Siegfried Eggl, Zouhair Benkhaldoun, Genoveva Micheva, Samuel T. Spencer, David V. Stark, Benjamin Winkel, Meredith Rawls, Mike W. Peel
Satellite constellation interference occurs across astronomical disciplines. We present examples of interference from radio and $gamma$-Ray astronomy to optical and spectroscopic interference in ground-based and space-borne facilities. In particular, we discuss the impact of artificial satellites on the Hubble Space Telescope (HST), the High Energy Stereoscopic System (H.E.S.S.), an Imaging Atmospheric Cherenkov Telescope, as well as possible mitigation strategies for the European Southern Observatory 4-metre Multi-Object Spectrograph Telescope (ESO 4MOST). Furthermore, we shed light on how ground-based optical telescopes such as the Oukaimeden Observatory contribute to IAU Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (IAU CPS) efforts that quantify satellite brightness.
{"title":"SatHub Panel: Satellite Interference in Observatories Around the World","authors":"Siegfried Eggl, Zouhair Benkhaldoun, Genoveva Micheva, Samuel T. Spencer, David V. Stark, Benjamin Winkel, Meredith Rawls, Mike W. Peel","doi":"arxiv-2408.15222","DOIUrl":"https://doi.org/arxiv-2408.15222","url":null,"abstract":"Satellite constellation interference occurs across astronomical disciplines.\u0000We present examples of interference from radio and $gamma$-Ray astronomy to\u0000optical and spectroscopic interference in ground-based and space-borne\u0000facilities. In particular, we discuss the impact of artificial satellites on\u0000the Hubble Space Telescope (HST), the High Energy Stereoscopic System\u0000(H.E.S.S.), an Imaging Atmospheric Cherenkov Telescope, as well as possible\u0000mitigation strategies for the European Southern Observatory 4-metre\u0000Multi-Object Spectrograph Telescope (ESO 4MOST). Furthermore, we shed light on\u0000how ground-based optical telescopes such as the Oukaimeden Observatory\u0000contribute to IAU Centre for the Protection of the Dark and Quiet Sky from\u0000Satellite Constellation Interference (IAU CPS) efforts that quantify satellite\u0000brightness.","PeriodicalId":501423,"journal":{"name":"arXiv - PHYS - Space Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The vast majority of the orbital population today is unobservable and untracked because of their small size. These lethal non-trackable objects will only become more numerous as more payloads and debris are launched into orbit and increase the collision rate. In this paper, the long-term effect of collisions is simulated with an efficient Monte-Carlo method to simulate the future LEO environment including lethal non-trackable objects, which is typically ignored due to the large computational resources required. The results show that simulations that do not incorporate lethal non-trackable debris would be omitting a large number of debilitating collisions with active payloads and catastrophic collisions to a smaller effect. This shows the importance of simulating small debris in the long-term evolution of the orbital population, which is often omitted in the literature. This increased debris population and consequentially the risk to orbital payloads diminishes as smaller lethal non-trackable objects are considered. An efficient and validated model is used to simulate these numerous small objects. Several future cases such as launches of registered megaconstellations, improved post-mission disposal rates and no-future launches are explored to understand the effect of the inclusion or exclusion of lethal non-trackable objects.
