H4: Space weather at planetary bodies in the Solar System


Insoo Jun (NASA/JPL, USA), Insoo.Jun@jpl.nasa.gov, ijun.8206@gmail.com

Zhonghua Yao  (IGGCAS, China), z.yao@ucl.ac.uk 

Christina Plainaki (ASI, Italy),  christina.plainaki@asi.it


Manuel Grande (Aberystwyth University, UK), manerg1111@gmail.com


H3 Cluster: Jingnan Guo


Based on a 2008 European definitionby [COST 724 Final Report, Ed. J. Lilensten et al.], “Space Weather is the physical and phenomenological state of natural space environments. The associated discipline aims, through observation, monitoring, analysis and modelling, at understanding and predicting the state of the Sun, the interplanetary and planetary environments, and the solar and non-solar driven perturbations that affect them; and also at forecasting and now-casting the possible impacts on biological and technological systems.” The discipline of Planetary Space Weather refers to the study of the variability of planetary body enviornments (e.g., atmospheres, exospheres, ionospheres, intrinsic or induced magnetospheres) determined by the variability of the solar activity or/and the interplanetary space dynamics, or/and (e.g., in case of outer Solar System moons) the dynamics of the magnetosphere in which the Solar System body is embedded.

The Space Weather conditions around a planetary body within our Solar System, are strongly determined by the interactions between the body in question and its local space environment. For planets with internally-generated fields (e.g., Mercury, Earth, Jupiter, Saturn, Uranus, and Neptune), the solar wind interaction with planetary magnetic fields generally takes the form of a dayside compressed and nightside extended magnetized environment called a planetary magnetosphere. For planets in the inner heliosphere, the main driver for Space Weather phenomena is solar activity, which is in a continuous interplay with the galactic cosmic ray radiation, modulated by the solar wind.  Solar activity is pivotal in driving particle acceleration and energy dissipation for these magnetospheric environments. For outer giant planets far from the Sun, the solar wind energy input to the planets is generally much less. For these planets, internal sources (e.g., their strong internal magnetic fields and dense plasmaspheres and dust rings) are believed to be the primary sources of magnetospheric plasma dynamics.

The solar wind or/and the UV radiation from the Sun can contribute in atmospheric escape, especially at planetary bodies lacking an intrinsic magnetic field (e.g., Mars, Venus, Titan), even at large time scales. From a planetary space weather/space climate perspective, our current understanding of the agents of atmospheric escape to space can provide hints for solving the puzzle of planetary atmosphere evolution and, moreover, for investigating scenarios for exoplanetary systems.   

With increasing efforts in space exploration, the need for an in depth understanding of the space environments around planetary bodies other than Earth emerges. Environmental specification for the design and maintenance of spacecraft and systems in space requires a strongly interdisciplinary approach in the field of Planetary Space Weather science. Of key importance is the improvement of our ability to predict the fluxes of energetic particles that can be detected when a shock passes by a spacecraft, since they can pose major hazards due to Space Weather phenomena.

Understanding Space Weather phenomena at planetary bodies of our Solar System requires studies on the following topics:

(a) The background solar wind which includes the slow solar wind and the fast solar wind (more in H1); (b) Transient heliospheric structures such as stream interaction regions (stream interaction regions or SIRs are formed by high-speed streams interacting with slow solar wind, see H1); (c) Generation and propagation in the Solar System of Coronal Mass Ejections ( see H2); (d) Acceleration and propagation of Solar Energetic Particles (SEPs) in the heliosphere (see H3); (e) Variability of the radiation environment at different distances from the Sun and within planetary systems   

The different types of variations, due to the intrinsically different plasma properties, cause different types of “space weather effects” at each planet depending on the planet’s heliospheric distance, magnetospheric strength and structure, atmospheric composition and structure, and surface properties.


Working together with the H1, H2 and H3 clusters, the cluster H4 is intended to provide a scientific frame for the comparative study of different space weather phenomena at a variety of planetary bodies within our Solar System (e.g., the Earth-like planets in the inner-heliosphere and the gas and ice giants in the outer-heliosphere, including their moons). Such an approach will help to understand the physical phenomena at large, pushing current Space Weather models to their limits. Ultimately in view of the new discoveries associated with exoplanets, a better understanding of the influence of space weather on different planets will help us to better characterize the potential effects of different stellar environments on exoplanets and to develop realistic scenarios on potential habitability of those exoplanets. Synergies between solar physics, Heliophysics, planetary science, and stellar physics communities can improve our ability to predict extreme Space Weather in the Solar System or beyond.

(Potential) Action Topics:

To understand, characterize, and predict space weather at different planets, several crucial issues are required:

  • Characterize mass and energy circulation driven by the solar wind and by internal planetary processes:
    • In coordination with H1, develop models and observations of the propagation of the solar wind from the Sun to different heliospheric distances
    • Study the interaction of solar wind with planetary magnetospheres
    • Study the plasma and neutral particle circulation within planetary systems with focus on the mass and energy exchange among ionospheres and neutral atmospheres, plasma sheets, moon torus and dust rings.
    • Investigate the dynamical role of the magnetospheric environment within a giant planetary system in moon exosphere generation and loss processes
  • Systematically investigate the impacts of plasma and energetic particles (of solar or non solar origin) on the environments of planetary bodies: 
    • In coordination with H3, observe and model SEPs arriving at different distances from the Sun (inner Solar System science)
    • Study the variability of radiation environment within planetary systems, including also possible effects on radiation belts, planetary atmospheres, moon exospheres and surfaces
    • Study how planetary aurora respond to magnetospheric perturbations
  • Investigate the influences of heliospheric activity (such as CMEs and SIRs) on planetary magnetospheres:
    • In coordination with H2, observe and model the propagation of solar eruptions and their interactions with planetary bodies
    • Study magnetic reconnection and wave-particle interactions on particle energization throughout the planetary system
    • Study particle (such as heavy ions) energization in planetary magnetospheres
  • Better understand and characterize the astroboiological impacts of galactic cosmic rays, flares, CMEs, energetic particles, and winds on exoplanetary environments (e.g., atmospheric escape, chemistry, biosignatures, climate, and the habitability of exoplanets) in the framework of comparative studies with interdisciplinary perspectives:
    • Study the mechanisms of X-ray and EUV (XUV) driven exoplanetary atmospheric escape
    • Study the effects of energetic particles on prebiotic chemistry and the impact of energetic particles on the surface dosage on terrestrial exoplanets
    • Study the impacts of XUV emission and energetic particles events on exoplanetary biosignatures, climate, and habitability

Generate inputs to global space weather roadmap

Investigate the future space weather architecture need at Mars for future human/robotic exploration

Provide important input for the design and development of payload instruments, electronics, and components on board space craft, that can survive intense Space Weather conditions.

Investigate space weathering at air-less bodies in the solar system, as a result of Space Weather conditions.

  • Space weathering is the alteration of a planetary surface resulting from the body’s exposure to space. Solar wind, GCRs, UV radiation and micrometeoroids are among the main agents of space weathering. From a Space Weather perspective, the characterization of the variability of space conditions around an airless body is of help while interpreting surface remote-sensing and/or in situ observations (add-on value of planetary Space Weather to planetary sciences).

Address ancient planetary space weather, which may be associated with the evolution of planetary habitability

  • For example, what caused Earth’s great oxidation event (GOE), and what caused Mars’ atmosphere escape?