Seven rings make no sense if we want to convey unity. Seven seas is a western oversimplification born in from an era of conquest. This cannot define earth.

The background cannot be blue (ocean) if the ambition lies in space exploration. The background can only be black or white to put earth in a cosmological context.

The symbol cannot be easily drawn from memory.

For me it can only be this one: https://up.kibakoapp.com/X8eIrGvYi4