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NASA NTRS1992

The plasma instrumentation for the Galileo Mission

The Galileo Mission's plasma instrumentation package encompasses a nested set of four spherical-plate electrostatic analyzers and three miniature magnetic mass spectrometers which identify the composition of the positive ion plasmas; the spectrometers' energy range is species-dependent. Two instrument microprocessors allow in-flight implementation of operational modes by ground command that are tailored for such specific regimes as the magnetosheath and the plasma sheet of the environs of Jupiter. Observational objectives include field-aligned currents, 3D ion bulk flows, Galilean satellite pickup ions, and the spatial distributions of plasmas.

Frank, L. A.↗

NASA NTRS1992

Gas ionization solar spectral monitor (GISSMO)

We are currently developing an instrument free from optical components to measure the full-disk solar spectrum in the extreme ultraviolet regime covering wavelengths from 75-500 A. The instrument, which will be launched aboard a NASA Black Brant sounding rocket in September 1992, consists of a windowless noble gas ionization cell followed by a toroidal electrostatic analyzer to spatially disperse photoelectrons as a function of their energies. A microchannel plate based position sensitive detector will be used to detect individual electrons, indirectly returning the solar EUV spectrum.

Vickers, James S.↗

NASA NTRS1992

The Ulysses solar wind plasma investigation - Experiment description and initial in-ecliptic results

During the in-ecliptic flight of Ulysses from the Earth toward its encounter with Jupiter, the Los Alamos solar wind plasma experiment has performed well. Briefly described, the instrumentation contains two independent electrostatic analyzers, one for ions and one for electrons. Initial analysis of solar wind electron core temperatures obtained between 1.15 and 3.76 AU yields a gradient of T (proportional to) R(exp -0.7) which is flatter than expected for adiabatic expansion of a single-temperature Maxwellian velocity distribution and steeper than that obtained from Mariner-Voyager.

Bame, S. J.↗

NASA NTRS1994

Observations of nonadiabatic acceleration of ions in Earth's magnetotail

We present observations of the three-dimensional velocity distributions of protons in the energy range 20 eV to 52 keV at locations within and near the current sheet of Earth's magnetotail at geocentric radial distances 35 to 87 R(sub E). These measurements were acquired on December 8, 1990, with a set of electrostatic analyzers on board the Galileo spacecraft during its approach to Earth in order to obtain one of its gravitational assists to Jupiter. It is found that the velocity distributions are inadequately described as quasi-Maxwellian distributions such as those found in the central plasma sheet at positions nearer to Earth. Instead the proton velocity distributions can be categorized into two major types. The first type is the 'lima bean' shaped distribution with high-speed bulk flows and high temperatures that are similar to those found nearer to Earth in the plasma sheet boundary layer. The second type consists of colder protons with considerably lesser bulk flow speeds. Examples of velocity distributions are given for the plasma mantle, a region near the magnetic neutral line, positions earthward and tailward of the neutral line, and the plasma sheet boundary layer. At positions near the neutral line, only complex velocity distributions consisting of the colder protons are found, whereas both of the above types of distributions are found in and near the current sheet at earthward and tailward locations. Bulk flows are directed generally earthward and tailward at positions earthward and tailward of the neutral line, respectively. Only the high-speed, hot distribution is present in the plasma sheet boundary layer. The observations are interpreted in terms of the nonadiabatic acceleration of protons that flow into the current sheet from the plasma mantle. For this interpretation the hot, 'lima bean' shaped distributions are associated with meandering, or Speiser, orbits in the current sheet. It is suggested that the colder, lower-speed proton velocity distributions are the result of fractional or few gyromotions before ejection out of the current sheet, but this speculation must be further investigated with appropriate kinetic simulation of trajectories.