{"title":"Simulating the Evolution of Lethal Non-Trackable Population and its Effect on LEO Sustainability","authors":"Daniel Jang, Richard Linares","doi":"arxiv-2408.15025","DOIUrl":"https://doi.org/arxiv-2408.15025","url":null,"abstract":"The vast majority of the orbital population today is unobservable and\u0000untracked because of their small size. These lethal non-trackable objects will\u0000only become more numerous as more payloads and debris are launched into orbit\u0000and increase the collision rate. In this paper, the long-term effect of\u0000collisions is simulated with an efficient Monte-Carlo method to simulate the\u0000future LEO environment including lethal non-trackable objects, which is\u0000typically ignored due to the large computational resources required. The\u0000results show that simulations that do not incorporate lethal non-trackable\u0000debris would be omitting a large number of debilitating collisions with active\u0000payloads and catastrophic collisions to a smaller effect. This shows the\u0000importance of simulating small debris in the long-term evolution of the orbital\u0000population, which is often omitted in the literature. This increased debris\u0000population and consequentially the risk to orbital payloads diminishes as\u0000smaller lethal non-trackable objects are considered. An efficient and validated\u0000model is used to simulate these numerous small objects. Several future cases\u0000such as launches of registered megaconstellations, improved post-mission\u0000disposal rates and no-future launches are explored to understand the effect of\u0000the inclusion or exclusion of lethal non-trackable objects.","PeriodicalId":501423,"journal":{"name":"arXiv - PHYS - Space Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Munakata, Y. Hayashi, M. Kozai, C. Kato, N. Miyashita, R. Kataoka, A. Kadokura, S. Miyake, K. Iwai, E. Echer, A. Dal Lago, M. Rockenbach, N. J. Schuch, J. V. Bageston, C. R. Braga, H. K. Al Jassar, M. M. Sharma, M. L. Duldig, J. E. Humble, I. Sabbah, P. Evenson, T. Kuwabara, J. Kóta
This paper presents the global analysis of two extended decreases of the galactic cosmic ray intensity observed by world-wide networks of ground-based detectors in 2012. This analysis is capable of separately deriving the cosmic ray density (or omnidirectional intensity) and anisotropy each as a function of time and rigidity. A simple diffusion model along the spiral field line between Earth and a cosmic-ray barrier indicates the long duration of these events resulting from about 190$^circ$ eastern extension of a barrier such as an IP-shock followed by the sheath region and/or the corotating interaction region (CIR). It is suggested that the coronal mass ejection merging and compressing the preexisting CIR at its flank can produce such the extended barrier. The derived rigidity spectra of the density and anisotropy both vary in time during each event period. In particular we find that the temporal feature of the ``phantom Forbush decrease'' reported in an analyzed period is dependent on rigidity, looking quite different at different rigidities. From these rigidity spectra of the density and anisotropy, we derive the rigidity spectrum of the average parallel mean-free-path of pitch angle scattering along the spiral field line and infer the power spectrum of the magnetic fluctuation and its temporal variation. Possible physical cause of the strong rigidity dependence of the ``phantom Forbush decrease'' is also discussed. These results demonstrate the high-energy cosmic rays observed at Earth responding to remote space weather.
{"title":"Global analysis of the extended cosmic-ray decreases observed with world-wide networks of neutron monitors and muon detectors; temporal variation of the rigidity spectrum and its implication","authors":"K. Munakata, Y. Hayashi, M. Kozai, C. Kato, N. Miyashita, R. Kataoka, A. Kadokura, S. Miyake, K. Iwai, E. Echer, A. Dal Lago, M. Rockenbach, N. J. Schuch, J. V. Bageston, C. R. Braga, H. K. Al Jassar, M. M. Sharma, M. L. Duldig, J. E. Humble, I. Sabbah, P. Evenson, T. Kuwabara, J. Kóta","doi":"arxiv-2408.14696","DOIUrl":"https://doi.org/arxiv-2408.14696","url":null,"abstract":"This paper presents the global analysis of two extended decreases of the\u0000galactic cosmic ray intensity observed by world-wide networks of ground-based\u0000detectors in 2012. This analysis is capable of separately deriving the cosmic\u0000ray density (or omnidirectional intensity) and anisotropy each as a function of\u0000time and rigidity. A simple diffusion model along the spiral field line between\u0000Earth and a cosmic-ray barrier indicates the long duration of these events\u0000resulting from about 190$^circ$ eastern extension of a barrier such as an\u0000IP-shock followed by the sheath region