The solar wind is stripping oxygen and carbon from Venus

The Bepicolombo The mission, a joint effort between JAXA and ESA, is the second (and most advanced) mission to visit the least explored Mercury in the Solar System. Through two probes and advanced scientific instruments, the mission addressed several unsolved questions, including the origin of Mercury's magnetic field, the bright objects around them („holos”), and the water ice around its poles. Pepicolombo revealed some interesting facts about Venus during its brief visit.

In particular, both probes probed a previously unexplored region of Venus' magnetic environment during their second pass on August 10, 2021. A recent study, an international team of scientists analyzed the data and found that traces of carbon and oxygen had been stripped from the upper layers of Venus' atmosphere and accelerated to speeds that could escape the planet's gravity. These data may provide new clues about how atmospheric loss and interactions between the solar wind and planetary atmospheres affect planetary evolution.

The study was led by CNRS researcher Lina Hadid Plasma Physics Laboratory (LPP) and Observatoire de Paris. He was accompanied by researchers Institute of Space and Astronautical Sciences (ISAS) at JAXA, The Max Planck Institute for Solar System Research (MBS), CNRS Astrophysics and Planetary Research Institute (IRAP), The Atmospheres, Atmospheres, Space Observatory (LATMOS), The Institute of Geophysics and Extraterrestrial Physics (IGEP), The Space Research Institute (SRI), and many other universities.

Although Venus does not have an intrinsic magnetic field like Earth's, the upper atmosphere of Venus has a weak magnetic field as a result of interactions between the solar wind and electrically charged particles. Surrounding this „induced magnetosphere” is the „magnetosphere” where the solar wind slows down and heats up. In August 2021, two spacecraft of the PepliColumbo – ESA Orbit of Mercury (MPO) and JAXA's Mercury's magnetosphere orbits (MMO, aka. Mio) – transited Venus on the final leg of its journey toward Mercury, using the planet's gravity to slow its course and its upper atmosphere.

Both spacecraft spent 90 minutes passing through the magnetosphere and the tail of the magnetic regions closest to the Sun. Mission controllers take advantage of this opportunity to collect data on the number and mass of charged particles encountered. Mios Mass spectrum analyzer (MSA) and the Mercury Ion Analyzer (MIA), which is part of the study Mercury plasma particle test (MPPE). The team also relied on Europlanet's Sun-Planet Interactions Digital Environment on Request (SPIDER) space weather modeling instrument to determine how atmospheric particles propagate through the magnetosphere.

As Hadith explained Publication of the Europlanet SocietyAnalysis of this data provides insight into the chemical and physical processes that eject the atmosphere from this region of the magnetosphere:

“This is the first time positively charged carbon ions have been ejected from the atmosphere of Silver. These are heavy ions that are generally slow moving, so we're still trying to understand the mechanisms at play. An electrostatic 'wind' lifts them away from the planet or they can be accelerated by centrifugal processes.

In particular, these findings will help scientists figure out what happened to Venus' surface water. Like Earth, much of Venus' surface was once covered by oceans, which disappeared about 700 million years ago. The most widely held theory is that this coincided with a massive rewarming event that flooded the atmosphere with carbon dioxide and led to the greenhouse effect. Over time, the solar wind stripped away the water, leaving behind an atmosphere 90 times denser than Earth's, and composed of carbon dioxide, along with small amounts of nitrogen and trace gases.

Two spacecraft that have previously visited Venus – NASA's Pioneer Venus Orbiter and ESAs Venus Express – Detailed studies of atmospheric loss were conducted. However, their orbital paths have left some regions unexplored, leaving many questions about the planet's atmospheric dynamics unanswered. Mo Persson, a researcher at the Swedish Institute of Space Physics and co-author of the study, said:

„Recent results suggest that escape from the Venusian atmosphere cannot fully explain the loss of its historical water content. This study is an important step in uncovering the truth about the historical evolution of the Venusian atmosphere, and future work will help fill in many gaps.”

Over the next decade, several spacecraft, including ESA, are destined for Venus Imagination Mission, NASA Venus Emissivity, Radio Science, INSAR, Topography and Spectroscopy (True) Orbiter and A study of deep atmosphere Venus noble gases, chemistry and imaging (DAVINCI) study, and of India Thanks Orbital Overall, these spacecraft will characterize the Venusian atmosphere, magnetosphere, atmosphere, surface, and interior. This research will lead to improved models that predict how once habitable planets can become hostile to life as we know it.

read more: Europlanet Society, Natural Astronomy