Earth's Space Environment Research Articles

Sustainable skies and the Earth–space environment

Sustainable skies and the Earth–space environment

Statistical Study of Confined Filament/Prominence Eruptions during Solar Cycle 23

Filament/prominence eruptions can have a significant impact on Earth's upper atmosphere and space environment, and are the primary drivers of what is now called space weather. To distinguish the different types of filament eruptions we statistically examine them during the 23rd Solar cycle. In this study we use 159 filament eruptions using the List of interplanetary (IP) Shocks Observed during Solar Cycle 23 (May 1996 – January 2008) and their Source Information Environmental Satellites (GOES) X-ray plots (see Gopalswamy et al. [Gopalswamy N., H. Xie, P. Mäkelä, S. Akiyama, S. Yashiro et al. (2010) Interplanetary shocks lacking type II radio bursts, Astrophys. J., 710, 1111–1126]). It is found that 69% of the filament eruptions are confined eruptions, while 31% are ejective eruptions. Confined eruptions are 110 and 34 events (21%). They are due to active filaments and 76 events (48%) are due to disappearing filaments. The occurrences of active and disappearing filaments during the increasing phase of solar cycle 23 is found to be 80% while in the decreasing phase they are 13%. We have found that the dominant X-ray flare energy of confined eruptions is that of C class. The most common filaments field extent is located between 5 and 15 degrees. The most common flare duration is between 16 and 40 minutes.

Technical Overview and Prospect of India’s First Solar Mission - Aditya L1 Spacecraft

The Aditya-L1 mission represents a significant milestone in solar research, aimed at unlocking the mysteries of our closest star, the Sun. This paper provides an overview of the mission's objectives, scientific instruments, and key findings. By placing a spacecraft in a Lagrangian point L1 orbit, Aditya-L1 offers an unprecedented vantage point for continuous solar observations. The primary scientific goals include studying the Sun's dynamic atmosphere, monitoring solar variability, and enhancing our understanding of space weather and its impact on Earth. The paper discusses the advanced instrumentation onboard, such as the Visible Emission Line Coronagraph (VELC), the Solar Ultraviolet Imaging Telescope (SUIT), and the Aditya Solar Wind Particle Experiment (ASPEX), highlighting their contributions to solar science. Furthermore, this paper presents early results and insights obtained from Aditya-L1's observations, shedding light on solar phenomena, solar eruptions, and their influence on Earth's space environment. The Aditya-L1 mission stands as a testament to international collaboration and technological advancements, poised to reshape our understanding of the Sun and its profound effects on our solar system.

Radiation based satellite attitude and thermal parameters estimation considering conduction effect

Accurate attitude information of satellites is a prerequisite for many space missions requiring some pointing capabilities. A radiation-based (RB) thermopile measurement package has recently been proposed for satellite attitude estimation with potential cost and power benefits. However, previous related researches have not considered all modes of the thermal communication, and have specifically neglected the conduction effect on and between the satellite surfaces as a simplifying assumption to initially develop the innovative measurement equation. As this assumption is practically difficult to implement for contemporary satellites operating in near Earth space environment, the present work complements the effect of conduction terms both in the measurement model as well as in relations pertaining to the solar RB attitude knowledge. In addition, another simplifying assumption of constant Earth albedo factor (AF) is also removed. Moreover, the present study simultaneously estimates the satellite attitude as well as its surface’s thermal characteristics (TC). The stochastic estimation algorithm used in the current study is based on the unscented Kalman filter (UKF) for attitude estimation via the new proposed sensor pack and measurement model. Finally, the study is augmented with a thorough sensitivity analysis against satellite internal heat radiation, environmental and initial conditions that have been verified via Monte Carlo simulations (MCS) to assess the merits of the proposed modified thermal model for RB concurrent satellite attitude and TC estimations.