and/or the corotating interaction region\u0000(CIR). It is suggested that the coronal mass ejection merging and compressing\u0000the preexisting CIR at its flank can produce such the extended barrier. The\u0000derived rigidity spectra of the density and anisotropy both vary in time during\u0000each event period. In particular we find that the temporal feature of the\u0000``phantom Forbush decrease'' reported in an analyzed period is dependent on\u0000rigidity, looking quite different at different rigidities. From these rigidity\u0000spectra of the density and anisotropy, we derive the rigidity spectrum of the\u0000average parallel mean-free-path of pitch angle scattering along the spiral\u0000field line and infer the power spectrum of the magnetic fluctuation and its\u0000temporal variation. Possible physical cause of the strong rigidity dependence\u0000of the ``phantom Forbush decrease'' is also discussed. These results\u0000demonstrate the high-energy cosmic rays observed at Earth responding to remote\u0000space weather.","PeriodicalId":501423,"journal":{"name":"arXiv - PHYS - Space Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Olifer, P. Manavalan, D. Headrick, S. Palmers, B. Harbarenko, J. Cai, J. Fourie, O. Bauer, I. Mann
Understanding energetic electron precipitation is crucial for accurate space weather modeling and forecasting, impacting the Earth's upper atmosphere and human infrastructure. This study presents a low-cost, low-mass, and low-power solution for high-fidelity analysis of electron precipitation events by measuring the resulting bremsstrahlung X-ray emissions. Specifically, we report on results from the flight of a radiation detector payload based on a silicon pixel read-out Timepix detector technology, and its successful utilization onboard a `burster' weather balloon. We launched this payload during the May 2024 superstorm, capturing high-resolution measurements of both background galactic cosmic ray radiation as well as storm-time energetic electron precipitation. We further developed particle and radiation detection algorithms to separate bremsstrahlung X-rays from other particle species in the pixel-resolved trajectories as seen in the Timepix detector. The measurements revealed a distinctive four-peak structure in X-ray flux, corresponding to periodic four-minute-long bursts of energetic electron precipitation between 21:20 and 21:40 UT. This precipitation was also observed by a riometer station close to the balloon launch path, further validating balloon measurements and the developed X-ray identification algorithm. The clear periodic structure of the measured precipitation is likely caused by modulation of the electron losses from the radiation belt by harmonic Pc5 ULF waves, observed contemporaneously on the ground. The study underscores the potential of compact, low-cost payloads for advancing our understanding of space weather. Specifically, we envision a potential use of such Timepix-based detectors in space science, for example on sounding rockets or nano-, micro-, and small satellite platforms.
了解高能电子沉淀对于准确的空间天气建模和预报至关重要，它影响着地球高层大气和人类基础设施。本研究提出了一种低成本、低质量和低功率的解决方案，通过测量由此产生的轫致辐射 X 射线辐射，对电子析出事件进行高保真分析。具体来说，我们报告了基于硅像素读出Timepix探测器技术的辐射探测器有效载荷的飞行结果，及其在 "爆破 "气象气球上的成功应用。我们在 2024 年 5 月的超级风暴期间发射了这一有效载荷，捕获了背景银河宇宙射线辐射和风暴时高能电子沉淀的高分辨率测量数据。我们进一步开发了粒子和辐射探测算法，以便将轫致辐射 X 射线与 Timepix 探测器所见的像素分辨轨迹中的其他粒子种类区分开来。测量结果表明，X射线通量中存在一个明显的四峰结构，它与世界标准时间21:20至21:40之间长达四分钟的周期性高能电子猝灭相对应。靠近气球发射路径的一个里氏计站也观测到了这种降水，进一步验证了气球测量结果和开发的 X 射线识别算法。测量到的降水具有明显的周期性结构，这可能是由于地面同时观测到的 Pc5 超低频谐波对辐射带电子损失的调制造成的。这项研究强调了小型、低成本有效载荷在促进我们了解空间天气方面的潜力。具体而言，我们设想这种基于 Timepix 的探测器可能会用于探空火箭或纳米、微米和小卫星平台等方面的科学研究。
{"title":"Low-cost Monitoring of Energetic Particle Precipitation: Weather Balloon-borne Timepix Measurements During the May 2024 Superstorm","authors":"L. Olifer, P. Manavalan, D. Headrick, S. Palmers, B. Harbarenko, J. Cai, J. Fourie, O. Bauer, I. Mann","doi":"arxiv-2408.14635","DOIUrl":"https://doi.org/arxiv-2408.14635","url":null,"abstract":"Understanding energetic electron precipitation is crucial for accurate space\u0000weather modeling and forecasting, impacting the Earth's upper atmosphere and\u0000human infrastructure. This study presents a low-cost, low-mass, and low-power\u0000solution for high-fidelity analysis of electron precipitation events by\u0000measuring the resulting bremsstrahlung X-ray emissions. Specifically, we report\u0000on results from the flight of a radiation detector payload based on a silicon\u0000pixel read-out Timepix detector technology, and its successful utilization\u0000onboard a `burster' weather balloon. We launched this payload during the May\u00002024 superstorm, capturing high-resolution measurements of both background\u0000galactic cosmic ray radiation as well as storm-time energetic electron\u0000precipitation. We