Charge Analyzer Responsive Local Oscillations

The first transatlantic radio transmission, demonstrated by Marconi in December of 1901, revealed the essential role of the ionosphere for radio communications. This ionized layer of the upper atmosphere controls the amount of radio power transmitted through, reflected off of, and absorbed by the atmospheric medium. Low-frequency radio signals can propagate long distances around the globe via repeated reflections off of the ionosphere and the Earth's surface. Higher frequency radio signals can punch through the ionosphere to be received at orbiting satellites. However, any turbulence in the ionosphere can distort these signals, compromising the performance or even availability of space-based communication and navigations systems. The physics associated with this distortion effect is analogous to the situation when underwater images are distorted by convecting air bubbles. In fact, these ionospheric features are often called 'plasma bubbles' since they exhibit some of the similar behavior as underwater air bubbles. These events, instigated by solar and geomagnetic storms, can cause communication and navigation outages that last for hours. To help understand and predict these outages, a world-wide community of space scientists and technologists are devoted to researching this topic. One aspect of this research is to develop instruments capable of measuring the ionospheric plasma bubbles. Figure 1 shows a photo of the Charge Analyzer Responsive to Local Oscillations (CARLO), a new instrument under development at NASA Marshall Space Flight Center (MSFC). It is a frequency-domain ion spectrum analyzer designed to measure the distributions of ionospheric turbulence from 1 Hz to 10 kHz (i.e., spatial scales from a few kilometers down to a few centimeters). This frequency range is important since it focuses on turbulence scales that affect VHF/UHF satellite communications, GPS systems, and over-the-horizon radar systems. CARLO is based on the flight-proven Plasma Local Anomalous Noise Environment (PLANE) instrument, previously flown on a U.S. Air Force low-Earth orbiting satellite, which successfully measured ion turbulence in five frequency decades from 0.1 Hz to 10 kHz (fig 2)

ISS Local Environment Spectrometers (ISLES)

In order to study the complex interactions between the space environment surrounding the ISS and the ISS surface materials, we propose to use lowcost, high-TRL plasma sensors on the ISS robotic arm to probe the ISS space environment. During many years of ISS operation, we have been able to condut effective (but not perfect) extravehicular activities (both human and robotic) within the perturbed local ISS space environment. Because of the complexity of the interaction between the ISS and the LEO space environment, there remain important questions, such as differential charging at solar panel junctions (the so-called "triple point" between conductor, dielectric, and space plasma), increased chemical contamination due to ISS surface charging and/or thruster activation, water dumps, etc, and "bootstrap" charging of insulating surfaces. Some compelling questions could synergistically draw upon a common sensor suite, which also leverages previous and current MSFC investments. Specific questions address ISS surface charging, plasma contactor plume expansion in a magnetized drifting plasma, and possible localized contamination effects across the ISS

SPORT Mission Science

No abstract availabl

Eigenanalysis of Space Weather Climate Data: Discovering Structure within Large Multivariate Data Sets

No abstract availabl

Progress toward Miniature Space Weather Stations

Responding to a growing need to specify (nowcast) and predict (forecast) hazardous space weather events and their deleterious effects on space systems, the authors have developed a prototype suite of instruments that would serve as a key component of a miniature space weather station. Space environment data have been gathered over several solar cycles, and though these data assist space operators in predicting hazards to space systems based upon derived climatology, no true forecasting ability yet exists. (As an analogy, consider for example the difference between tropospheric weather reports based on data-driven forecast models versus a prediction based upon the average temperature for a given city on a given date over the last hundred years.) True space weather forecasting models require assimilation of space-based in situ data into physics-based models. Data collection of fundamental characteristics, such as plasma density and temperature, neutral wind and bulk ion velocity, and electric and magnetic field strengths is required at multiple grid points, similar to tropospheric weather stations that measure temperature, wind speed, humidity, etc. Recent breakthroughs in fabrication techniques have enabled the development of a suite of instruments that is comprised of 16 individual analyzers, each of which is capable of providing a unique measurement of a partially ionized space environment. The suite is designed to measure ion spectra differential in energy and angle, bulk ion velocities, bulk neutral velocities, and ion and neutral mass spectra. Preliminary functional testing has indicated the ability to resolve He, O, O2, and Ar; separation of O2 and N2 has proved elusive to date. In the prototype suite, the instrument assembly that houses the 16 analyzers is stacked to a conventional Printed Circuit Board (PCB) with anodes and circuit components and an electronics enclosure containing a high voltage power supply, amplifier Application Specific Integrated Circuits (ASICs), and a Rad Hard microcontroller. The suite configuration, including all aforementioned components, has a total volume of 7 cm ´ 7 cm ´ 4 cm = 196 cm3, a mass of 400 g, and a peak power requirement of 1.5 W (for neutral measurements). Challenges inherent to miniaturization of spacecraft capable of providing real utility are identified and addressed

High-Frequency Density Oscillations from a Plasma Source Used for Simulating Low-Earth Orbit Plasma Environment