Frank, L. A.↗

NASA NTRS1995

High-voltage space-plasma interactions measured on the PASP Plus test arrays

The Photovoltaic Array Space Power Plus Diagnostics (PASP Plus) experiment was developed by the Air Force's Phillips Laboratory with support from NASA's Lewis Research Center. It was launched on the Advanced Photovoltaic and Electronics EXperiments (APEX) satellite on August 3, 1994 into a 70 degree inclination, 363 km by 2550 km elliptical orbit. This orbit allows the investigation of space plasma effects on high-voltage operation (leakage current at positive voltages and arcing at negative voltages) in the perigee region. PASP Plus is testing twelve solar arrays. There are four planar Si arrays: an old standard type (used as a reference), the large-cell Space Station Freedom (SSF) array, a thin 'APSA' array, and an amorphous Si array. Next are three GaAs on Ge planar arrays and three new material planar arrays, including InP and two multijunction types. Finally, there are two concentrator arrays: a reflective-focusing Mini-Cassegrainian and a Fresnel-lens focusing Mini-Dome. PASP Plus's diagnostic sensors include: Langmuir probe to measure plasma density, an electrostatic analyzer (ESA) to measure the 30 eV to 30 KeV electron/ion spectra and determine vehicle negative potential during positive biasing, and a transient pulse monitor (TPM) to characterize the arcs that occur during the negative biasing. Through positive biasing of its test arrays, PASP Plus investigated the snapover phenomenon, which took place over the range of +100 to +300 V. It was found that array configurations where the interconnects are shielded from the space plasma (i.e., the concentrators or arrays with 'wrap-through' connectors) have lower leakage current. The concentrators exhibited negligible leakage current over the whole range up to +500 V. In the case of two similar GaAs on Ge arrays, the one with 'wrap-through' connectors had lower leakage current than the one with conventional interconnects. Through negative biasing, PASP Plus investigated the arcing rates of its test arrays. The standard Si array, with its old construction (exposed rough-surface interconnects), arced significantly over a wide voltage and plasma-density range. The other arrays arced at very low rates, mostly at voltages greater than -350 V and plasma densities near or greater than 10(exp 5)/cm(exp -3). AS expected according to theory, arcing was more prevalent when array temperatures were cold (based on biasing in eclipse).

Guidice, Donald A.↗

NASA NTRS1995

Observations of the 3-D distribution of interplanetary electrons and ions from solar wind plasma to low energy cosmic rays

The 3-D Plasma and Energetic Particle instrument on the GGS Wind spacecraft (launched November 1, 1994) is designed to make measurements of the full three-dimensional distribution of suprathermal electrons and ions from solar wind plasma to low energy cosmic rays, with high sensitivity, wide dynamic range, good energy and angular resolution, and high time resolution. Three pairs of double-ended telescopes, each with two or three closely sandwiched passivated ion implanted silicon detectors measure electrons and ions from approximately 20 keV to greater than or equal to 300 keV. Four top-hat symmetrical spherical section electrostatic analyzers with microchannel plate detectors, a large and a small geometric factor analyzer for electrons and a similar pair for ions, cover from approximately 3 eV to 30 keV. We present preliminary observations of the electron and ion distributions in the absence of obvious solar impulsive events and upstream particles. The quiet time electron energy spectrum shows a smooth approximately power law fall-off extending from the halo population at a few hundred eV to well above approximately 100 keV The quiet time ion energy spectrum also shows significant fluxes over this energy range. Detailed 3-D distributions and their temporal variations will be presented.

Lin, R. P.↗

NASA NTRS1961

Two Instruments for Measuring Distributions of Low-Energy Charged Particles in Space

Current estimates indicate that the bulk of interplanetary gas consists of protons with energies between 0 and 20 kev and concentrations of 1 to 105 particles/cu cm. Methods and instrumentation for measuring the energy and density distribution of such a gas are considered from the standpoint of suitability for space vehicle payloads. It is concluded that electrostatic analysis of the energy distribution can provide sufficient information in initial experiments. Both magnetic and electrostatic analyzers should eventually be used. Several instruments designed and constructed at the Ames Research Center for space plasma measurements, and the methods of calibration and data reduction are described. In particular, the instrument designed for operation on solar cell power has the following characteristics: weight, 1.1 pounds; size, 2 by 3 by 4 inches; and power consumption, 145 mw. The instrument is designed to yield information on the concentration, energy distribution, and the anisotropy of ion trajectories in the 0.2 to 20 kev range.

