Logo: to the web site of Uppsala University

uu.sePublications from Uppsala University
Change search
Link to record
Permanent link

Direct link
Alternative names
Publications (10 of 59) Show all publications
Andrews, D. J., Stergiopoulou, K., Andersson, L., Eriksson, A., Ergun, R. & Pilinski, M. (2023). Electron densities and temperatures in the Martian ionosphere: MAVEN LPW observations of control by crustal fields. Journal of Geophysical Research - Space Physics, 128(3), Article ID e2022JA031027.
Open this publication in new window or tab >>Electron densities and temperatures in the Martian ionosphere: MAVEN LPW observations of control by crustal fields
Show others...
2023 (English)In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 128, no 3, article id e2022JA031027Article in journal (Refereed) Published
Abstract [en]

Mars Express and Mars Atmosphere and Volatile Evolution (MAVEN) observations have demonstrated the influence of Mars's spatially variable crustal magnetic fields upon the configuration of the plasma in the ionosphere. This influence furthermore leads to variations in ionospheric escape, conceivably in part through the modification of the plasma density and electron temperature in the upper ionosphere. In this study, we examine MAVEN Langmuir Probe and Waves data, finding a clear correspondence between the structure of the crustal fields and both the measured electron temperatures and densities, by first constructing an "average " profile from which departures can be quantified. Electron temperatures are shown to be lower in regions of strong crustal fields over a wide altitude range. We extend previous analyses to cover the nightside ionosphere, finding the same effects present to a lesser degree, in contrast to previous studies where the opposite relationship was found between densities and crustal fields. We further determine the altitude range over which this coupling between both plasma density (and temperature) and crustal fields is effective and use measurements made by MAVEN in the solar wind to explore the dependence of this crustal field control on the coupling to the solar wind and the interplanetary magnetic field (IMF). Based on this, there is some suggestion that variations in the solar wind dynamic pressure are associated with modulation of the effects of the crustal fields on plasma density, whereas the strength of the IMF modulates the crustal fields effects on both electron densities and temperatures.

Place, publisher, year, edition, pages
American Geophysical Union (AGU), 2023
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-481217 (URN)10.1029/2022JA031027 (DOI)000934590000001 ()
Funder
Swedish National Space Board, DNR 156/16
Available from: 2022-08-06 Created: 2022-08-06 Last updated: 2023-03-13Bibliographically approved
Stergiopoulou, K., Jarvinen, R., Andrews, D. J., Edberg, N. J. T., Dimmock, A. P., Kallio, E., . . . Khotyaintsev, Y. V. (2023). Solar Orbiter Model-Data Comparison in Venus' Induced Magnetotail. Journal of Geophysical Research - Space Physics, 128(2)
Open this publication in new window or tab >>Solar Orbiter Model-Data Comparison in Venus' Induced Magnetotail
Show others...
2023 (English)In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 128, no 2Article in journal (Refereed) Submitted
Abstract [en]

We investigate the structure of the Venusian magnetotail utilizing magnetic field and electron density measurements that cover a wide range of distances from the planet, from the first two Solar Orbiter Venus flybys. We examine the magnetic field components along the spacecraft trajectory up to 80 Venus radii down the tail. Even though the magnetic field behavior differs considerably between the two cases, we see extended electron density enhancements covering distances greater than ∼20 RV in both flybys. We compare the magnetic field measurements with a global hybrid model of the induced magnetosphere and magnetotail of Venus, to examine to what degree the observations can be understood with the simulation. The model upstream conditions are stationary and the solution encloses a large volume of 83 RV × 60 RV × 60 RV in which we look for spatial magnetic field and plasma variations. We rotate the simulation solution to describe different stationary upstream IMF clock angle cases with a 10° step and find the clock angle for which the agreement between observations and model is maximized along Solar Orbiter's trajectory in 1-min steps. We find that in both flybys there is better agreement with the observations when we rotate the model for some intervals, while there are parts that cannot be well reproduced by the model irrespective of how we vary the IMF clock angle, suggesting the presence of non-stationary features in  the Venus-solar wind interaction not accounted for in the hybrid model.