We present data from ground-based, vacuum-chamber tests demonstrating the ability to modulate the output of a plasma source capable of producing a low-Earth orbit (LEO) type plasma. We obtained plasma oscillations up to 2.5 kHz impingent on stationary test equipment, which corresponds to meter-level ionospheric structures in LEO. This plasma source is, therefore, suitable for developing scientific instruments that measure the LEO plasma environment, in situ, with meter-level spatial resolution. Measurements were made using a fixed-bias collector and an electrometer sampling at 40 kHz. A mechanical aperture was established at the output of the plasma source via two concentric grids. The outer grid was free to rotate in the azimuthal direction with respect to the fixed inner grid. An identical, alternating hole pattern in the two grids resulted in a variable aperture that cycles through 90 open/close cycles per revolution. The frequency of the plasma oscillations is limited by the mechanism used to spin the grids and the bearing assembly on which the grids rotate. Higher frequencies are obtainable by upgrading the drive mechanism, allowing the possibility of centimeter-level spatial resolution

Tethered Satellites as an Enabling Platform for Operational Space Weather Monitoring Systems

Tethered satellites offer the potential to be an important enabling technology to support operational space weather monitoring systems. Space weather "nowcasting" and forecasting models rely on assimilation of near-real-time (NRT) space environment data to provide warnings for storm events and deleterious effects on the global societal infrastructure. Typically, these models are initialized by a climatological model to provide "most probable distributions" of environmental parameters as a function of time and space. The process of NRT data assimilation gently pulls the climate model closer toward the observed state (e.g., via Kalman smoothing) for nowcasting, and forecasting is achieved through a set of iterative semi-empirical physics-based forward-prediction calculations. Many challenges are associated with the development of an operational system, from the top-level architecture (e.g., the required space weather observatories to meet the spatial and temporal requirements of these models) down to the individual instruments capable of making the NRT measurements. This study focuses on the latter challenge: we present some examples of how tethered satellites (from 100s of m to 20 km) are uniquely suited to address certain shortfalls in our ability to measure critical environmental parameters necessary to drive these space weather models. Examples include long baseline electric field measurements, magnetized ionospheric conductivity measurements, and the ability to separate temporal from spatial irregularities in environmental parameters. Tethered satellite functional requirements are presented for two examples of space environment observables

Science CONOPS for Application of SPORT Mission Data to Study Large (~1000km) Ionospheric Plasma Depletions

The Scintillation Prediction Observations Research Task (SPORT) mission is a single 6U CubeSat space weather satellite planned for an October 2022 launch into an ISS-like orbit. The primary purpose of the SPORT mission is to determine the longitudinal effects on equatorial plasma bubble (EPB) growth resulting from the offset dipole magnetic field of the Earth. By combining field and plasma measurements from SPORT with other low-altitude (i.e., alt \u3c 1000 km) spacecraft, it is possible to investigate large-scale (\u3e 1000 km) EPB structures. The types of investigation made possible by measurements from SPORT and other contemporaneous missions include 1) dynamics of depleted magnetic flux tubes; 2) dynamics of field-aligned EPB expansion versus propagation speed; 3) EPB vertical extent; and 4) EPB temporal evolution. To support these investigation types, the respective modes of conjunctions are: 1) simultaneous intersection of a magnetic flux tube; 2) intersection of magnetic flux tube separated in time; 3) Simultaneous Latitude/Longitude position conjunction; and 4) Non-simultaneous latitude/longitude position conjunction. This paper will summarize the SPORT satellite and data used for Science CONOPS to accomplish these objectives

The interaction of relativistic electron beams with the near-earth space environment.

A model based on several established analytical computational techniques has been developed to study the interaction of relativistic (E $\sim$ MeV) electron beams with the Earth's upper atmosphere and ionosphere. The emphasis is on the analysis of active experiments involving beams launched from a satellite in Low Earth Orbit (LEO) or from a suborbital sounding rocket. The Beam-Atmosphere Interaction (BAI) forms a subset of physical phenomena associated with the injection of charged particle beams from a spacecraft. The present study extends the analysis of the BAI from the keV range of past experiments, and it is motivated in part by the recent advances in technology which allow MeV electron beams to be launched from spacecraft. The model is designed to accept beam and environmental parameters as input, such as beam current, energy, and mean divergence, and to compute quantities of interest resulting from the relativistic BAI as output, such as ionization and bremsstrahlung emissions. The BAI is examined by first computing the electron beam energy loss using the Continuous Slowing Down Approximation (CSDA) and the beam cross sectional area by using the envelope equations which describe beam dynamics in the paraxial approximation. These results are used to complete a first-order stability analysis associated with the Beam-Plasma Interaction (BPI) and to calculate secondary electron fluxes resulting from electron-impact ionization. With a steady-state relativistic electron beam source, secondary electrons will cascade in energy until an equilibrium is reached. Model results for beam energies from 1 to 100 MeV are in reasonable agreement with previously established values of the collisional range and fractional energy loss due to radiative processes. The stability analysis shows that beams of lower current and higher energy and divergence are less susceptible to instability, and that the Earth's magnetic field plays a significant role in stability against certain transverse modes. As a sample of practical application of the model, bremsstrahlung fluxes incident on detectors onboard a satellite in LEO were compared with those incident on balloon detectors. Future potential applications include analysis of stratospheric odd-nitrogen production from relativistic electron precipitation events and ionospheric modification due to sprite propagation.Ph.D.Physics, Atmospheric SciencePure SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/131457/2/9909918.pd