A DEVICE FOR TAKING INTO ACCOUNT THE ALTITUDE OF AN AIRCRAFT DURING AERO- GAMMA-SURVEYING

ATOMMS represents a new class of active, airborne, limb-viewing spectrometer that is a cross between Global Positioning System (GPS) occultations and NASA's Microwave Limb Sounder. ATOMMS will characterize atmospheric water vapour and ozone by actively probing the absorption lines at 22.2 GHz, 183.3 GHz and 195 GHz, respectively. Two instrument packages are being constructed for NASA's WB-57F high altitude research aircraft, now equipped with precise WAVES gimballed pointing systems. One aircraft will generate multiple tones near the 22 GHz water line and 183 GHz to 204 GHz absorption lines and transmit them across the Earth's limb through the atmosphere to receivers on a second aircraft. Flight paths of the two aircraft begin over the horizon, with the two aircraft flying at 65 kft altitude. This creates a rising occultation geometry as the aircrafts fly towards each other. ATOMMS provides the sensitivity, vertical spatial resolution and accuracy needed to satisfy key monitoring needs for temperature, pressure, moisture and ozone. The 100 to 200 m ATOMMS vertical resolution will far surpass the 1 to 4 km vertical resolution of present state-of-the-art satellite radiometers opening a window into atmospheric scales previously inaccessible from space. Predicted precisions of individual ATOMMS temperature, pressure and moisture profiles are unprecedented at ~0.4 K, 0.1% and 1-3% respectively, extending from near the surface to the flight altitude of ~20 km. ATOMMS ozone profiles precise to 1-3% will extend from the upper troposphere well into the mesosphere. Other trace constituents such as water isotopes can be measured with performance similar to that of ozone. The ATOMMS experiment is a pathfinder experiment for eventual implementation on a constellation of satellites. Space observations from multiple satellites in precessing orbits will allow for global spatial coverage and increased altitude coverage. Our long term goal is a constellation of approximately a dozen small spacecraft making ATOMMS measurements that will provide dense, global coverage and complete cloud- penetration and diurnal sampling every orbit. The ATOMMS instruments have been completed and are now undergoing extensive laboratory and ground testing. We report on the laboratory testing results including the differential amplitude and phase stability of the instrument and systems integration testing. We will also report on ground testing experiments, where the ATOMMS instruments, located on two building tops, were used to measure atmospheric water vapour content. Comparison measurements were made using in-situ hygrometers. Further ground-based tests are planned to exercise the full ATOMMS system, including the GPS-based positioning and time correction system, accelerometer system and dual-one-way phase correction system. We will also discuss planned instrument upgrades to be implemented in preparation for air-to-ground and air-to-air flights on the WB-57F aircraft.

A description is given of a wide dynamic range pulse height analyzer system developed for use on High Energy Cosmic Ray Experiment (HECRE) Balloon Flights. A wide dynamic range of 100,000 is obtained by extending the range of a basic 1024 channel analyzer through the use of multiple ranges and range selection. The system described here contains four 100,000 pulse height analyzers. Each 100,000 pulse height analyzer consists of a group of cordwood welded modules mounted and interconnected on a printed circuit card. Four of these card assemblies, the required clock drive circuitry (discrete components mounted and interconnected on a separate card) and three input-output connectors are interconnected and mounted on the system board.

The goals, design and performance characteristics of the Solar Flux Radiometer flown on the Large Probe of the Pioneer-Venus Multiprobe spacecraft launched on 8 August 1978 are described. Radiance measurements of the Venusian atmosphere in several spectral channels between 400 and 1800 nm as a function of altitude were made to further understand the role of solar radiation in the thermal balance of the atmosphere. Elevation and azimuthal measurements on the radiation field were made with five optical channels. Twelve filtered Si and Ge photovoltaic detectors were maintained near 30°C with a phase-change material. The detector output currents were processed with logarithmic transimpedance converters before being multipliexed and digitized with an 11-bit A/D converter. Atmospheric sampling in both elevation and azimuth was done according to a Gaussian integration scheme. The data output was serial digital at an average rate of 20 bits/sec and included housekeeping (sync, spin period, sample timing and mode). The received data were used to determine the deposition of solar energy in the atmosphere of Venus along with upward and downward fluxes and radiances with an altitude resolution of several hundred meters between 67 km and the surface.