further developed particle and radiation detection algorithms\u0000to separate bremsstrahlung X-rays from other particle species in the\u0000pixel-resolved trajectories as seen in the Timepix detector. The measurements\u0000revealed a distinctive four-peak structure in X-ray flux, corresponding to\u0000periodic four-minute-long bursts of energetic electron precipitation between\u000021:20 and 21:40 UT. This precipitation was also observed by a riometer station\u0000close to the balloon launch path, further validating balloon measurements and\u0000the developed X-ray identification algorithm. The clear periodic structure of\u0000the measured precipitation is likely caused by modulation of the electron\u0000losses from the radiation belt by harmonic Pc5 ULF waves, observed\u0000contemporaneously on the ground. The study underscores the potential of\u0000compact, low-cost payloads for advancing our understanding of space weather.\u0000Specifically, we envision a potential use of such Timepix-based detectors in\u0000space science, for example on sounding rockets or nano-, micro-, and small\u0000satellite platforms.","PeriodicalId":501423,"journal":{"name":"arXiv - PHYS - Space Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Relativistic charged particle beam can be used as destructive beam weapons in space for debris removal tasks. The trajectories of charged particles are affected by both electric and magnetic forces in the Earth's magnetic field. In this paper, we firstly analyzed the correlation parameters of the charged particle beam as a weapon when it propagated in the geomagnetic field. Then the models were constructed based on COMSOL Multiphysics and the IGRF model was adopted in the simulation. The gyro-radius and the related uncertainty were analyzed by simulation of the charged particle transport in the geomagnetic field at different altitudes. The charged beam spot radius divergency was also simulated. The magnetic field pinch effect can be found and can limit the beam spreading.
{"title":"Study of the relativistic charged particle beam propagation in Earth's magnetic field","authors":"Meihua Fang, Zheng liang, Yingkui Gong, Jianfei Chen, Guiping Zhu, Ting Liu, Yu Tian, Yu Zhou","doi":"arxiv-2409.06713","DOIUrl":"https://doi.org/arxiv-2409.06713","url":null,"abstract":"Relativistic charged particle beam can be used as destructive beam weapons in\u0000space for debris removal tasks. The trajectories of charged particles are\u0000affected by both electric and magnetic forces in the Earth's magnetic field. In\u0000this paper, we firstly analyzed the correlation parameters of the charged\u0000particle beam as a weapon when it propagated in the geomagnetic field. Then the\u0000models were constructed based on COMSOL Multiphysics and the IGRF model was\u0000adopted in the simulation. The gyro-radius and the related uncertainty were\u0000analyzed by simulation of the charged particle transport in the geomagnetic\u0000field at different altitudes. The charged beam spot radius divergency was also\u0000simulated. The magnetic field pinch effect can be found and can limit the beam\u0000spreading.","PeriodicalId":501423,"journal":{"name":"arXiv - PHYS - Space Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. M. Liu, B. N. Zhao, J. B. Cao, C. J. Pollock, C. T. Russell, Y. Y. Liu, X. N. Xing, P. A. Linqvist, J. L. Burch
Chorus is one of the strongest electromagnetic emissions naturally occurring in space, and can cause hazardous radiations to humans and satellites1-3. Although chorus has attracted extreme interest and been intensively studied for decades4-7, its generation and evolution remain highly debated, due to the complexity of the underlying physics and the limited capacity of previous spacecraft missions7. Chorus has also been believed to be governed by planetary magnetic dipolar fields5,7. Contrary to such conventional expectation, here we report unexpected observations of chorus in the terrestrial neutral sheet where magnetic dipolar effect is absent. Using unprecedentedly high-cadence data from the Magnetospheric Multiscale Mission, we present the first, ultrafast measurements of the wave dispersion relation and electron three-dimensional distributions within the waves, showing smoking-gun evidences for chorus-electron interactions and development of electron holes in the wave phase space. We estimate field-particle energy transfer inside the waves and find that the waves were extracting energy from local thermal electrons, in line with the wave positive growth rate derived from instability analysis. Our observations, opening new pathways for resolving long-standing controversies regarding the chorus emissions, are crucial for understanding nonlinear energy transport ubiquitously observed in space and astrophysical environments.