Performance index of a network of ground-based optical sensors for space objects observation and measurements

The total number of space objects in Earth orbits is estimated to be over 600 thousands over 1 cm, while the current number of those that are constantly tracked and cataloged is around 25 thousands. In our era, where the space traffic is increasing every year, and so the risk of possible collisions, there is a global need to take control of the near Earth space environment, in particular the low Earth orbit. This is a common problem for every country and it can be solved with a global collaboration between nations. In addition, the uncertainty associated with the measured position of orbiting objects is one of the main factors impacting performance, accuracy and timeliness. For this reason, aiming for the coordination of a multitude of sensors is one of the most important aspects targeted in the domain. This paper proposes an algorithm to estimate the performance of a globally-distributed network of optical assets, equipped with off-the-shelf components, deployed in multiple sites distributed across different locations. The quantitative performance measure is calculated as the portion of total cataloged debris that is visible by the network in a 24 h time window, considering space objects of size down to 3 cm. The proposed algorithm takes as input all objects of the NORAD catalog, the whole set of objects’ physical data provided by the DISCOS and SATCAT catalogs, and optical and atmospheric data. It then propagates the space object population to obtain their position in the selected time window, filters out all the objects that are not in the ground station network line-of-sight for a sufficient amount of time to guarantee a feasible orbit determination, and on the remaining ones it estimates the signal-to-noise Ratio achievable by the assets, leveraging an advanced algorithm that models their optical performance. These values are directly translated into a probability of detection, thus providing a performance index for the given ground sensor network configuration that can be used as an objective function to be optimized when evaluating different architectures.

Impact of 100 MeV high-energy proton irradiation on β-Ga2O3 solar-blind photodetector: Oxygen vacancies formation and resistance switching effect

β-Ga2O3 based solar-blind photodetectors have strong radiation hardness and great potential applications in Earth's space environment due to the large bandgap and high bond energy. In this work, we investigated the photoelectric properties influence of β-Ga2O3 photodetector irradiated by 100 MeV high-energy protons which are the primary components in the inner belt of the Van Allen radiation belts where solar-blind photodetectors mainly worked. After proton irradiation, due to the formation of more oxygen vacancies and their migration driven by bias at the metal/semiconductor interface, transportation of carriers transforms with electron tunneling conduction for low-resistance state and thermionic emission for high resistance state. As a result, the current–voltage curves of β-Ga2O3 solar-blind photodetectors exhibit apparent hysteresis loops. The photoresponsivity of β-Ga2O3 photodetectors slightly increases from 1.2 × 103 to 1.4 × 103 A/W after irradiation, and the photoresponse speed becomes faster at a negative voltage while slower at positive voltage. The results reveal the effects of high-energy proton irradiation on β-Ga2O3 solar-blind photodetectors and provide a basis for the study of their use in a radiation harsh environment.

Scientific objectives and preliminary plans for EUV and X-ray observations of late-type stars

<p indent="0mm">Searching for extraterrestrial life is one of the most important targets for exploration of the universe. To achieve this goal, it is of critical importance to understand the connection between host stars (mainly cool dwarf stars) and habitable exoplanets. In recent years, more and more researchers have realized that the space weather phenomenon (i.e., solar activity and its impact on the Earth space environment) should also exist in star-planet systems beyond the solar system. As the main sources of space weather, various types of magnetic activity in host stars’ coronae can produce strong electromagnetic and particle radiation that could damage biological tissues, change the chemical composition and lead to the erosion of the planetary atmospheres, thus affecting the origin and survival of life. However, our understanding of the stellar coronae is very limited, which greatly hampers our understanding of the impact of space weather on habitability. Thus, we suggest effectively probing the physical parameters of the coronae and monitoring various types of coronal activity of host stars as soon as possible. To achieve this, we need to build next-generation dedicated EUV and X-ray<sc>(1–350 Å,</sc> most importantly <sc>170–285 Å</sc> and <sc>90–140 Å)</sc> telescopes to perform long-term and continuous spectroscopic and photometric observations of nearby host stars (including but not limited to the host stars of some potentially habitable exoplanets). We describe detailed scientific objectives for such observations, propose the required technical specifications to achieve these scientific goals, and provide preliminary designs of the optical systems. With these telescopes, we could unambiguously detect stellar coronal mass ejections, probe large-scale coronal structures such as coronal holes and active region loop systems, routinely measure the coronal magnetic field, and largely enrich our understanding of stellar flares and coronal plasma properties. By monitoring changes in the stellar emission during exoplanet transits, we may also infer critical information about exoplanetary atmospheres, ionospheres and magnetospheres. Based on these observations, we can substantially improve our understanding of exoplanetary space weather and accurately evaluate its role in forming a habitable world.

