group on Spaceborne GNSS-R: Scene Study.” In particular, this standard would provide a means for describing: a) The terminology assigned to GNSS-R data and products, such as the product levels. b) The structure and content of the data. This includes, but is not limited to, units of measure, data organization, data description, data encoding, and data storage format. c) The metadata. This includes and is not limited to metadata, methods and algorithms applied to the data, parameters related to the algorithms, citation information, instrument calibration and characterization, and description of the input signals. The purpose of this standard is to provide a set of specifications and recommended practices that can be used to describe any known and future spaceborne GNSS-R data set, allowing users to work with different GNSS-R data sets at the same time. The definition of such standard would also allow any software that uses these data to fully operate and ingest any spaceborne GNSS-R input data as they will conform to the same standard

Clinical grade ACE2 as a universal agent to block SARS-CoV-2 variants

The recent emergence of multiple SARS-CoV-2 variants has caused considerable concern due to both reduced vaccine efficacy and escape from neutralizing antibody therapeutics. It is, therefore, paramount to develop therapeutic strategies that inhibit all known and future SARS-CoV-2 variants. Here, we report that all SARS-CoV-2 variants analyzed, including variants of concern (VOC) Alpha, Beta, Gamma, Delta, and Omicron, exhibit enhanced binding affinity to clinical grade and phase 2 tested recombinant human soluble ACE2 (APN01). Importantly, soluble ACE2 neutralized infection of VeroE6 cells and human lung epithelial cells by all current VOC strains with markedly enhanced potency when compared to reference SARS-CoV-2 isolates. Effective inhibition of infections with SARS-CoV-2 variants was validated and confirmed in two independent laboratories. These data show that SARS-CoV-2 variants that have emerged around the world, including current VOC and several variants of interest, can be inhibited by soluble ACE2, providing proof of principle of a pan-SARS-CoV-2 therapeutic

Syncytiotrophoblast Microvesicles Released from Pre-Eclampsia Placentae Exhibit Increased Tissue Factor Activity

Background: Pre-eclampsia is a complication of pregnancy associated with activation of coagulation. It is caused by the placenta, which sheds increased amounts of syncytiotrophoblast microvesicles (STBM) into the maternal circulation. We hypothesized that STBM could contribute to the haemostatic activation observed in pre-eclampsia. Methodology/Principal Findings: STBM were collected by perfusion of the maternal side of placentae from healthy pregnant women and women with pre-eclampsia at caesarean section. Calibrated automated thrombography was used to assess thrombin generation triggered by STBM-borne tissue factor in platelet poor plasma (PPP). No thrombin was detected in PPP alone but the addition of STBM initiated thrombin generation in 14/16 cases. Pre-eclampsia STBM significantly shortened the lag time (LagT, P = 0.01) and time to peak thrombin generation (TTP, P = 0.005) when compared to normal STBM. Blockade of tissue factor eliminated thrombin generation, while inhibition of tissue factor pathway inhibitor significantly shortened LagT (p = 0.01) and TTP (P,0.0001), with a concomitant increase in endogenous thrombin potential. Conclusions/Significance: STBM triggered thrombin generation in normal plasma in a tissue factor dependent manner, indicating that TF activity is expressed by STBM. This is more pronounced in STBM shed from pre-eclampsia placentae. As more STBM are shed in pre-eclampsia these observations give insight into the disordered haemostasis observed in thi