Place, publisher, year, edition, pages
American Geophysical Union (AGU), 2023
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-481216 (URN)10.1029/2022JA031023 (DOI)000949130300001 ()
Available from: 2022-08-06 Created: 2022-08-06 Last updated: 2023-04-19Bibliographically approved
Stergiopoulou, K., Andrews, D. J., Edberg, N. J. T., Halekas, J., Lester, M., Sanchez-Cano, B., . . . Gruesbeck, J. R. (2022). A Two-Spacecraft Study of Mars' Induced Magnetosphere's Response to Upstream Conditions. Journal of Geophysical Research - Space Physics, 127(4), Article ID e2021JA030227.
Open this publication in new window or tab >>A Two-Spacecraft Study of Mars' Induced Magnetosphere's Response to Upstream Conditions
Show others...
2022 (English)In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 127, no 4, article id e2021JA030227Article in journal (Refereed) Published
Abstract [en]

This is a two-spacecraft study, in which we investigate the effects of the upstream solar wind conditions on the Martian induced magnetosphere and upper ionosphere. We use Mars Express (MEX) magnetic field magnitude data together with interplanetary magnetic field (IMF), solar wind density, and velocity measurements from the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, from November 2014 to November 2018. We compare simultaneous observations of the magnetic field magnitude in the induced magnetosphere of Mars (|B|(IM)) with the IMF magnitude (|B|(IMF)), and we examine variations in the ratio |B|(IM)/|B|(IMF) with solar wind dynamic pressure, speed and density. We find that the |B|(IM)/|B|(IMF) ratio in the induced magnetosphere generally decreases with increased dynamic pressure and that a more structured interaction is seen when comparing induced fields to the instantaneous IMF, where reductions in the relative fields at the magnetic pile up boundary (MPB) are more evident than in the field strength itself, along with enhancements in the immediate vicinity of the optical shadow of Mars. We interpret these results as evidence that while the induced magnetosphere is indeed compressed and induced field strengths are higher during periods of high dynamic pressure, a relatively larger amount of magnetic flux threads the region compared to that available from the unperturbed IMF during low dynamic pressure intervals.

Place, publisher, year, edition, pages
American Geophysical Union (AGU)American Geophysical Union (AGU), 2022
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-473189 (URN)10.1029/2021JA030227 (DOI)000778129500001 ()
Funder
Swedish National Space Board, DNR 156/16Swedish National Space Board, 162/14
Available from: 2022-04-27 Created: 2022-04-27 Last updated: 2024-01-15Bibliographically approved
Sanchez-Cano, B., Lester, M., Andrews, D. J., Opgenoorth, H., Lillis, R., Leblanc, F., . . . Roman, M. T. (2022). Mars' plasma system. Scientific potential of coordinated multipoint missions: "The next generation". Experimental astronomy, 54(2-3), 641-676
Open this publication in new window or tab >>Mars' plasma system. Scientific potential of coordinated multipoint missions: "The next generation"
Show others...
2022 (English)In: Experimental astronomy, ISSN 0922-6435, E-ISSN 1572-9508, Vol. 54, no 2-3, p. 641-676Article in journal (Refereed) Published
Abstract [en]

The objective of this White Paper, submitted to ESA's Voyage 2050 call, is to get a more holistic knowledge of the dynamics of the Martian plasma system, from its surface up to the undisturbed solar wind outside of the induced magnetosphere. This can only be achieved with coordinated multi-point observations with high temporal resolution as they have the scientific potential to track the whole dynamics of the system (from small to large scales), and they constitute the next generation of the exploration of Mars analogous to what happened at Earth a few decades ago. This White Paper discusses the key science questions that are still open at Mars and how they could be addressed with coordinated multipoint missions. The main science questions are: (i) How does solar wind driving impact the dynamics of the magnetosphere and ionosphere? (ii) What is the structure and nature of the tail of Mars' magnetosphere at all scales? (iii) How does the lower atmosphere couple to the upper atmosphere? (iv) Why should we have a permanent in-situ Space Weather monitor at Mars? Each science question is devoted to a specific plasma region, and includes several specific scientific objectives to study in the coming decades. In addition, two mission concepts are also proposed based on coordinated multi-point science from a constellation of orbiting and ground-based platforms, which focus on understanding and solving the current science gaps.

Place, publisher, year, edition, pages
Springer Nature, 2022
Keywords
Mars, Plasma, Coordinated multipoint missions, Future missions, Science gaps, ESA-Voyage2050
National Category
Astronomy, Astrophysics and Cosmology Aerospace Engineering
Identifiers
urn:nbn:se:uu:diva-512877 (URN)10.1007/s10686-021-09790-0 (DOI)000718072900001 ()36915625 (PubMedID)
Available from: 2023-10-02 Created: 2023-10-02 Last updated: 2024-01-17Bibliographically approved
Lillis, R. J., Mitchell, D., Montabone, L., Heavens, N., Harrison, T., Stuurman, C., . . . Tripathi, A. (2021). MOSAIC: A Satellite Constellation to Enable Groundbreaking Mars Climate System Science and Prepare for Human Exploration. The Planetary Science Journal, 2(5), Article ID 211.
Open this publication in new window or tab >>MOSAIC: A Satellite Constellation to Enable Groundbreaking Mars Climate System Science and Prepare for Human Exploration
Show others...
2021 (English)In: The Planetary Science Journal, E-ISSN 2632-3338, Vol. 2, no 5, article id 211Article in journal (Refereed) Published
Abstract [en]

