| 1. |
- Zouganelis, I., et al.
(författare)
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The Solar Orbiter Science Activity Plan : Translating solar and heliospheric physics questions into action
- 2020
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Ingår i: Astronomy and Astrophysics. - : EDP SCIENCES S A. - 0004-6361 .- 1432-0746. ; 642
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Tidskriftsartikel (refereegranskat)abstract
- Solar Orbiter is the first space mission observing the solar plasma both in situ and remotely, from a close distance, in and out of the ecliptic. The ultimate goal is to understand how the Sun produces and controls the heliosphere, filling the Solar System and driving the planetary environments. With six remote-sensing and four in-situ instrument suites, the coordination and planning of the operations are essential to address the following four top-level science questions: (1) What drives the solar wind and where does the coronal magnetic field originate?; (2) How do solar transients drive heliospheric variability?; (3) How do solar eruptions produce energetic particle radiation that fills the heliosphere?; (4) How does the solar dynamo work and drive connections between the Sun and the heliosphere? Maximising the mission's science return requires considering the characteristics of each orbit, including the relative position of the spacecraft to Earth (affecting downlink rates), trajectory events (such as gravitational assist manoeuvres), and the phase of the solar activity cycle. Furthermore, since each orbit's science telemetry will be downloaded over the course of the following orbit, science operations must be planned at mission level, rather than at the level of individual orbits. It is important to explore the way in which those science questions are translated into an actual plan of observations that fits into the mission, thus ensuring that no opportunities are missed. First, the overarching goals are broken down into specific, answerable questions along with the required observations and the so-called Science Activity Plan (SAP) is developed to achieve this. The SAP groups objectives that require similar observations into Solar Orbiter Observing Plans, resulting in a strategic, top-level view of the optimal opportunities for science observations during the mission lifetime. This allows for all four mission goals to be addressed. In this paper, we introduce Solar Orbiter's SAP through a series of examples and the strategy being followed.
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| 2. |
- Maksimovic, M., et al.
(författare)
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First observations and performance of the RPW instrument on board the Solar Orbiter mission
- 2021
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 656
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Tidskriftsartikel (refereegranskat)abstract
- The Radio and Plasma Waves (RPW) instrument on the ESA Solar Orbiter mission is designed to measure in situ magnetic and electric fields and waves from the continuum up to several hundred kHz. The RPW also observes solar and heliospheric radio emissions up to 16 MHz. It was switched on and its antennae were successfully deployed two days after the launch of Solar Orbiter on February 10, 2020. Since then, the instrument has acquired enough data to make it possible to assess its performance and the electromagnetic disturbances it experiences. In this article, we assess its scientific performance and present the first RPW observations. In particular, we focus on a statistical analysis of the first observations of interplanetary dust by the instrument's Thermal Noise Receiver. We also review the electro-magnetic disturbances that RPW suffers, especially those which potential users of the instrument data should be aware of before starting their research work.
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| 3. |
- Maksimovic, M., et al.
(författare)
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The Solar Orbiter Radio and Plasma Waves (RPW) instrument
- 2020
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Ingår i: Astronomy and Astrophysics. - : EDP SCIENCES S A. - 0004-6361 .- 1432-0746. ; 642
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Tidskriftsartikel (refereegranskat)abstract
- The Radio and Plasma Waves (RPW) instrument on the ESA Solar Orbiter mission is described in this paper. This instrument is designed to measure in-situ magnetic and electric fields and waves from the continuous to a few hundreds of kHz. RPW will also observe solar radio emissions up to 16 MHz. The RPW instrument is of primary importance to the Solar Orbiter mission and science requirements since it is essential to answer three of the four mission overarching science objectives. In addition RPW will exchange on-board data with the other in-situ instruments in order to process algorithms for interplanetary shocks and type III langmuir waves detections.
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| 4. |
- Zaslavsky, A., et al.
(författare)
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First dust measurements with the Solar Orbiter Radio and Plasma Wave instrument
- 2021
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 656, s. A30-
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Tidskriftsartikel (refereegranskat)abstract
- Context. Impacts of dust grains on spacecraft are known to produce typical impulsive signals in the voltage waveform recorded at the terminals of electric antennas. Such signals (as may be expected) are routinely detected by the Time Domain Sampler (TDS) system of the Radio and Plasma Waves (RPW) instrument on board Solar Orbiter. Aims. We investigate the capabilities of RPW in terms of interplanetary dust studies and present the first analysis of dust impacts recorded by this instrument. Our purpose is to characterize the dust population observed in terms of size, flux, and velocity. Methods. We briefly discuss previously developed models of voltage pulse generation after a dust impact onto a spacecraft and present the relevant technical parameters for Solar Orbiter RPW as a dust detector. Then we present the statistical analysis of the dust impacts recorded by RPW /TDS from April 20, 2020 to February 27, 2021 between 0.5AU and 1AU. Results. The study of the dust impact rate along Solar Orbiter's orbit shows that the dust population studied presents a radial velocity component directed outward from the Sun. Its order of magnitude can be roughly estimated as nu(r,dust) similar or equal to 50 km s(-1), which is consistent with the flux of impactors being dominated by fi-meteoroids. We estimate the cumulative flux of these grains at 1AU to be roughly F-beta similar or equal to 8 x 10(-5) m(-2) s(-1) for particles of a radius r greater than or similar to 100 nm. The power law index ffi of the cumulative mass flux of the impactors is evaluated by two di fferents methods, namely: direct observations of voltage pulses and indirect e ffect on the impact rate dependency on the impact speed. Both methods give the following result: delta similar or equal to 0.3-0.4. Conclusions. Solar Orbiter RPW proves to be a suitable instrument for interplanetary dust studies, and the dust detection algorithm implemented in the TDS subsystem an e fficient tool for fluxes estimation. These first results are promising for the continuation of the mission, in particular, for the in situ study of the inner Solar System dust cloud outside of the ecliptic plane, which Solar Orbiter will be the first spacecraft to explore.