Bader, Michel↗

NASA NTRS2012

DSCOVR High Time Resolution Solar Wind Measurements

The Deep Space Climate Observatory (DSCOVR), previously known as Triana, spacecraft is expected to be launched in late 2014. It will carry a fluxgate magnetometer, Faraday Cup solar wind detector and a top-hat electron electrostatic analyzer. The Faraday Cup will provide an unprecedented 10 vectors/sec time resolution measurement of the solar wind proton and alpha reduced distribution functions. Coupled with the 40 vector/sec vector magnetometer measurements, the identification of specific wave modes in the solar wind will be possible for the first time. The science objectives and data products of the mission will be discussed.

Szabo, Adam↗

NASA NTRS2013

Solar Array and Auroral Charging Studies of DMSP Spacecraft

The SSJ electrostatic analyzers and the SSIES plasma instruments on the DMSP spacecraft in low Earth polar orbit can be used to conduct case studies of auroral and solar array charging. We will use a program written in the Interactive Data Language (IDL) to evaluate questionable charging events in the SSJ records by comparing charging signatures in SSJ and SSIES data. In addition, we will assemble a number of case studies of solar array charging showing the signatures from the SSJ data and compare them to the SSIES charging signatures. In addition, we will use Satellite Tool Kit (STK) to propagate orbits, obtain solar intensity, and use to verify onset of charging with sunrise.

Matias, Kelwin↗

NASA NTRS2013

Solar Array and Auroral Charging Studies of DMSP Spacecraft

The SSJ electrostatic analyzers and the SSIES plasma instruments on the DMSP spacecraft in low Earth polar orbit can be used to conduct case studies of auroral and solar array charging. We will use a program written in the Interactive Data Language (IDL) to evaluate questionable charging events in the SSJ records by comparing charging signatures in SSJ and SSIES data. In addition, we will assemble a number of case studies of solar array charging showing the signatures from the SSJ data and compare to the SSIES charging signatures. In addition we will use Satellite Tool Kit (STK) to propagate orbits, obtain solar intensity, and use to verify onset of charging with sunrise.

Matias, Kelwin↗

NASA NTRS2017

The Magnetospheric Source Region of the Bright Proton Aurora

The bright proton aurora is generally understood to be the projection of the Central Plasma Sheet where there is sufficient particle energy to cause auroral luminosity and strong pitch angle scattering (presumably due to field line curvature). This region is often interpreted as the transition region between dipolar and tail-like magnetic topologies. The location of auroral features relative to the peak in the proton aurora has been used, for example, to argue that the substorm onset arc lies on field lines that thread this transition region. In this paper, we present statistics of proton aurora luminosity computed from Time History of Events and Macroscale Interactions in Substorms electrostatic analyzer measurements for various radial distances in the magnetotail. These results are compared to ground observations of proton auroral luminosity and used to derive a statistical source region of the bright proton aurora.

Spanswick, E.↗

NASA NTRS2020

Coronagraphic Observations of the Lunar Sodium Exosphere 2018-2019

Remote observations of the lunar sodium corona have been obtained with the Goddard Lunar Coronagraph located at the Winer Observatory in Sonoita, Arizona. We previously reported the results of observations in the spring, 2017, observing season (Killen et al., 2019). We report herein the results of the 2018–2019 observing campaign. We show definitive effects on the corona - the extended lunar sodium exosphere above 150 km from the surface - of enhanced ion flux onto the Moon as measured by the ARTEMIS ElectroStatic Analyzer. The three observations in this dataset with the largest column abundances are associated with entrance of the Moon into the magnetosheath. The enhancement in the exosphere due to ion flux is not long-lived after the enhanced ion influx decreases, confirming the findings of Killen et al., 2012. The column abundance is greatest at both the dawn and dusk terminators as predicted and simulated by Smyth and Marconi, 1995. The cause of the increased scale height at the terminators is consistent with radiation pressure acceleration anti-sunward. We report a shallow decline of column abundance with increasing latitude which is also consistent with radiation pressure acceleration. Most of our measured scale heights are on the order of 800–1800 km, increasing at high latitudes, consistent with the data set published in Killen et al., 2019. Although the intensity extrapolated to the surface decreases with latitude, the scale height increases with latitude, so that the exospheric column decreases more slowly with increasing latitude than does a cosine function.