Impact of short-term geomagnetic activity on the variability of meteorological parameters

The paper deals with space weather prediction problem. The investigation of the possible effect of powerful magnetospheric storms on the evolving character of meteorological processes in the atmosphere to identify the correlation between magnetospheric disturbances and meteorological variations is presented in the paper. The investigation is preconditioned by the fact that Georgia is prone to hydrometeorological hazards, and it is essential to investigate their causing physical processes. Meteorological effects resulting from fluctuations in the solar wind are poorly represented in weather and climate models. A geomagnetic storm is a significant disturbance of Earth's magnetosphere exchanging energy from the solar wind into Earth's space environment. These storms result from solar wind variations that significantly change the currents, plasmas, and fields in Earth's magnetosphere. Geomagnetic indices measure geomagnetic activity occurring over short periods. They have been constructed to study the response of the Earth's ionosphere and magnetosphere to changes in solar activity. The correlation between geomagnetic storms and meteorological elements (temperature, precipitation, wind) has been carried out for the Georgian region using meteorological observation and NASA's Solar Dynamics Observatory and NOAA Space Weather Prediction Centre data. The results show that there exists dependence between meteorological parameters and geomagnetic disturbances.

The UN COPUOS Guidelines for the Long-term Sustainability of Outer Space Activities

The United Nations has addressed the concept of sustainable development on Earth in a number of global summits and fora for the past 40 years. Extending the concept of sustainability to outer space is a much more recent development, arising from the realization that the Earth's orbital space environment constitutes a finite resource that is being used by an increasing number of space actors that include States, commercial actors and other non-governmental entities. The proliferation of space debris, the increasing complexity of space operations, the emergence of large constellations of satellites, and the increased risks of collisions and interference with the operation of satellites raise concerns about the safety of space operations and the long-term sustainability (LTS) of space activities. Addressing these developments and risks requires international cooperation. The leading international forum to discuss questions of international cooperation in space activities is the United Nations Committee on the Peaceful Uses of Outer Space (UN COPUOS). In 2010, the Committee began its consideration of this topic with a view to producing a set of internationally agreed guidelines that States could follow to ensure that their space activities would not cause harm to the space environment or the safety of space operations. Following a broad international process conducted under the aegis of COPUOS, in June 2019 the Committee adopted a set of 21 voluntary, non-binding UN COPUOS Guidelines for the Long-term Sustainability of Outer Space Activities (‘COPUOS LTS Guidelines’). This paper provides a brief overview of the development of these guidelines, summarizes the salient features of the guidelines and discusses the implementation of these guidelines from the perspectives of government, industry and civil society. In adopting this set of LTS Guidelines, COPUOS acknowledged that more work needs to be done on this topic and it agreed to establish a follow-up LTS working group with a five-year mandate to continue the work. The main themes and challenges facing the next phase of the LTS discussions in COPUOS are also discussed.

Report on VERSIM 2020

The 9th VLF/ELF Remote Sensing of Ionospheres and Magnetospheres Workshop (VERSIM 2020) was successfully held as a virtual meeting during the week of 16–20 November 2020. The meeting had been rescheduled from the original meeting (23–27 March 2020 at the Uji Campus, Kyoto University, Japan), cancelled due to the COVID-19 pandemic. The VERSIM workshop aims to bring together scientists from all across the globe to present and discuss topics related to the excitation, propagation, and effects of electromagnetic waves in the ELF/VLF (300 Hz – 30 kHz) range. The VERSIM group was established as a joint URSI/IAGA work group in 1975. It has been the main scientific body to specifically focus on whistlers in the Earth's ionosphere and magnetosphere (whistler waves were one of the first electromagnetic signals detected by ground instruments, and gave important clues about the Earth's active space environment). The scope of this group has grown substantially over the years. It has grown particularly in recent years with the recognition that whistler-mode chorus and hiss waves play a particularly important role in shaping the dynamics of the Earth's high-energy radiation belts (particularly topical in light of the continuing successful operation of the Van Allen Probes and the Arase (ERG) spacecraft). Whistler waves are also known to be intimately involved in the magnetic reconnection process (which is currently very topical due to the launch of the MMS satellite) and solar flaring. In addition to the traditional VERSIM topics, results of recent space missions, such as Arase, MMS, and the Van Allen Probes, were presented.

