| 1. |
- Vaivads, Andris, et al.
(författare)
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Turbulence Heating ObserveR - satellite mission proposal
- 2016
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Ingår i: JOURNAL OF PLASMA PHYSICS. - 0022-3778. ; 82
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Tidskriftsartikel (refereegranskat)abstract
- The Universe is permeated by hot, turbulent, magnetized plasmas. Turbulent plasma is a major constituent of active galactic nuclei, supernova remnants, the intergalactic and interstellar medium, the solar corona, the solar wind and the Earth's magnetosphere, just to mention a few examples. Energy dissipation of turbulent fluctuations plays a key role in plasma heating and energization, yet we still do not understand the underlying physical mechanisms involved. THOR is a mission designed to answer the questions of how turbulent plasma is heated and particles accelerated, how the dissipated energy is partitioned and how dissipation operates in different regimes of turbulence. THOR is a single-spacecraft mission with an orbit tuned to maximize data return from regions in near-Earth space - magnetosheath, shock, foreshock and pristine solar wind - featuring different kinds of turbulence. Here we summarize the THOR proposal submitted on 15 January 2015 to the 'Call for a Medium-size mission opportunity in ESAs Science Programme for a launch in 2025 (M4)'. THOR has been selected by European Space Agency (ESA) for the study phase.
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| 2. |
- Farrugia, C. J., et al.
(författare)
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MMS Observations of Reconnection at Dayside Magnetopause Crossings During Transitions of the Solar Wind to Sub-Alfvénic Flow
- 2017
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Ingår i: Journal of Geophysical Research - Space Physics. - : Blackwell Publishing Ltd. - 2169-9380 .- 2169-9402. ; 122:10, s. 9934-9951
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Tidskriftsartikel (refereegranskat)abstract
- We present MMS observations during two dayside magnetopause crossings under hitherto unexamined conditions: (i) when the bow shock is weakening and the solar wind transitioning to sub-Alfvénic flow and (ii) when it is reforming. Interplanetary conditions consist of a magnetic cloud with (i) a strong B (∼20 nT) pointing south and (ii) a density profile with episodic decreases to values of ∼0.3 cm−3 followed by moderate recovery. During the crossings the magnetosheath magnetic field is stronger than the magnetosphere field by a factor of ∼2.2. As a result, during the outbound crossing through the ion diffusion region, MMS observed an inversion of the relative positions of the X and stagnation (S) lines from that typically the case: the S line was closer to the magnetosheath side. The S line appears in the form of a slow expansion fan near which most of the energy dissipation is taking place. While in the magnetosphere between the crossings, MMS observed strong field and flow perturbations, which we argue to be due to kinetic Alfvén waves. During the reconnection interval, whistler mode waves generated by an electron temperature anisotropy (Te⊥>Te∥) were observed. Another aim of the paper is to distinguish bow shock-induced field and flow perturbations from reconnection-related signatures. The high-resolution MMS data together with 2-D hybrid simulations of bow shock dynamics helped us to distinguish between the two sources. We show examples of bow shock-related effects (such as heating) and reconnection effects such as accelerated flows satisfying the Walén relation.
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| 3. |
- Retinò, A., et al.
(författare)
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Particle energization in space plasmas : towards a multi-point, multi-scale plasma observatory
- 2021
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Ingår i: Experimental astronomy. - : Springer Nature. - 0922-6435 .- 1572-9508.
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Tidskriftsartikel (refereegranskat)abstract
- This White Paper outlines the importance of addressing the fundamental science theme “How are charged particles energized in space plasmas” through a future ESA mission. The White Paper presents five compelling science questions related to particle energization by shocks, reconnection, waves and turbulence, jets and their combinations. Answering these questions requires resolving scale coupling, nonlinearity, and nonstationarity, which cannot be done with existing multi-point observations. In situ measurements from a multi-point, multi-scale L-class Plasma Observatory consisting of at least seven spacecraft covering fluid, ion, and electron scales are needed. The Plasma Observatory will enable a paradigm shift in our comprehension of particle energization and space plasma physics in general, with a very important impact on solar and astrophysical plasmas. It will be the next logical step following Cluster, THEMIS, and MMS for the very large and active European space plasmas community. Being one of the cornerstone missions of the future ESA Voyage 2050 science programme, it would further strengthen the European scientific and technical leadership in this important field.
