Periodic Reporting for period 3 - SERPENTINE (Solar EneRgetic ParticlE aNalysis plaTform for the INner hEliosphere)
Reporting period: 2023-07-01 to 2024-06-30
The SERPENTINE project answered several outstanding questions about the origin of Solar Energetic Particle (SEP) events and provided an advanced platform for the analysis and visualization of high-level datasets to benefit the wider heliophysics community. The key data came from the most recent European and US missions, i.e. Solar Orbiter, Parker Solar Probe and BepiColombo, which have opened completely new avenues to investigate SEPs.
The strongest SEP events constitute so-called solar radiation storms, which are part of space weather. These storms pose a radiation hazard to satellites in Earth orbit and beyond. Since a major part of our technology dependent society relies on the space sector (global navigation satellite systems, satellite telecommunication systems, Earth observation), a radiation storm knocking down a part of in-orbit resources could lead to severe consequences for the global economy. The strongest radiation storms can also have health effects on humans in space and even at flight altitudes in polar regions. Solar radiation storms also affect the polar ionosphere rendering HF radio communications unavailable during storm times, prohibiting air traffic over the poles. Thus, understanding SEP events is one of the key prerequisites for developing space weather forecasting capabilities in the future. The project focused on unraveling the causes of currently poorly understood large gradual and widespread SEP events, which pose the greatest radiation risks.
The overall scientific objective SERPENTINE was to understand the acceleration and heliospheric transport of particles in these events, addressing the following science questions:
Q1: What are the primary causes for widespread SEP events observed in the heliosphere?
Q2: What are the shock acceleration mechanisms responsible for accelerating ions from thermal/suprathermal energies to near-relativistic energies in the corona and in the interplanetary medium?
Q3: What is the role of shocks in electron acceleration in large gradual and widespread events? How does it relate to ion acceleration and what is its importance relative to flare acceleration?
SERPENTINE project has also the following technical objectives to achieve a maximal impact for exploitation of the data:
T1: Produce and distribute catalogs of SEP events and in-situ shock events.
T2: Provide an analysis platform with the data and tools for analysis along with visualization of the modeled heliospheric state.
T3: Produce and deliver high-level and multi-instrument datasets for SEPs and the necessary ancillary data.
Thus, the platform is expected to significantly foster the further exploitation of the data from European space-borne and ground-based instrumentation and interactions between different communities during and after the project period.
The strongest SEP events constitute so-called solar radiation storms, which are part of space weather. These storms pose a radiation hazard to satellites in Earth orbit and beyond. Since a major part of our technology dependent society relies on the space sector (global navigation satellite systems, satellite telecommunication systems, Earth observation), a radiation storm knocking down a part of in-orbit resources could lead to severe consequences for the global economy. The strongest radiation storms can also have health effects on humans in space and even at flight altitudes in polar regions. Solar radiation storms also affect the polar ionosphere rendering HF radio communications unavailable during storm times, prohibiting air traffic over the poles. Thus, understanding SEP events is one of the key prerequisites for developing space weather forecasting capabilities in the future. The project focused on unraveling the causes of currently poorly understood large gradual and widespread SEP events, which pose the greatest radiation risks.
The overall scientific objective SERPENTINE was to understand the acceleration and heliospheric transport of particles in these events, addressing the following science questions:
Q1: What are the primary causes for widespread SEP events observed in the heliosphere?
Q2: What are the shock acceleration mechanisms responsible for accelerating ions from thermal/suprathermal energies to near-relativistic energies in the corona and in the interplanetary medium?
Q3: What is the role of shocks in electron acceleration in large gradual and widespread events? How does it relate to ion acceleration and what is its importance relative to flare acceleration?
SERPENTINE project has also the following technical objectives to achieve a maximal impact for exploitation of the data:
T1: Produce and distribute catalogs of SEP events and in-situ shock events.
T2: Provide an analysis platform with the data and tools for analysis along with visualization of the modeled heliospheric state.
T3: Produce and deliver high-level and multi-instrument datasets for SEPs and the necessary ancillary data.
Thus, the platform is expected to significantly foster the further exploitation of the data from European space-borne and ground-based instrumentation and interactions between different communities during and after the project period.
We have analyzed SEP events that were observed in connection with flares and shock waves driven by coronal mass ejections (CMEs) including their in-situ counterparts when crossing the spacecraft. Altogether dozens of multi-spacecraft events have been cataloged, addressing T1, and case studies of best observed events have provided first answers to the science questions of SERPENTINE. We found that there are probably multiple reasons causing widespread SEP events in the heliosphere: broad sources (shock waves), transport perpendicular to the magnetic field, and multiple narrower sources operating at the same time, an even new scenario. SERPENTINE has also analyzed data from older missions leading to another catalog of SEP events based on the Helios mission (from mid 1970s to early 1980s).
