Space Weather

The service "Spacecraft Operations - Space Weather in the Solar System Space" provides forecasts, nowcasts and alerts related to space weather in the heliosphere. The service is aimed at solar system mission operators who require information, at locations away from the Earth, in order to make informed decisions on the planning and execution of spacecraft operations.
The focus has been on the assessment of solar wind and solar wind transient propagation within the heliosphere. Forecasts are primarily based upon models driven by remote observations of the Sun and corona. Access to historical mission data provides additional context upon which to base operational decisions. Future developments are expected to extend the support for assessment of SEPs and extension of the solar wind modelling beyond the orbit of Mars.

This service is implemented through a combination of products, tools and alerts which can be found through the following tabs along with expert support provided by the teams constituting the SWE Network. Should you require further guidance in the use of this service, or have specific questions about any aspects of the service presented here, don't hesitate to contact the Helpdesk.

A set of models and in-orbit sensor datasets are provided with the help of tools and products such as those listed below. Additional relevant products, tools and alerts can be found by selecting the desired tabs given at the top of this page.

For technical forecasts of the heliospheric weather conditions please consider the following products and tools

For the current heliospheric conditions the products shown below can be useful. Please note that there is a lack of near-real-time data from solar system locations away from the Earth and STEREO-A. For other locations consider using the model products given above.

More advanced users may wish to understand and model particular heliospheric features themselves. A few modelling tools are provided below to assist with this.

This service page is curated by the Heliospheric Weather ESC. For further information, please contact SSCC Helpdesk.

Introduction

Heliospheric Weather encompasses the effects of the solar wind, including the transient structures therein, as they propagate out from the Sun's corona through the heliosphere. This includes heliospheric effects that directly influence the Earth and also other locations within the heliosphere that may be relevant to interplanetary exploration missions.

The fundamental structure of the heliosphere is governed by the Sun's magnetic structure and solar wind outflows. The solar wind can be simplistically described as comprising a radially-expanding, quasi-static background. The origin of this background solar wind leads to its delineation into regions of high- and slow-speed solar wind, along the interfaces of which can form extensive swathes of compressed plasma/magnetic field known as Stream Interaction Regions and Co-rotating Interaction Regions (CIR) that endure for multiple solar rotations.

Coronal Mass Ejections (CMEs)

Through the background solar wind propagate immense plasma/magnetic field transients, termed Coronal Mass Ejections (CME) that have been ejected from the Sun. The shocks that form in front of these structures can accelerate particles to 10's of MeV while the large scale interaction with planetary magnetospheres or ionospheres can have large scale impacts particularly on technological systems as a result of induced currents.

The video below is an Enlil (3d MHD) simulation of the radial propagation of several solar Coronal Mass Ejections (CME) during the September 2017 event. The Sun is at the centre of this view and the Earth is to the right. The circular view is as if looking down on the plane containing the Earth's orbit and the fan view is as if looking from the side. The upper panels are the solar wind density and the lower panels are solar wind speed. The spiral structures are formed from the combination of the solar rotation with the radial emission (like a garden sprinkler). CMEs are impulsive events and therefore it is easier to see their radial propagation.

CMEs typically have speeds of a few hundred to a several thousand km/s. This means that propagation to 1AU will take a day or more from its initial detection and more than twice this time to reach Mars. Fast CMEs will tend to be slowed due to drag type forces as they propagate through the slower background solar wind. If there are multiple CMEs separated in time the first may interact with the background solar wind essentially clearing the path for the following CME so that it is not slowed as much as might otherwise be expected.

Solar Energetic Particles (SEPs)

Alongside, but associated with, the bulk plasma phenomena are high-energy particle populations known as Solar Energetic Particle (SEP) events that originate either through energisation processes occurring at the site of solar flares or at interplanetary shocks. These can be particularly hazardous to space segment assets due to their ability to temporarily blind optical systems (such as star trackers) or cause anomalies in spacecraft systems due to single event effects.

Energetic particles are guided by the Interplanetary Magnetic Field (IMF) which forms a spiral pattern therefore source active regions (prompt) or shocks (gradual) to the west of the observer are most likely to have good connectivity. Due to their high speed energetic particles can reach 1AU from the source region in tens of minutes. Therefore for operational timescales probabilistic forecasts of solar flares and connectivity are used to assess the likelihood of a particular active region giving rise to a SEP event within the next few days.

Energetic particles from CME related shock fronts may provide more warning as the shocks are more slowly moving, tend to form with increasing distance from the Sun and may not initially be on magnetic field lines that are well connected with the observer. These gradual events may be less intense than the prompt events from solar active regions but are longer lasting and therefore may result in extended periods of blinding of attitude control system sensors such as star trackers.

In addition to the sporadic SEP events, there is also the energetic galactic cosmic rays background. This is a slowly varying energetic particle spectrum originating from outside the solar system. It is modulated by the solar cycle with the peak occurring around solar minimum. Due to the slowly varying nature of this background, long-term statistical models can be used during the early mission planning to determine the spectrum and cumulative fluxes that are anticipated. While individual SEP events can be more intense, the GCR contribution to the long-term dose is nevertheless significant and may be the cause of random single event effects outside of periods of enhanced space weather activity.