Development of an Empirical Model for Estimating the Quiet Day Curve (QDC) Over the Brazilian Sector

AbstractThe Embrace Magnetometer Network (Embrace MagNet) uses a series of magnetometers over South America to monitor the Earth's space environment and to study space weather. One of the common techniques used to study the effects of the magnetic disturbances in the globe is through the quiet day curve (QDC) of the geomagnetic field components. These types of QDC are calculated based on geomagnetic field data collected by magnetometers in the five quietest days for each month at each station. Thus, we developed and implemented an empirical model based on the QDC H component obtained by the Embrace MagNet. This model ought to be used as a prediction device when data are not available. The proposed algorithm is a function of the solar activity, the day of the year, and the universal time, which was adjusted based on 12 stations across to the South America sector between 2010 and 2018. Our results show that the values computed by this model are in good agreement with the observational data for the QDC. Finally, it is essential to mention that the QDC model presented in this study is the only available predicting tool of the Embrace MagNet stations to date, providing data with a high confidence level in the Brazilian sector.

Development of New Capabilities Using Machine Learning for Space Weather Prediction

With the development of space exploration and space environment measurements, the numerous observations of solar, solar wind, and near Earth space environment have been obtained in last 20 years. The accumulation of multiple data makes it possible to better use machine learning technique, which has achieved unforeseen results in industrial applications in last decades, for developing new approaches and models in space weather investigation and prediction. In this paper, the efforts on the forecasting methods for space weather indices, events, and parameters using machine learning are briefly introduced based on the study works in recent years. These investigations indicate that machine learning, especially deep learning technique can be used in automatic characteristic identification, solar eruption prediction, space weather forecasting for solar and geomagnetic indices, and modeling of space environment parameters.

Science Research and Utilization Planning of China's Space Station in Operation Period 2022-2032

The core module of China's Space Station (CSS) is scheduled to be launched around the end of 2020, and the experimental module I and II will be launched in the next two years. After on-orbit constructions, CSS will be transferred into an operation period over 10 years (2022-2032 and beyond) to continuously implement space science missions. At present, based on the project selection and research work in the ground development period of CSS, China is systematically making a utilization mission planning for the operation period, which focuses on the fields of aerospace medicine and human research, space life science and biotechnology, microgravity fluid physics, combustion science, materials science, fundamental physics, space astronomy and astrophysics, Earth science, space physics and space environment, space application technology, <i>etc</i>. In combination with the latest development trend of space science and technology, China will continue to update planning for science research and technology development, carry out project cultivation, payload R&D, and upgrade onboard and ground experiment supporting systems to achieve greater comprehensive benefits in science, technology, economy, and society.

Spectral analysis on the solar parameters and empirical orthogonal functions of foF2 data obtained by singular value decomposition

