BepiColombo and Solar Orbiter compare notes at Venus 

Europlanet 2024 RI/ISAS/JAXA Press Release
Thursday, 26 January 2023

The convergence of two spacecraft at Venus in August 2021 has given a unique insight into how the planet is able to retain its thick atmosphere without the protection of a global magnetic field. 

The ESA/JAXA BepiColombo mission, enroute to study Mercury, and the ESA/NASA Solar Orbiter, which is observing the Sun from different perspectives, are both using a number of gravity-assists from Venus to change their trajectories and guide them on their way.  On 9-10 August 2021, the missions flew past Venus within a day of each other, sending back observations synergistically captured from eight sensors and two vantage points in space. The results have been published in Nature Communications.

Unlike Earth, Venus does not generate an intrinsic magnetic field in its core. Nonetheless, a weak, comet-shaped ‘induced magnetosphere’ is created around the planet by the interaction of the solar wind – a stream of charged particles emitted by the Sun – with electrically charged particles in Venus’s upper atmosphere. Around this magnetic bubble, the solar wind is slowed, heated and deflected like the wake of a boat in a region called ‘magnetosheath’.

During the flyby, BepiColombo swooped along the long tail of the magnetosheath and emerged through the blunt nose of the magnetic regions closest to the Sun. Meanwhile, Solar Orbiter captured a peaceful solar wind from its location upfront of Venus.

“These dual sets of observations are particularly valuable because the solar wind conditions experienced by Solar Orbiter were very stable. This meant that BepiColombo had a perfect view of the different regions within the magnetosheath and magnetosphere, undisturbed by fluctuations from solar activity,” said lead-author Moa Persson of the University of Tokyo in Kashiwa, Japan, who was funded to carry out the study by the European Commission through the Europlanet 2024 Research Infrastructure (RI) project.

BepiColombo’s flyby was a rare opportunity to investigate the ‘stagnation region’, an area at the nose of the magnetosphere where some of the largest effects of the interaction between Venus and the solar wind are observed. The data gathered gave the first experimental evidence that charged particles in this region are slowed significantly by the interactions between the solar wind and Venus, and that the zone extends to an unexpectedly large distance of 1,900 kilometres above the planet’s surface.

The observations also showed that the induced magnetosphere provides a stable barrier that protects the atmosphere of Venus from being eroded by the solar wind. This protection remains robust even during solar minimum, when lower ultraviolet emissions from the Sun reduce the strength of the currents that generate the induced magnetosphere. The finding, which is contrary to previous predictions, sheds new light on the connection between magnetic fields and atmospheric loss due to the solar wind.

‘The effectiveness of an induced magnetosphere in helping a planet retain its atmosphere has implications for understanding the habitability of exoplanets without internally-generated magnetic fields,” said co-author Sae Aizawa of JAXA’s Institute of Space and Astronautical Science (ISAS).

BepiColombo comprises a pair of spacecraft, Mio, the JAXA-led Mercury Magnetospheric Orbiter, and MPO, the ESA-led Mercury Planetary Orbiter, which have been stacked together for the journey to Mercury. The study combined data from Mio’s four particle sensors, the magnetometer and another particle instrument on MPO, and the magnetometer and solar wind analyser on Solar Orbiter. Europlanet’s SPIDER space weather modelling tools enabled the researchers to track in detail how features in the solar wind observed by Solar Orbiter were affected as they propagated towards BepiColombo through the venusian magnetosheath.

“The important results of this study demonstrate how turning sensors on during planetary flybys and cruise phases can lead to unique science,” said co-author Nicolas Andre, the coordinator of the Europlanet SPIDER service at the Institut de Recherche en Astrophysique et Planétologie (IRAP) in Toulouse, France.