Abstract. This paper presents details of the University of Colorado (CU) “Pilatus” unmanned research aircraft, assembled to provide measurements of aerosols, radiation and thermodynamics in the lower troposphere. This aircraft has a wingspan of 3.2 m and a maximum take-off weight of 25 kg, and it is powered by an electric motor to reduce engine exhaust and concerns about carburetor icing. It carries instrumentation to make measurements of broadband up- and downwelling shortwave and longwave radiation, aerosol particle size distribution, atmospheric temperature, relative humidity and pressure and to collect video of flights for subsequent analysis of atmospheric conditions during flight. In order to make the shortwave radiation measurements, care was taken to carefully position a high-quality compact inertial measurement unit (IMU) and characterize the attitude of the aircraft and its orientation to the upward-looking radiation sensor. Using measurements from both of these sensors, a correction is applied to the raw radiometer measurements to correct for aircraft attitude and sensor tilt relative to the sun. The data acquisition system was designed from scratch based on a set of key driving requirements to accommodate the variety of sensors deployed. Initial test flights completed in Colorado provide promising results with measurements from the radiation sensors agreeing with those from a nearby surface site. Additionally, estimates of surface albedo from onboard sensors were consistent with local surface conditions, including melting snow and bright runway surface. Aerosol size distributions collected are internally consistent and have previously been shown to agree well with larger, surface-based instrumentation. Finally the atmospheric state measurements evolve as expected, with the near-surface atmosphere warming over time as the day goes on, and the atmospheric relative humidity decreasing with increased temperature. No directional bias on measured temperature, as might be expected due to uneven heating of the sensor housing over the course of a racetrack pattern, was detected. The results from these flights indicate that the CU Pilatus platform is capable of performing research-grade lower tropospheric measurement missions.

Abstract γ photons altimeter, which is a low altitude measurement of the spacecraft based on Compton effect at the moment when it lands on earth, is an important equipment for spacecraft landing control. Manned spacecraft landing control needs γ-ray altitude control system to revise ignition signal for retrograde landing rocket at different landing speed. To make the spacecraft speed zero at the moment landing on the surface, a method that makes ignition altitude correction of the spacecraft at different landing speeds is figured out, which is based on the number of γ-ray particles reflected field gradient. According to the established theoretical model, the method feasibility is proved by a mathematical derivation and verified by an experiment, and the adaptability of the method under different parameters is also described. The results indicate that the error of the altitude signal error is less than 0.05 m at the height of 0.5 m to 1.5 m when the landing speed of spacecraft is in the range of 6 m/s to 10 m/s. The method provided has great significance for the manned spacecraft engineering need.

Monitoring the ambient dose equivalent rate at aviation altitudes is an ambitious task, which requires sophisticated dosemeter systems and the possibility to carry out such measurements on board aircraft. A rather simple approach has been investigated in this study: soundings with weather balloons up to an altitude of 30 km. This paper summarises the measurements carried out between 2011 and 2016. The results indicate that annual measurements of the ambient dose equivalent rate at altitudes of around 20 km are a reliable tool to monitor the variation of the dose rate in the atmosphere owing to the solar activity.

The experiment (Project Apeiro) aims to determine cosmic ray flux in the lower stratospheric regions of the atmosphere by deploying a measurement instrument on a High-Altitude Balloon platform. This paper illustrates the design and construction of the experimental equipment and also highlights the precautions and tests undertaken to qualify the instrument for a near-space flight. Cosmic ray flux is measured by using detectors constructed with an optically coupled combination of scintillator blocks and photo-multiplier tubes. The signal from the detectors is recorded with a high speed data acquisition system (DAQ). The flight computer acquires data from the DAQ and other sensors and stores them on a memory. The flight data is also continuously transmitted to the ground station over a telemetry channel. The flight was conducted from Hyderabad, India on February 2, 2019. Preliminary analysis of the flight indicates nominal operation of all equipment, and has been presented in this paper.

The use of sounding rockets for calibrating solar cells offers two principal advantages: there is no effect due to the terrestrial atmosphere and the cells are recoverable immediately after calibration. Four n/p photovoltaic cells were calibrated in space and successfully recovered from a NASA Aerobee rocket that reached a peak altitude of 251 km. Two of the cells were optically filtered with 0.6 to 0.9-micron bandpass filters. The short-circuit current agreed to within 4% of the laboratory calibration; variation of cell output due to atmospheric attenuation in the altitude range of 80 to 251 km was 0.4% for the unfiltered cells.

Bonded to aircraft skin, it facilitates cloud avoidance. Airborne cloud detector consists of three major components: Aluminum patch durably bonded to aircraft skin, surge arrester, and dual-sensitivity charge-rate amplifier. Operation based on fact that aircraft surfaces become charged when ice or water particles strike them. Using increased gain sensitivities, cloudparticle detector reliable, noise-free, low-cost, high-sensitivity indicator of type of clouds that cause most problems for LFC aircraft at cruise altitude.