moon↗

NASA NTRSDate not supplied

Dione: A Pathfinder Mission for Understanding the Iono-sphere-Thermosphere Responses to Magnetospheric Forcing

Dione is a NASA small satellite prototype for future constellations that in different configurations will provide global and localized measurements of Ionosphere-Thermosphere responses to Magnetospheric energy input in a variety of scales, enabling their better forecast and prediction. This is done with a comprehensive sensor package which includes four instruments: a miniaturized fluxgate magnetometer providing magnetic field measurements with two sensor heads, an ion sensor that measures vector plasma drifts and deduce the in-situ electric fields, an electrostatic analyzer that measures precipitating electrons and up-going secondary electrons, and a neutral mass spectrometer measuring total neutral density and composition. Dione is 3-axis stabilized in a circular low-earth (400-600 km), high-inclination orbit, traversing the auroral precipitation and high latitude currents in every orbit. This paper focuses on the mission-level architecture, but provides contextual information on the science objectives, instruments, and space-craft.

Jaime Esper↗

NASA NTRSDate not supplied

Heliophysics Environmental & Radiation Measurement Experiment Suite (HERMES): A Small External Payload for the Lunar Gateway with Big Challenges

Currently scheduled for liftoff in 2024, Gateway will be an outpost orbiting the moon for astronauts headed to and from the lunar surface and serve as a staging point for deep space exploration. In January of 2020 NASA headquarters contacted Goddard Space Flight Center to request that they develop a Heliophysics instrumentation package for Gateway. This package would later become known as HERMES-Heliophysics Environmental & Radiation Measurement Experiment Suite. HERMES consists of a Miniaturized Electron pRoton Telescope (MERIT), an Electron Electrostatic Analyzer (EEA), Solar Probe Analyzers (SPAN)-A-ions, and Noise Eliminating Magnetometer Instrument in a Small Integrated System (NEMISIS), which consists of one fluxgate and two Magneto-Inductive Magnetometers. From the beginning the HERMES mission faced a number of Challenges. It was constrained to fit in a small, half meter, cube and it was required to weigh no more than 25kg. A new boom design for the magnetometer would be required and for safety reasons it must be able to retract autonomously with power removed. To complicate matters the location of the SORI-Small ORU- (Orbital Replacement Unit) Robotics Interface, the primary interface for the HERMES platform to the Gateway elements, was undetermined. Also, the mechanical, thermal and electrical interfaces are not fully defined. The Canadian Space Agency is still in process of designing the version of the SORI that will be flown on the Power and Propulsion Element (PPE) and Habitation and Logistics Outpost (HALO) elements, each of which are being developed by different contractors. At the time of initiating the HERMES project, neither of the Gateway module providers were under contract. Additionally, we would later learn the ISS heritage SORI modules were not originally designed for launching on the Gateway elements with a payload directly attached but rather were intended to be brought up on a separate carrier outfitted with launch locks and specialized launch structures from which the robotic arm on Gateway would then be used to detach the payload and install it on the SORI adapters while on orbit. Launching the integrated Payload/SORI on the PPE and HALO elements complicates the stiffness requirements and coupled loads analysis. Adding to this are serious constraints on Field-Of-View (FOV) for solar viewing and severe radiation exposure considerations brought on by slowly raising the orbit through the Van Allen Belts. Just to make things a little more challenging the budget for the entire project was intended to be a low-cost tailored Class-D mission approach. Plus, the effects of Corona VIrus Disease 2019 (COVID-19) were not factored in from the beginning. This paper will discuss what’s being done to overcome these challenges and put HERMES on track for a 2024 Launch Readiness Date (LRD).

