Impact of magnetotail plasma processes on the Venus atmospheric loss

How have planetary atmospheres evolved? Why do the present-day atmospheres of Venus and Earth so differ?

The Earth has oceans but Venus is arid containing only a tiny amount of water in its atmosphere, while these planets have evolved differently since their formation. As Venus presumably possessed an ocean four billion years ago, a lot of water must have disappeared. How did it happen, and where did the water go?

Many scientists believe that Venus’ water has been lost to space due to the lack of a dipole magnetic field. Our recent studies using spacecraft data revealed that this is not very accurate. Loss of water to space does occur but is not as significant as had been thought.

We identified a considerable return flow of ions in the Venus’ magnetotail, meaning that ions go back to Venus instead of out to space. This return flow decreased the net loss of atmospheric water to space. Our results imply that plasma processes in the magnetotail have actively protected Venus’ water from erosion.

However, it is still an open question which plasma process provides Venus-ward momentum for the magnetospheric ions. In this project, we investigate one candidate process: the magnetic reconnection.

We systematically survey correlations between magnetic-reconnection-related signatures and ion return flows using the Venus Express data.

We will answer the question “Can the magnetic reconnection process consistently explain the observed ion return flow signatures?”