The Triple Magnesium Ionospheric Photometer (Tri-MIP) has been developed as a 1U CubeSat-compatible sensor to detect a mid-ultraviolet (MUV), Mg+ doublet emission near 280 nm, produced by solar resonant excitation, as a tracer of dayside Sporadic-E (Es). The initial flight of Tri-MIP on the Slingshot-1 spacecraft launched into a circular orbit at 500 km altitude and 45 inclination. Paired with a 1U scanning ultraviolet mirror (SUVM) on the Slingshot-1 spacecraft, Tri-MIP provides altitude profiles of Mg+ airglow emissions through limb scans of Earth's ionosphere along the wake direction of the orbit. Tri-MIP is especially well-suited for Es detection and may allow for the observation of faint signatures of Es that are otherwise not visible with other commonly used remote plasma detection methods such as ground-based ionosondes or GPS radio occultation experiments. This manuscript presents a highlight of results from a year of on-orbit operation for the Slingshot-1 Tri-MIP. The following results demonstrate a new technological development that could provide future insight into Es formation or dynamics. Published by Elsevier B.V. on behalf of COSPAR. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

The Variable Voltage Ion Protection Experiment (VVIPRE) is a demonstration space experiment built by the U.S. Naval Research Laboratory to show how low-cost variable voltage power supplies can protect sensitive spaceflight detectors from space plasma ion damage, extend sensor lifetimes, and deliver high-quality measurements of the Earth's upper atmosphere. VVIPRE is a limb-scanned far- and extreme-ultraviolet imaging spectrograph that uses a microchannel plate (MCP) intensified crossed delay line (XDL) detector. The primary mission operated aboard the International Space Station (ISS) from Mar 20, 2023 through April 22, 2024. Spacecraft charging and ambient ion impingement can cause noise, detector damage, and reduced sensor lifetime on-orbit, particularly for extreme ultraviolet detectors open to the space environment. The low-SWaP, software-controlled variable voltage power supplies compensate for variations in spacecraft potential to reduce or eliminate this unwanted ion flow. Naturally occurring ultraviolet airglow can then be measured to specify the atmosphere globally. VVIPRE demonstrated successful ion mitigation and delivered space environment remote sensing data suitable for DoD model use. Bright dayglow spectral emissions cause natural aging of the detector MCP which appears as localized gain sag, and the high data rate (300 kbps) afforded by the ISS facilitated assessment and mitigation of this effect in two-dimensional spectral images. The VVIPRE on-orbit performance and applicability of this technology to future sensors are discussed.

Abstract A novel model called PyIRI was recently developed. It constructs the ionospheric electron density for the entire day and on the entire global grid in one computation, which has a very low computational overhead. PyIRI introduced a novel approach to the computation of the global and diurnal functions and their matrix multiplication with Consultative Committee on International Radio (CCIR) coefficients or the International Union of Radio Science (URSI) coefficients, that enabled this global approach for the density specification. Since the International Reference Ionosphere‐based Real‐Time Assimilative Model (IRTAM) produces coefficients in a similar format as CCIR/URSI coefficients, the PyIRI computational approach was extended to work with IRTAM coefficients. This technical note describes the PyIRTAM software and provides usage examples. The PyIRTAM tool is made publicly available through PyPI and GitHub.

Abstract ANCHOR is a novel assimilative model developed at the U.S. Naval Research Laboratory, which was designed for rapid assimilative runs. ANCHOR uses recently developed PyIRI model for the background and for the formation of the background covariance matrix. It only takes a few minutes for ANCHOR to complete the data assimilation (DA) for one day, including data pre‐processing and model set up. ANCHOR extracts ionospheric parameters from radio occultation (RO) and ionosonde data using PyIRI formalism and assimilates them as point measurements into maps of the background parameters using a Kalman Filter approach. This paper introduces the ANCHOR algorithm, discusses its coordinate system and background, explains the background covariance formation, discusses the extraction of the ionospheric parameters from the data and the assimilation process, and, finally, shows the results of the observing system simulation experiment with synthetic data simulated using the SAMI3 model. ANCHOR reduces the root mean square errors in the analysis by more than a half for all of the ionospheric parameters in comparison to the background. Finally, this paper discusses advantages and limitations of the parametrized ionospheric DA, highlighting the avenues for its future improvement.

Abstract The International Reference Ionosphere (IRI) model is widely used in the ionospheric community and considered the gold standard for empirical ionospheric models. The development of this model was initiated in the late 1960s using the FORTRAN language; for its programming approach, the model outputs were calculated separately for each given geographic location and time stamp. The Consultative Committee on International Radio (CCIR) and International Union of Radio Science (URSI) coefficients provide the skeleton of the IRI model, as they define the global distribution of the maximum useable ionospheric frequency foF2 and the propagation factor M(3,000)F2. At the U.S. Naval Research Laboratory, a novel Python tool was developed that enables global runs of the IRI model with significantly lower computational overhead. This was made possible through the Python rebuild of the core IRI component (which calculates ionospheric critical frequency using the CCIR or URSI coefficients), taking advantage of NumPy matrix multiplication instead of using cyclic addition. This paper explains in detail this new approach and introduces all components of the PyIRI package.