The geomagnetic storm is an important weather issue in the earth’s ionosphere-magnetosphere system. Many linear and nonlinear systems are involved in this earth-space environment. In order to understand the nonlinearly evolving dynamical system of magnetosphere and ionosphere, Time series analysis of foF2 data, Disturbance Storm Index Dst, Geomagnetic activity Index Ap and some other parameters during various solar cycles has been carried out in this work. The hourly data of critical frequency of F2 layer (foF2) for three ionosonde stations [Townsville (TV51R) 19.7°S, 146.9°E; Canberra (CB53N) 35.3°S, 149.1°E; Juliusruh (JR055) 54.6°N, 13.4°E] have been noted for 4 solar cycles viz., Solar Cycle 20, 21, 22 and 23. Hourly time series analysis has been performed to achieve some functional approaches such as statistical, analytical and spectral approach etc. to examine for the presence of periodicities in the data. Time Series is a sequential set of data which can be measured over time, and since the data being used for this work had been recorded as a function of time under various conditions, the appearance of missing observations in time series data is a very common issue. Different series may require different approaches to estimate these missing values. As such, to vanquish the problem of missing data we have attempted to estimate the missing value of foF2 data for various stations using the technique of Singular Value Decomposition (SVD). Another important method, Lomb Scargle Periodogram (LSP) has been performed on the Empirical Orthogonal Functions (EOFs) u1 and u2 (that has been obtained by SVD) along with the solar parameters such as solar flux f10.7, sun spot number (SSN) etc. and geomagnetic indices such as Dst index, Kp index & Ap index etc. for the four solar cycles to find the correlation, if any. For all the plots after performing LSP the power has been found out at 99% confidence level to see how much significant the generated data with respect to the parameters is. The periodicity obtained after performing LSP are divided into three terms namely:– (a) short-term periodicity, in which 27 days periodicity is found to be prominent, (b) mid-term periodicity, in which 1.3 year periodicity is found to be very common and (c) long-term periodicity, in which 11 years periodicity is very regular in almost among all the parameters and in the EOFs.

GUMICS-4 analysis of interplanetary coronal mass ejection impact on Earth during low and typical Mach number solar winds

Abstract. We study the response of the Earth's magnetosphere to fluctuating solar wind conditions during interplanetary coronal mass ejections (ICMEs) using the Grand Unified Magnetosphere-Ionosphere Coupling Simulation (GUMICS-4). The two ICME events occurred on 15–16 July 2012 and 29–30 April 2014. During the strong 2012 event, the solar wind upstream values reached up to 35 particles cm−3, speeds of up to 694 km s−1, and an interplanetary magnetic field of up to 22 nT, giving a Mach number of 2.3. The 2014 event was a moderate one, with the corresponding upstream values of 30 particles cm−3, 320 km s−1 and 10 nT, indicating a Mach number of 5.8. We examine how the Earth's space environment dynamics evolves during both ICME events from both global and local perspectives, using well-established empirical models and in situ measurements as references. We show that on the large scale, and during moderate driving, the GUMICS-4 results are in good agreement with the reference values. However, the local values, especially during high driving, show more variation: such extreme conditions do not reproduce local measurements made deep inside the magnetosphere. The same appeared to be true when the event was run with another global simulation. The cross-polar cap potential (CPCP) saturation is shown to depend on the Alfvén–Mach number of the upstream solar wind. However, care must be taken in interpreting these results, as the CPCP is also sensitive to the simulation resolution.

The dynamo-wind feedback loop : Assessing their non-linear interplay

AbstractThough generated deep inside the convection zone, the solar magnetic field has a direct impact on the Earth space environment via the Parker spiral. It strongly modulates the solar wind in the whole heliosphere, especially its latitudinal and longitudinal speed distribution over the years. However the wind also influences the topology of the coronal magnetic field by opening the magnetic field lines in the coronal holes, which can affect the inner magnetic field of the star by altering the dynamo boundary conditions. This coupling is especially difficult to model because it covers a large variety of spatio-temporal scales. Quasi-static studies have begun to help us unveil how the dynamo-generated magnetic field shapes the wind, but the full interplay between the solar dynamo and the solar wind still eludes our understanding.We use the compressible magnetohydrodynamical (MHD) code PLUTO to compute simultaneously in 2.5D the generation and evolution of magnetic field inside the star via an α-Ω dynamo process and the corresponding evolution of a polytropic coronal wind over several activity cycles for a young Sun. A multi-layered boundary condition at the surface of the star connects the inner and outer stellar layers, allowing both to adapt dynamically. Our continuously coupled dynamo-wind model allows us to characterize how the solar wind conditions change as a function of the cycle phase, and also to quantify the evolution of integrated quantities such as the Alfvén radius. We further assess the impact of the solar wind on the dynamo itself by comparing our results with and without wind feedback.