The Martian climate system has been revealed to rival the complexity of Earth's. Over the last 20 yr, a fragmented and incomplete picture has emerged of its structure and variability; we remain largely ignorant of many of the physical processes driving matter and energy flow between and within Mars' diverse climate domains. Mars Orbiters for Surface, Atmosphere, and Ionosphere Connections (MOSAIC) is a constellation of ten platforms focused on understanding these climate connections, with orbits and instruments tailored to observe the Martian climate system from three complementary perspectives. First, low-circular near-polar Sun-synchronous orbits (a large mothership and three smallsats spaced in local time) enable vertical profiling of wind, aerosols, water, and temperature, as well as mapping of surface and subsurface ice. Second, elliptical orbits sampling all of Mars' plasma regions enable multipoint measurements necessary to understand mass/energy transport and ion-driven escape, also enabling, with the polar orbiters, dense radio occultation coverage. Last, longitudinally spaced areostationary orbits enable synoptic views of the lower atmosphere necessary to understand global and mesoscale dynamics, global views of the hydrogen and oxygen exospheres, and upstream measurements of space weather conditions. MOSAIC will characterize climate system variability diurnally and seasonally, on meso-, regional, and global scales, targeting the shallow subsurface all the way out to the solar wind, making many first-of-their-kind measurements. Importantly, these measurements will also prepare for human exploration and habitation of Mars by providing water resource prospecting, operational forecasting of dust and radiation hazards, and ionospheric communication/positioning disruptions.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2021
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-497479 (URN)10.3847/PSJ/ac0538 (DOI)000917388200001 ()
Available from: 2023-03-01 Created: 2023-03-01 Last updated: 2023-03-01Bibliographically approved
Stergiopoulou, K., Andrews, D. J., Edberg, N. J. T., Halekas, J., Kopf, A., Lester, M., . . . Sanchez-Cano, B. (2020). Mars Express Observations of Cold Plasma Structures in the Martian Magnetotail. Journal of Geophysical Research - Space Physics, 125(10), Article ID e2020JA028056.
Open this publication in new window or tab >>Mars Express Observations of Cold Plasma Structures in the Martian Magnetotail
Show others...
2020 (English)In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 125, no 10, article id e2020JA028056Article in journal (Refereed) Published
Abstract [en]

We present observations from five Mars Express (MEX) orbits in September 2016 while the spacecraft passed through the Martian induced magnetotail at altitudes up to 3,500 km. On these orbits, the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument was operated in Active Ionospheric Sounding (AIS) mode at much higher altitude than normal, acting as a local sounder and detecting cold plasma structures in this region. In this paper we combine MARSIS tail measurements with solar wind data from the Solar Wind Ion Analyzer (SWIA) instrument and the Magnetometer (MAG) from Mars Atmosphere and Volatile EvolutioN (MAVEN) in order to investigate possible factors affecting plasma transport from the dayside and through the terminator. MARSIS observed structured cold ionospheric plasma along its trajectory, at all altitudes and solar zenith angles (SZAs). Isolated regions of cold plasma were also observed on each orbit as the spacecraft crossed the terminator, even at high altitudes. We conclude that the variability of plasma seen in the tail results from a multifactorial transport process, the development of which cannot be attributed to a sole parameter influencing it, despite the availability of simultaneous high quality solar wind measurements.

Place, publisher, year, edition, pages
American Geophysical Union (AGU), 2020
Keywords
SUPRATHERMAL ELECTRON DEPLETIONS, CRUSTAL MAGNETIC-FIELD, SOLAR-WIND INTERACTION, NIGHTSIDE IONOSPHERE, MONOCHROMATIC RADIATION, GLOBAL SURVEYOR, ATMOSPHERE, VARIABILITY, IONIZATION, DEPENDENCE
National Category
Fusion, Plasma and Space Physics Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-433378 (URN)10.1029/2020JA028056 (DOI)000600990300035 ()
Funder
Swedish National Space Board, DNR 156/16Swedish National Space Board, 162/14Swedish National Space Board, 135/13Swedish Research Council, 621-2013-4191
Available from: 2021-02-03 Created: 2021-02-03 Last updated: 2022-08-06Bibliographically approved
Sanchez-Cano, B., Lester, M., Witasse, O., Morgan, D. D., Opgenoorth, H., Andrews, D. J., . . . Cardesin-Moinelo, A. (2020). Mars' Ionospheric Interaction With Comet C/2013 A1 Siding Spring's Coma at Their Closest Approach as Seen by Mars Express. Journal of Geophysical Research - Space Physics, 125(1), Article ID e2019JA027344.
Open this publication in new window or tab >>Mars' Ionospheric Interaction With Comet C/2013 A1 Siding Spring's Coma at Their Closest Approach as Seen by Mars Express
Show others...
2020 (English)In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 125, no 1, article id e2019JA027344Article in journal (Refereed) Published
Abstract [en]