Irving Joseph Burt↗

NASA NTRSDate not supplied

Heliophysics Environmental & Radiation Measurement Experiment Suite (HERMES): A Small External Payload for Gateway with Big Challenges

Currently scheduled for liftoff in 2024, Gateway will be an outpost orbiting the moon for astronauts headed to and from the lunar surface and will serve as a staging point for deep space exploration. In January 2020, NASA Headquarters contacted Goddard Space Flight Center (GSFC) with a request that they provide a Heliophysics instrumentation package for Gateway. This package would later become known as the Heliophysics Environmental & Radiation Measurement Experiment Suite (HERMES). HERMES consists of four high-heritage instruments – a Miniaturized Electron pRoton Telescope (MERIT), an Electron Electrostatic Analyzer (EEA), a Solar Probe Analyzer-Ions (SPAN-I), and Noise Eliminating Magnetometer Instrument in a Small Integrated System (NEMISIS), which consists of one fluxgate and two magneto-inductive magnetometers. Launching HERMES with Gateway would provide an opportunity to conduct early science experiments on Gateway, but the plan to develop HERMES concurrently with Gateway and launch with the co-manifested vehicle brought numerous technical challenges for the pathfinder payload. HERMES was intended to be a low-cost, tailored Class-D mission, and maintaining that programmatic position proved difficult as the technical challenges grew. The effects of Coronavirus Disease 2019 (COVID-19) were not factored in from the beginning and also created programmatic challenges. This paper will discuss what’s being done to overcome the technical and programmatic challenges to put HERMES on track for a 2024 Launch Readiness Date (LRD).

Joe Burt↗

NASA NTRS2022

Rocket Measurements of Electron Energy Spectra From Earth's Photoelectron Production Layer

Photoelectrons are crucial to atmospheric physics. They heat the atmosphere, strengthen planetary ambipolar electric fields, and enhance the outflow of ions to space. However, there exist only a handful of measurements of their energy spectrum near the peak of photoproduction. We present calibrated energy spectra of pristine photoelectrons at their source by a prototype Dual Electrostatic Analyzer (DESA) instrument flown on 11 July 2021 aboard the Dynamo-2 sounding rocket (NASA № 36.357). Photopeaks arising from 30.4 nm He-II spectral line were observed throughout the flight above 120 km. DESA also successfully resolved the rarely observed N2 absorption feature. Below 10 eV observations were in good agreement with the GLOW suprathermal electron. Above 10 eV fluxes substantially deviated from the model by as much as an order of magnitude.

Glyn A. Collinson↗

NASA NTRSDate not supplied

The HERMES Payload for Gateway: Heliophysics Enabled by Lunar Exploration

At launch, the first two modules of the Gateway space station will carry external payloads from NASA and ESA designed to observe the space environment. The NASA payload is the Heliophysics Environmental and Radiation Measurement Experiment Suite (HERMES). The HERMES instrumentation includes an ion mass spectrometer, an electron electrostatic analyzer, a proton and electron telescope for energetic particles, and a set of magnetometers. After an approximately one year transit to the Moon, HERMES will begin a science campaign that addresses heliophysics and space-weather objectives. Analyses of the in-situ measurements from HERMES will leverage observations from other Heliophysics spacecraft missions to enable multipoint studies of structure in the solar wind and in the magnetotail. Gateway’s polar lunar orbit is advantageous for this purpose. HERMES also is a pathfinder for future payloads on human-exploration vessels, for which there will be pragmatic interest in the variable radiation environment. Thus, with observations enabled by the ARTEMIS Program, HERMES is expected to be enabling of future exploration missions. Additionally, although HERMES objectives have a space-weather focus, the measurements also can be useful for studies of the Moon. Data, algorithms, calibrations, and related software produced by the project will be fully open and accessible through a Science Operations Center. In this presentation we provide an overview of science plans, including expectations for collaboration with other HSO missions and with international partners. Plain-Language Summary: The HERMES scientific payload will be attached to the HALO module of the Artemis Program's Gateway lunar outpost. HERMES will observe space weather conditions from lunar orbit. The data will be freely available for studies of the Moon and its space environment.

William R Paterson↗

NASA NTRSDate not supplied

The HERMES Payload for Gateway: Heliophysics Enabled by Lunar Exploration

W.R. Paterson↗