Another dataset comes from the STEREO mission with two spacecraft orbiting the Sun approximately at Earth’s distance but at different positions relative to the Earth. We analyzed a comprehensive sample of events for which an analysis of the solar eruption associated with the event was performed earlier. Our study established a connection between the shock strength and the energetic electrons — a major step forward in our understanding of the role of coronal shocks in the acceleration of electrons to the highest energies and an answer to Q3. We also used the STEREO dataset to study shock acceleration of electrons in-situ and confirmed the role of the shocks in relativistic electron acceleration in several events.
The extensive in-situ instrument suite of Solar Orbiter has been particularly exploited by SERPENTINE. Using Solar Orbiter, the world’s most complete and up-to-date catalog of (interplanetary) shock waves in the inner heliosphere was built. The spacecraft was also used as an “outpost” upstream of Earth to elucidate the peculiar behavior of a strong shock wave as observed by a fleet of 6 spacecraft near-Earth. We found that the first stages of particle acceleration happen in an irregular fashion in space and time at interplanetary shock, a crucial ingredient to unveil their acceleration to the highest energies.
The project also produced and released several analysis tools, e.g. the Solar-MACH tool (https://solar-mach.github.io/) which shows the configuration of the heliospheric spacecraft and planets in their orbits around the Sun at any given time. Other tools gaining popularity, based on Jupyter Notebooks, provide easier access to data and time series analysis tools for the broad community, as well as tools for analyzing solar context observations, like CMEs and their shocks, ensuring the possibility of identification and characterization of events beyond the project aims and duration. SERPENTINE also contributed new datasets to existing analysis platforms and provided access to several catalogs of SEP events and shocks through a server operated at the University of Alcala.
The project results have been published in dozens of papers as well as presented in conferences and workshops. Key results have also been published as short and easy-to-understand News Items at the project website and advertised in Twitter / X.
Another dataset comes from the STEREO mission with two spacecraft orbiting the Sun approximately at Earth’s distance but at different positions relative to the Earth. We analyzed a comprehensive sample of events for which an analysis of the solar eruption associated with the event was performed earlier. Our study established a connection between the shock strength and the energetic electrons — a major step forward in our understanding of the role of coronal shocks in the acceleration of electrons to the highest energies and an answer to Q3. We also used the STEREO dataset to study shock acceleration of electrons in-situ and confirmed the role of the shocks in relativistic electron acceleration in several events.
The extensive in-situ instrument suite of Solar Orbiter has been particularly exploited by SERPENTINE. Using Solar Orbiter, the world’s most complete and up-to-date catalog of (interplanetary) shock waves in the inner heliosphere was built. The spacecraft was also used as an “outpost” upstream of Earth to elucidate the peculiar behavior of a strong shock wave as observed by a fleet of 6 spacecraft near-Earth. We found that the first stages of particle acceleration happen in an irregular fashion in space and time at interplanetary shock, a crucial ingredient to unveil their acceleration to the highest energies.
The project also produced and released several analysis tools, e.g. the Solar-MACH tool (https://solar-mach.github.io/) which shows the configuration of the heliospheric spacecraft and planets in their orbits around the Sun at any given time. Other tools gaining popularity, based on Jupyter Notebooks, provide easier access to data and time series analysis tools for the broad community, as well as tools for analyzing solar context observations, like CMEs and their shocks, ensuring the possibility of identification and characterization of events beyond the project aims and duration. SERPENTINE also contributed new datasets to existing analysis platforms and provided access to several catalogs of SEP events and shocks through a server operated at the University of Alcala.
The project results have been published in dozens of papers as well as presented in conferences and workshops. Key results have also been published as short and easy-to-understand News Items at the project website and advertised in Twitter / X.
The project has provided several answers to its science questions. In addition to heliophysicists, also the astrophysics community will have a great interest on scientific results on particle acceleration. The project has also published most of its data analysis tools to the community.
An important impact is the foundation the project gives for the development of space weather applications. SEP events are one of the main deleterious aspects of space weather, capable of disrupting satellite services and air traffic over polar areas. Europe has a vibrant application developer community, including several enterprises, working on space weather prediction tools and that sector will exploit the improved access to data generated by SERPENTINE.
Other sectors that the project will cater to include the university education and space agencies and policymakers that take decisions on future solar and heliospheric missions to be launched. The project will continue to make an effort to educate the general public on solar eruptions and their effects on society. These efforts have been done both through events and video material targeted to the public and through postings in social media.
An important impact is the foundation the project gives for the development of space weather applications. SEP events are one of the main deleterious aspects of space weather, capable of disrupting satellite services and air traffic over polar areas. Europe has a vibrant application developer community, including several enterprises, working on space weather prediction tools and that sector will exploit the improved access to data generated by SERPENTINE.
Other sectors that the project will cater to include the university education and space agencies and policymakers that take decisions on future solar and heliospheric missions to be launched. The project will continue to make an effort to educate the general public on solar eruptions and their effects on society. These efforts have been done both through events and video material targeted to the public and through postings in social media.