{"title":"Ultrafast measurement of field-particle energy transfer during chorus emissions in space","authors":"C. M. Liu, B. N. Zhao, J. B. Cao, C. J. Pollock, C. T. Russell, Y. Y. Liu, X. N. Xing, P. A. Linqvist, J. L. Burch","doi":"arxiv-2408.13156","DOIUrl":"https://doi.org/arxiv-2408.13156","url":null,"abstract":"Chorus is one of the strongest electromagnetic emissions naturally occurring\u0000in space, and can cause hazardous radiations to humans and satellites1-3.\u0000Although chorus has attracted extreme interest and been intensively studied for\u0000decades4-7, its generation and evolution remain highly debated, due to the\u0000complexity of the underlying physics and the limited capacity of previous\u0000spacecraft missions7. Chorus has also been believed to be governed by planetary\u0000magnetic dipolar fields5,7. Contrary to such conventional expectation, here we\u0000report unexpected observations of chorus in the terrestrial neutral sheet where\u0000magnetic dipolar effect is absent. Using unprecedentedly high-cadence data from\u0000the Magnetospheric Multiscale Mission, we present the first, ultrafast\u0000measurements of the wave dispersion relation and electron three-dimensional\u0000distributions within the waves, showing smoking-gun evidences for\u0000chorus-electron interactions and development of electron holes in the wave\u0000phase space. We estimate field-particle energy transfer inside the waves and\u0000find that the waves were extracting energy from local thermal electrons, in\u0000line with the wave positive growth rate derived from instability analysis. Our\u0000observations, opening new pathways for resolving long-standing controversies\u0000regarding the chorus emissions, are crucial for understanding nonlinear energy\u0000transport ubiquitously observed in space and astrophysical environments.","PeriodicalId":501423,"journal":{"name":"arXiv - PHYS - Space Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The open solar flux, that is, the total magnetic flux escaping the Sun, is one of the most important parameters connecting solar activity to the Earth. The open solar flux is commonly estimated from photospheric magnetic field measurements by making model assumptions about the solar corona. However, the question in which way the open solar flux is directly related to the distribution of the photospheric magnetic field is still partly unknown. We aim to reconstruct the open solar flux directly from the photospheric magnetic fields without making any assumptions about the corona and without using coronal hole observations, for instance. We modified an earlier vector sum method by taking magnetic field polarities into account and applied the method to the synoptic magnetograms of six instruments to determine the open solar flux from solar cycles 21-24. Results. The modified vector sum method produces a vector of the global solar magnetic field whose magnitude closely matches the open solar flux from the potential field source surface (PFSS) model both by the absolute scale and the overall time evolution for each of the six magnetograms. The latitude of this vector follows the Hale cycle by always pointing toward the dominantly positive-polarity hemisphere, and its longitude coincides with the location of the main coronal holes of the McIntosh Archive. We find multi-year periods during which the longitude of the vector slowly drifts or stays rather stationary in the Carrington frame. These periods are punctuated by times when the longitude moves rapidly in the Carrington frame. By comparing the magnitude of this vector to the open solar flux calculated from the PFSS model with different source surface heights, we find that the best match is produced with a source surface height $R_{ss} = 2.4 - 2.5R_odot$.