On 19 October 2014, Mars experienced a close encounter with Comet C/2013 A1 Siding Spring. Using data from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) on board Mars Express (MEX), we assess the interaction of the Martian ionosphere with the comet's coma and possibly magnetic tail during the orbit of their closest approach. The topside ionospheric electron density profile is evaluated from the altitude of the peak density of the ionosphere up to the MEX altitude. We find complex and rapid variability in the ionospheric profile along the MEX orbit, not seen even after the impact of a large coronal mass ejection. Before closest approach, large electron density reductions predominate, which could be caused either by comet water damping or comet magnetic field interactions. After closest approach, a substantial electron density rise predominates. Moreover, several extra topside layers are visible along the whole orbit at different altitudes, which could be related to different processes as we discuss. Plain Language Summary The comet Siding Spring made a single flyby through the solar system in October 2014, passing close to Mars on 19 October 2014, at only one third of the Earth-Moon distance. For about 10 hr, the Martian ionosphere (upper atmosphere) was in touch with the cometary coma (also called cometary atmosphere). In this work, we use data from the Mars Express mission to evaluate the behavior of the ionosphere of Mars at the comet closest approach. We find that the Martian ionosphere suffered a quick and complex variability with large density increases and decreases every few kilometers. This variability was caused by the presence of the comet, and we discuss different processes that could have occurred.

National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-414323 (URN)10.1029/2019JA027344 (DOI)000535392400044 ()
Available from: 2020-06-25 Created: 2020-06-25 Last updated: 2020-06-25Bibliographically approved
Barabash, S., Voshchepynets, A., Holmstrom, M., Frahm, R. A., Nillsson, H., Andrews, D. J., . . . Winningham, J. D. (2020). Observations of Sounder Accelerated Electrons by Mars Express. Journal of Geophysical Research - Space Physics, 125(1), Article ID e2019JA027206.
Open this publication in new window or tab >>Observations of Sounder Accelerated Electrons by Mars Express
Show others...
2020 (English)In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 125, no 1, article id e2019JA027206Article in journal (Refereed) Published
Abstract [en]

The electron sensor of the Analyzer of Space Plasmas and Energetic Atoms experiment detects accelerated electrons during pulses of radio emissions from the powerful topside sounder: the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) on board the Mars Express spacecraft. Accelerated electrons are observed at energies up to 400 eV at the times when MARSIS transmits at a frequency between the local plasma frequency and its harmonics (up to 4 times the plasma frequency). When the electron density and magnetic field strength are low (similar to 10(3) cm(-3), similar to 10 nT), the accelerated electrons are almost monoenergetic electron beams. An increase in density and magnetic field (similar to 3 . 10(3) cm(-3), similar to 50 nT) leads to substantial broadening of the energy spectrum of the accelerated electrons. It is concluded that in the latter case, electrons are accelerated by the variable spacecraft potential resulting from the imbalance of the electron and ion currents to the MARSIS antenna during transmission.

National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-414317 (URN)10.1029/2019JA027206 (DOI)000535392400012 ()
Funder
Swedish National Space Board, 169/15Swedish National Space Board, 127/14
Available from: 2020-06-25 Created: 2020-06-25 Last updated: 2020-06-25Bibliographically approved
Němec, F., Morgan, D. D. D., Kopf, A. J., Gurnett, D. A., Pitoňák, D., Fowler, C. M., . . . Andersson, L. (2019). Characterizing Average Electron Densities in the Martian Dayside Upper Ionosphere. Journal of Geophysical Research - Planets, 124(1), 76-93
Open this publication in new window or tab >>Characterizing Average Electron Densities in the Martian Dayside Upper Ionosphere
Show others...
2019 (English)In: Journal of Geophysical Research - Planets, ISSN 2169-9097, E-ISSN 2169-9100, Vol. 124, no 1, p. 76-93Article in journal (Refereed) Published
Abstract [en]

