I don't think it's atmospheric drag unless deployment took several days. On the graph the change in perigee doesn't start until several about 2-3 days after the

I don't think it's atmospheric drag unless deployment took several days. On the graph the change in perigee doesn't start until several about 2-3 days after the sail was deployed. [0] https://planetary.s3.amazonaws.com/assets/images/charts-diagrams/2019/20190731_apogeegraph-02_f840.png https://planetary.s3.amazonaws.com/assets/images/charts-diag...