{"title":"Straight outta photosphere: Open solar flux without coronal modeling","authors":"Ismo Tähtinen, Timo Asikainen, Kalevi Mursula","doi":"arxiv-2408.11525","DOIUrl":"https://doi.org/arxiv-2408.11525","url":null,"abstract":"The open solar flux, that is, the total magnetic flux escaping the Sun, is\u0000one of the most important parameters connecting solar activity to the Earth.\u0000The open solar flux is commonly estimated from photospheric magnetic field\u0000measurements by making model assumptions about the solar corona. However, the\u0000question in which way the open solar flux is directly related to the\u0000distribution of the photospheric magnetic field is still partly unknown. We aim\u0000to reconstruct the open solar flux directly from the photospheric magnetic\u0000fields without making any assumptions about the corona and without using\u0000coronal hole observations, for instance. We modified an earlier vector sum\u0000method by taking magnetic field polarities into account and applied the method\u0000to the synoptic magnetograms of six instruments to determine the open solar\u0000flux from solar cycles 21-24. Results. The modified vector sum method produces\u0000a vector of the global solar magnetic field whose magnitude closely matches the\u0000open solar flux from the potential field source surface (PFSS) model both by\u0000the absolute scale and the overall time evolution for each of the six\u0000magnetograms. The latitude of this vector follows the Hale cycle by always\u0000pointing toward the dominantly positive-polarity hemisphere, and its longitude\u0000coincides with the location of the main coronal holes of the McIntosh Archive.\u0000We find multi-year periods during which the longitude of the vector slowly\u0000drifts or stays rather stationary in the Carrington frame. These periods are\u0000punctuated by times when the longitude moves rapidly in the Carrington frame.\u0000By comparing the magnitude of this vector to the open solar flux calculated\u0000from the PFSS model with different source surface heights, we find that the\u0000best match is produced with a source surface height $R_{ss} = 2.4 -\u00002.5R_odot$.","PeriodicalId":501423,"journal":{"name":"arXiv - PHYS - Space Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The paper presents a novel concept of a 3D structural metasurface with mechanically morphing capability that can be used as a transmit- or reflect-array to manipulate electromagnetic beams for applications in RF sensing and communications for both space and ground stations. They can be controlled using low-power actuators to deform the surface profile which is then utilised as a lens or a reflector for beamforming and steering. The proposed simulated structural metasurfaces can be used for either beam-steering or to generate bespoke contour beams for satellite communication and sensing.
{"title":"Structural Morphing Metasurface for Electromagnetic Beam Manipulation","authors":"Aakash Bansal, William Whittow","doi":"arxiv-2408.11231","DOIUrl":"https://doi.org/arxiv-2408.11231","url":null,"abstract":"The paper presents a novel concept of a 3D structural metasurface with\u0000mechanically morphing capability that can be used as a transmit- or\u0000reflect-array to manipulate electromagnetic beams for applications in RF\u0000sensing and communications for both space and ground stations. They can be\u0000controlled using low-power actuators to deform the surface profile which is\u0000then utilised as a lens or a reflector for beamforming and steering. The\u0000proposed simulated structural metasurfaces can be used for either beam-steering\u0000or to generate bespoke contour beams for satellite communication and sensing.","PeriodicalId":501423,"journal":{"name":"arXiv - PHYS - Space Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Sun exhibits episodic surges of magnetic activity across a range of temporal and spatial scales, the most prominent of which is the 11-ish year modulation of sunspot production. Beside the ~170 (min to max) decadal variation in sunspot production there is a less-explored quasi-annual variation in the range of 25-50 sunspots/year in magnitude. In addition, there is there is a slower, ~80 year period, 10-50 variation in the sunspot number, that is commonly referred to as the 'Gleissberg Cycle.' Using a suite of contemporary and historical observations we will illustrate these elements of our star's episodic behavior and present a hypothesis that may provide a consistent physical link between the observed 'climatic', 'decadal' and 'seasonal' magnetic variation of our star.