We use more than 10years of the Martian topside ionospheric data measured by the Mars Advanced Radar for Subsurface and Ionosphere Sounding radar sounder on board the Mars Express spacecraft to derive an empirical model of electron densities from the peak altitude up to 325km. Altogether, 16,044 electron density profiles obtained at spacecraft altitudes lower than 425km and at solar zenith angles lower than 80 degrees are included in the analysis. Each of the measured electron density profiles is accurately characterized by the peak electron density, peak altitude, and three additional parameters describing the profile shape above the peak: (i) steepness at high altitudes, (ii) main layer thickness, and (iii) transition altitude. The dependence of these parameters on relevant controlling factors (solar zenith angle, solar irradiance, crustal magnetic field magnitude, and Sun-Mars distance) is evaluated, allowing for a formulation of a simple empirical model. Mars Atmosphere and Volatile EvolutioN Extreme Ultraviolet monitor data are used to show that the solar ionizing flux can be accurately approximated by the F10.7 index when taking into account the solar rotation. Electron densities predicted by the resulting empirical model are compared with electron densities locally evaluated based on the Mars Advanced Radar for Subsurface and Ionosphere Sounding measurements, with the Langmuir Probe and Waves electron density measurements on board the Mars Atmosphere and Volatile EvolutioN spacecraft, and with electron densities obtained by radio occultation measurements. Although the electron densities measured by the Langmuir Probe and Waves instrument are systematically somewhat lower than the model electron densities, consistent with former findings, the model performs reasonably well.

Abstract [en]

Plain Language Summary

The ionosphere of Mars is the ionized part of its atmosphere, on the dayside ultimately controlled by the solar irradiation. Information about the electron density in there can be, among others, obtained by the radar sounding from a spacecraft orbiting the planet. Such measurements have been performed since 2005 by the Mars Advanced Radar for Subsurface and Ionosphere Sounding on board the Mars Express spacecraft, and they provide us with electron density profiles from the spacecraft altitude down to the altitude of the peak electron density. We use more than 10years of such measurements to develop an empirical model of typical ionospheric electron densities. The obtained results are compared with electron densities measured in situ by the Langmuir Probe and Waves instrument on board the MAVEN spacecraft available since 2014. A reasonable agreement between the model predictions and these independent observations is found. Finally, the analysis of solar radiation measured by Extreme Ultraviolet monitor on board the MAVEN spacecraft is used to show that, when the solar rotation is properly accounted for, the solar ionizing flux at Mars can be surprisingly well approximated by the solar radio flux measured at Earth.

Keywords
MARSIS, MAVEN LPW, Mars ionosphere
National Category
Fusion, Plasma and Space Physics Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-378741 (URN)10.1029/2018JE005849 (DOI)000459245700005 ()
Available from: 2019-03-11 Created: 2019-03-11 Last updated: 2019-03-11Bibliographically approved
Akbari, H., Andersson, L., Andrews, D. J., Malaspina, D., Benna, M. & Ergun, R. (2019). In Situ Electron Density From Active Sounding: The Influence of the Spacecraft Wake. Geophysical Research Letters, 46(17-18), 10250-10256
Open this publication in new window or tab >>In Situ Electron Density From Active Sounding: The Influence of the Spacecraft Wake
Show others...
2019 (English)In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 17-18, p. 10250-10256Article in journal (Refereed) Published
Abstract [en]

Results obtained in the Martian ionosphere by the Langmuir Probe and Waves instrument aboard the Mars Atmosphere and Volatile EvolutioN Mission spacecraft are presented. The results include ionospheric electron densities determined from the frequency of Langmuir waves. Since the amplitude of thermal Langmuir waves is often below the instrument's detection level, Langmuir Probe and Waves excites these waves by injecting into the plasma a 3.3-V white noise signal. Electric field spectral measurements obtained shortly after the excitation show a resonance line at frequencies slightly below the local plasma frequency. The observed resonance line is interpreted to originate from plasma waves excited in the wake behind the spacecraft. These results reveal an important phenomenon in electron density estimation from stimulated Langmuir waves. The observed phenomenon, not previously reported by earlier missions, may be a common process in active sounding that can affect in situ electron density measurements.

Place, publisher, year, edition, pages
AMER GEOPHYSICAL UNION, 2019
Keywords
Langmuir probe, in situ electron density, relaxation sounding, Martian ionosphere, satellite wake
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-408848 (URN)10.1029/2019GL084121 (DOI)000485376800001 ()
Available from: 2020-04-15 Created: 2020-04-15 Last updated: 2020-04-15Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-7933-0322

Search in DiVA

Show all publications