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| 4. |
- Nakamura, R, et al.
(författare)
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Substorm observations in the early morning sector with Equator-S and Geotail
- 1999
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Ingår i: Annales Geophysicae. - : SPRINGER VERLAG. - 0992-7689 .- 1432-0576. ; 17:12, s. 1602-1610
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Tidskriftsartikel (refereegranskat)abstract
- Data from Equator-S and Geotail are used to study the dynamics of the plasma sheet observed during a substorm with multiple intensifications on 25 April 1998, when both spacecraft were located in the early morning sector (03-04 MLT) at a radial distance o
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| 5. |
- Soucek, J., et al.
(författare)
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EMC Aspects Of Turbulence Heating Observer (THOR) Spacecraft
- 2016
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Ingår i: Proceedings Of 2016 Esa Workshop On Aerospace Emc (Aerospace Emc). - : Institute of Electrical and Electronics Engineers (IEEE). - 9789292213039
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Konferensbidrag (refereegranskat)abstract
- Turbulence Heating ObserveR (THOR) is a spacecraft mission dedicated to the study of plasma turbulence in near-Earth space. The mission is currently under study for implementation as a part of ESA Cosmic Vision program. THOR will involve a single spinning spacecraft equipped with state of the art instruments capable of sensitive measurements of electromagnetic fields and plasma particles. The sensitive electric and magnetic field measurements require that the spacecraft-generated emissions are restricted and strictly controlled; therefore a comprehensive EMC program has been put in place already during the study phase. The THOR study team and a dedicated EMC working group are formulating the mission EMC requirements already in the earliest phase of the project to avoid later delays and cost increases related to EMC. This article introduces the THOR mission and reviews the current state of its EMC requirements.
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| 6. |
- Vaivads, A, et al.
(författare)
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Compressional Pc5 type pulsations in the morningside plasma sheet
- 2001
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Ingår i: ANNALES GEOPHYSICAE. - : EUROPEAN GEOPHYSICAL SOCIETY. - 0992-7689. ; 19:3, s. 311-320 Language: English
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Tidskriftsartikel (refereegranskat)abstract
- We study compressional pulsations in Pc5 frequency range observed in the dawn-side at distances of about 10 R-E, close to the magnetic equator. We use data obtained during two events of conjunctions between Equator-S and Geotail: 1000-1700 UT on 9 March 1
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| 7. |
- Yamauchi, M., et al.
(författare)
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Plasma-neutral gas interactions in various space environments : Assessment beyond simplified approximations as a Voyage 2050 theme
- 2022
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Ingår i: Experimental astronomy. - : Springer Nature. - 0922-6435 .- 1572-9508.
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Tidskriftsartikel (refereegranskat)abstract
- In the White Paper, submitted in response to the European Space Agency (ESA) Voyage 2050 Call, we present the importance of advancing our knowledge of plasma-neutral gas interactions, and of deepening our understanding of the partially ionized environments that are ubiquitous in the upper atmospheres of planets and moons, and elsewhere in space. In future space missions, the above task requires addressing the following fundamental questions: (A) How and by how much do plasma-neutral gas interactions influence the re-distribution of externally provided energy to the composing species? (B) How and by how much do plasma-neutral gas interactions contribute toward the growth of heavy complex molecules and biomolecules? Answering these questions is an absolute prerequisite for addressing the long-standing questions of atmospheric escape, the origin of biomolecules, and their role in the evolution of planets, moons, or comets, under the influence of energy sources in the form of electromagnetic and corpuscular radiation, because low-energy ion-neutral cross-sections in space cannot be reproduced quantitatively in laboratories for conditions of satisfying, particularly, (1) low-temperatures, (2) tenuous or strong gradients or layered media, and (3) in low-gravity plasma. Measurements with a minimum core instrument package (< 15 kg) can be used to perform such investigations in many different conditions and should be included in all deep-space missions. These investigations, if specific ranges of background parameters are considered, can also be pursued for Earth, Mars, and Venus.
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