{"title":"Deciphering Solar Magnetic Activity: Some (Unpopular) Thoughts On the Coupling of the Sun's \"Weather\" and \"Climate\"","authors":"Scott W. McIntosh, Robert J. Leamon","doi":"arxiv-2408.10354","DOIUrl":"https://doi.org/arxiv-2408.10354","url":null,"abstract":"The Sun exhibits episodic surges of magnetic activity across a range of\u0000temporal and spatial scales, the most prominent of which is the 11-ish year\u0000modulation of sunspot production. Beside the ~170 (min to max) decadal\u0000variation in sunspot production there is a less-explored quasi-annual variation\u0000in the range of 25-50 sunspots/year in magnitude. In addition, there is there\u0000is a slower, ~80 year period, 10-50 variation in the sunspot number, that is\u0000commonly referred to as the 'Gleissberg Cycle.' Using a suite of contemporary\u0000and historical observations we will illustrate these elements of our star's\u0000episodic behavior and present a hypothesis that may provide a consistent\u0000physical link between the observed 'climatic', 'decadal' and 'seasonal'\u0000magnetic variation of our star.","PeriodicalId":501423,"journal":{"name":"arXiv - PHYS - Space Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nahuel Andrés, Norberto Romanelli, Christian Mazelle, Li-Jen Chen, Jacob R. Gruesbeck, Jared R. Espley
Using Mars Atmosphere and Volatile EvolutioN Magnetometer observations, we report the first statistical study of ultra-low frequency (ULF) waves at the Martian foreshock. The analyzed foreshock ULF wave events are observed in the 0.008-0.086 Hz frequency range, with nearly circular and elliptical left-handed polarization in the spacecraft reference frame. These waves are propagated quasi-parallel to the ambient magnetic field, with a moderate wave amplitude. All these properties are consistent with fast magnetosonic waves, most likely generated through the ion-ion right-hand resonant instability. In addition, our results suggest that the associated resonant backstreaming protons' velocities parallel to the mean magnetic field in the solar wind reference frame is $1.33 pm 0.40$ times the solar wind velocity. The similarity between our results and previous reports at other foreshocks may indicate the presence of a common acceleration process acting in planetary bow shocks and that is responsible for this particular backstreaming population.
{"title":"Foreshock Ultra-Low Frequency Waves at Mars: Consequence on the Particle Acceleration Mechanisms at the Martian Bow Shock","authors":"Nahuel Andrés, Norberto Romanelli, Christian Mazelle, Li-Jen Chen, Jacob R. Gruesbeck, Jared R. Espley","doi":"arxiv-2408.09003","DOIUrl":"https://doi.org/arxiv-2408.09003","url":null,"abstract":"Using Mars Atmosphere and Volatile EvolutioN Magnetometer observations, we\u0000report the first statistical study of ultra-low frequency (ULF) waves at the\u0000Martian foreshock. The analyzed foreshock ULF wave events are observed in the\u00000.008-0.086 Hz frequency range, with nearly circular and elliptical left-handed\u0000polarization in the spacecraft reference frame. These waves are propagated\u0000quasi-parallel to the ambient magnetic field, with a moderate wave amplitude.\u0000All these properties are consistent with fast magnetosonic waves, most likely\u0000generated through the ion-ion right-hand resonant instability. In addition, our\u0000results suggest that the associated resonant backstreaming protons' velocities\u0000parallel to the mean magnetic field in the solar wind reference frame is $1.33\u0000pm 0.40$ times the solar wind velocity. The similarity between our results and\u0000previous reports at other foreshocks may indicate the presence of a common\u0000acceleration process acting in planetary bow shocks and that is responsible for\u0000this particular backstreaming population.","PeriodicalId":501423,"journal":{"name":"arXiv - PHYS - Space Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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