Publication details:

Persson et al. BepiColombo mission confirms stagnation region of Venus and reveals its large extent. Nature Communications vol 13, 7743 (2022). https://doi.org/10.1038/s41467-022-35061-3 

Further information

Science and Housekeeping data for the study were obtained from eight sensors on three spacecraft:

• Mio
  • Mercury Electron Analyzer (MEA)
  • Mercury Ion Analyzer (MIA)
  • Mass Spectrum Analyzer (MSA) 
  • Energetic Neutral Atom (ENA)
• MPO 
  • Magnetometer (MAG)
  • Miniature Ion Precipitation Analyzer (MIPA) 
• Solar Orbiter 
  • Magnetometer (MAG)
  • Proton Alpha Spectrometer (PAS)

Image

The convergence of BepiColombo and Solar Orbiter spacecraft at Venus in August 2021 was a rare opportunity to investigate the ‘stagnation region’, an area of the venusian magnetosphere where some of the largest effects of the interaction between Venus and the solar wind are observed. Credit: CC BY-Nc-SA 4.0 – Thibaut Roger/Europlanet 2024 RI

Download full resolution image as JPG, PNG or PDF.

Video

Dr Moa Persson describes the observations by BepiColombo and Solar Orbiter of Venus’s induced magnetosphere and magnetosheath.

Dr Sae Aizawa explains how the solar wind interacts with magnetic fields and atmospheres at different planets in our Solar System.

Science Contacts

Dr Moa Persson
The University of Tokyo
Kashiwa
Japan
moa.persson@irap.omp.eu

Dr Sae Aizawa
Institute of Space and Astronautical Science (ISAS)
Japan Aerospace Exploration Agency (JAXA)
Sagamihara
Japan
sae.aizawa@irap.omp.eu

Dr Go Murakami
Institute of Space and Astronautical Science (ISAS)
Japan Aerospace Exploration Agency (JAXA)
Sagamihara
Japan
go@stp.isas.jaxa.jp

Dr Nicolas André
Institut de Recherche en Astrophysique et Planétologie (IRAP)
Toulouse
France
Nicolas.andre@irap.omp.eu

Media Contacts

Anita Heward
Press Officer
Europlanet 2024 Research Infrastructure (RI)
+44 7756 034243
aheward@europlanet-society.org

Further Information

About ISAS/JAXA

In October 2003, the Japan Aerospace Exploration Agency (JAXA) was established as an independent administrative institution, integrating the Institute of Space and Astronautical Science (ISAS), the National Space Development Agency of Japan (NASDA) and the National Aerospace Laboratory of Japan (NAL). ISAS became one of four principal sections within the newly established organization. Its mission is to advance space science – scientific research conducted in outer space – in Japan, mainly by collaboration with universities. It also actively contributes to JAXA’s and Japan’s entire space development. 

ISAS’s new efforts and results in space science are published in Japan and shared with the international community, thus promoting JAXA’s status and enhancing Japan’s intellectual reputation in the world.

Web: https://www.isas.jaxa.jp/en/

Twitter: @ISAS_JAXA_EN

About Europlanet

Since 2005, Europlanet has provided Europe’s planetary science community with a platform to exchange ideas and personnel, share research tools, data and facilities, define key science goals for the future, and engage stakeholders, policy makers and European citizens with planetary science.

The Europlanet 2024 Research Infrastructure (RI) has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 871149 to provide access to state-of-the-art research facilities and a mechanism to coordinate Europe’s planetary science community. The project builds on a €2 million Framework 6 Coordination Action (EuroPlaNet), a €6 million Framework 7 Research Infrastructure (Europlanet RI) and a €10 million Horizon 2020 Research Infrastructure (Europlanet 2020 RI) funded by the European Commission. 

The Europlanet Society promotes the advancement of European planetary science and related fields for the benefit of the community and is open to individual and organisational members. The Society’s aims are:

• To expand and support a diverse and inclusive planetary community across Europe through the activities of its 10 Regional Hubs. 
• To build the profile of the sector through outreach, education and policy activities
• To underpin the key role Europe plays in planetary science through developing links at a national and international level. 

Europlanet 2024 RI project website: www.europlanet-2024-ri.eu

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