For planets with strong magnetospheres, the trapped radiation environment may pose the greatest to degradation of spacecraft systems. Planetary magnetosphere modelling and account of anticipated spacecraft trajectories must be taken into account to assess the potential exposure and impact together with space weather conditions that drive the magnetospheric activity.

Spacecraft Operations - Solar System Missions

For spacecraft operations within the solar system, the solar wind and CME forecasts and forecaster commentaries provide the short and medium term assessment of the conditions which are likely to prevail and should be considered when assessing operations activities. In particular, the current products provide information on the potential for high speed solar wind streams and for the arrival of CMEs and SIRs in the vicinity of a spacecraft.

The human forecaster augmented products and commentaries provide a good starting point for assessing the prevailing and likely conditions at near-Earth (Alert/E, ROB/SIDC and Enlil/E) and a selected set of Heliospheric locations (currently Mercury, Venus and Mars; Enlil/Me/V/Ma). For situations including Earthward directed CMEs a 24 member ensemble of low resolution Enlil runs is also undertaken in order to help assess the uncertainty in the forecast arrival times. The DBEM model allows the user to undertake their own quick assessment of CME propagation taking account of CME launch characteristics and heliospheric drag conditions. Automatic runs of DBEM are undertaken for near-Sun characterised CMEs and can be accessed from the HPARC/PR product.

Forecasts of energetic particles at L1 are provided by the HESPERIA set of products.

Due to the lack of near-real-time in-situ plasma measurements away from the near-Earth (and STEREO-A), real-time alerting is limited to warnings resulting from model predictions and the heliospheric regions near to the Earth and STEREO-A. The best estimates of conditions at these locations is from the forecasts. Use of Nowcasts at L1 may be useful to assess the current accuracy of the forecast models and when considering co-rotating structures. Within the space weather network a few different models are used for forecasting the solar wind speed, these make use of different techniques such as physics based, empirical and persistence. The SWFSC/E provides an overview of the current model outputs which can be a useful starting point.

A number of tools are provided to assist users in assessing the propagation of space weather related phenomena within the heliosphere. The PROPTOOL incorporates simple models for radial, co-rotating and SEP propagation while the DBM is dedicated to giving an estimate of CME arrival time and speed.

When trying to assess if a spacecraft anomaly could be related to space weather effects a starting point could be to check the current flare activity by examining one of the Solar Flare products from the "Solar Activity: Nowcast" menu on the Products tab. If there appears to be activity around the time the anomaly was observed then the PROPTOOL can be used to help determine if SEPs linked to the flare are well connected with the target location.

The Magnetic Connectivity Tool (MAGCTOOL) provides and extends some of the elements of PROPTOOL and has the advantage that you do not need to download a Java application. The tool provides the mapping of the magnetic footprint of a spacecraft to the solar surface. Since solar energetic particles are guided by the interplanetary magnetic field, the proximity of the magnetic footprint to an a solar active region can aid the assessment of an SEP event affecting the target.

The event timeline tool, HPARC/PR under the Tools tab, may also provide useful information on any identified solar wind transients (such as CMEs) that may have been recorded at the relevant time.

Additional contextual information is available from the archive products and may help to assess operational activities based on previous measurements. The AMDA tool allows data mining of a broad range of scientific data from current and recent space missions.

Caveats

Users should be aware that the accuracy of forecasts away from the Sun-Earth line is expected to be reduced due to the additional uncertainties (such as propagation direction) and evolution of features (compared to their identification and characterisation from a Sun-Earth line perspective).

For further information, please contact SSCC Helpdesk. 

The products provided for this service are split into forecast and nowcast for three physical domains consisting of 1) Solar Activity; 2) Interplanetary Medium at L1; and 3) Interplanetary Medium Outside L1. Access to archive and reconstructed products from these physical domains and related alerts are also provided. The Solar activity provides the driver for space weather effects within the solar system and on planetary environments. The L1 and Outside L1 products provide forecasts and nowcasts of the enviroment at those locations.

The tools that are currently provided support 1) The modelling of solar wind transients (such as CMEs) which can be used to help assess potential arrival at a particular heliospheric location; 2) Access to space environment tools that can help to predict the likely environment to be encounted; 3) Archive data mining;

The following alerts are relevant to the Space Weather in the Solar System service area. They provide alerts related to transient phenomena such as flares and CMEs. Within the heliospheric context the user should be aware that there are constraints on alerting for locations away from the Sun-Earth line due to the lack of NRT assets upon which to do the assessment.

This section provides links to web pages or resources that are not part of the ESA Space Weather Network or esa.int domain. These sites are not under ESA control, and therefore ESA is not responsible for any of the information or links that you may find there.

Reference documents

Currently there are no documents available under this section.