Quantifying the Uncertainty of Using Solar Wind Measurements for Geospace Inputs

AbstractPredictive models for the Earth's space environment routinely use parameters from the solar wind as inputs. Measurements from spacecraft orbiting the first Lagrange point serve as convenient values for these inputs. The mass, momentum, and energy input into the Earth's space environment, however, are a function of the shocked and processed plasma within the magnetosheath, which can vary significantly from the pristine solar wind at the first Lagrange point. Here statistical measurements from the OMNI data set are combined with measurements by the THEMIS mission within the magnetosheath to generate uncertainty values for pressure and magnetic clock angle. These uncertainties are generated to account for known physical processes in the foreshock and magnetosheath as well as the position of the spacecraft being used to generate the OMNI data set.

Development of an international compendium of guidelines for the long-term sustainability of outer space activities

The Earth's orbital space environment constitutes a finite resource that is being used by an increasing number of States, international intergovernmental organizations and non-governmental entities. The proliferation of space debris, the increasing complexity of space operations, the emergence of large constellations and the increased risks of collision and interference with the operation of space objects are raising concerns about the long-term sustainability of outer space activities. Addressing these developments and risks requires international cooperation. In 2010, the United Nations Committee on the Peaceful Uses of Outer Space (UN COPUOS) established a working group to address these matters and to propose a set of voluntary, non-binding guidelines for States that represent a compendium of internationally recognized measures for, and commitments to, ensuring the long-term sustainability of outer space activities and, in particular, enhancing the safety of space operations. This paper describes the efforts of this Working Group in the context of other multilateral space security initiatives. The first twelve guidelines, which were agreed in 2016, are briefly discussed, as well as the linkages of this process with the recommendations contained in the report of the Group of Governmental Experts on Transparency and Confidence-Building Measures in Outer Space Activities. The paper ends with some reflections on factors shaping the negotiations of the remaining draft guidelines as the Working Group enters its final round of negotiations in 2018.

BIRDS-1 CubeSat Constellation Using Compact UHF Patch Antenna

BIRDS-1 satellites, a constellation of five identical 1U CubeSats, were designed, manufactured, assembled, integrated, and tested at LASINE Laboratory, Kyutech, Japan. Students from five nations (Japan, Ghana, Mongolia, Nigeria, and Bangladesh) collaborated to develop a number of CubeSats with coordinated ground coverage, named “Joint Global Multi-Nation BIRDS,” or abbreviated as “BIRDS.” To establish the downlink communication between satellite and Earth, an UHF patch antenna was utilized. Patch antennas offer an ideal solution to Cube satellite communication requirements due to their compact dimension and lightweight. However, the limited surface area available in CubeSats, conventional UHF and VHF patch antennas cannot be used. In this paper, a compact coaxial fed UHF (437.375 MHz) patch antenna system for 1U BIRDS-1 CubeSat (small satellite) is presented. The proposed antenna consists of a spiral meander line patch at the top side and partial ground plane another side of the substrate. A shorting pin has also been utilized to change the resonance to the required UHF band. For the intended 1U BIRDS-1 application, the goal is to mount on satellite body within a limited area of 1U BIRDS-1 satellite. The proposed antenna dimension ( $0.105\lambda \times 0.047\lambda \times 0.002 \lambda $ at 437.375 MHz) and characteristics are compatible with any CubeSat standard structure. A prototype of the antenna was developed with a 1.57-mm-thick single layer Roger’s substrate having a relative permittivity of 2.2, and measured results are consistent with simulation. The proposed UHF antenna has integrated and tested with 1U BIRDS-1 satellite. Finally, the satellite was successfully launched on June 3, 2017, from the John F. Kennedy Space Center, the USA at Low Earth Orbit for earth observations, message relay, space environment, and technology demonstration through the International Space Station.

Ushering in a New Frontier in Geospace Through Data Science

AbstractOur understanding and specification of solar‐terrestrial interactions benefit from taking advantage of comprehensive data‐intensive approaches. These data‐driven methods are taking on new importance in light of the shifting data landscape of the geospace system, which extends from the near Earth space environment, through the magnetosphere and interplanetary space, to the Sun. The space physics community faces both an exciting opportunity and an important imperative to create a new frontier built at the intersection of traditional approaches and state‐of‐the‐art data‐driven sciences and technologies. This brief commentary addresses the current paradigm of geospace science and the emerging need for data science innovation, discusses the meaning of data science in the context of geospace, and highlights community efforts to respond to the changing landscape.