The UK's Defence Science and Technology Laboratory (Dstl) is partnering with the US Naval Research Laboratory (NRL) on a joint mission to launch miniature sensors that will advance space weather measurement and modelling capabilities. The Coordinated Ionospheric Reconstruction Cubesat Experiment (CIRCE) comprises two 6U cube-satellites that will be launched into a near-polar low earth orbit (LEO), targeting 500 km altitude, in 2021. The UK contribution to CIRCE is the In situ and Remote Ionospheric Sensing (IRIS) suite, complementary to NRL sensors, and comprising three highly miniaturised payloads provided to Dstl by University College London (UCL), University of Bath, and University of Surrey/Surrey Satellite Technology Ltd (SSTL). One IRIS suite will be flown on each satellite, and incorporates an ion/neutral mass spectrometer, a tri-band global positioning system (GPS) receiver for ionospheric remote sensing, and a radiation environment monitor. From the US, NRL have provided two 1U Triple Tiny Ionospheric Photometers (Tri-TIPs) on each satellite (Nicholas et al., 2019), observing the ultraviolet 135.6 nm emission of atomic oxygen at night-time to characterize the two-dimensional distribution of electrons.

Metal atoms and ions are deposited into the Earth's Upper Atmosphere and Ionosphere via meteor ablation. The neutral atoms can undergo charge exchange with extant O+, O-2(+), and N-2(+) ions to become metallic ions. Metallic ions have lifetimes of several days in the ionosphere, allowing vertical wind shear to compress them into thin, dense layers that subsequently produce Sporadic-E propagation of HF radio signals. The Triple Magnesium Ionospheric Photometer (Tri-MIP) instrument was developed by the US Naval Research Laboratory (NRL) to observe airglow emissions from magnesium ions (Mg+) in the Earth's atmosphere and measure global-scale Mg+ density from orbit as a proxy for the metallic ion population. This CubeSat compatible Space Weather sensor is a 1U ionospheric photometer that observes the ultraviolet 280 nm fluorescent emission of Mg+ on the sunlit portion of the orbit. The primary objective is to characterize the Mg+ distribution in the Earth's atmosphere. We present the Tri-MIP instrument concept, laboratory measurements, and upcoming mission concepts.

The Triple Tiny Ionospheric Photometer (Tri-TIP) is a compact, ultraviolet (UV) sensor that has been developed as part of the Coordinated Ionospheric Reconstruction Cubesat Experiment (CIRCE). Tri-TIP will measure OI 135.6 nm emissions in the nighttime ionosphere that will be tomo-graphically inverted to determined vertical profiles of electron density in the orbit plane. The Volume Emission Rate Tomography (VERT) method has previously been validated using data from a limb scanning UV spectrometer. The current work will assess the viability of the VERT method when applied to fixed, overlapping view angles from a CubeSat platform.

The Rocket Experiment for Neutral Upwelling 2 (RENU2) sounding rocket launched from the Andoya Space Center on 13 December 2015 into the dayside polar cusp. An ultraviolet photomultiplier tube (UV PMT) on the RENU2 payload was oriented to look up along the spin axis for emissions of neutral atomic oxygen above the payload. Data from the UV PMT have been compared to predicted auroral emissions calculated by the Global Airglow (GLOW) model. The comparison between GLOW calculations driven by RENU2 electron precipitation measurements and UV PMT data suggest enhanced neutral density in the cusp at altitudes above the RENU2 trajectory.

The NASA Global‐scale Observations of the Limb and Disk (GOLD) mission has flown an ultraviolet‐imaging spectrograph on SES‐14, a communications satellite in geostationary orbit at 47.5°W longitude. That instrument observes the Earth's far ultraviolet (FUV) airglow at ~134–162 nm using two identical channels. The observations performed include limb scans, stellar occultations, and images of the sunlit and nightside disk from 6:10 to 00:40 universal time each day. Initial analyses reveal interesting and unexpected results as well as the potential for further studies of the Earth's thermosphere‐ionosphere system and its responses to solar‐geomagnetic forcing and atmospheric dynamics. Thermospheric composition ratios for major constituents, O and N2, temperatures near 160 km, and exospheric temperatures are retrieved from the daytime observations. Molecular oxygen (O2) densities are measured using stellar occultations. At night, emission from radiative recombination in the ionospheric F region is used to quantify ionospheric density variations in the equatorial ionization anomaly (EIA). Regions of depleted F region electron density are frequently evident, even during the current solar minimum. These depletions are caused by the “plasma fountain effect” and are associated with the instabilities, scintillations, or “spread F” seen in other types of observations, and GOLD makes unique observations for their study.

The LRCTF (Laser Ranging Characterization and Test Facility) is a unique facility built at NASA GSFC to provide thermal-optical testing of the next generation GPS LRA (Global Positioning Satellite’s Laser Retroreflector Array) laser ranging target. The 400mm diameter target is an array consisting of 48 total internal reflection retroreflectors and has an optical cross section requirement of 100 MSM (million square meters). To verify that the array meets this requirement during on-orbit conditions, the LRCTF is equipped with a 400mm test beam, a data product output consisting of full aperture FFDPs (Far Field Diffraction Patterns) and a thermal chamber. The FFDPs are used to calculate the OCS. This paper will describe the facility design, alignment approach, and verification process.