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| 5. |
- Hadid, L. Z., et al.
(författare)
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Solar Orbiter's first Venus flyby : Observations from the Radio and Plasma Wave instrument
- 2021
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 656
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Tidskriftsartikel (refereegranskat)abstract
- Context. On December 27, 2020, Solar Orbiter completed its first gravity assist manoeuvre of Venus (VGAM1). While this flyby was performed to provide the spacecraft with sufficient velocity to get closer to the Sun and observe its poles from progressively higher inclinations, the Radio and Plasma Wave (RPW) consortium, along with other operational in situ instruments, had the opportunity to perform high cadence measurements and study the plasma properties in the induced magnetosphere of Venus.Aims. In this paper, we review the main observations of the RPW instrument during VGAM1. They include the identification of a number of magnetospheric plasma wave modes, measurements of the electron number densities computed using the quasi-thermal noise spectroscopy technique and inferred from the probe-to-spacecraft potential, the observation of dust impact signatures, kinetic solitary structures, and localized structures at the bow shock, in addition to the validation of the wave normal analysis on-board from the Low Frequency Receiver.Methods. We used the data products provided by the different subsystems of RPW to study Venus' induced magnetosphere.Results. The results include the observations of various electromagnetic and electrostatic wave modes in the induced magnetosphere of Venus: strong emissions of similar to 100 Hz whistler waves are observed in addition to electrostatic ion acoustic waves, solitary structures and Langmuir waves in the magnetosheath of Venus. Moreover, based on the different levels of the wave amplitudes and the large-scale variations of the electron number densities, we could identify different regions and boundary layers at Venus.Conclusions. The RPW instrument provided unprecedented AC magnetic and electric field measurements in Venus' induced magnetosphere for continuous frequency ranges and with high time resolution. These data allow for the conclusive identification of various plasma waves at higher frequencies than previously observed and a detailed investigation regarding the structure of the induced magnetosphere of Venus. Furthermore, noting that prior studies were mainly focused on the magnetosheath region and could only reach 10-12 Venus radii (R-V) down the tail, the particular orbit geometry of Solar Orbiter's VGAM1, allowed the first investigation of the nature of the plasma waves continuously from the bow shock to the magnetosheath, extending to similar to 70R(V) in the far distant tail region.
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| 6. |
- Meyer-Vernet, Nicole, et al.
(författare)
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The physics and detection of nanodust in the solar system
- 2015
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Ingår i: Plasma Physics and Controlled Fusion. - : Institute of Physics Publishing (IOPP). - 0741-3335 .- 1361-6587. ; 57:1
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Tidskriftsartikel (refereegranskat)abstract
- The mass distribution of small bodies in the solar system extends over more than 35 orders of magnitude, from asteroids to nanodust, which bridge the gap between molecules and macroscopic submicron grains. The small size of nanograins compared to the relevant basic scales gives them peculiar properties. Some of these properties affect their electric charging and their large charge-to-mass ratio drives their acceleration to very high speeds in moving magnetised plasmas, as the solar wind and rotating planetary magnetospheres. The electric charge and/or high speed of nanograins have enabled them to be detected serendipitously in various parts of the solar system by several instruments designed to study larger dust, plasma particles, or waves, on a number of spacecraft. These discoveries have opened an emerging field of research, in which many open questions remain, in particular concerning the lower size limit of the particles.
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| 7. |
- Moncuquet, M., et al.
(författare)
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The radio waves and thermal electrostatic noise spectroscopy (SORBET) experiment on BEPICOLOMBO/MMO/PWI : Scientific objectives and performance
- 2006
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Ingår i: Advances in Space Research. - : Elsevier. - 0273-1177 .- 1879-1948. ; 38:4, s. 680-685
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Tidskriftsartikel (refereegranskat)abstract
- SORBET (Spectroscopie des Ondes Radio and du Bruit Electrostatique Thermique) is a radio HF spectrometer designed for the radio and Plasma Waves Instrument onboard BepiColombo/Mercury Magnetospheric Orbiter (MMO), which performs remote and in situ measurements of waves (electromagnetic and electrostatic). Technically, SORBET includes a plasma wave spectrometer, with two E-field inputs from the two perpendicular electric antennas and one B-field input from a search coil, in the range 2.5-640 kHz. This frequency band includes the local gyrofrequency and plasma frequency expected on most part of the MMO orbits. SORBET also includes a higher frequency radio receiver for remote sensing in the range 500 kHz-10.2 MHz. Owing to its capabilities, SORBET will be able to address the following scientific objectives: High resolution mapping(similar to 30 km) of electron density and temperature in the solar wind and in the Hermean magnetosphere and exo-ionosphere, via the technique of Quasi-Thermal Noise (QTN) spectroscopy. These QTN measurements will be determinant for the dynamic modeling of the magnetosphere and will provide a fundamental input for the chemistry of cold ionized species (Na, K, O, . . .) in Mercury's environment. Detection and study of Hermean radio emissions, including possible cyclotron emissions (up to similar to 10-20 kHz) from mildly energetic electrons in most highly magnetized (polar?) regions, and possible synchrotron radiation (up to a few MHz?) from more energetic electrons. Monitoring of solar radio emissions up to similar to 10 MHz in order to create a solar activity index from the view point of Mercury, allowing to correlate it with the Hermean magnetospheric response. We especially discuss the capabilities of SORBET for performing the QTN spectroscopy in Mercury's magnetosphere, using the two electric dipole antennas equipping MMO, called MEFISTO and WPT.
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